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Techno-functional attribute and antioxidative capacity of edible insect protein preparations and hydrolysates thereof: Effect of multiple mode sonochemical action
Abstract
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.
... Li, Ma, Li, Zhang, & Dai, 2016) and pulsed electric field (Buchmann, Brändle, Haberkorn, Hiestand, & Mathys, 2019;Zhou, He, & Zhou, 2017). Among them, ultrasonication, a novel physical technology, is widely used to pretreat samples so as to reduce power consumption, shorten extraction time and improve protein extractability and functionality (Elhag et al., 2019;Hadiyanto & Adety, 2018;Mintah et al., 2019). reported that ultrasound action increased the extractability of protein from rice flour by 51.15% over conventional method (alkali extraction). ...
... 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. ...
... From Table 2, the solubility of untreated and sonicated SP was pH dependent. A reduction in solubility was noticed with increased pH 2-4 (linked to the isoelectric point), and then improved by increasing pH up to 10. Comparable outcome due to the impact of pH on solubility was also observed (Mintah et al., 2019). Sonication improved the solubility of SP (Table 2) reference to the traditionally treated protein (p < 0.05). ...
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.
... For example, Kingwascharapong et al. [35] reported a significant rise in the FRAP, ABTS, and DPPH values of LoPro pre-processed with ultrasound (10-30 min, 20 kHz, 750 W). Mintah et al. [36] reported a significant rise in the ABTS, FRAP, and superoxide scavenging activities of the hydrolysates prepared from ultrasonicated protein extracted from H. illucens (600 W, 40 kHz) and observed alterations in the microstructure, protein secondary structure, and the particle size. ...
... Both these technologies (Mic and Ult) have been reported to improve the antioxidant potential of InsecProHs and insect proteins. Processing with ultrasound (600 W, 40 kHz) significantly improved the antioxidative properties of InsecProHs and isolates [36]. Combining ultrasound (10-30 min, 750 W, 20 kHz) with the extraction process of protein from Bombay locusts yielded a product with the highest electron-donating ability and radical scavenging properties [35]. ...
Locust protein hydrolysates (LoProHs) pre-processed with microwave and ultrasonication were developed and evaluated for their potential for enhancing the quality of the stored meat emulsion (MEmul). Locust protein (LoPro) samples pre-processed with ultrasonication (Ult) or microwave (Mic) or with no treatment (Not) were hydrolysed with alcalase enzyme (3%). The microwave pre-processed (Mic-LoProHs) and ultrasonicated (Ult-LoProHs) hydrolysates showed significantly (P < 0.05) higher antioxidant [FRAP (ferric reducing antioxidant power) and ABTS and DPPH radical scavenging activities] and antimicrobial [minimum inhibitory concentration (MIC) and inhibitory halos (mm)] potential. The MEmul samples incorporated with Mic-LoProHs and Ult-LoProHs at the maximum level of 1.5% exhibited significantly (P < 0.05) improved results for all the quality parameters such as antioxidant potential (FRAP, ABTS and DPPH), protein oxidation (total carbonyl content), lipid stability, and microbial quality during refrigerated storage (4 ± 1 °C) of two-weeks compared to the control MEmul without any LoProHs. A positive (P < 0.05) impact of the LoProHs was found on the sensory quality of MEmul samples after one week of storage. The digestion simulation improved (P < 0.05) the antioxidant potential of the MEmul samples.
... Microwave processing was reported to increase the degree of hydrolysis of CP using alcalase enzyme in addition to increasing the release of bioactive peptides (Hall & Liceaga, 2020). Similarly, the ultrasonication process (40 kHz, 600 W) increased the antioxidant activity of the hydrolysates developed from insect protein (Hermetia illucens) and the highest values of 85.00%, 45.96%, and 1.49% were observed for ABTS, superoxide scavenging, and FRAP, respectively, compared to untreated samples (71.05%, 38.08%, and 1.29%, respectively) (Mintah et al., 2019). Kingwascharapong, Chaijan, and Karnjanapratum (2021) also reported a significant rise in the antioxidant properties (ABTS, DPPH, FRAP) of ultrasonicated (750 W, 20 kHz, 10-30 min) locust protein samples. ...
... The study suggested that microwave energy led to various conformational changes, protein bond re-orientation, and protein unfolding and enhanced the hydrolysis by facilitating access of proteolytic enzymes to hydrolytic sites. Mintah et al. (2019) evaluated the effect of the ultrasonication process (40 kHz, 600 W) on the antioxidant activity of IPH and preparations. The results showed that ultrasonicated isolates and hydrolysates exhibited the best techno-functional characteristics and strong antioxidant activity over a wider pH (2-12). ...
The study was carried out to investigate cricket protein hydrolysates' (CPH) potential to enhance the storage stability of cheddar cheese. The cricket protein (CP) samples pre-processed with microwave (T1), ultrasonication (T2) or without pre-treatment (T0) were used for developing the CPH using alcalase enzyme (3%). Freeze-dried CPH were incorporated in the cheese samples (CPH-T1, CPH-T2 and CPH-T0) at the maximum level of 1.5% and were analysed for quality during 3 months of storage (4 ± 1 °C) compared to the control samples without CPH. The pre-treatments significantly improved the antimicrobial and antioxidant potential of the CPH. The CPH exhibited a significant positive effect on antioxidant potential, lipid stability, protein oxidation, microbial growth, and sensory quality of the cheddar cheese during storage. Digestion simulation showed a significant positive impact on the antioxidant activity of the cheddar cheese. Our results indicate the potential of CPH to enhance the quality of fat-rich foods during storage.
... Hydrolysates and fermentates have been developed for the purpose of reducing some antinutritional factors of insect meals such as chitin [149], improving organoleptic properties, increasing shelf life [189,190], providing antioxidant properties [149,191,192], increased nutrient digestibility, production of antimicrobial substances, and health-promoting molecules [149]. Enzymatic hydrolysis using a variety of enzymes, such as alkalase, papain, peptidase, protease; and alcalase, papain, peptidase, protease; and biological hydrolysis using yeasts (Yarrowia lipolytica and Debaryomyces hansenii) have been studied to obtain peptides with bioactive properties and to improve protein digestibility, mainly. ...
... The functional properties of insect-based food ingredients, such as antioxidant capacity, antimicrobial activity, inhibition of platelet aggregation, enzymatic inhibition, and antidiabetic potential, have been less studied than their nutritional properties as food ingredients [208,209]. The literature shows that ingredients obtained from insects such as aqueous extracts [125], meals [191,210,211], and proteins and peptides [126,212,213], exhibit high antioxidant capacity, so they could have potential use in health disorders associated with oxidative stress [214]. The antioxidant capacity is due to the presence of phenolic compounds, proteins, peptides, chitin, fatty acids, and others [215,216]. ...
Insects have been proposed as an alternative source of nutrients to conventional foods, mainly protein sources because they have excellent nutritional quality and are sustainable. However, there are multiple barriers to mass consumption of insects, primarily the rejection and neophobia they provoke in individuals from Western cultures. Several studies have indicated that the acceptance of insects as food ingredients could be improved “if insects did not look like insects.” Therefore, the focus of current research is to transform commodity-type ingredients such as insect flour and oil through various technologies applied in the food industry such as protein concentration, encapsulation, hydrolysis, fermentation, deodorization, to develop food ingredients with better sensory and technological properties are better accepted by people as a part of their diet. Interestingly, some food ingredients obtained from insects also have functional properties that could increase interest in consumption. These aspects will be reviewed in this chapter for further consideration of insects as food ingredients of the future.
... 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]. ...
... was assessed ( Figure 1). All preparations exhibited a Ushaped Psolubility trend (especially the dried SP isolates) with the lowest (Psolubility) value at pH 4.0, consistent with data from other studies [1,12]. Additionally, all samples displayed maximal Psolubility under extreme alkaline (pH 10.0, 12.0) conditions. ...
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.
... Klompong et al. 46 commented that the configurations of protein, such as shape, size, and surface hydrophobicity, could govern the antioxidative activity, in which changes in protein configurations directly affect antioxidative function of peptides. UAP caused protein unfolding, consequently exposing hydrophobic regions, in which low molecular weight peptides could also be generated in some degree, depending on the severity of UAP condition used 7,8,13 . Our results support this effect on surface hydrophobicity and free α-amino group content (Table 2). ...
... Liu et al. 49 working with silkworm moth (Bombyx mori) reported that lower molecular weight peptides had higher antioxidative activity, and showed more amino acids exposure that could interact with free radicals. Mintah et al. 13 working with black soldier fly larvae (Hermetia illucens) found that the difference in ultrasound condition used determined the variations of antioxidative activity of the extracted protein. It was also reported that those variations were governed by amino acid compositions of the relative peptides 50 . ...
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.
... Insect proteins. Solubility has been reported for proteins obtained from different species, including Gryllodes sigillatus, Locusta migratoria L., Tenebrio molitor, Hermetia illucens, Acheta domesticus, Bombyx mori, and Schistocerca gregaria (Felix et al. 2020, Gravel & Doyen 2020, Kim et al. 2017, Mintah et al. 2019, Ndiritu et al. 2019, Stone et al. 2019. The solubility of the proteins in whole (nonfractionated) meals was low (<30%) at pH 3-9, which might be partly related to intensive downstream processing, such as sterilization and roasting (Hall et al. 2017, Ndiritu et al. 2019, Purschke et al. 2018a, Stone et al. 2019. ...
... Solubility was enhanced at higher pH values and higher ionic strengths (Kim et al. 2017). By extraction and fractionation, dissolution behavior was improved, but reported solubility of extracts from H. illucens and B. mori were still below 60% at pH 3-9, which is lower than many other protein sources (Felix et al. 2020, Mintah et al. 2019. In contrast, proteins extracted from T. molitor, Patanga succincta, Chondracris roseapbrunner, and L. migratoria had higher solubilities, especially in the slightly alkaline pH range where solubilities were greater than 90% (Bußler et al. 2016, Gravel & Doyen 2020, Purschke et al. 2018b, Zielińska et al. 2018). ...
Proteins obtained from alternative sources such as plants, microorganisms, and insects have attracted considerable interest in the formulation of new food products that have a lower environmental footprint and offer means to feed a growing world population. In contrast to many established proteins, and protein fractions for which a substantial amount of knowledge has accumulated over the years, much less information is available on these emerging proteins. This article reviews the current state of knowledge on alternative proteins and their sources, highlighting gaps that currently pose obstacles to their more widespread application in the food industry. The compositional, structural, and functional properties of alternative proteins from various sources, including plants, algae, fungi, and insects, are critically reviewed. In particular, we focus on the factors associated with the creation of protein-rich functional ingredients from alternative sources. The various protein fractions in these sources are described as well as their behavior under different environmental conditions (e.g., pH, ionic strength, and temperature). The extraction approaches available to produce functional protein ingredients from these alternative sources are introduced as well as challenges associated with designing large-scale commercial processes. The key technofunctional properties of alternative proteins, such as solubility, interfacial activity, emulsification, foaming, and gelation properties, are introduced. In particular, we focus on the formation of isotropic and anisotropic structures suitablefor creating meat and dairy product analogs using various structuring techniques. Finally, selected studies on consumer acceptance and sustainability of alternative protein products are considered.
... The antitumor activity of silkworm pupae protein hydrolysates was also investigated [268,269], although more evidence will be needed to validate these results. Techniques, such as ultrasound, have been applied to assist enzymatic hydrolysis and increase production of bioactive compounds [270]. One of the first and most frequently studied insect peptide hydrolysates was derived from the proteins of the species Bombyx mori. ...
The increasing size of the human population and the shortage of highly valuable proteinaceous ingredients has prompted the international community to scout for new, sustainable, and natural protein resources from invertebrates (e.g., insects) and underutilized legume crops, unexploited terrestrial and aquatic weeds, and fungi. Insect proteins are known for their nutritional value, being rich in proteins with a good balance of essential amino acids and being a valuable source of essential fatty acids and trace elements. Unconventional legume crops were found rich in nutritional, phytochemical, and therapeutic properties, showing excellent abilities to survive extreme environmental conditions. This review evaluates the recent state of underutilized legume crops, aquatic weeds, fungi, and insects intended as alternative protein sources, from ingredient production to their incorporation in food products, including their food formulations and the functional characteristics of alternative plant-based proteins and edible insect proteins as novel foods. Emphasis is also placed on safety issues due to the presence of anti-nutritional factors and allergenic proteins in insects and/or underutilized legumes. The functional and biological activities of protein hydrolysates from different protein sources are reviewed, along with bioactive peptides displaying antihypertensive, antioxidant, antidiabetic, and/or antimicrobial activity. Due to the healthy properties of these foods for the high abundance of bioactive peptides and phytochemicals, more consumers are expected to turn to vegetarianism or veganism in the future, and the increasing demand for such products will be a challenge for the future.
... clanis Bilineata tingtauica Mell (Wang et al., 2021), and H. illucens (Mintah et al., 2019) has different effects. For example, it modifies particle size, solubility, increases sulfhydryl content, increases surface hydrophobicity and rheological properties in proteins extracted due to its physical effects such as capillary surface waves and acoustic cavitation. ...
The most abundant Orthoptera in Mexico is a small grasshopper (Sphenarium purpurascens) which is considered a food source with increased nutritional value due to its high protein content. Insect proteins have gained relevance because of their high potential as gelling, texturing, and extender agents in the food industry. The objective of this study was to evaluate the effect of substituting meat with a soluble protein extract from grasshopper obtained by alkalisation or alkalisation-piezoelectric ultrasound, on the techno-functional, physicochemical, and sensory characteristics of cooked meat models (sausages). The soluble protein was extracted in NaHCO3 pH 8 and a piezoelectric ultrasound 5-mm sonotrode at 20 kHz with 99% amplitude. Different formulations with meat substitution: 0%, 5%, 10%, and 15% were prepared and characterised for their rheological behaviour, emulsion stability, weight loss by cooking, total protein content, colour, and texture. Sensory evaluation was conducted with consumers using a test involving check-all-that-apply and overall liking. The alkalisation-piezoelectric ultrasound method improved the solubility and the techno-functional properties of the soluble grasshopper protein when applied in sausages at maximum levels of 10% meat substitution. The sensory evaluation indicated that the formulation with 5% meat substitution exhibited the same acceptability as the control sample. Given these results, the soluble protein treated with alkalisation and piezoelectric ultrasound could be used as an extender in meat products.
... These effects result in the more effective exclusion of smaller particles while cleaning fruits and vegetables. Similarly, these cavitation benefits also help in removing microorganisms [5,[16][17][18], enzymolysis [19][20][21][22][23], protein modification [24][25][26][27][28]. Moreover, a large number of publications mainly focus on the application of ultrasound technology in food processing using lab-scale equipment. ...
Ultrasound as an eco-friendly green technology has been widely studied in food processing. Nevertheless, there is a lack of publications regarding the application of ultrasound in food processing using large-scale reactors. In this paper, the mechanisms and the devices of multi-frequency power ultrasound (MFPU) are described. Moreover, the MFPU applied in enzymolysis of protein, and washing of fruits and vegetables are reviewed. The application of MFPU can improve the enzymolysis of protein through modification on enzyme, modification on substrate materials, and facilitation of the enzymatic hydrolysis process. The ultrasound treatment can enhance the removal of microorganisms, and pesticides on the surface of fruits and vegetables. Furthermore, the reactors of ultrasound-assisted enzymolysis of protein, and washing of fruits and vegetables on the industrial scale are also detailed. This review paper also considers future trends, limitations, drawbacks, and developments of ultrasound application in enzymolysis and washing.
... 118 ultrasound-treated black soldier fly (Hermetia illucens) protein isolates and hydrolysates showed the highest antioxidant activity and exhibited excellent solubility and foam expansion capacity over a wide ph range compared with the untreated samples. 119 The high-intensity ultrasound treatment of sunflower protein isolates led to a significant increase in surface hydrophobicity, solubility, emulsifying capacity, emulsion stability, foaming capacity, foam stability, oil-binding capacity and sulfhydryl content, but a decrease in water-binding capacity and lysine content of the isolates. 114 The sonication of sunflower protein samples apparently resulted in molecular unfolding, thereby exposing previously buried hydrophobic groups and regions. ...
The structure of food proteins influences their function and hence their use in developing food products. Researchers have frequently employed enzymes to modify and study protein techno-functionality under different conditions and to enhance the biological functions or health-promoting properties of proteins. As more people continue to show interest not only in the nutritive aspect of food proteins but also in the sustainability of food processing and product development methods, there has been a growing effort by researchers and the food industry to provide food protein products that are consistent with the expectations of today's consumers. Not only is the use of green processing methods such as supercritical fluid extrusion, ohmic heating, pulsed electric field and high hydrostatic pressure on the increase, there is also heightened interest in innovative high-tech strategies for food delivery and controlled nutrient release such as micro- and nanoencapsulation. This chapter reviews the various sources of food proteins, including non-traditional sources such as algae and insects, the effects of various processing methods on food protein structure and functionality, novel delivery systems and technologies in food protein product development and the growing impact of consumers on product development, including the increasing consumption of and even preference for plant-based meat alternatives. It is concluded that although there are promising signs of increased use of sustainable processing methods and seemingly endless possibilities in the development of new food protein products, there are also challenges such as the microbiological and allergenic risks inherent in using members of the class Insecta for food.
... BSFLP-SF, and BSFLP-FF were prepared as done for BSFLP-T, only that the pretreatment (conditioning) was done using respective sonic modes (sweep, and fixed frequency) of a Multiple The BSFLP-SF conditions were 500 ms, 5.5 L, 600 W, and 40±2 kHz (sweep-cycle, in-bath water volume, power, and frequency respectively), with a pulse-on and off time of 15 s and 5 s accordingly [16]. The sonic conditions for the BSFLP-FF were the same as BSFLP-SF, except that the frequency (in this case) was just 40 kHz. ...
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.
... After sonication, the solubility of WPI increased, this probably because cavitational effects during ultrasonication. This finding was similitude with other reporting of increases in protein solubility after ultrasonication pretreatment [36][37][38]. ...
The instability of allicin makes it easily decomposed into various organic sulfur compounds, resulting in significant decrease in biological activity. In this study, allicin was firstly extracted with water, then bound with whey protein isolates (WPI) which were pretreated by ultrasound to form conjugates, and the stability, water solubility and emulsibility of conjugates were as well investigated. The research results showed that there were no significant differences in the extraction yields of allicin from water, 40% and 80% ethanol. Appropriate frequency (20/40 kHz), power (50 W/L) and time (20 min) of ultrasonic pretreatments significantly increased (P < 0.05) the sulfhydryl groups content of WPI by 35.05% over control, causing improvement in binding ability of protein to allicin. The binding process of allicin-WPI displayed good fit with Elovich kinetic model (R2=0.9781). The mass retention rate of the conjugates (in 60% combination rate) with ultrasonic pretreating kept at 95.97% after 14 days of storage at 25℃, whereas allicin’s mass retention rate was only 61.79% at same storage condition. The water solubility of the prepared conjugates was significantly higher than allicin. And with optimal condition ultrasonic pretreatment of WPI, the conjugates showed the highest emulsifying capacity and emulsion stability (49.56 m2/g, 10.06 min). In conclusion, the ultrasonically pretreated allicin-WPI conjugates exhibited better stability, water solubility and emulsifying properties compared to allicin, this expands the application field of allicin.
... Ultrasonication attracts great attention because of its moderate influence on protein and targeted processes for enhancing the safety and quality of treated food [14,15], with numerous benefits such as easy control, simple operation, short processing time and low consumed energy [16]. Earlier works have provided indication for the enhancement in enzymolysis [17], and functionalities [7,18] of protein following sonication. Additionally, sonication has been utilised to modify the physical and structural attributes [19] of proteins due to its cavitation action (shear-forces, microjets, shockwave, turbulence), which could induce partial unfolding of protein. ...
Impacts of localized enzymolysis and sonication on physical, techno-functional, and structure attributes of sunflower meal protein (SMP) and its hydrolysate (SMPH) were studied. SMP was subjected to enzymolysis (using alcalase) to prepare SMPH with various degrees of hydrolysis (6 – 24% DH). Enzymolysis decreased colour lightness, turbidity, and particle size of unsonicated and sonicated SMP, while it increased the absolute values of zeta potential (P < 0.05). Sonication improved oil absorption capacity and dispersibility over unsonicated samples. Contrarily, sonicated preparations showed a decrease in water holding capacity. Intrinsic fluorescence and FTIR spectral analyses suggested that SMPH had more movable/flexible secondary structures than SMP. Moreover, the changes in sulfhydryl clusters and disulfide linkages following sonication demonstrated limited unfolding of SMP and SMPH structure and decrease in intermolecular interactions. SDS-PAGE profile exhibited significant reduction in molecular weight (MW) of sonicated SMP, whereas did not display differences between unsonicated and sonicated SMPH. From further MW analysis, SMPH was categorized with high proportion of small-sized peptides ≤ 3 kDa fractions, which increased from 78.64 to 93.01% (control) and from 82.3 to 93.88% (sonication) with enzymolysis (6 – 24DH). Localized enzymolysis and sonication can be utilised to modify the physical and conformational attributes of SMP and SMPH, which could enhance their functionalities and broaden the utilisation area in food industry.
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