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Influence of mealworms (Tenebrio molitor larvae) and their protein derivatives on the structural and rheological properties of tofu
Abstract
This study investigates the effects of incorporating mealworms into tofu, regarding its structural and rheological properties. Tofu samples were prepared using only soybean flour (S), or by replacing soybean flour with mealworms (M), mealworm protein isolate (MPI), or mealworm protein hydrolysate (MPH) at a 1:1 ratio (SM, SMPI, and SMPH, respectively). Results revealed that S partial substitution with M, MPI, and MPH affected the particle size, polydispersity index, and zeta potential of soymilk. Intrinsic fluorescence and surface hydrophobicity showed the early formation of large aggregates in SMPI. As for tofu, gelation of SM mainly occurred due to soybean protein-protein interactions, suggesting that M can prevent gelation, as evidenced by the SDS-PAGE and ATR-FTIR patterns. SMPI had the highest ionic bonds, hydrogen bonds, and hydrophobic interaction content, whereas S had the highest SS bond content. Furthermore, SMPH, enriched with small molecules, exhibited the highest proportion of random coil and disrupted amide bands, leading to limited protein-protein interactions. Finally, apparent viscosity of soymilk, temperature sweep during tofu preparation, frequency sweep, and microstructure analyses of tofu indicated that MPI contributed to hardness (927.9 g/cm2) and gel-like properties, while M and MPH led to softer (135.0 g/cm2 and 32.0 g/cm2, respectively) and more liquid-like tofu compared to S (504.3 g/cm2). In conclusion, this study provides insights into selecting mealworm derivatives with varying structural and rheological properties, enhancing their applicability in gel-type food systems.
... Notably, dried T. molitor is the first insect-based food approved by the European Union as a novel food resource (Gonzalez-de la Rosa et al. 2024). Current studies have reported the incorporation of T. molitor in various foods, including tofu, biscuits, and egg yolk-free mayonnaise-type products (Cozmuta et al. 2023;Gkinali et al. 2024;Oh and Kim 2024). However, consumer acceptance of edible insects remains low, limiting the widespread use of T. molitor in the market. ...
This study aimed to explore the influence of high hydrostatic pressure (HHP) treatment on the structure, functional characteristics, and bioactivities of Tenebrio molitor protein. The results showed that HHP induced dissociation of T. molitor protein, exposing hydrophobic groups and reducing particle size, which in turn reduced turbidity. Additionally, 600 MPa treatment significantly reduced the foaming stability and emulsifying activity of T. molitor protein. Treatments at 200 MPa and 400 MPa significantly reduced emulsion stability, whereas 400 MPa treatment significantly increased oil retention. HHP treatment also altered the secondary and tertiary structures of T. molitor protein, as demonstrated by circular dichroism and fluorescence spectra. Furthermore, HHP treatment significantly affected the antibacterial and antioxidant activities of T. molitor protein. This study provides a theoretical framework for using HHP to modify T. molitor protein.
This study aims to evaluate the inhibitory effects of mealworm (Tenebrio molitor larva) tofu on dexamethasone (DEX)-induced muscle atrophy. Tofu was prepared using mealworm powder (SM), protein isolate (SMPI), and hydrolysate (SMPH), and compared with soybean-only tofu (S). The effects of these tofu ethanolic extracts were assessed in vitro using C2C12 cells and in vivo using C57BL/6N mice fed a diet containing 15% tofu under DEX-induced muscle atrophy conditions. Treatment with SM and SMPH significantly increased the myotube diameter and decreased the expression levels of muscle degradation-related mRNA genes and proteins in C2C12 cells. In animal model, SM and SMPH improved grip strength (0.036 and 0.043 N/g body weight, respectively) and enlarged cross-sectional area (1,350 and 1,270 μm2, respectively) compared to the DEX-treated group on a normal diet (DEX CON: 0.031 N/g body weight and 1,140 μm2, respectively). SM and SMPH reduced levels of creatine phosphokinase (428 and 440 IU/L, respectively) and myoglobin (5.31 and 5.12 ng/mL, respectively) compared with those of DEX CON (821 IU/L and 8.37 ng/mL, respectively). Moreover, SM and SMPH suppressed mRNA and protein expression related to muscle degradation. These findings suggest that mealworms, particularly in the intact (SM) and protein hydrolysate (SMPH) forms, have considerable potential as alternative protein sources to replace soybeans in the diet, thereby preventing muscle atrophy and reducing protein breakdown.
Processing edible insects into protein extracts may improve consumer acceptability. However, a better understanding of the effects of food processing on the proteins is needed to facilitate their incorporation into food matrices. In this study, soluble proteins from Tenebrio molitor (10% w/v) were pressurized using high hydrostatic pressure (HHP) at 70–600 MPa for 5 min and compared to a non-pressurized control (0.1 MPa). Protein structural modifications were evaluated using turbidity measurement, particle-size distribution, intrinsic fluorescence, surface hydrophobicity, gel electrophoresis coupled with mass spectrometry, and transmission electron microscopy (TEM). The observed decrease in fluorescence intensity, shift in the maximum emission wavelength, and increase in surface hydrophobicity reflected the unfolding of mealworm proteins. The formation of large protein aggregates consisting mainly of hexamerin 2 and ⍺-amylase were confirmed by protein profiles on gel electrophoresis, dynamic light scattering, and TEM analysis. The typical aggregate shape and network observed by TEM after pressurization indicated the potential involvement of myosin and actin in aggregate formation, and these were detected by mass spectrometry. For the first time, the identification of mealworm proteins involved in protein aggregation phenomena under HHP was documented. This work is the first step in understanding the mealworm protein–protein interactions necessary for the development of innovative insect-based ingredients in food formulations.
The denaturation and lower solubility of commercial potato proteins generally limited their industrial application. Effects of high-intensity ultrasound (HIUS) (200, 400, and 600 W) and treatment time (10, 20, and 30 min) on the physicochemical and functional properties of insoluble potato protein isolates (ISPP) were investigated. The results revealed that HIUS treatment induced the unfolding and breakdown of macromolecular aggregates of ISPP, resulting in the exposure of hydrophobic and R-SH groups, and reduction of the particle size. These active groups contributed to the formation of a dense and uniform gel network of ISPP gel and insoluble potato proteins/egg white protein (ISPP/EWP) hybrid gel. Furthermore, the increase of solubility and surface hydrophobicity and the decrease of particle size improved the emulsifying property of ISPP. However, excessive HIUS treatment reduced the emulsification and gelling properties of the ISPP. It could be speculated that the formation of a stable secondary structure of ISPP initiated by cavitation and shearing effect might play a dominant role on gel strengthens and firmness. Meanwhile, the decrease in relative content of β-turn had a positive effect on the formation of small particle to improve emulsifying property of ISPP.
The consumption of insects (entomophagy) has recently attracted global attention for health reasons as well as environmental and economic benefits. Achieving environmentally sustainable food security is currently one of the biggest global challenges. A wide range of edible insect species, with their high contents in protein, fat, minerals, vitamins and fiber, can play a significant role in addressing food insecurity. Advantages of entomophagy include a high feed-conversion efficiency of insects and the rearing on organic side streams, adding value to waste and decreasing environmental contamination. Compared to cattle raising, insects emit relatively few greenhouse gases and little ammonia and require significantly less land and water. The nutritional quality of edible insects appears to be equivalent and sometimes superior to that of foods derived from birds and mammals. Insect farming may offer a sustainable means of food production. Since edible insects are calorie dense and highly nutritious, their consumption has the potential to reduce famine worldwide. The presence of high-quality protein and various micronutrients as well as potential environmental and economic benefits render edible insects globally a major potential future food. However, consumer acceptance remains a major obstacle to the adoption of insects as a food source in many Western countries.
Consumers’ dietary patterns have a significant impact on planetary and personal health. To address health and environmental challenges one of the many possible solutions is to substitute meat consumption with alternative protein sources.
This systematic review identifies 91 articles with a focus on the drivers of consumer acceptance of five alternative proteins: pulses, algae, insects, plant-based alternative proteins, and cultured meat. This review demonstrates that acceptance of the alternative proteins included here is relatively low (compared to that of meat); acceptance of insects is lowest, followed by acceptance of cultured meat. Pulses and plant-based alternative proteins have the highest acceptance level. In general, the following drivers of acceptance consistently show to be relevant for the acceptance of various alternative proteins: motives of taste and health, familiarity, attitudes, food neophobia, disgust, and social norms. However, there are also differences in relevance between individuals and alternative proteins. For example, for insects and other novel alternative proteins the drivers of familiarity and affective processes of food neophobia and disgust seem more relevant. As part of gaining full insight in relevant drivers of acceptance, the review also shows an overview of the intervention studies that were included in the 91 articles of the review, providing implications on how consumer acceptance can be increased. The focal areas of the intervention studies included here do not fully correspond with the current knowledge of drivers. To date, intervention studies have mainly focussed on conscious deliberations, whereas familiarity and affective factors have also been shown to be key drivers. The comprehensive overview of the most relevant factors for consumer acceptance of various categories of alternative proteins thus shows large consistencies across bodies of research. Variations can be found in the nuances showing different priorities of drivers for different proteins and different segments, showing the relevance of being context and person specific for future research.
This study focused on the effect of the heating process on the whole cotyledon soymilk and tofu. Whole cotyledon soymilk was made from soybean cotyledon and processed by enzymatic hydrolysis using cellulase and high-pressure homogeneity. In this study, a one-step heating method was selected for the cooking process of whole cotyledon soybean milk, and the whole cotyledon soybean milk was heated to 90 °C and held for 4 min. Results showed that the protein, total saccharides and dietary fiber content of the whole cotyledon soymilk were higher than those of the tradition soymilk due to the existence of bean dregs (okara). Both protein aggregation and protein–polysaccharide interaction were observed during the heating process. We also found a change in soymilk physicochemical characteristics such as particle size distribution, viscosity, surface hydrophobicity and soluble protein during the heating process. The results in this study showed that compared with traditional tofu, the phytic acid and trypsin inhibitor content in whole cotyledon tofu was lower, so its protein had higher digestibility in vitro. In conclusion, whole cotyledon tofu had better health properties and application prospects.
Background:
The relationships between dietary intake of soybean products and incident hypertension were still uncertain. This study aimed to illustrate the associations between intake of soybean products with risks of incident hypertension and longitudinal changes of blood pressure in a prospective cohort study.
Methods:
We included 67, 499 general Chinese adults from the Project of Prediction for Atherosclerosis Cardiovascular Disease Risk in China (China-PAR). Information about soybean products consumption was collected by standardized questionnaires, and study participants were categorized into the ideal (≥ 125 g/day) or non-ideal (< 125 g/day) group. Hazard ratios (HRs) and corresponding 95% confidence intervals (95% CIs) for incident hypertension were calculated using Cox proportional hazard models. Among participants with repeated measures of blood pressure, generalized linear models were used to examine the relationships between soybean products consumption and blood pressure changes.
Results:
During a median follow-up of 7.4 years, compared with participants who consumed < 125 g of soybean products per day, multivariable adjusted HR for those in the ideal group was 0.73 (0.67-0.80). This inverse association remained robust across most subgroups while significant interactions were tested between soybean products intake and age, sex, urbanization and geographic region (P values for interaction < 0.05). The mean systolic and diastolic blood pressure levels were 1.05 (0.71-1.39) mmHg and 0.44 (0.22-0.66) mmHg lower among participants in the ideal group than those in the non-ideal group.
Conclusions:
Our study showed that intake of soybean products might reduce the long-term blood pressure levels and hypertension incidence among Chinese population, which has important public health implications for primary prevention of hypertension.
Although the yellow mealworm (Tenebrio molitor L.) is a promising alternative protein source, the effects of processing conditions on functional properties are unclear. In this study, a protein extract of yellow mealworm larvae (PEYM) was subjected to different heat temperature (55°C, 75°C, and 95°C) with different time (20, 40, and 60 min) to evaluate the functional properties and protein oxidation. Different heat temperature treatment significantly affected the exposure of surface hydrophobicity of the proteins and protein molecule aggregation, which reached maximum levels at 95°C for 60 min. Protein oxidation was inversely proportional to the temperature. Both the highest carbonyl value (1.49 nmol/mg protein) and lowest thiol value (22.94 nmol/mg protein) were observed at 95°C for 60 min. The heating time-temperature interaction affected several functional properties, including solubility, emulsifying potential, and gel strength (GS). Solubility decreased near the isoelectric point (pH 5 to 6). As the temperature and heating time increased, emulsifying properties decreased and GS increased. The oil absorption capacity and foaming properties decreased and the water absorption capacity increased. These results confirmed that PEYM is a suitable source of proteins for processing and applications in the food industry.
The aim of this research was to study the application of MIR spectroscopy as an alternative to conventional methods to determine fat and protein content. Samples of the main species used to produce meat products were analyzed, showing all of them absorption bands at similar wavenumbers though with different intensity. Correlation analysis of absorption intensities showed that bands around 2925, 2854, and 1746 cm−1 are associated with fat content, whereas bands around 3288, 1657, and 1542 cm−1 are associated with proteins. During the validation process, prediction models of fat and protein content were successfully obtained with R2 0.9173 and 0.7534, respectively. Finally, a good result (R2 = 0.8829) was obtained on the estimation of the lipid content when the information at only one wavenumber was used.
To assess whether Fourier Transform Infrared (FTIR) spectroscopy could be used to evaluate and monitor lipid extraction processes, the extraction methods of Folch, Bligh and Lewis were used. Biomass of the oleaginous fungi Mucor circinelloides and Mortierella alpina were employed as lipid-rich material for the lipid extraction. The presence of lipids was determined by recording infrared spectra of all components in the lipid extraction procedure, such as the biomass before and after extraction, the water and extract phases. Infrared spectra revealed the incomplete extraction after all three extraction methods applied to M.circinelloides and it was shown that mechanical disruption using bead beating and HCl treatment were necessary to complete the extraction in this species. FTIR spectroscopy was used to identify components, such as polyphosphates, that may have negatively affected the extraction process and resulted in differences in extraction efficiency between M.circinelloides and M.alpina. Residual lipids could not be detected in the infrared spectra of M.alpina biomass after extraction using the Folch and Lewis methods, indicating their complete lipid extraction in this species. Bligh extraction underestimated the fatty acid content of both M.circinelloides and M.alpina biomass and an increase in the initial solvent-to-sample ratio (from 3:1 to 20:1) was needed to achieve complete extraction and a lipid-free IR spectrum. In accordance with previous studies, the gravimetric lipid yield was shown to overestimate the potential of the SCO producers and FAME quantification in GC-FID was found to be the best-suited method for lipid quantification. We conclude that FTIR spectroscopy can serve as a tool for evaluating the lipid extraction efficiency, in addition to identifying components that may affect lipid extraction processes.
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.
Pesticides are essential agrochemicals used to protect plants from diseases, pests and weeds. However, the formulation defects of conventional pesticides cause food toxicity and ecological environmental problems. In this study, a novel, efficient and environmentally friendly formulation of lambda-cyhalothrin, a solid nanodispersion, was successfully developed based on melt-emulsification and high-speed shearing methods. The solid nanodispersion presented excellent advantages over conventional pesticide formulations in such formulation functions as dispersibility, stability and bioavailability. The formulation is free of organic solvents, and the use of surfactant is reduced. Therefore, the application of the solid nanodispersion in crop production will improve efficacy and reduce the occurrence of both pesticide residues in food and environmental pollution from pesticides.
The use of soybean protein isolates (SPI) and corn starch (CS) for the manufacturing of textured protein by thermo-mechanical means requires a characterization of their thermal properties. SPI and CS mixtures were examined at starch mass fractions from 0 (pure SPI) to 100 (pure CS). The blends were determined by means of differential scanning calorimetry, with water content of 30, 50, and 70 % and heating rate of 5 and 10 °C min−1 over 20 to 130 °C. The results obtained showed that protein in the blend increased the onset (T
o) and peak (T
p) temperatures of the starch gelatinization, while starch in the blend decreased the ΔH and ΔT1/2 of the protein. T
o, T
p, and ΔT1/2 of SPI and CS decreased significantly with the increase of water content. T
p and ΔT1/2 of SPI and CS had a marked increase with an increase of heating rate from 5 to 10 °C min−1. These results suggested that there was no chemical reaction between SPI and CS when they were heated from 20 to 130 °C. SPI in the blend restricted the CS gelatinization, while the presence of CS protected the SPI from denaturation. The increasing water content did promote thermal transition of the mixture. Higher heating rate leads to higher transition temperature.
High intensity ultrasonic (HUS, 20kHz, 400W) pre-treatments of soybean protein isolate (SPI) improved the water holding capacity (WHC), gel strength and gel firmness (final elastic moduli) of glucono-δ-lactone induced SPI gels (GISG). Sonication time (0, 5, 20, and 40min) had a significant effect on the above three properties. 20min HUS-GISG had the highest WHC (95.53±0.25%), gel strength (60.90±2.87g) and gel firmness (96340Pa), compared with other samples. Moreover, SH groups and non-covalent interactions of GISG also changed after HUS pre-treatments. The HUS GISG had denser and more uniform microstructures than the untreated GISG. Rheological investments showed that the cooling step (reduce the temperature from 95 to 25°C at a speed of 2°C/min) was more important for the HUS GISG network formation while the heat preservation step (keep temperature at 95 for 20min) was more important for the untreated GISG. HUS reduced the particle size of SPI and Pearson correlation test showed that the particle size of SPI dispersions was negatively correlated with WHC, gel strength and gel firmness.
Textural properties, water-holding capacity, and color characteristics of alkali-extracted chicken dark meat have been studied. Alkali extraction was carried out at 4 different pH values (10.5, 11.0, 11.5, and 12.0). At higher pH of extraction, cooking loss and water loss were found to be significantly decreased (P < 0.05). The lightness (L* value) of the recovered samples treated at higher pH was found to be significantly lower (P < 0.05). Whiteness of uncooked samples also decreased significantly at higher extraction pH values. Protein samples extracted at higher pH values were found to be harder, and the maximum (4,956 g of force) value was shown by samples prepared at pH 11.5. Chewiness values were significantly increased (P < 0.05) for protein samples extracted at pH values of 11.5 and 12.0. Dynamic viscoelastic behavior of samples was assessed in the temperature range of 7 to 100 degrees C. The dynamic viscoelastic behavior of raw chicken dark meat as revealed by storage modulus indicated considerable gel-forming ability. The maximum storage modulus (G') value of 439 kPa was measured at 66.7 degrees C. Storage modulus was found to decrease for the recovered protein samples and be lowest at higher pH values. However, the recovered protein samples did show substantial gel-forming ability when stored with cryoprotectants. Tan delta values denoted 2 clear transitions for raw dark meat; however, only 1 major transition at 50.1 degrees C was evident for pH-treated samples, probably reflecting the loss of collagen in processing. In conclusion, this process of protein recovery may offer the possibility to use the underused poultry resources for preparation of functional foods.
This study evaluated the antioxidant and anti-inflammatory capacities of tofu fortified with mealworm (Tenebrio molitor larvae) proteins and their derivatives. The synergistic effects of plant- and animal-based proteins as well as the advantages of bioactive peptides were evaluated. Tofu was prepared by soy (S), by mixing in a 1:1 ratio of soy and mealworm powder (SM), soy and mealworm protein isolate (SMPI), and soy and mealworm protein hydrolysate (SMPH). SM, SMPI, and SMPH tofu had different proximate compositions, particularly in terms of their protein and lipid contents, compared to S. Mealworm derived tofus had a higher amount of essential, branched-chain, and total amino acids than S. The in vitro ileal digestibility of SMPH (94.10%) was significantly higher than that of S (58.35%), SM (64.64%), and SMPI (73.38%). Moreover, SM, SMPI, and SMPH had higher antioxidant and radical scavenging capacity and total phenolic content than S. Mealworm derived tofu had strong anti-inflammatory effects against lipopolysaccharide (LPS)-induced cytokines, such as tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-6. Conclusively, tofu developed from mealworm and its protein derivatives can potentially be used to fortify traditional tofu; SMPH, in particular, has the most significant potential among all tofu variations in terms of functionality and nutritional value, providing added health benefits.
Optimal heat treatment of the soymilks is important to the production of tofu. In this study, soymilk with protein concentration of 40 mg/mL were heated at different temperatures for the fixed 50 seconds and were characterized by surface hydrophobicity, disulfide linked protein species determined by non-reducing SDS-PAGE and protein structural elements determined by the circular dichroism (CD). Tofu gels were prepared by acidifying the heated soymilks at 60 ℃ and 80 ℃ respectively and gelation time, gel mechanical properties as well as gel viscoelastic properties were determined by rheological analysis. The results showed that most soymilks’ properties except surface hydrophobicity changed rapidly when heating temperature was higher than 80 ℃. Gelation time, storage modulus (G') at the end of acidifying and cooling processes as well as retardation time (λ) and recovery rate of tofu gels were affected by the heat treatments of soymilks. The distances between the standardized data describing heated soymilks and tofu gels respectively were calculated and compared. It was found that gelation time, G' and λ were most closely related to disulfide bond linked polymer, [CD]222 and surface hydrophobicity respectively. This study will provide useful information to the improvement of tofu processing.
Heat-induced plant protein gels commonly require high protein concentration and extensive heating. Modifying the structure of plant proteins may promote their gelation under milder conditions. In this study, Alcalase (EC No. 3.4.21.62) was used to quickly (3 min) hydrolyze pea proteins (PP), and the physicochemical properties and gelling capacity of the hydrolysates (PPH) were then investigated. PPH showed a degree of hydrolysis of more than 6.5%, and most of the peptides were smaller than 15 kDa. Their intrinsic fluorescence intensity and surface hydrophobicity were lower compared to those of PP, indicating increased water accessibility and polarity. Differential scanning calorimetry (DSC) showed the onset and denaturation temperature were higher in PPH than those in PP. But the former was unstable under heat (85°C) and aggregated to form gels at 5% protein concentration. The PPH gels showed an average G’ of ~170 Pa and ~15 Pa at pH7 and pH8, respectively. Their viscosities were ~30-80 times higher than those of the PP solution at low shear rate (<0.1 s-1) under the same heating conditions and pH. Addition of NaCl, urea, thiourea and dithiothreitol decreased the gel strength remarkably, suggesting electrostatic and hydrophobic interactions, and hydrogen and disulfide bonds contributed to the gelation. Confocal and electron microscopy showed that PPH-based gels either had a network composed of thread-like structure (pH7) or large coarse aggregates with irregular shape (pH8). The findings shed light on the gelation mechanisms of enzymatically modified pea proteins.
Proteins are essential on human nutrition and health, and it is crucial for the development of the human body. While animal protein is considered to be the primary dietary protein source for decades, there is a paradigm shift in recent years on the dietary consumption patterns among the general population towards plant-based food proteins. As a result, plant protein production in the food industry has skyrocketed. Research has led to a closer look at diverse plant sources and their capacity to replace conventional animal-based proteins for health and environmental reasons. Soy protein is a high-quality protein with a protein digestibility-corrected amino acid score (PDCAAS) of 1.00, which is close to some of the proteins from animal sources, such as meat and dairy. Soy proteins contain well-balanced essential amino acids except for sulfur-containing ones like methionine. They also have desirable textures with endless possibilities to formulate various sophisticated soy-based food products. Due to their high protein content and versatility in developing food products, soy proteins are the primary supply of plant-based proteins and are widely consumed by diverse populations worldwide. This review first briefly compared plant-based proteins as well as animal proteins regarding their health and environmental benefits, amino acid composition, and protein digestibility. As one of the most popular plant proteins, soy protein was introduced, and its byproducts-making processes (heat processing, protein isolation, and fermentation) were discussed in detail. Finally, the relationship between soy protein consumption and chronic diseases such as cardiovascular diseases, women menopausal symptoms, osteoporosis, cancer, and abdominal body fat, was highlighted by analyzing recent clinical studies.
Background
The very recently released EFSA's scientific opinion on the safety of dried (whole or ground) Tenebrio molitor larvae (yellow mealworm) considering their uses in various food products and the following approval by The Standing Committee on Plants, Animals, Food and Feed, brought T. molitor into the spotlight. This is EFSA's first opinion on edible insects as a novel food pursuant to Regulation (EU) 2015/2283.
Scope and approach
This review aims to summarize existing information regarding the features that may corroborate the sustainability and increase the acceptability of T. molitor larvae as food ingredient. Towards this end, aspects related to rearing and farming conditions, nutrient content and technological approaches for the recovery of protein and lipid fractions are addressed. Special emphasis was posed on their protein techno-functional properties and the development of new T. molitor larva-based food products.
Key findings and conclusions
The larvae of yellow mealworm are considered among the most promising alternatives to address the predicted deficiency of conventional food protein. Owing to their notable protein, lipid, vitamin, and mineral content, they could serve as future ingredients for industrial purposes (e.g. substitutes of traditional animal sources) bringing environmental and economic advantages. Several methods of T. molitor larvae protein extraction have been studied leading to different characteristics of the final protein preparations. Compared to conventional protein sources the protein fraction of T. molitor has not been much investigated with respect to its physicochemical and techno-functional properties, the knowledge of which is essential to allow their effective inclusion in food formulations.
In order to explore ways to improve the quality of the cold-set gel of soy protein, soy protein isolate (SPI) with different concentrations was preheated to produce soluble SPI aggregates (SSA), of which the gelation processes induced by glucono-δ-lactone (GDL) and gel properties were investigated in this study. The results showed that with the increasing SPI concentrations, the SSA showed increment in the particle size and quantity of net surface charge, accompanied with reduction in the surface hydrophobicity. During the acidification process, compared with the SSA generated from SPI of 20 mg/mL, the SSA produced from SPI of 60 mg/mL exhibited a slower intermolecular binding in the “pre-aggregation” stage, but was preferred to form beaded aggregates rather than irregular protein clusters, which led to earlier gelation onset and a more uniform gel network; the hardness, elasticity, water holding capacity and toughness of the resulting gel were also increased. Besides, with the rise of SPI concentrations for preparing SSA, the disulfide bond in the gel structure was strengthened. Therefore, adjusting the characteristics of SSA such as its charge states through controlling the preheating process could be utilized to regulate the properties of the acid-induced SPI gel, so as to help improve the quality of cold-set gel products of soy protein.
Background
Legume pulses are one of the most versatile and nutritious protein sources with bioactive dietary ingredients. Utilizing innovative nonthermal technologies in legume processing can considerably enhance the quality and digestibility of protein isolates (PIs) or concentrates (PCs) and respective protein hydrolysates (PHs). High pressure (HP), as an interesting alternative to traditional processing, provides legume-based protein supplements with superior bioavailability and health benefits in the food industry.
Scope and approach
This review discusses the effect of HP treatments at different pressure levels on the physicochemical, rheological, thermal, structural, functional, nutritional, and digestibility properties of PIs, PCs, and PHs prepared from legume crops (soy, pea, chickpea, beans, and lentil). It also presents promising strategies to improve the functionality and quality of these proteins.
Key findings and conclusions
The techno-functional (e.g., water holding capacity, gelation, foaming capacity and stability, emulsifying activity, and emulsion physicochemical stability) and bio-functional (e.g., in vitro antioxidant and digestibility) properties of legume-derived PIs or PCs were significantly improved as affected by HP treatment. Moreover, HP could greatly reduce the anti-nutritional factors and allergenicity of pulse protein products. HP-assisted enzymatic hydrolysis also led to a substantial reduction in the stability of protein secondary structures, enthalpy, and steady shear viscosity of legume proteins. The HP-assisted proteolytic process significantly improved the production of bioactive peptides with excellent antihypertension, antiradical, and antioxidant activities.
The potential of using insect proteins to encapsulate and protect hydrophobic nutraceuticals within biopolymer nano-complexes was examined. Insect proteins were used to form nanoparticles that were uncoated or coated with chitosan. Initially, the nature of the curcumin-mealworm protein interaction was investigated. Curcumin mainly interacted with the hydrophobic core of the insect protein nanoparticles through hydrophobic forces. About one curcumin molecule bound per protein molecule in both the absence and presence of chitosan. The binding constants (K) were 1.1 × 104 M-1 and 0.7 × 104 M-1 for curcumin loaded in the uncoated and coated nanoparticles, respectively. Differential scanning calorimetry showed increased thermal stability of the proteins after interaction with curcumin or chitosan. Encapsulation efficiency of the curcumin within the biopolymer nano-complexes was 30-47% depending on the system. Transmission electron microscopy and dynamic light scattering analysis showed that the biopolymer nano-complexes were spherical and relatively small (d = 143-178 nm). FTIR suggests that curcumin was stabilized more effectively in the coated nano-complexes, due to non-covalent intermolecular interactions. Curcumin release under oral, gastric, and intestinal conditions showed that over 90% of the nutraceutical was released after exposure to model gastrointestinal conditions. The findings demonstrate the potential of using insect proteins for fabricating colloidal delivery systems for water-insoluble nutraceuticals.
Over the past decade, the potential of edible insects as a novel ingredient in high value-added products has been investigated to find alternatives to conventional protein sources that are expensive, over-exploited and harmful to the environment. This review assesses the state of insects as an alternative protein source from production to consumption. More specifically, this review details the conventional procedures related to the production of insect flours as well as insect-derived ingredients such as protein concentrates and isolates. As a source of alternative protein in food ingredient formulations, the available data on the functionalities of edible insect ingredients is also examined and compared to conventional animal- and plant-based protein sources. Finally, the major challenges facing entomophagy in the mainstream food industry are explored. This review highlights the fact that insect proteins can serve as functional ingredients in food preparation. However, additional comparative studies are required to assess the functionality of various insect proteins compared to conventional proteins, regardless of processing method. To be incorporated into large scale industries, more research is needed to optimize processing methods to obtain the best compromise between cost-effectiveness, functionality, tastiness and sustainability, while ensuring consumer safety.
The emerging demand for protein with a reduced environmental impact is currently the biggest challenge in food production. From this perspective, the first aim was to assess differences between dough rheological properties and bread characteristics as a function of two factors: flour type (mealworm flour (Tenebrio molitor), cricket flour (Acheta domesticus), and chickpea flour (Cicer arietinum)) and percentage of substitution (5%, 10%, and 15%). The second aim was to investigate the extent of any improvement compared to the control (100% wheat flour). Crude protein, moisture, fat, ashes and carbohydrates were determined. Substitution with both insect and chickpea flours significantly affected dough rheological properties and bread characteristics. In particular, substitution with 15% cricket flour increased dough stability and reduced the degree of softening. However, substitution with chickpea flour at 5% proved optimal. Notably, dough stability improved and bread volume increased. The results confirm that cricket flour could be used to obtain bread enriched in protein. Moreover, substitution with 5% chickpea flour was optimal to improve breadmaking. A real step forward could be made in food production, by adopting this unusual mix of tradition (rediscovering legumes) and innovation (the use of insects), improving bakery products and reducing environmental impacts.
Microbial transglutaminase (MTGase) has been developed as a new tofu coagulant in recent years due to its good hydrophilicity, high catalytic activity, and strong thermal stability. This study aimed to investigate the effect of MTGase on the physicochemical properties and immunoreactivity of tofu relative to conventional coagulants [brine and glucono-δ-lactone (GDL)]. Structural changes of the MTGase cross-linked soymilk protein were characterized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), circular dichroism (CD) spectroscopy, ultraviolet (UV) absorption spectroscopy, and fluorescence spectroscopy. The IgE-binding capacity of MTGase cross-linked proteins was tested by enzyme-linked immunosorbent assay (ELISA). The physicochemical properties, quality characteristics, and surface microstructures of five different types of tofu were determined by the Kjeldahl nitrogen method, texture analysis, and scanning electron microscopy (SEM). The digestibility of tofu was evaluated in vitro by simulated gastrointestinal (GIS) digestion. A cell sensitization experiment was performed in vitro to evaluate the capability of tofu digestion products to induce the release of bioactive mediators from human basophil leukemia (KU812) cells. Results indicated that MTGase significantly changed the advanced structure of the soymilk protein. Compared with tofu without MTGase, the composite coagulant tofu containing MTGase exhibited better quality. MTGase improved the water-holding capacity (WHC) of the internal mesh structure and increased the yield of tofu. The digestion products of the composite coagulant tofu, especially the GDL plus MTGase tofu, induced KU812 cells to release fewer bioactive mediators compared with those of MTGase-free tofu. MTGase can not only improve the quality of conventional coagulant tofu but also reduce the potential allergenicity of tofu to a certain extent.
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.
Introducing okara to develop high-fiber tofu (HFT) can effectively increase the utilization of soy residues as well as enhance the nutrition of tofu. However, okara degrades the glucono-δ-lactone (GDL)-induced tofu quality. Current results showed that microbial transglutaminase (TGase) remarkably enhanced the gel strength, water holding capacity and viscoelasticity of HFT. During heating of soymilk, AB and A 1,2,4 subunits of 11S were more prone to aggregate via disulfide (SS) bonds to form larger soluble protein aggregates under neutral condition, while the SS-mediated insoluble aggregates were formed under acid condition by GDL and predominantly contributed to the structure of tofu without TGase. TGase-induced intermolecular ε-(γ-glutamyl) lysine strengthened protein network and contributed the most to HFT structure. TGase promoted formation of protein aggregates more orderly, and okara was well-wrapped by protein network. These results demonstrated that the macro-protein aggregates crosslinked by TGase conspicuously strengthened the gel network and significantly elevated the HFT quality.
The effects of partial enzymatic hydrolysis of soymilk on the characteristics of transglutaminase (TG)‐crosslinked tofu gel were studied. SDS‐PAGE showed that the molecular weight of the partially hydrolyzed soybean protein was reduced to that of a digested peptide (less than 43.0 kDa) when papain was added at more than 50 μL/100 mL soymilk. The content of free sulfhydryls, β‐sheets, and random coils in papain‐treated soymilk increased. When TG was added to soy milk after papain treatment and tofu gel was formed, its storage modulus increased from 957.44 to 1241.39 Pa. The gel strength, water‐holding capacity, and nonfreezing water content of the tofu gel were greater than those without enzyme treatment. Scanning electron microscopy revealed that limited papain hydrolysis stimulated TG‐catalyzed cross‐linking of soymilk to form a dense gel network structure, whereas an extended enzymatic hydrolysis of soymilk did not promote crosslinking by TG.
Practical Application
This work investigated the effect of partial hydrolysis on TG cross‐linked tofu gel. Partial hydrolysis of soybean protein with papain can promote TG cross‐linking reaction, thus form a dense network structure, increase gel strength, and water‐holding capacity. Therefore, it can be used to produce a good gel product with higher gel strength, springiness, water‐holding capacity, and a more dense microstructure.
The present study compared the texture, water holding capacity, and microstructure, as well as performed a particle and sensory evaluation, of soymilk-cow's milk gels induced by acidification of a commercial starter culture with the addition of glucono-δ-lactone (GDL). Texture analysis indicated that gels made with different amounts of GDL had diverse properties. The water holding capacity (WHC) results suggested that the gels had some WHC differences. In addition, the gels with less GDL did not form a network structure. The particle size distribution of the soymilk-cow's milk gels were approximately 3.5 μm. The sensory evaluation results were consistent with the texture properties and microstructure of the gels. This work clearly demonstrated that modulating the usage of GDL for casein and soy protein aggregation enabled the mixture of soy milk and cow's milk to obtain a new category of milk gel products.
Structured protein mixtures of plant and animal origin offer a pathway for the design of high protein food products with less ecological and economical footprint. This approach can also be used to adapt a nutritional requirement for specific consumers. The rheological properties, distribution and interaction of proteins, and structural characteristics of mixtures of soy protein isolate (SPI) and whey protein isolate (WPI) at different ratios with a total protein concentration of 6, 12 or 16% (w/v) were studied using small deformation rheology, sodium dodecyl sulfate-poly- acrylamide gel electrophoresis and confocal laser scanning microscopy. Upon heating to 95 °C, whey protein formed the primary structure of protein network in all of the SPI/WPI mixed systems. Reduction of WPI in the mixed protein systems led to weakening of the gel strength. SPI acted primarily as particulate fillers but the hydrophobic associations between SPI and WPI additionally contribute to the overall elastic property. The gel network structure itself, thus, was found to depend on the amount of SPI in the mixed protein system. Hence, altering the ratio of SPI and WPI could produce protein gels at the similar strength but with different microstructures and at various protein concentrations.
Due to a rising demand for proteins, food industry is considering new alternative protein sources that can be used for human food. The aim of this research was to explore the potential use of insects' flour as protein-rich ingredient for bakery products. Hermetia illucens, Acheta domestica and Tenebrio molitor were ground and used to replace 5% wheat flour in doughs and breads. The protein content of the insect flours ranged from 45% to 57% (d.m.) and fat content from 27% to 36% (d.m.). The inclusion of insects' flour affected the rheological properties (water absorption and stability), of dough during mixing, having less water adsorption. Breadmaking process could be carried out with all the composite flours. Breads containing A. domestica flour showed similar specific volume and texture parameters than wheat bread, but with higher content of proteins and fibers. Globally, results confirmed the usefulness of insects' flour for making breads with improved nutritional value.
Industrial relevance
This study evaluated the potential application of three different insects as protein source ingredients for bakery products. Results confirm that insects flour could be added to replace wheat flour in breads without significantly affecting dough properties and leading to breads with acceptable technological quality and improved nutritional profile.
The objective of this study was to determine the effects of adding pre-treated mealworm larvae (Tenebrio molitor) and silkworm pupae (Bombyx mori) flours on nutritional, physicochemical and textural properties of emulsion sausages. Whole freeze-dried insects were sequentially ground, defatted, and acid-hydrolyzed. Control sausage was formulated with 60% lean pork, 20% ice and 20% back fat, and insect treatments were prepared with replacement of 10% lean pork by each pre-treated insect flour. Defatting and/or acid hydrolysis significantly increased the protein content of two insect flours, but acid hydrolysis slightly decreased protein solubility (P = 0.002). The addition of pre-treated insect flours had no impact on protein solubility of emulsion sausages, but increased cooking yield and hardness in a similar extent, regardless of pre-treating methods and insect types (P > 0.05). Our results suggest that through separation processing, mealworm larvae and silkworm pupae can be further optimized as a novel protein ingredient for emulsified meat products.
In order to elucidate the heat-induced wheat gluten gel formation mechanism, changes in chemical interactions and protein conformation were investigated during gelation. The contribution of ionic and hydrogen bonds were found to decrease from 0.746 and 4.133 g/L to 0.397 and 2.733 g/L, respectively, as the temperature increased from 25 to 90 °C. Moreover, the free SH content remarkably decreased from 37.91 to 19.79 μmol/g during gelation. Ultraviolet absorption spectra and intrinsic fluorescence spectra suggested that wheat gluten unfolded during the heating process. In addition, wheat gluten gels treated at 80 and 90 °C exhibited a “steric hindrance” effect, which can be attributed to the formation of aggregates. Fourier transform infrared spectra suggested that the random coil content increased at low temperatures (40 and 50 °C), whereas the content of intermolecular β-sheets due to protein aggregation increased from 38.10% to 44.28% when the gelation temperature was 90 °C.
Proteins play a crucial role in determining texture and structure of many food products. Although some animal proteins (such as egg white) have excellent functional and organoleptic properties, unfortunately, they entail a higher production cost and environmental impact than plant proteins. It is rather unfortunate that plant protein functionality is often insufficient because of low solubility in aqueous media. Enzymatic hydrolysis strongly increases solubility of proteins and alters their functional properties. The latter is attributed to 3 major structural changes: a decrease in average molecular mass, a higher availability of hydrophobic regions, and the liberation of ionizable groups. We here review current knowledge on solubility, water- and fat-holding capacity, gelation, foaming, and emulsifying properties of plant protein hydrolysates and discuss how these properties are affected by controlled enzymatic hydrolysis. In many cases, research in this field has been limited to fairly simple set-ups where functionality has been assessed in model systems. To evolve toward a more widely applied industrial use of plant protein hydrolysates, a more thorough understanding of functional properties is required. The structure-function relationship of protein hydrolysates needs to be studied in depth. Finally, test model systems closer to real food processing conditions, and thus to real foods, would be helpful to evaluate whether plant protein hydrolysates could be a viable alternative for other functional protein sources.
We manufactured rice-whole soybean curd by a microbial transglutaminase (MTGase) with a mixture of hydrolyzed rice and micronized whole soybean powder (MWSP) and analyzed its rheological properties, including texture, viscoelasticity, protein cross-linking, and surface structure. A 40% rice suspension digested with a Termamyl enzyme at for 20 min showed a 9.0% reducing sugar and a consistency of , resulting in a great reduction in consistency. A MWSP suspension with 22% solid content was transformed into a typical tofu texture. MWSP curd fortified with 7.5% rice showed enhanced texture properties, with a hardness of 639.6 dyne/, and a springiness of 0.96. In a MWSP suspension (18~22% w/v) treated with 5% MTGase, viscoelasticity increased dependently with MWSP concentration, and a 22% MWSP indicated a G' value of 5.1 Pa and a G'' value of 9.0 Pa. Furthermore, soybean proteins present in the 22% MWSP curd largely disappeared or formed polymers with a high molecular weight by MTGase reaction within 30 min. MWSP (22%) fortified with 7.5% rice showed similar polymerization patterns on SDS-PAGE. The surface structure of the rice-MWSP curds was more dense and homogeneous network due to the addition of hydrolyzed rice. However, the surface structure of all rice-MWSP curds became rough and showed a non-homogeneous network after cold storage.
The contribution of phytate to the gelation properties of soymilk was studied by a phytase treatment to reduce the phytate in soymilk. The breaking stress of the gel prepared from the phytase-treated soymilk was higher than that from the untreated soymilk when glucono-delta-lactone (GDL) was used as a coagulant. As the phytate content of the soy protein isolate was decreased, so the breaking stress of the GDL-gel was increased as in the case of soymilk. This result indicates that the phytate in soy protein affects its coagulative reaction and hardness of the GDL-gel. An increase in viscosity and change in the zeta potential of soymilk resulted from the decomposition of phytate.
Alkali (pH(12)) and acid (pH(1.5)) pH-treated soy protein isolates (SPI) were incorporated (0.25-0.75% protein) into sols of myofibrillar protein (MP, 3%, in 0.6M NaCl at pH6.25) with or without 0.1% microbial transglutaminase (TG) to investigate the potential as meat processing ingredients. Static and dynamic rheological measurements showed significant enhancements of MP gelling ability by the inclusion of pH(1.5)-treated as well as preheated SPI (90°C, 3min). A 7-h incubation with TG accentuated the gel-strengthening effect by these SPI samples. The B subunit in 11S of SPI was the main component manifesting structure reinforcement in the mixed gels. The MP gelling properties were also greatly improved (P<0.05) by the addition of 10% canola oil emulsions stabilized by pH-treated SPI. The principal force in the MP gels incorporated with pH-treated SPI was hydrophobic patches; in the presence of TG, cross-linking of previously dissociated A and B subunits of 11S was also intimately involved.
The formation of coacervates between soybean protein isolate (SPI) and chitosan was investigated by turbidimetric analysis and coacervate yield determination as a function of pH, temperature, time, ionic strength, total biopolymer concentration (TB(conc)) and protein to polysaccharide ratio (R(SPI/Chitosan)). The interaction between SPI and chitosan yielded a sponge-like coacervate phase and the optimum conditions for their coacervation were pH 6.0-6.5, a temperature of 25 °C, and a R(SPI/Chitosan) ratio of four independently of TB(conc). NaCl inhibited the complexation between the two biopolymers. Fourier transform infrared spectroscopy (FTIR) revealed that the coacervates were formed through the electrostatic interaction between the carboxyl groups of SPI (-COO(-)) and the amine groups of chitosan (-NH(3)(+)), however hydrogen bonding was also involved in the coacervation. Differential scanning calorimetry (DSC) thermograms indicated raised denaturation temperature and network thermal stability of SPI in the coacervates due to SPI-chitosan interactions. Scanning electron microscopy (SEM) micrographs revealed that the coacervates had a porous network structure interspaced by heterogeneously sized vacuoles.
The serum total cholesterol concentration was significantly lower in the kori-tofu feeding group than in the soy protein isolate (SPI) group, except on the 28th day of the experiment. The high-molecular-weight fraction (HMF) content of the kori-tofu protein was significantly higher than that of SPI. This difference in the HMF content may have influenced the cholesterol-lowering effect of the protein.
Soy protein isolate (SPI) was modified by ultrasound pretreatment (200 W, 400 W, 600 W) and controlled papain hydrolysis, and the emulsifying properties of SPIH (SPI hydrolysates) and USPIH (ultrasound pretreated SPIH) were investigated. Analysis of mean droplet sizes and creaming indices of emulsions formed by SPIH and USPIH showed that some USPIH had markedly improved emulsifying capability and emulsion stabilization against creaming during quiescent storage. Compared with control SPI and SPIH-0.58% degree of hydrolysis (DH), USPIH-400W-1.25% (USPIH pretreated under 400W sonication and hydrolyzed to 1.25% DH) was capable of forming a stable fine emulsion (d43=1.79 μm) at a lower concentration (3.0% w/v). A variety of physicochemical and interfacial properties of USPIH-400W products have been investigated in relation to DH and emulsifying properties. SDS-PAGE showed that ultrasound pretreatment could significantly improve the accessibility of some subunits (α-7S and A-11S) in soy proteins to papain hydrolysis, resulting in changes in DH, protein solubility (PS), surface hydrophobicity (H0), and secondary structure for USPIH-400W. Compared with control SPI and SPIH-0.58%, USPIH-400W-1.25% had a higher protein adsorption fraction (Fads) and a lower saturation surface load (Γsat), which is mainly due to its higher PS and random coil content, and may explain its markedly improved emulsifying capability. This study demonstrated that combined ultrasound pretreatment and controlled enzymatic hydrolysis could be an effective method for the functionality modification of globular proteins.
Steady-state intrinsic tryptophan fluorescence spectroscopy is used as a rapid, robust and economic way for screening the thermal protein conformational stability in various formulations used during the early biotechnology development phase. The most important parameters affecting protein stability in a liquid formulation, e. g. during the initial purification steps or preformulation development, are the pH of the solution, ionic strength, presence of excipients and combinations thereof. A well-defined protocol is presented for the investigation of the thermal conformational stability of proteins. This allows the determination of the denaturation temperature as a function of solution conditions. Using intrinsic tryptophan fluorescence spectroscopy for monitoring the denaturation and folding of proteins, it is crucial to understand the influence of different formulation parameters on the intrinsic fluorescence probes of proteins. Therefore, we have re-evaluated and re-assessed the influence of temperature, pH, ionic strength, buffer composition on the emission spectra of tryptophan, phenylalanine and tyrosine to correctly analyse and evaluate the data obtained from thermal-induced protein denaturation as a function of the solution parameters mentioned above. The results of this study are a prerequisite for using this method as a screening assay for analysing the conformational stability of proteins in solution. The data obtained from intrinsic protein fluorescence spectroscopy are compared to data derived from calorimetry. The advantage, challenges and applicability using intrinsic tryptophan fluorescence spectroscopy as a routine development method in pharmaceutical biotechnology are discussed.
The effects of pressure (0.1 MPa to 400 MPa) on intrinsic fluorescence of beta-lactoglobulin and on its binding of retinol and cis-parinaric acid have been studied at neutral and acid pHs. In neutral pH, fluorescence emission spectra of beta-lactoglobulin tryptophanes are characterized by an irreversible 14 nm red-shift indicating pressure-induced folding changes. The intensity of the fluorescence of retinol in beta-lactoglobulin-retinol complex is enhanced by a pressure increase up to 150 MPa. It decreases at higher pressures and disappears altogether at 300 MPa. beta-Lactoglobulin-retinol complex does not reassociate after decompression at neutral pH. At acid pH condition, the fluorescence quenching by pressure of beta-lactoglobulin tryptophans is coupled with a 2 nm spectral shift and is fully reversible demonstrating almost complete restoration of globulin folding. The evolution of retinol fluorescence in beta-lactoglobulin-retinol complex is also entirely reversible between 0.1 MPa and 400 MPa and the complex never dissociates in the studied pressure range. beta-lactoglobulin-cis-parinaric acid complexes at neutral and acid pH values dissociate irreversibly at 200 MPa and 350 MPa, respectively.
Effects of high hydrostatic pressure on the quality and functionality of protein isolates, concentrates, and hydrolysates derived from pulse legumes: A review
- Gharibzahedi