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Characterization of edible soldier fly protein and hydrolysate altered by multiple-frequency ultrasound: Structural, physical, and functional attributes
Abstract
The effect of conventional (control), and different ultrasonic treatment modes (fixed, and sweep frequency ultrasound) on structural, physical and functional traits of soldier fly (Hermetia illucens) larvae protein preparations and hydrolysates were examined. Ultrasonication significantly increased lightness (L*) of protein isolates by x¯ 7.46% compared to control. Sonic-treated (particularly sweep-type) isolates and hydrolysates showed significant increases in thiol value, reconstitutability function (pH 2-10), and surface charge; and significant decreases in turbidity, and particle size, relative to controls. Protein isolates were characterized by higher molecular weight ( MW ) using SDS-PAGE, whereas hydrolysates were lower (with no observable variances). By numerical estimation, hydrolysates (especially the sweep-treated) showed significantly lower MW (<1000 Da). Deconvoluted FTIR spectra (α-helix, β–sheet/turn, random coil fractions), and UV spectra analyses showed differences in samples. Treatment type (sweep/ fixed frequency ultrasound) could be used to alter protein structure, modify functionality, and thereby usage of H. illucens protein/hydrolysate preparations.
... Efforts to enhance the technofunctionalities of SP applying physical [9], chemical [10] and enzymatic approaches [11] are reported. Application of proteolysis (enzymolysis) is essentially considered a suitable and valuable approach for enhancing the functionality of native proteins and keeping their nutritive attributes by preparing peptides with high antioxidative action [12,13]. ...
... The turbidity (Ttur) of SP and SPH solutions (1.4 mg/mL in 0.05 M (pH 7.0) phosphate buffer) was assayed by determining the absorbance at an ambient temperature using a spectrophotometer at 600 nm. The absorbance was then utilized as a Ttur index [13]. ...
... This implied that enzymolysis caused a breakdown of SP molecules (as supported by the observations of Mweight analysis (Section 3.6), resulting in the release and/or formation of small-sized peptide(s). Similar outcomes due to freeze and convection oven drying [16,27], as well as enzymolysis [13] on Psizing were recorded (by other researchers). ...
The influence of freeze and convection (at 40 and 50 °C) drying on the physical, functional, and rheological attributes of sunflower protein (SP) and its hydrolysate (SPH) was investigated. Compared with convectively-dried samples, the lightness, turbidity, bulk density, and particle size values of the freeze-dried SP and SPH were substantially higher, but the browning index was lower (p < 0.05). Additionally, freeze-dried samples exhibited good solubility and foaming characteristics, whereas lower emulsion properties with the most pH values were observed. Furthermore, SPHs possessed higher solubility as well as foamability over SPs under varying pH values (2.0-10.0), whilst reduction in the emulsion activity index was clearly observed (p < 0.05). Convectively-dried powders exhibited greater viscosity and consistency coefficient; and significantly lower flow behavior index of dispersions, relative to the respective freeze-dried preparations, indicating that dehydration methods influenced the flow behavior of the investigated samples. From a molecular weight analysis, convectively-dried samples at various temperatures were characterized with high proportion of small-sized particles at ≤1 kDa fractions over the respective powders obtained by freeze drying. The observations made, thus, would benefit food processors and manufacturers in electing better dehydration technique based on the desired traits of SP and SPH powders for successful application in food product formulations.
... They reported that ultrasonication, especially probe sonication, considerably enhanced solubility, emulsifying capacity/ stability, foamability and foam stability, whereas water binding efficacy (WB e ) was reduced. Also, Mintah et al. (2020) found that sonication improved dispersibility, oil absorption efficacy and sulfhydryl groups of insect protein and its hydrolysates, whilst reduction in WB e , particle size, turbidity and surface charge were observed. ...
... Furthermore, native SP does not have desirable functionality (mainly solubility and oil holding efficacy) for food preparation , due to the denaturation of protein during oil extraction. The technique (ultrasonication) applied in treating SP impacts functionality and structural traits of other isolated proteins (Hu et al., 2013;Li et al., 2020;Mintah et al., 2019Mintah et al., , 2020. Nonetheless, the influences of sonication-aided extraction on functionality and structural attributes of SP have not yet been examined in depth. ...
... Oil holding efficiency (OH e ) of SP was quantified based on the protocol of Mintah et al. (2020). SP solutions (1 g/ 5 mL in sunflower oil) were vortexed for 5 min with a S0200-Vortex (Labnet Int. ...
Effect of mono and dual frequency (20, 28 and 20/28 kHz) ultrasound action on extraction kinetics, functional, and structural traits of sunflower protein (SP) was examined. A simplified model based on Fick's second law was developed, and the mass transfer of soluble SP in a heterogeneous system was successfully described. Findings suggested that ultrasound action significantly increased (p < 0.05) the release and diffusion of soluble SP across the cell wall into extraction solvent, causing enhanced observed rate constant (k) and diffusion-effective coefficient (Ds) values over control. Moreover, dual frequency sonication (20/28 kHz) considerably increased oil holding efficacy and surface charge (by 21.07 and 32.15%, respectively), but reduced water holding efficacy and particle size (by 40.74 and 26.61%, respectively) relative to untreated sample (p < 0.05). Also, ultrasonicated SP displayed excellent solubility under varying pH (2−10), likened to the control (p < 0.05). Scanning electron microscopy (SEM) and atomic force microscopy (AFM) outcomes indicated that ultrasonicated SP showed irregular fragments, heterogenous/ disordered structure and small-sized particles, suggesting that sonication (notably 20/28 kHz) destroyed the cross-linkages among SP molecules. FT-IR spectroscopy exhibited that ultrasonication improved the content of β-sheet from 8.52–18.94% and random coil from 11.63–21.71%, whereas reductions in α-helix and β-turn were noticed, implying limited unfolding of SP structure and decreases in intermolecular interactions. Intrinsic fluorescence analysis revealed that dual frequency treatment was observed to be more efficient in altering the tertiary structure of SP reference to single frequency and control.
Industrial relevance
Sunflower protein, isolated from sunflower residue, is a potentially low-cost resource for food applications. Ultrasonication is reported to improve the extraction of proteins as well as enhancing their functionalities. The existing study displayed that ultrasonication (observably dual frequency treated) was successfully applied to improve the extractability of soluble sunflower protein, and enhanced its functionality (solubility and OHe) reference to control. The research outcomes may benefit food/ chemical industries in extraction and/or alteration of sunflower protein in new applications.
... Extraction conditions, as well as solvent and insect species can strongly influence extraction yield and properties of the isolated proteins. Satisfactory protein yields have been obtained by using alkaline solutions (Laroche et al., 2019;Mintah et al., 2020;Mishyna et al., 2019;Zhao et al., 2016) since pH values between 10 and 12 have displayed to lead to higher insect protein solubility (Bußler et al., 2016b;Purschke et al., 2018b,c;Udomsil et al., 2019;Yi et al., 2017;Zhao et al., 2016). However, use of chemical solvents has shown negative effects on protein functionality, impacting several parameters such as emulsion capacity, foaming capacity and foaming stability (Ndiritu et al., 2017). ...
... However, lower extraction yields have been shown when aqueous solutions of ascorbic acid have been used (Amarender et al., 2020;Ndiritu et al., 2017;Yi et al., 2013). Improved results have been reached by using NaCl, as displayed on T. molitor (Yi et al., 2017), or increasing pH (Purschke et al., 2018b), temperature, solid/liquid ratio and/or extraction time (Bußler et al., 2016b;Mintah et al., 2020). Defatting can also increase the protein extract yields, as shown for several insect species (Amarender et al., 2020;Kim et al., 2019). ...
... US coupled with heat treatments (thermosonication) or high pressure (manosonication) has found application also in sterilisation and enzyme inactivation, allowing to obtain interesting results in terms of shelf-life extension, without altering the sensorial characteristics of the food (Cameron et al., 2009;Mintah et al., 2019b;O'Donnell et al., 2010). However, when US is not applied properly, it can be responsible for increase of temperature, with negative effects on nutritional and organoleptic characteristics (Farkas and Mohacsi-Farkas, 2011;Mintah et al., 2020). Despite these drawbacks, US is the mostly used novel technology in the food sector so far (Priyadarshini et al., 2019). ...
The processing of insects is paramount to deliver safe and high quality raw materials, ingredients and products for large-scale food and feed applications. Depending upon the nature of the initial material and the desired end product, the processing pathways vary and may include several unit operations currently already used in food and feed processing. Insect processing pathways can involve harvesting, pre-processing, decontamination, further processing, packaging and storage. Several traditional and industrial decontamination methods have been proposed for edible insects, which include smoking, drying, blanching/boiling, marination, cooking, steaming, toasting and their combinations. Further processing steps are employed to produce insect meal, insect flour or extracted insect fractions. Each operation will have a different impact on the chemical and microbiological properties of the final product. Novel food processing technologies (e.g. high pressure processing, pulsed electric field, ultrasound and cold plasma) have shown potential to modify, complement or replace the conventional processing steps in insect processing. These technologies have been tested for microbial decontamination, enzyme inactivation, drying and extraction. Further, these are considered to be environmentally friendly and may be implemented for versatile applications to improve the processing efficiency, safety and quality of insect based products. Future research focuses in insect processing are development of efficient, environmentally friendly and low-cost processes; waste minimisation and incorporation of by-products/co-products.
... [52] It has also been used as a pretreatment for the extraction of protein preparations and hydrolysates in Hermetia illucens. [53] Ultrasound is considered as a green extraction technology for its low use of solvents, energy efficiency and low cost. ...
... For that reason, insect flours are usually defatted to reduce their lipid content. [25,53,60,65,[82][83][84][85] Hexane or ethanol are the most common solvents used during the defatting step to reduce the fat content of the flours. [81,82] Insect flours are used for the formulation of food products [30,70,[86][87][88][89][90] or as a starting material for the production of protein concentrate or isolate. ...
... Mintah et al. [53] Tenebrio molitor Microwave drying 8, 10, 13, 16, 20 min at 2 kW Blanching for 40 s followed by microwave drying (8, 10 or 13 min) did not yield larvae with a water activity below 0.60, which is necessary to eliminate all microbial growth, but drying times of 16 or 20 min yielded average water activities of 0.16 and 0.23, respectively. ...
Edible insects and their ingredients are considered as a novel, sustainable and high-quality nutritional source for their potential use as food and feed. However, they are highly oxidizable and potentially unsafe. Dehydration of insects removes moisture and extends their shelf life. Moreover, it is considered as a prerequisite and/or pretreatment for some extraction technologies for ingredient production. Drying technologies (sun drying, smoke drying, roasting, freeze drying and oven drying) have been used to dry insects, both at a laboratory and industrial level. Different drying pretreatments (thermal blanching, microwave-assisted drying and pulsed electric field) have been explored to improve the final quality of the insect products, extending their shelf life and reducing total energy consumption. Therefore, this article aimed to review the current research available in edible insect drying processing technologies, addressing their effectiveness and their influence over different quality parameters such as protein/lipid extraction efficiency, sensory characteristics of the final products, microbiological safety, shelf life and their impact on bioactive compounds.
... This method is going to produce functional food with improved and upgraded functional properties and protein nutritional value. From perspectives of a food science and technology, attempts have developed protein hydrolysates from different insects including cricket, Gryllodes sigillatus (L.) [15]; migratory locusts, Locusta migratoria (L.) [16]; mealworm, Tenebrio molitor (L.) [17] and black soldier fly (BSF), Hermetia illucens (L.) [18,19,20,21,22,23,24,25]. For the antioxidant properties of black soldier fly (BSF) hydrolysates, there are reports through few attempts on the hydrolysis of black soldier fly (BSF) [19,21]. ...
... From perspectives of a food science and technology, attempts have developed protein hydrolysates from different insects including cricket, Gryllodes sigillatus (L.) [15]; migratory locusts, Locusta migratoria (L.) [16]; mealworm, Tenebrio molitor (L.) [17] and black soldier fly (BSF), Hermetia illucens (L.) [18,19,20,21,22,23,24,25]. For the antioxidant properties of black soldier fly (BSF) hydrolysates, there are reports through few attempts on the hydrolysis of black soldier fly (BSF) [19,21]. Caligiani,et al. [18] and Mintah [20], reported the method of chemical and enzymatic hydrolysis of BSF for extraction and characterization of different fractions for the antioxidant properties of black soldier fly (BSF). ...
Book Available online at: https://www.bhumipublishing.com/books/ PREFACE We are delighted to publish our book entitled "Advances in Animal Science Volume I". This book is the compilation of esteemed articles of acknowledged experts in the fields of basic and applied animal science. This book is published in the hopes of sharing the excitement found in the study of animal science. Animal science can help us unlock the mysteries of our universe, but beyond that, conquering it can be personally satisfying. We developed this digital book with the goal of helping people achieve that feeling of accomplishment. The articles in the book have been contributed by eminent scientists, academicians. Our special thanks and appreciation goes to experts and research workers whose contributions have enriched this book. We thank our publisher Bhumi Publishing, India for taking pains in bringing out the book. Finally, we will always remain a debtor to all our well-wishers for their blessings, without which this book would not have come into existence.
... Therefore, functional and antioxidant properties could be improved or modified for different food applications based on selective processing. Moreover, Mintah et al. [90] studied the structural attributes of the above-mentioned ultrasonically pretreated H. illucens protein isolates and hydrolysates and noted that the thiol value, dispersibility (pH 2-10), and surface charge of the isolate and hydrolysate treated by ultrasonic wave (especially sweep-type) were significantly increased, while the turbidity and the particle size of hydrolysate and protein isolate substantially decreased. At the same time, the secondary structural components were changed. ...
... Presently, there is growing interest in the preparation of isolated proteins and/or hydrolysate from insects as functional and natural additives in the industry to improve the nutritional quality and functionality of food products [90]. Moreover, the use of such in food formulations as an alternative protein source could increase consumer acceptability [108]. ...
Due to the recent increase in the human population and the associated shortage of protein resources, it is necessary to find new, sustainable, and natural protein resources from invertebrates (such as insects) and underutilized plants. In most cases, compared to plants (e.g., grains and legumes) and animals (e.g., fish, beef, chicken, lamb, and pork), insect proteins are high in quality in terms of their nutritional value, total protein content, and essential amino acid composition. This review evaluates the recent state of insects as an alternative protein source from production to application; more specifically, it introduces in detail the latest advances in the protein extraction process. As an alternative source of protein in food formulations, the functional characteristics of edible insect protein are comprehensively presented, and the risk of allergy associated with insect protein is also discussed. The biological activity of protein hydrolyzates from different species of insects (Bombyx mori, Hermetia illucens, Acheta domesticus, Tenebrio molitor) are also reviewed, and the hydrolysates (bioactive peptides) are found to have either antihypertensive, antioxidant, antidiabetic, and antimicrobial activity. Finally, the use of edible insect protein in various food applications is presented.
... From a food science and technology perspective, studies have developed protein hydrolysates from different insects including crickets (Gryllodes sigillatus) [12], migratory locusts (Locusta migratoria L.) [13], mealworms (Tenebrio molitor) [14] and black soldier flies (BSF) (H. illucens) [15][16][17][18]. Few studies have been conducted on BSF hydrolysis, including the antioxidant properties of BSF hydrolysates [16,18], and chemical and enzymatic hydrolysis of BSF for extraction and characterization of different fractions [15,17]. ...
... illucens) [15][16][17][18]. Few studies have been conducted on BSF hydrolysis, including the antioxidant properties of BSF hydrolysates [16,18], and chemical and enzymatic hydrolysis of BSF for extraction and characterization of different fractions [15,17]. BSF enzymatic hydrolysis, functional properties, antioxidant activity, nutritional value and protein structure have not been evaluated through a systematic approach. ...
The effects of chemical protein extraction, and enzymatic hydrolysis with Alcalase, papain and pepsin, on the functional properties, antioxidant activity, amino acid composition and protein structure of black soldier fly (H. illucens) larval protein were examined. Alcalase hydrolysates had the highest degree of hydrolysis (p 0.05). The emulsifying stability and foam capacity were significantly lower in protein hydrolysates than protein concentrate (p < 0.05). The antioxidant activity of protein hydrolysates from protein concentrate and Alcalase was higher than that with papain and pepsin (p < 0.05), owing to the higher hydrophobic amino acid content. Raman spectroscopy indicated structural changes in protein α-helices and β-sheets after enzymatic hydrolysis.
... Microwave drying takes less time to dry the insects as compare to other drying techniques (Mintah et al., 2020). The microwave-dried crickets showed increase in micronutrient content and reduction in microbial load (Bawa et al., 2020). ...
The growing global demand for meat and the limitations of agricultural land and resources have prompted the search for alternative protein sources. Edible insects can be used as a meat substitute because of their significant protein content, high food-to-feed conversion ratio, and mere greenhouse gas emissions. Entomophagy, or the eating of insects, has long been practised by numerous ethnic groups across the world. Approximately 2000 edible insect species are being consumed. Edible insects are only available during certain seasons; therefore, many processing procedures are used to preserve them for extended periods. Traditional processing processes include drying, roasting, and boiling, which aim at imparting local taste and flavour. Along with these traditional drying methods, a number of novel approaches have been developed to reduce nutrient loss while also extending shelf life. Insect-based foods are becoming progressively essential to improve nutritional content while also reducing environmental risk. Because eating whole edible insects has an adverse impact on public acceptance, adding insects as an ingredient has spurred considerable attention in recent years. Insect-enriched food products have numerous benefits as well as challenges. The inclusion of a small amount of insect flour contributes to the additional nutritional and health benefits, however, the inclusion of a higher amount of insect powder frequently modifies the traditional taste preferences of many products. A massive portion of the population still does not accept edible insects due to their distinct flavours and taste. Raising awareness about the benefits of entomophagy, as well as understanding the sensory qualities of insect-added food products will aid in developing a more palatable and acceptable product.
... Specifically, Qingke protein solubility increased by 12.24% following singlefrequency ultrasound treatment relative to the control. This result may be due to cavitation and/or physical effects (e.g., turbulence, instantaneous high pressure, and high shear force) caused by ultrasonic-induced non-covalent force destruction (e.g., hydrogen bonds, hydrophobic interactions) and induction of protein conformational changes [25]. Protein solubility increased by 35.37% and 43.54% relative to the control following dual-and tri-frequency ultrasound treatments, respectively. ...
There is a burgeoning demand for modified plant-based proteins with desirable physicochemical and functional properties. The cereal Qingke is a promising alternative protein source, but its use has been limited by its imperfect functional characteristics. To investigate the effect of ultrasound treatment on Qingke protein, we applied single- (40 kHz), dual- (28/40 kHz), and tri- (28/40/50 kHz) frequency ultrasound on the isolated protein and measured subsequent physicochemical and structural changes. The results showed that the physicochemical properties of proteins were modified following ultrasound treatment, and many of these changes significantly increased with increasing frequency. Compared with the native Qingke protein (control), the solubility, foaming activity, stability, and water or oil holding capacity of tri-frequency ultrasound modified Qingke protein increased by 43.54%, 20.83%, 20.51%, 28.9%, and 45.2%, respectively. Furthermore, ultrasound treatment altered the secondary and tertiary structures of the protein resulting in more exposed chromophoric groups and inner hydrophobic groups, as well as reduced β-sheets and increased random coils, relative to the control. Rheological and texture characterization indicated that the values of G' and G'', hardness, gumminess, and chewiness decreased after ultrasound treatment. This study could provide a theoretical basis for the application of multi-frequency ultrasonic technology for modification of Qingke protein to expand its potential use as an alternative protein source.
... The dispersibility was decreased in both the amplitude and sonication time for 30 min as seen in US3 and US6 samples. The possible reason was that prolonged sonication time during ultrasound treatment induces excessive protein unfolding and many hydrophobic groups, which promoted the hydrophobic interaction between the molecules, and the aggregation of proteins led to a decrease in dispersibility (Mintah et al., 2020). ...
The effect of ultrasonication treatment on the functional, structural, and microstructural properties of sunnhemp protein isolates (SHPIs) was investigated. The SHPI was extracted and modified ultrasonically (amplitude, 40 and 50%) at different time duration (10, 20, and 30 min). The results revealed improvement in functional attributes of all SHPIs samples after ultrasound treatment as compared to untreated sample. Among all the ultrasound-treated SHPIs, the maximum improvement in functional properties (solubility, emulsifying, foaming, water and oil binding) was observed in US5 (50% ultrasound amplitude for 20 min) sample. The findings of FTIR and fluorescence spectroscopy confirmed modification in the secondary and tertiary structures of SHPI. Circular dichroism results indicated alterations in the secondary structures of sunnhemp proteins. Particle size of all ultrasound treated samples were reduced and their disintegration was also observed by SEM analysis. Surface hydrophobicity was also improved in all ultrasound treated samples. Zeta potential values were found to be increased in all ultrasonically treated samples. SHPI showed enhancement in free and total sulfhydryl (SH) groups. Based on the findings of ultrasound-treatment, SHPI samples may serve as a substitute for animal proteins for a wide range of food applications.
Graphical Abstract
... The molecular weight distribution of SCPH was analyzed using SDS-PAGE method instead of gel filtration, considering the cost efficiency and practicality of the first method compared to the latter. Similar papers have also reported the use of SDS-PAGE to determine the distribution of protein hydrolysate of various sources, i.e. pea protein (Arteaga et al. 2020); lupin (Schlegel et al. 2019); soybean meal (Yang et al. 2020); insect (Mintah et al. 2020); chickpea (Xu et al. 2020); and beans (Saad et al. 2020). ...
The sea cucumber ethanol extracts (SCEEs) and protein hydrolysates (SCPHs) of Holothuria atra(HA), H. leucospilota(HL), and Bohadschia marmorata (BM) were prepared sequentially using 60% ethanol and Neutrase. The SCEE of HL contained phenolic acids (4.63 ± 0.50 µg GAE/mg extract) and was the most potent radical scavenger (91.76 ± 0.76%) at 10 mg/mL; whereas its SCPH contained hydrophobic amino acids (31.25 g/100 g) and inhibited glycation by 86.16 ± 5.92% at 5 mg/mL. Furthermore, the SCEE of HA inhibited tyrosinase by 49.93 ± 0.27% at 10 mg/mL, related to sulfated saponins (121.82 ± 3.52 µg xylose/mg extract). This study reports SCEEs as antityrosinase and SCPHs as antiglycation agents for the first time.
... Color is an important sensory parameter in the acceptability of food products [39]. The effect of USo on L*, a*, b* and ΔE of GSPI is presented in Table 3. ...
In this study, the influence of ultrasound on the physicochemical and functional properties of guamuchil seed protein isolate (GSPI) was investigated. The GSPI was prepared by alkaline extraction and isoelectric precipitation method followed by treating with ethanol (95%), from defatted guamuchil seed flour. GSPI suspensions (10%) were sonicated with a probe (20 kHz) at 3 power levels (200 W, 400 W, 600 W) for 15 and 30 min, in addition, to control treatment without ultrasound. Moisture content, water activity, bulk and compact densities and the L*, a* and b* color parameters of the GSPI decreased due to the ultrasound. Glutelin (61.1%) was the main protein fraction in GSPI. Results through Fourier transform infrared and fluorescence spectroscopy showed that ultrasound modified the secondary and tertiary protein structures of GSPI, which increased the surface hydrophobicity, molecular flexibility and in vitro digestibility of GSPI proteins by up to 114.8%, 57.3% and 12.5%, respectively. In addition, maximum reductions of 11.9% in particle size and 55.2% in turbidity of GSPI suspensions, as well as larger and more porous aggregates in GSPI lyophilized powders were observed by ultrasound impact. These structural and physicochemical changes had an improvement of up to 115.5% in solubility, 39.8% in oil absorption capacity, while the increases for emulsifying, foaming, gelling, flow and cohesion properties of GSPI were 87.4%, 74.2%, 40.0%, 44.4%, and 8.9%, respectively. The amelioration of the functional properties of GSPI by ultrasound could represent an alternative for its possible use as a food ingredient in industry.
... For example, Jiang et al. [26] and Yang et al. [33] reported increased β-sheet and decreased α-helix in black bean protein and rice protein, respectively. On the contrary, Hu et al. [34] reported no effects of US on soybean β-conglycinin and glycinin, while decreased β-sheet and increased α-helix induced by US treatment has been reported in edible fly protein [35]. These mixed results could be due to differences in the native protein and US conditions. ...
Pea protein is a promising alternative to animal-based protein and the interest in its application in food industry has been rapidly growing. In this study, pea protein isolates (PPI) were used to form protein-based edible films and the effect of ultrasound treatment on the structure of PPI and the structural, optical, mechanical and physicochemical properties of PPI-films were investigated. Ultrasound induced unfolding of PPI and exposed interior hydrophobic groups to protein surface while both PPI dissociation and formation of large aggregates were observed, as confirmed by measuring intrinsic emission fluorescence, surface hydrophobicity, surface charge, and particle size distribution and polydispersity index, respectively. FE-SEM showed that ultrasound decreased the cracks and protein aggregates at the surface of PPI-film. The film structure was also investigated by FTIR, which showed peak shift in amide I and II region and noticeable difference of protein secondary structure as affected by ultrasound. As a result of such structural changes caused by ultrasound, the properties of PPI-films were improved. Results showed that ultrasound greatly improved the film transparency, significantly increased film tensile strength but not elongation at break, and decreased moisture content and water vapor permeability of the film. This study provided structural data as evidence for utilizing ultrasound technique to develop PPI-films with improved optical, mechanical and water barrier properties.
... This indicated the increase of surface net charge due to the UAP used, especially at pH levels lower than 6 or higher than 8, compared with those from TP. This could favor dissolution/dissolution-related functional characteristics of proteins 6 . Similar results were also reported for milk and pea protein 44 , solder fly larvae 6 , frog skin gelatin 7 and fish skin collagen 9 . ...
Impact of ultrasound-assisted process (UAP) on yield, functional properties, antioxidant properties and molecular characteristics of protein extracted from Bombay locusts (BL) ( Patanga succinta L.) was studied. Different conditions of UAP were implemented for different amplitudes (40–60%) and times (10–30 min) during aqueous extraction. Notably, UAP could enhance yield and protein recovery, compared with those from typical process (TP) (continuously stirred at 100 rpm at room temperature for 1 h). UAP conditions used governed the change of surface hydrophobicity and free α-amino content of BL. UAP could improve solubility of BL, especially at pH levels higher than 2. UAP had no significant ( p > 0.05) detrimental effects on foaming capacity and stability of BL. Nevertheless, UAP, particularly at 50–60% amplitudes, affected the emulsion activity and stability of BL. UAP provided BL with high radical scavenging activities and good electron donating ability, especially that from 60% amplitude for 20 min (UAP-60/20). UAP-60/20 showed the impact on change of isoelectric point and molecular characteristic monitored by Fourier transform infrared (FTIR) of BL, compared to those from TP. In addition, BL was also an excellent source of both essential and nonessential amino acids. Therefore, UAP potentially enhanced BL extraction efficiency, resulting the BL with good functional and antioxidative properties.
... The ameliorative effect of full-fat HI larvae on PBM in the present study (aligned with our earlier studies and that of Kumar) could be due to the presence of functional molecules such as anti-microbial peptides, lauric acid, chitin, and novel polysaccharides such as choline, silkrose, and dipterose. In addition, the presence of low molecular weight peptides in HI larvae ranging mainly between 20 and 245 kDa may suggest a higher proportion of free amino acids, which are considered a fish attractant (Kanost, 2009;Kasumyan, 2016;Mintah et al., 2020;Rawski et al., 2020). These functional molecules may have been degraded by high temperature (Rawski et al., 2020) or other methods applied during the defatting of HI larvae. ...
Promoting a circular economy via the transformation of food waste into alternative and high-value protein sources for aquaculture diets is a novel approach to developing alternative raw materials to fishmeal (FM). This approach can reduce the ecological impact on the aquatic environment and simultaneously can provide an option for sustainable food waste management. In this context, we report a 56-day trial of feeding barramundi, Lates calcarifer on four iso‑nitrogenous and iso-lipidic diets where the control (0PBM-0HI) was a FM-based diet and the other test diets replaced FM protein with mixtures of a poultry by-product meal (PBM) and a full-fat Hermetia illucens (HI) larvae meal reared on fish waste: the test diets were 85% PBM + 15% HI (85PBM-15HI), 80% PBM + 20% HI (80PBM-20HI) and 75% PBM + 25% HI (75PBM-25HI). Fish fed PBM-HI-based diets showed an equal growth rate and amino acid profile when compared to the control group. Among all serum metabolites, alanine aminotransferase and glutamate dehydrogenase decreased in fish fed PBM-HI-based diets, whilst total protein levels improved in the same diets. Serum lysozyme and bactericidal activity were unchanged which supported the observation of similar infection rates against V. harveyi. Except for the kidney and intestine, catalase activity in the serum and liver increased in fish-fed PBM-HI-based diets. In assessing the gastrointestinal mucosal morphology, the goblet cells producing neutral mucins were higher in PBM-HI-fed fish than the control. PBM-HI diets also enhanced bacterial richness and diversity and increased abundance for Lactobacillus, Clostridium, and Ruminococcus. In summary, combining full-fat HI with PBM allowed complete replacement of FM with no negative effects on growth whilst improving gut health. Such diets would be beneficial for the aquaculture industry, both ecologically and economically, as well as providing value-adding to animal waste as alternative protein sources for aquafeed production.
... The growth improvement in fish fed 70PBM -30FHI over 70PBM -30DHI may be explained by the presence of AMPs and a high share of lauric acid in non-defatted HI larvae. HI larvae contain a high share of low molecular weight peptides, mainly between 20 and 245 kDa which are considered to act as a fish attractant (Mintah et al., 2020;Rawski et al., 2020), while lauric acid also plays a key role in stimulating immune response and stabilizing the microbiome of fish Lee et al., 2020;Terova et al., 2019). Complementary effects of FHI larvae in soybean and PBM-based diets have recently been reported in rainbow trout, Oncorhynchus mykiss (Kumar et al., 2020;Randazzo et al., 2021b), and barramundi (Chaklader et al., 2019;Chaklader et al., 2020b). ...
Poultry by-product meal (PBM) as a replacement for fish meal (FM), an expensive and unsustainable protein aquafeed ingredient, has been tested on different aquaculture fish species. However, the complete replacement of FM with a mixture of PBM and Hermetia illucens (HI) larvae in barramundi culture has not been previously investigated. In this study, results are presented on growth performance, fillet fatty acid composition, serum metabolites, skin mucosal barriers, hepatic steatosis, antioxidant activity, and immunity of juvenile barramundi, Lates calcarifer fed either a FM-based diet (0PBM-0HI) or two test diets in which total FM protein was replaced by a mixture of 70% PBM and 30% full-fat (FHI) and defatted HI larvae (DHI) meal (designated as 70PBM-30FHI and 70PBM-30DHI). After 56 days of feeding, the results showed that the growth was affected when fish were fed 70PBM-30DHI with a higher feed conversion ratio (FCR) with respect to 0PBM-0HI and 70PBM-30FHI diets. There was no variation in growth performance, feed utilization, and FCR between 0PBM-0HI and 70PBM-30FHI. The retention of total saturated and monounsaturated fatty acids increased in the fillet of juveniles fed 70PBM-30FHI and 70PBM-30DHI while total retention of polyunsaturated (PUFA), n-3 PUFA, and n-6 PUFA decreased than the control. Serum alanine transaminase (ALT) increased in fish fed 70PBM-30DHI whereas haptoglobin upsurged in 70PBM-30FHI compared to 0PBM-0HI. There were no significant effects in the serum immune response between dietary treatments whilst serum and liver CAT activity were negatively impacted by 70PBM-30DHI. The 70PBM-30DHI induced hepatic steatosis whilst 0PBM-0HI and 70PBM-30FHI showed no obvious change in the liver. Skin mucosal barriers were impacted by 70PBM-30DHI whilst 70PBM-30FHI fed fish showed a similar response to 0PBM-0HI. The fish fed on 70PBM-30DHI showed a higher proportion of infection rate with Vibrio harveyi than 70PBM-30FHI but showed no variation with the control-fed fish. In summary, FHI larvae meal could be a good complementary protein source, particularly when replacing FM completely with insect-based proteins.
... In the case of the closely related stellate sturgeon (Acipenser stellatus), it was shown that in the comparison of 19 ingredients that contained natural and artificial feed aromas, the most attractive in terms of smell and taste were Chironomidae insect larvae [53]. Insect haemolymph is known as rich in free amino acids, moreover, low molecular weight of Hermetia illucens proteins range mainly between 20 to 245 kDa, which may suggest the high share of low molecular weight peptides and free amino acids-which are considered as fish attractants in BSFL [56][57][58]. However, more experiments on insect-derived materials that are attractive for fish are required for future application to explain the role of insect protein, fat and chitin in feed acceptance. ...
This study provides data on the use of black soldier fly (Hermetia illucens) full-fat meal (BSFL) in Siberian sturgeon (Acipenser baerii) nutrition, examining pellet physical properties, growth performance, feed acceptance and utilization, apparent protein, and fat digestibility. The study consisted of: feed quality assessment; a growth performance; feed acceptance; digestibility trials. The effect of the use of BSFL as a replacement for fish meal (FM) and fish oil (FO) was investigated. The applied BSFL shares were 5%, 10%, 15%, 20%, 25%, and 30% of the diet, replacing up to 61.3% of FM and allowing us to reduce FO use by up to 95.4% in the case of 30% incorporation. The applied substitution affected feed quality, increasing the expansion rate, and decreasing feed density, sinking speed and water stability. However, body weight gain, specific growth rate, feed, and protein conversion ratios, were improved in groups fed BSFL. Moreover, feed acceptance was increased with treatments containing 10 to 30% BSFL. No effects on nutrients digestibility were observed. The results show that the use of BSFL as an FM and FO replacement may have positive effects on sturgeon growth performance, and BSFL can be developed as a promising alternative feed material.
Edible insects have emerged as promising protein sources with nutritional and functional advantages. There is a growing interest in implementing insect-based products as food ingredients in order to replace conventional animal-based foods and reduce their environmental footprint. Emerging technologies claim to improve protein technofunctionalities at the same time as they operate efficiently and sustainably. However, different processing parameters represent a relevant impact on product quality and extraction yielding. There is a lack of knowledge on how these processing conditions can be optimized to obtain an efficient and functional protein-enriched product. This review aims to shed light on the current studies involving insect products treated by alternative technologies such as high hydrostatic pressure, ultrasound, pulsed electric field and ohmic-heating, and how they have contributed to protein extraction and functionalization. The possible gaps for future research and the perspectives in this field are briefly discussed in the present work.
Oryctes rhinoceros larva has the potential to be developed into protein hydrolysates. In this study, O. rhinoceros larva was hydrolysed with crude papain protease extract at different concentrations (1, 2, and 3% w/w) and hydrolysis time (60, 120, 180 min). The objective of this study was to investigate the functional properties of protein hydrolysates from O. rhinoceros larva affected by different papain concentrations and hydrolysis time. Yield, protein concentration, and functional properties were measured and compared with whey protein. The result showed that the yield and protein concentration increased significantly (P<0.05) with increasing papain concentration. The water holding capacity varied between 1.66-4.23 g/g and OHC varied in the range of 2.61-5.24 g/g, higher than control (P<0.05). O. rhinoceros protein hydrolysate has good emulsifying activity and stability, ranging from 8.38 to 45.88 m ² /g and 12.09 to 30.87 min, respectively, while foam capacity ranged from 21.11% to 59.78% and foaming stability up to 25.11%. Generally, the functional properties of O. rhinoceros larva protein hydrolysate improved with the increase of the crude papain concentration and hydrolysis time. Several improved functional properties showed potential for developing O. rhinoceros larva protein hydrolysates as an alternative functional protein source in food ingredient formulation.
Insects have long been consumed by humans as a supplemental protein source, and interest in entomophagy has rapidly increased in recent years as a potential sustainable resource in the face of environmental challenges and global food shortages. However, food neophobia inhibits the widespread consumption of edible insects, despite their high nutritional and functional value. The own characteristics of edible insect protein such as foaming properties, emulsifying properties, gelling properties and essential amino acid ratio can be improved by drying, defatting, and extraction. Although nutritional value of some protein-enriched bread, pasta, and meat products, especially essential amino acid components was increased, replacement of conventional food with edible insects as a novel food source has been hindered owing to the poor cross-linking properties of edible insect protein. This deterioration in physicochemical properties may further limit the applicability of edible insects as food. Therefore, strategies must be developed to improve the quality of edible insect enriched food with physical, chemical, and biological methods. It was presented that an overview of the recent advancements in these approaches and highlight the challenges and prospects for this field. Applying these strategies to develop insect food in a more familiar form can help to make insect-enriched foods more appealing to consumers, facilitating their widespread consumption as a sustainable and nutritious protein source.
Enzymolysis kinetics, thermodynamics and molecular conformation of brewer’s spent grain protein (BSGP) pretreated with ultrasound were examined. Results showed that ultrasound pretreatment significantly reduced Michaelis constant (Km) and the thermodynamic parameters, including activation energy (Ea), enthalpy (ΔH), entropy (ΔS) and Gibbs free energy (ΔG) of BSGP during enzymolysis. Moreover, the initial reaction rate (Vi), association constant (Ka) and reaction rate constants (k) of BSGP pretreated with ultrasound were higher than those of native BSGP. The spectral analysis with Ultraviolet-visible (UV-Vis) and Fourier transform infrared (FTIR) manifested that ultrasound pretreatment exposed hydrophobic groups and induced molecular unfolding of BSGP. Particle size analysis and scanning electron microscopy (SEM) showed that ultrasound pretreatment decreased particle size while increasing flexibility of BSGP. All these structural changes resulted in the improvement on enzymolysis efficiency of BSGP pretreated with ultrasound. Therefore, ultrasound pretreatment could be an efficient method to enhance the enzymolysis sensibility of BSGP.
Insects represent a rich source of protein and a more sustainable alternative to conventional animal sources. Insect proteins are diverse in amino acid composition, structure, physicochemical and functional properties. Processing treatments cause changes in properties of insect proteins and protein-enriched fractions of varying purity, affecting their techno-functional properties and the possible application range. This review discusses recent findings on the effect of processing techniques on the techno-functionality of insect protein fractions including solubility, foaming, emulsifying, and gelling properties. It is demonstrated that a treatment type and its intensity alter physicochemical and functional properties to different degrees. The review also shows the potential for the production of insect-derived food ingredients with tailored functional properties using the diversity of available processing methods.
The aim of this study was to investigate the effects of simultaneous dual-frequency divergent ultrasound-assisted extraction (SDFUE) on the yield, structure, thermal and antioxidant activities of protein from Chlorella pyrenoidosa (CPP). Based on single factor experiments, the extraction conditions were optimized by response surface methodology (RSM). Under optimal conditions, ultrasonic power of 360 W, extraction temperature of 45 °C, 3% (w/v) alkali concentration and ultrasonic time of 20 min, the maximal extraction rate of CPP was 52.36 ± 0.31%, significantly higher than that of hot water extraction (HWE). In addition, the amino acid composition, the secondary and tertiary structure of CPP were significantly changed due to the unfolding of protein molecules and the exposure of hydrophobic groups. Moreover, the thermal property of CPP was more stable, the denaturation temperature and the heat required for denaturation were increased. Besides, the antioxidant properties of CPP (6 mg/mL) extracted by SDFUE showed that, the maximum 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity was 86.96 ± 0.33%, maximum 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging activity was 59.07 ± 0.31%, maximum Fe²⁺ chelating capacity was 34.37 ± 0.43%, and the maximum 2-Phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (PTIO) radical scavenging activity at pH 4.5 was 66.24 ± 0.98%, which were all improved obviously compared with that of HWE, PTIO trapping assay demonstrated that electron transfer (ET) was mainly involved in the antioxidant process of CPP. These findings revealed that ultrasound-assisted extraction not only increased the yield of CPP, but also enhanced its thermal and antioxidant properties, which was related to the changes of CPP structure. This work might break the traditional single-frequency ultrasonic extraction model and provide a reference for the utilization of ultrasonic extraction in the field of Chlorella pyrenoidosa as bioactive materials.
Ultrasonic-assisted enzymolysis is the application of ultrasound technology to enhance the process of enzymolysis. Traditional enzymolysis has been met with certain limitations which includes uneven stirring, decreased enzyme activity and protein accumulation as a result of minimal contact between the enzyme and substrate. Ultrasound assisted enzymolysis is based on the potential for cell molecule modification by ultrasound to improve bioavailability of nutrients while retaining the original quality, and the potential use of radical sonochemistry to achieve targeted hydroxylation of polyphenols and carotenoids. The cavitation effects and mechanical action of ultrasound can be advantageous during enzymolysis when applied appropriately. Ultrasound pretreatment of substrates can boost biological activity, alter protein structure, enhance protein conversion rate and accelerate enzyme hydrolysis. This review therefore, explored the principle of ultrasonic-assisted enzymolysis and its effects on protein extraction, biological activity and enzyme hydrolysis as reported by different researchers. Ultrasonic-assisted enzymolysis shows great potentials in enzyme hydrolysis and can be employed as a processing tool by the food and pharmaceutical industries.
This study sought to establish an optimized procedure for extraction of protein from microwave‐dried larvae of an edible insect, Hermetia illucens (HIL), and to determine and compare the amino acid (AA) component, intrinsic fluorescence (IF), and physicochemical/functional properties (PFPs) of protein isolates. Box–Behnken's design with the Box–Wilson methodology was applied in the optimization process. Following single‐factor investigations, the relational analysis indicated that the polynomial model could be used to illustrate the influence of extraction parameters on protein yield. Response–surface plots showed that extraction variables influenced (p < .05) protein yield of HIL. The optimized extraction (optimized protocol [OP]) conditions with highest yield (64.44%) were time—59.43 min, alkaline solution to sample ratio—24.85:1.00, and temperature—52.23°C. The protein extract obtained using the OP, compared with a modified protocol (MP) (with conditions: 60 min, 15:1 alkaline solution to sample ratio, and 40°C) showed content of 80.42 ± 0.90% and 76.91 ± 0.91%, respectively (p < .05). The AA‐scores were above that recommended by FAO. Variations existed between OP and MP extracts regarding PFPs, consistent with IF/AA‐values. The optimized extraction process was feasible, and the functional properties of HIL protein could be enhanced/modified for different food formulations.
Practical applications
Hermetia illucens (HIL), an edible insect rich in protein, is one most promising insect species for food applications with extra benefits to the environment. Consumption, however, is limited by many due to association of insects to vermin/dirt. The need to increase consumption globally is paramount, as there is high demand on the already scarce protein sources available worldwide. Extracting the constituents of edible insects for novel/food applications is a promising approach to upturn global consumption in the next 2–3 decades where humans may rely on insect protein. The success of scale‐up processing in this regard depends on process conditions for better yields. Therefore, determining an optimized technique for extraction of protein from HIL larvae was investigated as well as physicochemical/technofunctional properties, and fluorescence attribute. The extraction approach was feasible and the outcome of the study may benefit industry in extraction and/or modification of edible insect protein in novel applications.
We investigated the impact of sonochemical action and the reaction of Hermetia illucens larvae meal protein (HILMP) as regards enzymolysis under varied enzyme concentration and temperature to explain the mechanism and effect of sonication on molecular conformation, limits of kinetics, free‐Gibbs energy, and antioxidative capacity. Control treatment was used for comparison. The results showed sonochemical treatment enhanced HILMP‐enzymolysis efficiency at various enzyme volume, and temperature. Enzymolysis‐kinetics revealed sonochemical treatment increased the rate constant (p < .05) by 17.21%, 25.06%, 26.91%, and 41.38% at 323, 313, 303, and 293 K, respectively. On free‐Gibbs, sonochemical treatment reduced the reactants‐reactivity energy, enthalpy, and entropy by 30.53%, 35.05%, and 10.71%, respectively (p < .05). Changes in spectra of UV and fluorescence, and micrographic imaging indicated alterations of HILMP by sonochemical treatment. Antioxidative activity of sonochemically‐treated HILMP increased, compared to control. Thus, sonochemical treatment may be beneficial in the production of edible insect proteins with smaller molecular weights for different food and/or pharmaceutical applications.
Practical applications
Sonochemical pretreatment of HILMP positively impacted it enzymolysis rate‐reaction, stability of reaction products, structure, and bioactivity. Thus, the technique may be beneficial to industry in the processing/development of new (bioactive/pharmaceutical) products involving enzymolysis of edible insects (e.g., Hermetia illucens) protein; particularly at such a time where edible insects are projected to be a source of protein for human nutrition and livestock in the next few years.
Effect of ultrasound treatment on the physicochemical properties and structure of β‐lactoglobulin were investigated. β‐Lactoglobulin was treated with ultrasound at different amplitudes, temperatures, and durations. The surface hydrophobicity and free sulfhydryl group of β‐lactoglobulin were significantly increased after ultrasound treatment (p < .05). The maximal surface hydrophobicity and free sulfhydryl group were 5,812.08 and 5.97 μmol/g, respectively. Ultrasound treatment changed the physicochemical properties of β‐lactoglobulin including particle size (from 1.21 ± 0.05 nm to 1.66 ± 0.03 nm), absolute zeta potential (from 15.47 ± 1.60 mV to 27.63 ± 3.30 mV), and solubility (from 84.66% to 95.17%). Ultrasound treatment increased α‐helix and β‐sheet structures of β‐lactoglobulin. Intrinsic fluorescence intensity of ultrasound‐treated β‐lactoglobulin was increased with shift of λmax from 334 to 329 nm. UV absorption of β‐lactoglobulin was decreased with shift of λmax from 288 to 285 nm after ultrasound treatment. There were no significant changes in high‐performance liquid chromatography and protein electrophoretic patterns. These findings indicated that ultrasound treatment had high potential in modifying the physiochemical and structural properties of β‐lactoglobulin for industrial applications. Optimize the conditions of ultrasound treatment on physicochemical properties of β‐lactoglobulin using Box–Behnken design‐based response surface method. The effective method of preparation of β‐lactoglobulin was applied; the purity of β‐lactoglobulin isolated from raw cow milk was between 88% and 91%. Ultrasound treatment had a considerable impact on the physicochemical properties and structure of β‐lactoglobulin. Ultrasound treatment changed the structure of β‐lactoglobulin by altering α‐helix structures, β‐sheet structures, intrinsic fluorescence intensity, and UV absorption.
Effects of enzymatic hydrolysis on the physicochemical and functional properties of egg yolk were investigated in this study. Alcalase, neutrase and flavourzyme were used to hydrolyze egg yolk. Solubility, foaming properties, emulsifying and microstructure properties of egg yolk were determined after enzymatic hydrolysis. Results showed that alcalase had better efficiency of hydrolysis than neutrase and flavourzyme. Enzymatic hydrolysis caused a marked changes in protein solubility, surface hydrophobicity, molecular weight distributions, microstructure and other functional properties. It was observed that egg yolk and its hydrolysates exhibited a relatively smooth curve over the entire pH range; egg yolk hydrolysates with high DH had higher solubility than those having lower DH. Foam capacity and stability generally increased with increasing DH although foam stability showed a decrease at 15% DH. Hydrolysates of egg yolk showed scattered and fewer aggregated particles. This study demonstrated that egg yolk hydrolysates could be an excellent emulsifying agent for food and other applications.
Depending on the species, edible insects are highly nutritious and thus represent a noteworthy alternative food and feed source. The current work investigates the protein extractability and techno-functionality of insect flour fractions recovered from Tenebrio molitor and Hermetia illucens. T. molitor and H. illucens flours contained about 20% crude fat and 60% and 36 % crude protein, respectively. Defatting reduced the crude fat content to 2.8% (T. molitor) and 8.8% (H. illucens) and increased the crude protein content to 68% and 47%, respectively. To isolate proteins from the flours, protein solubility was optimized by varying the pH, the ionic strength, and the extraction temperature of the solvent. All products and by-products accumulated in the protein production process were characterized by composition, selected techno-functional properties, protein solubility, composition and structure as well as their microbial load.
A protocol for extraction of yellow mealworm larvae proteins was established, conditions were evaluated and the resulting protein extract was characterised. The freeze-dried yellow mealworm larvae contained around 33% fat, 51% crude protein and 43% true protein on a dry matter basis. The true protein content of the protein extract was about 75%, with an extraction rate of 70% under optimised extraction conditions using 0.25 M NaOH, a NaOH solution:ethanol defatted worm ratio of 15:1 mL/g, 40°C for 1 h and extraction twice. The protein extract was a good source of essential amino acids. The lowest protein solubility in distilled water solution was found between pH 4 and 5, and increased with either increasing or decreasing pH. Lower solubility was observed in 0.5 M NaCl solution compared with distilled water. The rheological tests indicated that temperature, sample concentration, addition of salt and enzyme, incubation time and pH alterations influenced the elastic modulus of yellow mealworm protein extract (YMPE). These results demonstrate that the functional properties of YMPE can be modified for different food applications.
Improving the quality and nutritional aspects of food is one of the key issues for healthy life of human beings. The stability during storage is an important parameter in quality assurance of food products. Various processing techniques such as high pressure, thermal, pulsed electric field and microwave have been used to prolong the shelf-life of food products. In recent years, ultrasound technology has been found to be a potential food processing technique. The passage of ultrasound in a liquid matrix generates mechanical agitation and other physical effects due to acoustic cavitation. Owing to its importance, a number of review articles and book chapters on the applications of ultrasound in food processing have been published in recent years. This article provides an overview of recent developments in ultrasonic processing of food and dairy systems with a particular focus on functionality of food and dairy ingredients. More specifically, the use of high frequency ultrasound in fat separation from milk and viscosity modification in starch systems and the use of low frequency ultrasound in generating nutritional food emulsions, viscosity modification and encapsulation of nutrients have been highlighted. The issues associated with the development of large scale ultrasonic food processing equipment have also been briefly discussed.
Arthropod development can be used to determine the time of colonization of human remains to infer a minimum postmortem interval. The black soldier fly, Hermetia illucens L. (Diptera. Stratiomyidae) is native to North America and is unique in that its larvae can consume a wide range of decomposing organic material, including carrion. Larvae development was observed on six resources: control poultry feed, liver, manure, kitchen waste, fruits and vegetables, and fish rendering. Larvae fed manure were shorter, weighed less, and took longer to develop. Kitchen waste produced longer and heavier larvae, whereas larvae fed fish had almost 100% mortality. Black soldier flies can colonize human remains, which in many instances can coincide with food and organic wastes. Therefore, it is necessary to understand black soldier fly development on different food resources other than carrion tissue to properly estimate their age when recovered from human remains.
Effects of high-intensity ultrasonication on functional and structural properties of aqueous bovine serum albumin (BSA) solutions were investigated. The functional properties of BSA were altered by ultrasonication. Surface activity of BSA increased. Minimal changes were observed in the global structure of BSA but surface charge increased particularly at basic pH values (e.g. pH > 9). While dynamic light scattering measurements indicated that the particle size increased up to 3.4 times after 90 min of sonication, no significant increase in the oligomeric state of BSA using blue native PAGE was observed. The amount of free sulfhydryl groups in BSA after 90 min of son-ication decreased. The increased particle size and decreased number of free sylfhydryl groups may be attributed to formation of protein aggregates. Surface hydrophobicity increased and circular dichroism spectroscopy and FTIR analysis indicated changes in the secondary structure of BSA. We hypothesize that mechanical, thermal and chemical effects of ultrasonication resulted in structural changes in BSA that altered the functional properties of the macromolecule which may be attributed to the formation of an ultrasonically induced state that differs from a thermally, mechanically or solvent induced state.
Aqueous solutions of reconstituted whey protein- concentrate (WPC) & isolate (WPI) powders were sonicated at 20 kHz in a batch process for 1–60 min. Sonication at 20 kHz increased the clarity of WPC solutions largely due to the reduction in the size of the suspended insoluble aggregates. The gel strength of these solutions when heated at 80°C for 20 min also increased with sonication, while gelation time and gel syneresis were reduced. These improvements in gel strength were observed across a range of initial pH values, suggesting that the mechanism for gel promotion is different from the well known effects of pH. Examining the microstructure of the whey protein gels indicated a compact network of densely packed whey protein aggregates arising from ultrasound treatment. Comparable changes were not observed with whey protein isolate solutions, which may reflect the absence of larger aggregates in the initial solution or differences in composition.
Hermetia illucens (edible insect) larvae protein, and hydrolysates were prepared using three pretreatment modes (conventional, fixed-frequency ultrasonic, and sweep-frequency). Protein subunit scores, microstructure, antioxidative activity, and techno-functional property of the respective isolates and hydrolysates were investigated. Alkaline protease hydrolysis significantly enhanced protein solubility, but impaired the emulsifying property and foaming stability. Isolates and hydrolysates treated by ultrasound exhibited highest antioxidative effect, and showed excellent solubility and foam expansion over wide (2–12) pH, likened the conventional. Ultrasonic, particularly sweep-frequency, treated hydrolysates overall showed superior solubility, foam, and antioxidative (ABTS, Superoxide scavenging, and Ferric-reducing) capacity than the remaining modes and isolates (p < 0.05). Treatment type influenced microstructure, functional attributes and antioxidative capacity of hydrolysates and isolates. Thus, functional/antioxidative property could be improved or modified for different food applications based on elected treatment. H. illucens isolate and hydrolysate preparations thereof could suitably be used in development of novel food formulations.
Functionalities, conformational characteristics and antioxidative capacities of sunflower meal protein isolate (SMPI) and its hydrolysates (SMPIH) at various degree of hydrolysis (DH) (6, 12, 18, 24%) were investigated following sonication. Enzymolysis notably enhanced the solubility, foaming properties and emulsion stability index (ESI) of untreated and sonicated SMPI at most examined pH. Nonetheless, emulsion activity index (EAI) of SMPI were more than SMPIH at all pH values, especially at pH 4.0–10.0 (P < 0.05). Compared with control, sonication improved solubility, foaming capacity and emulsification properties, but decreased foaming stability and had significant influence on the SMPI and SMPIH structure. Furthermore, sonication efficaciously enhanced reducing power and superoxide, and ABTS radical scavenging capacity of all preparations (P < 0.05) over control, confirmed by the analyses of hydrophobicities and content of amino acid compositions. Finally, our investigation suggests that sonicated SMPIH can create new opportunities for developing natural additives for different cosmetic, food and pharmacological preparations.
Hermetia illucens (edible insect) larvae protein, and hydrolysates were prepared using three pretreatment modes (conventional, fixed-frequency ultrasonic, and sweep-frequency). Protein subunit scores, microstructure, antioxidative activity, and techno-functional property of the respective isolates and hydrolysates were investigated. Alkaline protease hydrolysis significantly enhanced protein solubility, but impaired the emulsifying property and foaming stability. Isolates and hydrolysates treated by ultrasound exhibited highest antioxidative effect, and showed excellent solubility and foam expansion over wide (2-12) pH, likened the conventional. Ultrasonic, particularly sweep-frequency, treated hydrolysates overall showed superior solubility, foam, and antioxidative (ABTS, Superoxide scavenging, and Ferric-reducing) capacity than the remaining modes and isolates (p<0.05). Treatment type influenced microstructure, functional attributes and antioxidative capacity of hydrolysates and isolates. Thus, functional/antioxidative property could be improved or modified for different food applications based on elected treatment. H. illucens isolate and hydrolysate preparations thereof could suitably be used in development of novel food formulations.
The study investigated the effect of sonication conditions on antioxidant activity
of Hermetia illucens larvae meal protein hydrolysates. Three‐factor three‐level: pH
(7–9), time (10–30 min), and temperature (25–55°C) were optimized. Box–Behnken's
design was applied to optimize sonication treatment. Ferrous ion chelating activity
(ICA), DPPH‐radical scavenging activity (DPPHRSA), Hydroxyl radical scavenging ac‐
tivity (HRSA), and cupric ion chelating activity (CCA) were considered as responses.
Findings demonstrated that sonication preceding enzymolysis significantly impacted
on ICA, DPPHRSA, HRSA, and CCA. ANOVA showed the determination coefficient
(R2
) were 0.98 (ICA), 0.99 (DPPHRSA), 0.98 (HRSA), and 0.88 (CCA); demonstrating
that the models were reasonably fit with experimental results. Optimum sonication
conditions were pH (9), time (29.84 min), and temperature (54.93°C). For these con‐
ditions, the experimental data obtained [ICA (37.84%), DPPHRSA (43.19%), HRSA
(71.01%), and CCA (68.93%)] were consistent with predicted values, higher than con‐
trol, and supported by protein subunits, fluorescence spectra and microstructure.
Functionalities, conformational characteristics and antioxidative capacities of sunflower meal protein isolate (SMPI) and its hydrolysates (SMPIH) at various degree of hydrolysis (DH) (6, 12, 18, 24%) were investigated following sonication. Enzymolysis notably enhanced the solubility, foaming properties and emulsion stability index (ESI) of untreated and sonicated SMPI at most examined pH. Nonetheless, emulsion activity index (EAI) of SMPI were more than SMPIH at all pH values, especially at pH 4.0–10.0 (P < 0.05). Compared with control, sonication improved solubility, foaming capacity and emulsification properties, but decreased foaming stability and had significant influence on the SMPI and SMPIH structure. Furthermore, sonication efficaciously enhanced reducing power and superoxide, and ABTS radical scavenging capacity of all preparations (P < 0.05) over control, confirmed by the analyses of hydrophobicities and content of amino acid compositions. Finally, our investigation suggests that sonicated SMPIH can create new opportunities for developing natural additives for different cosmetic, food and pharmacological preparations.
The effect of gamma irradiation on physicochemical, antioxidant and functional properties of sunflower protein isolates was investigated. Protein isolates were irradiated at dose level of 0, 10 20, 30, 40 and 50 kGy. Protein solutions obtained from irradiated protein isolates were found more turbid and had higher particle size. Surface hydrophobicity was increased while sulfhydryl content was reduced indicating the conformational changes in protein isolates. Surface hydrophobicity was increased from 122.73 to 139.67 and free sulfhydryl content was decreased from 7.60 to 7.22 mmoL/g and total sulfhydryl content from 78.79 to 52.26 mmoL/g. Available lysine content decreased from 3.30 to 3.21 g/100 g. Lightness of protein isolates was reduced with increase in yellow-brown colour indicating the formation of Maillard reaction products. DPPH radical scavenging of protein isolates was increased from 5.79 to 19.46% and total antioxidant capacity was increased from 7.54 to 27.50%. Solubility, oil binding capacity, emulsion properties and foaming properties were improved, while water binding capacity was impaired. Gamma irradiation treatment can be used to change the conformation of proteins, which could improve their functionality and widen the application area in food systems.
This study examined the effect of dual‐frequency ultrasound (DFU) pretreatment on thermodynamics and kinetics of sunflower‐meal protein (SMP) using alcalase to improve efficiency in enzymolysis process. The concentration of hydrolyzed protein and kinetic parameters after traditional pretreatment (control) were investigated and compared with DFU‐assisted enzymolysis. The results indicated that DFU‐pretreatment enhanced SMP‐enzymolysis efficiency at different substrate and enzyme concentrations, temperature, and pH. Kinetics analysis showed DFU‐pretreatment reduced the Michaelis constant by 11.29%, while the apparent breakdown rate constant increased by 1.96%, indicating DFU‐pretreatment improved the affinity among substrate and enzyme. The rate constants for DFU‐pretreatment were increased by 45.96, 26.92, 21.14, and 27.89% at 293, 303, 313, and 323 K, respectively (p < .05). On Arrhenius kinetics, DFU reduced the activation energy, enthalpy and entropy by 24.28, 26.13, and 9.10%, respectively (p < .05). DFU had slight influence on Gibbs‐free energy when temperature increased from 293 to 323 K.
Practical applications
The positive impact of DFU pretreatment of sunflower meal protein on enzymatic hydrolysis kinetics makes this method suitable for use in the pharmaceutical and food process industries to yield peptides from residues of oil industry.
The arrowhead has attracted great research interest for their potential applications in pharmacy, food and biomedical areas. However, no information is reported about the nature and structure of the arrowhead protein (AP). Herein, effects of slit divergent ultrasound (28, 33, 40 KHz frequencies at 30-50 °C) and enzymatic (pepsin, trypsin, and alcalase) treatment on structure of AP were studied. In addition, changes in antioxidant activity of AP treated with ultrasound and enzymes were measured by chemical and cellular-based assays. The results showed that ultrasound treatment had considerable impact on the structure of AP and increased the susceptibility of AP to pepsin, trypsin and alcalase proteolysis. The changes in UV-Vis spectra, free sulfhydryl (SH) and disulfide bonds (SS) groups indicated that the structure of AP unfolded after ultrasound treatment. Besides, intrinsic fluorescence intensity of AP was increased by ultrasound treatment and then decreased after following enzymatic treatment. The circular dichroism (CD) analysis showed that ultrasound and enzymatic treatment decreased α-helix, β-turn of content of AP. However, the β-sheet and random coil content of AP increased. Interestingly, the AP after ultrasound and enzymatic treatment showed significant higher anti-oxidative activity in RAW 264.7 cells (p < 0.05) in comparison with control. In conclusion, the slit divergent ultrasonic provides a powerful endorsement for increasing the proteolysis of AP. Moreover, the improvement of the antioxidant activity of AP enzymatic hydrolysates provides a foundation of developing new type of plant-derived antioxidant peptides application.
This study investigated the functional properties of three species of edible insects: Gryllodes sigillatus, Schistocerca gregaria, and Tenebrio molitor. The water and oil holding capacity, solubility, and foaming and emulsion properties were evaluated. The protein solubility showed minimum values at pH 5. The highest water and oil holding capacity was noticeable for the T. molitor protein preparation (3.95 g/g) and for the G. sigilltus protein preparation (3.33 g/g), respectively. The G. sigillatus protein preparation also showed the highest foaming capacity, foam stability, and emulsion activity (99.0%, 92.0%, and 72.62%, respectively), while the protein preparation from S. gregaria exhibited the highest emulsion stability (51.31%). This study has shown that whole insects and protein preparations thereof can be suitable for development of new food formulations.
In this study, protein hydrolysate was prepared from the muscles of Chinese sturgeon (Acipenser sinensis). The effects of different conditions on the degree of hydrolysis (DH) by using papain were investigated. The DH of 24.89% was attained under the optimum conditions including solid-to-liquid mixing ratio of 1:1, enzyme-substrate ratio of 3%, pH 6, temperature of 70 °C, and incubation time of 6 h. The yield of protein hydrolysate was 17.47%, in which the protein content was 79.67% and amino acid content was 96.35%. The molecular weight of peptides decreased with the progress in hydrolysis time. Protein hydrolysate solubility ranged between 86.57% and 98.74%, emulsifying activity index was 11.0-13.27 m²/g, emulsion stability index was >94% at different pH levels, water holding capacity was 1.93 g water/g protein, oil holding capacity was 2.59 g oil/g protein, and foam capacity was 76.67%. The obtained fish protein hydrolysate contains improved functional properties and has potential applications in food industries.
An increasing use of vegetable protein is required to support the production of protein-rich foods which can replace animal proteins in the human diet. Amaranth, chia and quinoa seeds contain proteins which have biological and functional properties that provide nutritional benefits due to their reasonably well-balanced aminoacid content. This review analyses these vegetable proteins and focuses on recent research on protein classification and isolation as well as structural characterization by means of fluorescence spectroscopy, surface hydrophobicity and differential scanning calorimetry. Isolation procedures have a profound influence on the structural properties of the proteins and, therefore, on their in vitro digestibility. The present article provides a comprehensive overview of the properties and characterization of these proteins.
The influence of high intensity ultrasound (HIUS) on physicochemical and functional properties of sunflower protein isolates was investigated. Protein solutions (10% w/v) were treated with ultrasound probe (20 kHz) and ultrasound bath (40 kHz) for 5, 10, 20 and 30 min. Thermal stability of protein isolates was reduced as indicated by differential scanning calorimetry. Minimum thermal stability was observed at 20 min of sonication and increased further with increase in treatment time indicating aggregation at prolonged sonication. SDS-PAGE profile of proteins showed a significant reduction in molecular weight. Further, surface hydrophobicity and sulfhydryl content increased after HIUS treatment indicating partial unfolding of protein and reduction in the intermolecular interactions. The particle size analysis showed that HIUS treatment reduced the particle size. Less turbid solution were observed largely due to reduction in particle size. HIUS decreased the available lysine content in protein isolates. Solubility, emulsifying capacity, emulsion stability, foaming capacity, foam stability and oil binding capacity were improved significantly, while as, water binding capacity was decreased. The effect of HIUS on physicochemical and functional properties of sunflower protein isolates was more pronounced in probe sonication rather than bath sonication. Protein isolates with improved functional properties can be obtained using high intensity ultrasound technology.
Myosin from silver carp was sonicated with varying power output (100, 150, 200 and 250 W) for 3, 6, 9, and 12 min. The changes in the structure and physicochemical properties of myosin were evaluated by dynamic light scattering, SDS-PAGE and some physicochemical indexes. The ultrasound treatments induced a significant conversion of myosin aggregates to smaller ones with a more uniform distribution, and obvious enhancement in solubility. The structure of myosin was also notably changed by sonication, with a decrease in Ca²⁺-ATPase activity and SH content, and an increase in surface hydrophobicity. Furthermore, SH groups were oxidized, leading to a decrease in reactive SH and total SH contents. SDS-PAGE analysis revealed that ultrasound could induce the degradation of myosin heavy chain and change the protein fraction of myosin. Collectively, the ultrasonic treatment of 100 W for 3 min showed slight influence on the SH content, S0-ANS, and electrophoretic patterns, and the extent of changes in myosin structure and physicochemical properties tended to increase with ultrasonic power and time. The integrated data indicate that ultrasonic treatment can facilitate the improvement of the solubility and dispersion of myosin, but the choice of a suitable ultrasonic condition to avoid oxidation and degradation of myosin is very important.
This study evaluated the nutrient property and safety of the rice residue protein isolates (RRPI) product (extracted by different alkali concentrations) by exploring the protein functional, structural properties and lysinoalanine (LAL) formation. The results showed that with the rising of alkali concentration from 0.03 M to 0.15 M, the solubility, emulsifying and foaming properties of RRPI increased at first and then descended. When the alkali concentration was greater than 0.03 M, the RRPI surface hydrophobicity decreased and the content of thiol and disulfide bond, Lys and Cys significantly reduced. By the analysis of HPLC, the content of LAL rose up from 276.08 to 15,198.07 mg/kg and decreased to 1,340.98 mg/kg crude protein when the alkali concentration increased from 0.03 to 0.09 M and until to 0.15 M. These results indicated that RRPI alkaline extraction concentration above 0.03M may cause severe nutrient or safety problems of protein.
The high-volume/high-viscosity character of many commercially available weaning foods is a major constraint in providing children with enough calorie density. An attempt was made to formulate low-cost, nutritive but bulk-reduced, weaning foods using sorghum malt, green gram malt, and sesame flour. Sensory evaluation found the experimental preparations to have good acceptability. A weaning food containing 60% sorghum malt, 30% green gram malt, and 10% sesame flour was found to have satisfactory functional characteristics and nutritive value and is recommended. -from Authors
The objective of this review is to discuss the ultrasound-assisted extraction (UAE) of various compounds using clean, green solvents. We also outline fundamental mechanisms and factors associated with the design and the development of clean, green UAE systems. Growing consumer demands for greener alternatives and natural ingredients that do not involve toxic chemicals and the environmental and health risk associated with the use of chemical solvents have attracted the interest of industries to sustainable, non-toxic routes of extraction. UAE can benefit the chemical industry in multiple ways:
• enhancing extraction yield;
• enhancing aqueous extraction processes without using solvents;
• providing the opportunity to use alternative clean and/or green solvents by improving their extraction performance; and,
• enhancing extraction of heat-sensitive components under conditions that would otherwise have low or unacceptable yields.
In this study, our aim was to compare the effects of low-frequency (20 kHz) ultrasonication applied at various powers (150, 300, or 450W) and for different durations (12 or 24 min) on the functional and structural properties of black-bean protein isolate (BBPI) dispersions. In SDS-PAGE analysis, we detected no marked changes in protein electrophoretic patterns. However, secondary-structure analysis performed using circular dichroism indicated that all samples except Sample E (300W, 24 min) showed a decrease in the ox-helix proportion and an increase in beta-sheets content in the BBPI after ultrasonic treatment. Moreover, emission-fluorescence spectra revealed that the tertiary structure of black-bean proteins changed after ultrasonic treatment, and scanning electron microscopy of ultrasonicated BBPI samples showed that BBPI microstructure had changed and it contained larger aggregates when compared with the untreated BBPI sample. When medium-power ultrasonication was applied for 24 min, the particle size was minimized and the absolute zeta potential was maximized. Surface hydrophobicity and protein solubility of the BBPI dispersions were enhanced after ultrasonication, which increased the destruction of internal hydrophobic interactions of protein molecules and accelerated the molecular motion of proteins to cause protein aggregation. However, medium-power ultrasound treatment disrupted BBPI dispersions into small soluble protein aggregates by means of cavitation forces that induced increases in surface hydrophobicity and solubility. High-power ultrasound treatment caused a restructuring of BBPI aggregates, which led to an increase of particle size but a decrease in the absolute zeta potential.
Structural and functional properties of fish protein hydrolysates with different degrees of hydrolysis (DH) from surimi processing by-products, prepared by Protamex and Alcalase, were evaluated. As the DH increased, the zeta potentials of the hydrolysates increased (p>0.05). The surface hydrophobicity of the hydrolysates was significantly affected by DH (p<0.05). A wide variety of peptides were obtained after hydrolysis by Protamex and Alcalase. The hydrolysate with DH 10%, prepared by Protamex, contained more large protein molecules than did the others. Hydrolysis by both enzymes increased solubility to more than 65% over a wide pH range (pH 2-10). The interfacial activities of hydrolysates decreased with increasing DH (p<0.05). The hydrolysate with DH 10%, prepared by Protamex, exhibited the best interfacial properties among all of the samples. Thermal properties were also affected by the hydrolysis. The results reveal that structures and functionalities of the hydrolysates were determined both by DH and enzyme type employed.
Sunflower meal protein isolate (SMPI) is a promising food additive in different matrices. However, the uses of SMPI are limited because of the presence of antinutritional compounds like polyphenolic substances. Chlorogenic and caffeic acids are the dominants polyphenolics in the SMPI. These substances cause significant changes of the colour of the meal, proteins and food matrices during their extraction and use as food additives. Moreover, these substances lower the nutritional value of the end product due to their interaction with some amino acids such as lysine and methionine. Thus, the removal of these substances is important to enable the use of the SMPI and meal in general in a greater extent in food applications and replacing more expensive protein sources such as soy proteins. The aim of this work was to study the production of functional bread by supplementing wheat flour with sunflower meal protein isolate (SMPI). SMPI with low content of chlorogenic and caffeic acid was usefully produced following alkaline extraction and purification with succinic acid. Purified SMPI showed well balanced amino acid profile and was characterized by high water and fat absorption capacities. It was incorporated to dough formula at 8–12 % of the total wheat flour. The results showed that production of bread supplemented with SMPI was technologically feasible. The supplemented bread had high mass volume and nutritional quality compared to the control bread. The optimal SMPI to incorporate into dough formula without significant alteration of the final bread colour was established at 10 %. This study will be helpful to find economic ways to enhance the nutritional quality of wheat bread and to improve the profitability of sunflower meal residue.
The effects of low-frequency (20 kHz) ultrasonication at varying power (200, 400 or 600 W) and time (15 or 30 min) on functional and structural properties of reconstituted soy protein isolate (SPI) dispersions were examined. Ultrasonic treatments reduced both the storage modulus and loss modulus of SPI dispersions and formed more viscous SPI dispersions (fluid character). Moreover, ultrasound treatment significantly decreased the consistency coefficients and increased the flow behaviour index of SPI dispersions. Scanning electron microscopy of lyophilized ultrasonicated SPI showed different microstructure with larger aggregates compared to non-treated SPI. No significant change was observed in the protein electrophoretic patterns by SDS-PAGE. However, free sulfhydryl content, surface hydrophobicity and protein solubility of SPI dispersions were all increased with ultrasonic treatment. Differences in solubility profiles in the presence versus absence of denaturing (0.5% sodium dodecyl sulphate and 6 M urea) and reducing (mercaptoethanol) agents suggested a decrease in non-covalent interactions of SPI in dispersion after ultrasonic treatment. Secondary structure analysis by circular dichroism indicated lower α-helix and random coil in SPI treated at lower power, in contrast to higher α-helix and lower β-sheet in SPI treated with higher power (600 W). In conclusion, under the conditions investigated in this study, ultrasonic treatment resulted in partial unfolding and reduction of intermolecular interactions as demonstrated by increases in free sulfhydryl groups and surface hydrophobicity, leading to improved solubility and fluid character of SPI dispersions, while larger aggregates of ultrasonic-treated SPI in the dry state were formed after lyophilization.
In this paper, the effect of supercritical carbon dioxide (SC-CO2) treatment on the structure and conformation of whey protein isolate (WPI) were investigated. The WPI solution treated with SC-CO2 at 20MPa and 30–60°C for 1h showed that its turbidity and particle size were increased. The effect of SC-CO2 treatment at 60°C on the fluorescence intensity of WPI was elevated indicating partial denaturation of its fractions and exposure of more hydrophobic regions. The secondary structure change of SC-CO2 treated WPI revealed a decrease in the α-helix content, hydrogen bonds and an increase in the amount of β-sheet. A high shift of endothermic peak after SC-CO2 treatment was observed by the thermal analysis of WPI. These results confirmed that the structure and conformation of protein were modified with SC-CO2 treatment.
The use of high-intensity ultrasound for food processing applications is being constantly explored. Extraction of gingerol from ginger, homogenisation of milk and generation of high quality emulsions from food ingredients are some examples where ultrasonication has been found to be efficient, at least in laboratory-scale trials. These ultrasonic processes primarily rely upon the physical effects of ultrasound. However, the potential restrictions and/or uses of the chemical effects generated by ultrasound-induced cavitation phenomena have often been overlooked. Our investigation shows that unwanted reactions between ultrasonically generated radicals and food ingredients could be minimised by selecting lower ultrasonic frequencies for food processing. However, high frequency ultrasound could also be used for food processing, provided suitable radical scavengers are present in the solution. Preliminary results identified the potential of sonochemical hydroxylation of phenolic compounds as an efficient way of enhancing the antioxidant properties of certain food materials. Overall, these investigations have enabled the development of strategies for management of radical sonochemistry in food processing applications.
Soy protein ingredients must possess appropriate functional properties for food applications and consumer acceptability. these
are the intrinsic physicochemical characteristics which affect the behavior of protein in food systems during processing,
manufacturing, storage and preparation, e.g., sorption, solubility, gelation, surfactancy, ligand-binding, and film formation.
These properties reflect the composition and conformation of the proteins, their interactions with other food components,
and they are affected by processing treatments and the environment. Because functional properties are influenced by the composition,
structure and conformation of ingredient proteins, systematic elucidation of the physical properties of component protein
is expedient for understanding the mechanism of particular functional traints. The composition and properties of the major
components of soy proteins are summarized, and the functional properties of soy proteins of importance in current applications
(e.g., hydration, gelation, emulsifying, foaming and flavorbinding characteristics) are briefly reviewed.
Concentrations of “reactive” and total sulfhydryl groups and disulfide bonds were determined in raw and ultra-high-temperature sterilized skim milk and compared to values for conventional laboratory heat treatments with lower temperatures and longer times. The method of analysis, which represents a modification of previously reported methods, gave results agreeing with theoretical values calculated from the protein composition of milk. Analyses for total half-cystine, which included that protein deposited on the heating surfaces, indicated that 6 to 15% of this amino acid was lost during a heat treatment of 100 C for 30 min, presumably by volatilization. A smaller fraction was lost during ultra-high-temperature processing. Comparison of our data for direct heating with that previously reported for indirect heating suggests that less whey protein is “denatured” by the direct heating method. Studies of sterilized skim milk stored at refrigeration or room temperature suggested that the “reactive” sulfhydryl groups oxidized more rapidly and also that a larger fraction was oxidized during storage at room temperature. These concentrations of “reactive” sulfhydryl groups in sterilized milk have been correlated with undesirable “cooked” flavor and possibly could contribute to instability of milk protein through disulfide interchange reactions.
The seeds of two date palm (Phoenix dactylifera L.) cultivars, Deglet Nour and Allig, from the Degach region—Tunisia, were analysed for their main chemical composition. Studies were also conducted on properties of oil extracted from date pits. The following values (on a dry-weight basis) were obtained for Deglet Nour and Allig cultivars, respectively: protein 5.56 and 5.17%, oil 10.19 and 12.67%, Ash 1.15 and 1.12% and total carbohydrate 83.1 and 81.0%. Gas–liquid chromatography revealed that the major unsaturated fatty acid was oleic acid (41.3–47.7%), while the main saturated fatty acid was lauric acid (17.8%) for the Deglet Nour cultivar and palmitic acid for the Allig cultivar (15.0%). Capric, myristic, myristoleic, palmitoleic, stearic, linoleic and linolenic acids were also found. Thermal profiles of both date seed oils, determined by their DSC melting curves, revealed simple thermograms. Sensorial and physical profiles of Deglet Nour and Allig seed oil were based on studies of the CieLab (L∗, a∗, b∗) colour, oxidative stability, viscosity and microstructure. Results showed that date seed oil could be used in cosmetic, pharmaceutical and food products.
Protein hydrolysates from grass carp skin were obtained by enzymatic hydrolysis using Alcalase®. Hydrolysis was performed using the pH-stat method. The hydrolysis reaction was terminated by heating the mixture to 95 °C for 15 min. At 5.02%, 10.4%, and 14.9% degree of hydrolysis (DH), the hydrolysates were analyzed for functional properties. The protein hydrolysates had desirable essential amino acid profiles. Results demonstrated that the hydrolysates had better oil holding and emulsifying capacity at low DH. The water holding capacity increased with increased levels of hydrolysis. Enzymatic modification was responsible for the changes in protein functionality. These results suggest that grass carp fish skin hydrolysates could find potential use as functional food ingredients as emulsifiers and binder agents.
Antioxidative activity and functional properties of protein hydrolysates from yellow stripe trevally (Selaroides leptolepis) meat, hydrolyzed by Alcalase 2.4L (HA) and Flavourzyme 500L (HF) with different degrees of hydrolysis (DH) were investigated. As the DH increased, DPPH radical-scavenging activity and reducing power of HA decreased (p < 0.05) but no differences were observed for HF (p > 0.05). Metal chelating activity of both HA and HF increased with increasing DH (p < 0.05). HF generally had a higher (p < 0.05) chelating activity than had HA at the same DH tested. At low DH (5%), HA exhibited a better DPPH radical-scavenging activity while, at high DH (25%), HF had a higher (p < 0.05) reducing power. For the functional properties, hydrolysis by both enzymes increased protein solubility to above 85% over a wide pH range (2–12). When the DH increased, the interfacial activities (emulsion activity index, emulsion stability index, foaming capacity, foam stability) of hydrolysates decreased (p < 0.05), possibly caused by the shorter peptide chain length. At the same DH, the functionalities of protein hydrolysate depended on the enzyme used. The results reveal that antioxidative activity and functionalities of protein hydrolysates from yellow stripe trevally meat were determined by the DH and by the enzyme type employed.
The aim of this study was to examine the effect of ultrasound treatment on physical properties of soy proteins. For this purpose, soy protein isolates (SPI) and soy protein concentrate (SPC) were treated with ultrasound 20 kHz probe and ultrasound baths (40 and 500 kHz) system. In this study ultrasound treatment affected significant changes in texture of model systems prepared with soy protein concentrates, that gelled during ultrasound treatment with probe 20 and 40 kHz bath for 15 min. Model system prepared with SPI creamed during ultrasound treatment with probe 20 kHz for 15 min. Treatment with 20 kHz probe ultrasound lead to significant changes in conductivity, increased solubility for SPC, significantly increased specific surface area that is of interest in food texture and increased values of emulsion activity index. Weight mean diameter and volume–surface average diameter decreased significantly for all samples and all treatments. Flowing behaviour of SPI and SPC model systems has been greater influenced by ultrasound treatment. There was no improvement in foaming and emulsifying properties of soy protein model systems after 500 kHz bath treatment.
Proximate composition and physicochemical properties of a protein concentrate prepared from fenugreek seed were determined. The effects of pH and/or NaCl concentration on these properties were investigated. The protein content of fenugreek was found to be 28.4%. The crude fibre content was 9.3% and crude fat was 7.1%. The minimum protein solubility was observed at pH 4.5, which was 18.5%, while maximum protein solubility was observed at pH 11, which was 91.3%.Measurement of emulsion and foaming properties of fenugreek protein concentrate showed that they were greatly affected by pH levels and salt (NaCl) concentration. The minimum values of both emulsion and foam properties were attained at pH 4.5 which was the isoelectric point of the protein; maximum values were obtained at pH 2 and pH 12. Results showed that fenugreek protein concentrate had high oil absorption capacity (1.56 ml oil/g protein), water absorption capacity (1.68 ml H2O/g protein) and bulk density (0.66 g/ml).
Almond protein isolate (API) solutions were less viscous than those of soy protein isolate (SPI). The foaming capacity of API at pH 5.0 and 6.46 was comparable to that of SPI at pH 4.42 and 5.0. At pH 8.2, SPI had better foam capacity and stability compared to that of API. API had better oil absorption capacity than that of SPI [3.56 and 2.93 g/g dry weight basis (dwb), respectively]. Emulsion activity index (EAI) of API was significantly higher than that of SPI. API was easily hydrolyzed by pepsin in vitro.
In recent years, the physical and chemical effects of ultrasound in liquid and solid media have been extensively used in food processing applications. Harnessing the physical forces generated by ultrasound, in the absence and presence of cavitation, for specific food processing applications such as emulsification, filtration, tenderisation and functionality modification have been highlighted. While some applications, such as filtration and emulsification are "mature" industrial processes, other applications, such as functionality modification, are still in their early stages of development. However, various investigations discussed suggest that ultrasonic processing of food and dairy ingredients is a potential and viable technology that will be used by many food industries in the near future.
Acoustic cavitation, in simple terms, is the growth and collapse of preexisting microbubbles under the influence of an ultrasonic field in liquids. The cavitation bubbles can be characterized by the dynamics of oscillations and the maximum temperatures and pressures reached when they collapse. These aspects can be studied both experimentally and theoretically for a single bubble system. However, in a multibubble system, the formation of bubble streamers and clusters makes it difficult to characterize the cumulative properties of these bubbles. In this overview, some recently developed experimental procedures for the characterization of acoustic cavitation bubbles have been discussed.
Fourier transform ir (FTIR) spectra of 21 globular proteins have been obtained at 2 cm−1 resolution from 1600 to 1700 cm−1 in deuterium oxide solution. Fourier self-deconvolution was applied to all spectra, revealing that the amide I band of each protein except casein consists of six to nine components. The components are observed at 11 well-defined frequencies, although all proteins do not exhibit components at every characteristic frequency. The root mean square (RMS) deviation of 124 individual values from the 11 average characteristic frequencies is 1.9 cm−1. The observed components are assigned to helical segments, extended beta-segments, unordered segments, and turns. Segments with similar structures do not necessarily exhibit band components with identical frequencies. For instance, the lower frequency beta-structure band can vary within a range of approximately 15 cm−1. The relative areas of the individual components of the deconvolved spectra were determined by a Gauss–Newton, iterative curve-fitting procedure that assumed Gaussian band envelopes for the deconvolved components. The measured areas were used to estimate the percentage of helix and beta-structure for each of 21 globular proteins. The results are in good general agreement with values derived from x-ray data by Levitt and Greer. The RMS deviation between 22 values (alpha- and beta-content of 11 beta-rich proteins measured by both techniques) is 2.5 percentage points; the maximum absolute deviation is 4 percentage points.
Using an improved method of gel electrophoresis, many hitherto unknown
proteins have been found in bacteriophage T4 and some of these have been
identified with specific gene products. Four major components of the
head are cleaved during the process of assembly, apparently after the
precursor proteins have assembled into some large intermediate
structure.