Enzymatic hydrolysis of soy proteins and the hydrolysates utilisation

Unveiling the microbiota-mediated impact of different dietary proteins on post-digestive processes: A simulated in vitro approach

Protein digestion and microbial metabolism play crucial roles in overall health. However, the mechanisms that differentiate the digestion and metabolism of dietary proteins from different sources in the organism remain poorly understood. This study investigated the digestive properties and microbial fermentation of various animal proteins (chicken, pork, beef, and casein) and plant proteins (soy bean, mung bean, kidney bean, rice, and wheat) in an in vitro simulation. The results indicated that animal-derived proteins had higher essential amino acid content (33.97-37.12 g/100 g) and digestibility levels (49.15-60.94 %), and provided more small molecule peptides upon digestion. Nevertheless, soy bean and wheat proteins also exhibited higher digestibility (54.70 % and 60.94 %), probably due to the extraction process. The fermentation results showed that distinct metabolic profiles that emerged for different protein sources. Plant-derived proteins (especially kidney bean, rice and wheat) promoted the proliferation of beneficial bacteria and microbial diversification and stimulated short-chain fatty acids (SCFA) production. Conversely, meat proteins (pork, chicken, beef) had significantly lower microbial diversity and SCFA than these plant proteins. These findings provide valuable insights into the effects of dietary protein sources on digestion and gut microbiome, and offer scientific guidance for optimizing dietary choices to improve health.

Isolation and identification of bitter peptides during sequential hydrolysis of wheat gluten by enzyme preparations with endo-and exo-activities

The effect of the released amount and bitterness threshold of bitter peptides on the sensory properties of different wheat gluten hydrolysates (WGHs) after hydrolysis was investigated. The results showed that the endo-activity of the enzyme promoted the release of bitter peptides, leading to enhanced bitterness intensity in WGHs. With the increase in degree of hydrolysis (DH), the bitter threshold of bitter peptides became the main reason affecting bitterness of the WGHs. Proteax exerted the strong exo-activity at the DH of 20%, which could reduce bitterness of Pro-16 hydrolysates. The reason for debittering was the reduction in the content with molecular weights (MWs) of 500-1000 Da and the decrease of surface hydrophobicity (SH) in the Pro-20 M hydrolysates, which led to the increase of the bitterness threshold of bitter peptide. Meanwhile, HPLC-MS/MS analysis demonstrated the reduced proportion of C-terminal hydrophobic amino acids (HAAs) in Pro-20 M extracts verifying the cause of debittering.

Characterization of temperature-dependent subcritical water hydrolysis pattern of strong and floury rice cultivars and potential utilizations of their hydrolysates

This study investigated the effects of subcritical water (SW) temperatures on the hydrolysis pattern and characteristics of hydrolysates prepared with strong rice (SR) and floury rice (FR). The characteristics of the hydrolysates were generally dependent on the rice cultivar in the SW temperature range of 150-250 °C, while the cultivar dependence was diminished at temperatures greater than 300 °C. Based on brix and reducing sugar content, an optimal production of rice hydrolysates was obtained at a SW temperature range of 200-250 °C. However, thermal conversion of sugar into acids, 5-hydroxymethylfurfural (HMF) and furfural was manifested at 250 °C. The rice hydrolysates prepared at 250 ∼ 300 °C had the highest antioxidant activity with strong umami intensity, but they suppressed the growth of prebiotics. Therefore, the present study demonstrated that controlling the SW temperature is crucial to improve rice hydrolysis efficiency and to regulate the physiological activity of the hydrolysates.

Tea (Camellia sinensis (L.) Kuntze) as an emerging source of protein and bioactive peptides: A narrative review

Tea residues represent one of the major agricultural wastes that are generated after the processing of tea. They account for 21-28% of crude protein and are often discarded without the extraction of valuable proteins. Due to various bioactivity and functional properties, tea proteins are an excellent alternative to other plant-based proteins for usage as food supplements at a higher dosage. Moreover, their good gelation capacity is ideal for the manufacturing of dairy products, jellies, condensation protein, gelatin gel, bread, etc. The current study is the first to comprehend various tea protein extraction methods and their amino acid profile. The preparation of tea protein bioactive peptides and hydrolysates are summarized. Several functional properties (solubility, foaming capacity, emulsification, water/oil absorption capacity) and bioactivities (antioxidant, antihypertensive, antidiabetic) of tea proteins are emphasized.

Antioxidant effects and reaction volatiles from heated mixture of soy protein hydrolysates and coconut oil

Soy protein hydrolysates (SPHs) are prepared from soybean meal using commercially available protease enzymes and acid/alkali treatment. The antioxidant properties of SPHs were evaluated by measuring headspace oxygen consumption and conjugated diene formation in oil-in-water (O/W) emulsions. In addition, volatile profiles were analyzed for the heated mixture of SPHs and the coconut oil (SPHCO). Total amino acid content was the highest in double proteases. SPHs prepared from enzymes acted as better antioxidants than those prepared from acid/alkali treatments in O/W emulsions. SPHs prepared from double proteases generated the highest amounts of total volatiles and nitrogen-containing compounds in SPHCO. 2,3-Dihydro-3,5-dihydroxy-6-methyl-4H-pyran-4-one, 2-methyl-butanal, benzeneacetaldehyde, and 2,6-dimethylpyrazine were the major volatiles in SPHCO. Enzymatic SPHs act as natural antioxidants in the O/W emulsion matrix, and thermal reaction products from SPHCO may contribute to the production of a unique volatile flavor in plant protein-based foods.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10068-022-01189-7.

A Review on Edible Fungi-Derived Bioactive Peptides: Preparation, Purification and Bioactivities

Edible fungi bioactive peptides (BAPs) are extracted from fruiting bodies and the mycelium of edible fungus. They have various physiological functions such as antioxidant activity, antihypertensive activity, and antibacterial activity. In this paper, the preparation and purification methods of edible fungus BAPs were reviewed, their common biological activities and structure-activity relationships were analyzed, and their application prospects were discussed.

Impact of Different Enzymatic Processes on Antioxidant, Nutritional and Functional Properties of Soy Protein Hydrolysates Incorporated into Novel Cookies

Soy protein concentrate (SPC) was hydrolyzed using several commercial food-grade proteases (Alcalase, Neutrase, papain, Everlase, Umamizyme, Flavourzyme) and their combination to obtain promising ingredients in the manufacture of functional bakery products. In all cases, the hydrolysis caused nutritional, sensory, and rheological changes in SPC, as well as protein structural changes like increased surface hydrophobicity and content of exposed SH groups with the magnitude of these changes depending on enzyme specificity. The hydrolysis with the combination of Neutrase and Flavourzyme (NeuFlav) increased essential amino acid content by 9.8% and that of Lys by 32.6% compared to SPC. This hydrolysate showed also significant antioxidant activities including ABTS and superoxide anion scavenging activity and metal-chelating ability. The addition of all hydrolysates in wheat flour decreased water adsorption and increased development time to some extent due to gluten network weakening, but also decreased the rate of starch retrogradation, contributing to the increase of the shelf-life of bakery products. The NeuFlav tasted less bitter than other hydrolysates, while E-nose provided a discrimination index of 93 between control and hydrolysates. It appeared that the addition of the NeuFlav hydrolysate in a cookie formulation improved protein content and nutritional quality and directed to its higher general consumer acceptability than cookies formulated with only wheat flour.

Effects of Enzymatic Cottonseed Protein Concentrate as a Feed Protein Source on the Growth, Plasma Parameters, Liver Antioxidant Capacity and Immune Status of Largemouth Bass (Micropterus salmoides)

This study appraised the impact of enzymatic cottonseed protein concentrate (ECP) as a fish meal (FM) substitute on the growth and health of largemouth bass (Micropterus salmoides) (initial weight 14.99 ± 0.03 g). Five diets with equal nitrogen, fat, and energy were designed to replace 0%, 7.78%, 15.56%, 23.33%, and 31.11% FM by adding 0%, 3.6%, 7.2%, 10.8%, and 14.4% ECP, named ECP0, ECP3.6, ECP7.2, ECP10.8, and ECP14.4, respectively. We fed 300 fish with five experimental diets for 60 days. The results revealed that weight gain rate (WGR) and specific growth rate (SGR) did not notably reduce until the addition of ECP exceeded 7.2%. The proximate composition of fish was not affected by the amount of ECP added in diets. Plasma total protein (TP), albumin (ALB), and high-density lipoprotein (HDL) concentrations increased with the increase of ECP dosage, while the triglyceride (TG) and low-density lipoprotein (LDL) concentrations and alkaline phosphatase (ALP) activity showed an opposite trend. For hepatic antioxidant capacity, the hepatic total superoxide dismutase (T-SOD) and catalase (CAT) activities, glutathione (GSH) content, and the expression of nuclear factor erythroid 2-related factor 2 (Nrf2), superoxide dismutase (SOD), and CAT were increased by ECP, while the hepatic malondialdehyde (MDA) content and the expression of kelch-like-ECH-associated protein 1 (Keap1) were decreased. With regard to inflammation, the expression of nuclear factor-kappa B (NF-κB), interleukin-8 (IL-8), and tumor necrosis factor-α (TNF-α) were inhibited by ECP. In summary, the amount of ECP added to diet can reach 7.2% to replace 15.56% FM without hampering the growth of largemouth bass, and ECP can improve the antioxidant and immune capacity.

Effects of replacing dietary fish meal with enzyme-treated soybean meal on growth performance, intestinal microbiota, immunity and mTOR pathway in abalone Haliotis discus hannai

In addition to eliminating most of the anti-nutritional factors in soybean meal, enzyme-treated soybean meal (ESBM) can also increase the proportion of small peptides. It was found that ESBM can replace fish meal (FM) either partially or completely in diets for some fish and shrimp species. In the present study, the effects of replacing dietary FM with ESBM on growth performance, intestinal microbiota, immunity and mTOR pathway in abalone Haliotis discus hannai (initial weight: 16.75 ± 0.09 g) were investigated after a 100-day feeding trial. Five experimental diets were designed to replace 0%, 25%, 50%, 75% and 100% of dietary FM by ESBM, which were named as ESBM0 (control), ESBM25, ESBM50, ESBM75 and ESBM100, respectively. Results showed that ESBM could replace up to 75% of FM in the diet without significant effect on the weight gain rate (WGR, 118.05%-124.16%) of abalone. The increasing dietary ESBM levels significantly decreased the trypsin activity from 418.52 to 286.52 U/mg protein in the digestive gland. No significant differences in the contents of total cholesterol (T-CHO), ammonia (BLA) and malondialdehyde (MDA) in cell-free hemolymph were observed among the groups with replacement levels of dietary FM by ESBM from 0% to 75%. Excessive replacement level of FM with ESBM (ESBM100) significantly increased the MDA content (2.33 nmol/mg prot.) and pro-inflammatory-related gene expression in digestive gland. Compared with the control group, the mTOR pathway in muscle was significantly upregulated in the ESBM75 group. The digestive gland in the ESBM100 group contained more golden refractile spherules than those in the other groups. The abundance of intestinal microbes such as Halomonas, Zobellella and Bacillus was decreased in the ESBM100 group. In conclusion, up to 75% of replacement of dietary FM by ESBM had no negative effects on the growth performance, intestinal microbiota, immunity and mTOR pathway of abalone.

Cottonseed Meal Protein Isolate as a New Source of Alternative Proteins: A Proteomics Perspective

Cottonseed meal (CSM) is a good source of dietary proteins but is unsuitable for human consumption due to its gossypol content. To unlock its potential, we developed a protein extraction process with a gossypol removal treatment to generate CSM protein isolate (CSMPI) with ultra-low gossypol content. This process successfully reduced the free and total gossypol content to 4.8 ppm and 147.2 ppm, respectively, far below the US FDA limit. In addition, the functional characterisation of CSMPI revealed a better oil absorption capacity and water solubility than pea protein isolate. Proteome profiling showed that the treatment improved protein identification, while SDS-PAGE analysis indicated that the treatment did not induce protein degradation. Amino acid analysis revealed that post-treated CSMPI was rich in branched-chain amino acids (BCAAs). Mass spectrometry analysis of various protein fractions obtained from an in vitro digestibility assay helped to establish the digestibility profile of CSM proteins. Several potential allergens in CSMPI were also found using allergenic prediction software, but further evaluation based on their digestibility profiles and literature reviews suggests that the likelihood of CSMPI allergenicity remains low. Overall, our results help to navigate and direct the application of CSMPIs as alternative proteins toward nutritive human food application.

Preparation, Characterization and In Vitro Stability of a Novel ACE-Inhibitory Peptide from Soybean Protein

A soy protein isolate was hydrolyzed with Alcalase®, Flavourzyme® and their combination, and the resulting hydrolysates (A, F and A + F) were ultrafiltered and analyzed through SDS-PAGE. Fractions with MW < 1 kDa were investigated for their ACE-inhibitory activity, and the most active one (A < 1 kDa) was purified by semi-preparative RP-HPLC, affording three further subfractions. NMR analysis and Edman degradation of the most active subfraction (A1) enabled the identification of four putative sequences (ALKPDNR, VVPD, NDRP and NDTP), which were prepared by solid-phase synthesis. The comparison of their ACE-inhibitory activities suggested that the novel peptide NDRP might be the main agent responsible for A1 fraction ACE inhibition (ACE inhibition = 87.75 ± 0.61%; IC50 = 148.28 ± 9.83 μg mL−1). NDRP acts as a non-competitive inhibitor and is stable towards gastrointestinal simulated digestion. The Multiple Reaction Monitoring (MRM) analysis confirmed the presence of NDRP in A < 1 kDa.

Flavor challenges in extruded plant-based meat alternatives: A review

Demand for plant-based meat alternatives has increased in recent years due to concerns about health, ethics, the environment, and animal welfare. Nevertheless, the market share of plant-based meat alternatives must increase significantly if they are to support sustainable food production and consumption. Flavor is an important limiting factor of the acceptability and marketability of plant-based meat alternatives. Undesirable chemosensory perceptions, such as a beany flavor, bitter taste, and astringency, are often associated with plant proteins and products that use them. This study reviewed 276 articles to answer the following five research questions: (1) What are the volatile and nonvolatile compounds responsible for off-flavors? (2) What are the mechanisms by which these flavor compounds are generated? (3) What is the influence of thermal extrusion cooking (the primary structuring technique to transform plant proteins into fibrous products that resemble meat in texture) on the flavor characteristics of plant proteins? (4) What techniques are used in measuring the flavor properties of plant-based proteins and products? (5) What strategies can be used to reduce off-flavors and improve the sensory appeal of plant-based meat alternatives? This article comprehensively discusses, for the first time, the flavor issues of plant-based meat alternatives and the technologies available to improve flavor and, ultimately, acceptability.

Production of Plant Proteases and New Biotechnological Applications: An Updated Review

An updated review of emerging plant proteases with potential biotechnological application is presented. Plant proteases show comparable or even greater performance than animal or microbial proteases for by-product valorization through hydrolysis for, for example, cheese whey, bird feathers, collagen, keratinous materials, gelatin, fish protein, and soy protein. Active biopeptides can be obtained as high added value products, which have shown numerous beneficial effects on human health. Plant proteases can also be used for wastewater treatment. The production of new plant proteases is encouraged for the following advantages: low cost of isolation using simple procedures, remarkable stability over a wide range of operating conditions (temperature, pH, salinity, and organic solvents), substantial affinity to a broad variety of substrates, and possibility of immobilization. Vegetable proteases have enormous application potential for the valorization of industrial waste and its conversion into products with high added value through low-cost processes.

Altering almond protein function through partial enzymatic hydrolysis for creating gel structures in acidic environment

Protein inadequacy is the major problem for most plant-based dairy yoghurt substitutes. This study investigated three limited degree of hydrolysis (DH: 1%, 5%, and 9%) of almond protein and the combined effect of DH and hydrolysed almond protein (HP) to non-hydrolysed almond protein (NP) ratios (HP/NP: 40:60, 20:80, 10:90 and 5:95) on the physicochemical properties of resulting fermentation induced almond-based gel (yoghurt). The gel microstructure, particle size, firmness, pH, water holding capacity (WHC), lubrication, flow, and gelation characteristics were measured and associated with the DH, composition, and SDS-PAGE results. The results show significant differences in gel samples with the same HP/NP (40:60) ratio of protein but different protein DH. A higher DH (9%) resulted in samples with lower hardness (6.03 g), viscosity (0.11 Pa s at 50 s-1), cohesiveness (0.63) and higher friction (0.203 at 10 mm/s) compared to sample with 1% DH with higher hardness - 7.34 g, viscosity at 50 s⁻¹ - 0.16 Pa s, cohesiveness - 0.86 and friction at 10 mm/s - 0.194. Comparing samples with the same DH (5%) but different HP/NP ratios showed smaller coarse microgel particles (21.36 μm) and lower hardness (7.17 g), viscosity (0.14 Pa s at 50 s⁻¹) and friction value (0.189 at 10 mm/s) in samples with high HP/NP (40:60) compared to sample with low HP/NP (5:95) that contained significantly large coarse microgel particles (34.61 μm) with the gel being very hard (9.38 g), highly viscous (0.32 Pa s at 50 s⁻¹), and less lubricating (0.220 at 10 mm/s).

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Enzymatic treatment changes the almond protein profile.

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Increased the degree of hydrolysis weakens the gel strength.

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The more hydrolysed protein used in formulation the softer the gel.

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Limited hydrolysis may contribute to bacterial metabolism.

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The microstructure verifies the improvement of gel's water holding capacity.

Debittering effect of partially purified proteases from soybean seedlings on soybean protein isolate hydrolysate produced by alcalase

To explore the potential application of proteases from soybean seedlings in the debittering of soybean protein hydrolysates, soybean seeds were germinated from 1 to 10 days. It was found that the sixth day seedlings exhibited highest proteases activity (130 U/g). After partial purification, the activity of proteases (PSP) from the sixth day seedlings further increased to 2675 U/g. In addition, PSP exhibited maximum activity at 50 ℃ and pH 5.5, and mainly comprised of two proteins with the molecular weight of 64.57 and 25.12 kDa respectively. PSP could decrease the bitterness score of the soybean protein isolate hydrolysate (SPIH) produced by Alcalase 2.4L from 3.45 to 0 in 3 h. Meanwhile, the degree of hydrolysis of SPIH slightly increased from 11.87% to 15.61% without reducing the antioxidant activity. This study may provide a solution to the contradiction between removing the bitterness of soybean protein hydrolysates and maintaining the bioactivity.

Sunflower seed byproduct and its fractions for food application: An attempt to improve the sustainability of the oil process

The sunflower (Helianthus annus L.) is one of the main oil crops in the world grown for the production of edible and biodiesel oil. Byproducts of the extraction of sunflower oil constitute a raw material with potential for several applications in the food area due to its chemical composition, including the high content of proteins and phenolic compounds. Thoughtful of a consumer increasingly concerned with the environmental impact, we try to clarify in this review the potential of using sunflower seed byproducts and their fractions to enhance the production of potentially functional foods. The applications of sunflower seed byproduct include its transformation into flours/ingredients that are capable of improving the nutritional and functional value of foods. In addition, the protein isolates obtained from sunflower seed byproduct have good technological properties and improve the nutritional value of food products. These protein isolates can be used to obtain protein hydrolysates with technological and bioactive properties and as matrices for the development of edible, biodegradable, and active films for food. The sunflower seed byproduct is also a source of phenolic compounds with bioactive properties, mainly chlorogenic acid, which can be extracted by different methods and applied in the development of functional foods and active and bioactive food packaging. The use of sunflower seed byproduct and its fractions are promising ingredients for the development of healthier and less expensive foods as well as the alternative to decrease the environmental problems caused by the sunflower oil industry.

Physiologically Active Molecules and Functional Properties of Soybeans in Human Health-A Current Perspective

In addition to providing nutrients, food can help prevent and treat certain diseases. In particular, research on soy products has increased dramatically following their emergence as functional foods capable of improving blood circulation and intestinal regulation. In addition to their nutritional value, soybeans contain specific phytochemical substances that promote health and are a source of dietary fiber, phospholipids, isoflavones (e.g., genistein and daidzein), phenolic acids, saponins, and phytic acid, while serving as a trypsin inhibitor. These individual substances have demonstrated effectiveness in preventing chronic diseases, such as arteriosclerosis, cardiac diseases, diabetes, and senile dementia, as well as in treating cancer and suppressing osteoporosis. Furthermore, soybean can affect fibrinolytic activity, control blood pressure, and improve lipid metabolism, while eliciting antimutagenic, anticarcinogenic, and antibacterial effects. In this review, rather than to improve on the established studies on the reported nutritional qualities of soybeans, we intend to examine the physiological activities of soybeans that have recently been studied and confirm their potential as a high-functional, well-being food.

Health Benefits of Antioxidative Peptides Derived from Legume Proteins with a High Amino Acid Score

Legumes such as soybean, chickpea, lentil, cowpea, and mung bean, are valuable sources of protein with a high amino acid score and can provide bioactive peptides. This manuscript presents a review on legume-derived peptides, focusing on in vitro and in vivo studies on the potential antioxidative activities of protein hydrolysates and their characterization, amino acid sequences, or purified/novel peptides. The health implications of legume-derived antioxidative peptides in reducing the risks of cancer and cardiovascular diseases are linked with their potent action against oxidation and inflammation. The molecular weight profiles and amino acid sequences of purified and characterized legume-derived antioxidant peptides are not well established. Therefore, further exploration of legume protein hydrolysates is necessary for assessing the potential applications of antioxidant-derived peptides in the functional food industry.

Impact of Peptidase Activities on Plant Protein Hydrolysates Regarding Bitter and Umami Taste

The aim of this study was to investigate six food-grade peptidase preparations, namely, Flavourzyme 1000L, Protease P "Amano" 6SD, DeltazymAPS-M-FG, Promod278, ProteAX-K, and Peptidase R, regarding their use for the hydrolysis of soy, pea, and canola protein. The relationship between the specific peptidase activities and, first, the degree of hydrolysis, second, the free amino acid profiles of the hydrolysates, and, third, the corresponding taste of the hydrolysates was analyzed using a random forest model. The taste attributes bitter and umami were of special interest. The peptidase ProteAX-K was the biocatalyst most suited for the high umami and low bitter taste of the plant-based protein hydrolysates based on the experimental results and the random forest model.

Peptides from Extruded Lupin (Lupinus albus L.) Regulate Inflammatory Activity via the p38 MAPK Signal Transduction Pathway in RAW 264.7 Cells

In this study, protein was extracted from extruded lupin and submitted to gastroduodenal digests to obtain lupin peptides, which were characterized using ultraperformance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). After this, IQDKEGIPPDQQR (IQD), the lupine peptide monomer characterized after UPLC-MS/MS, was screened out by macrophage inflammatory cytokine production assay. RNA-sequencing analysis was performed to explore the mechanisms underlying the anti-inflammatory activity associated with this peptide. The results indicated that lupin peptides effectively inhibited the lipopolysaccharide-induced overproduction of proinflammatory mediators. IQD inhibited the production of tumor necrosis factor-α, interleukin (IL)-6, IL-1β, and monocyte chemoattractant protein-1 by 51.20, 38.52, 44.70, and 40.43%, respectively. RNA-sequencing results showed that IQD inhibited the inflammatory response by regulating the gene expression of the p38 mitogen-activated protein kinase pathway and inhibiting downstream inflammatory cytokines. These bioactive peptides may be used to develop new ingredients for anti-inflammatory nutritional supplements.

The Effect of Limited Proteolysis by Trypsin on the Formation of Soy Protein Isolate Nanofibrils

Nanofibril system constructed by protein self-assembly is widely used in the food industry because of purposive functional properties. Soy protein isolate nanofibrils (SPINs) were reported to form via heating at pH 2.0. In this research, the soy protein isolate (SPI) hydrolysate prepared by trypsin was used as a raw material for the formation of nanofibrils called soy protein isolate hydrolysate nanofibrils (SPIHNs). Microscopic images demonstrated the formation of two nanofibrils. Based on circular dichroism spectroscopy and Thioflavin T (ThT) fluorescence spectral, we concluded that β-sheet played an important role in SPIN and SPIHN’s structural composition. At the same time, the α-helix in SPI had not been destroyed, thereby favoring the formation of SPIHN. The surface hydrophobicity of SPIHN continued to increase during the heating process and reached the highest value when heating 8 h. SDS-PAGE analysis showed that peptides produced by enzyme-modified SPI affected the formation of SPIHN. These results proposed that enzymatic hydrolysis prior to acidic during fibrillation process affected the fibrillation of SPI, and the peptides formed by enzymatic hydrolysis were more efficient for the self-assembly process. This study will provide a theoretical basis for the future research of SPI nanofibril functionality.

Soybean (Glycine max) Protein Hydrolysates as Sources of Peptide Bitter-Tasting Indicators: An Analysis Based on Hybrid and Fragmentomic Approaches

The aim of this study was to analyze soybean proteins as sources of peptides likely to be bitter using fragmentomic and hybrid approaches involving in silico and in vitro studies. The bitterness of peptides (called parent peptides) was theoretically estimated based on the presence of bitter-tasting motifs, particularly those defined as bitter-tasting indicators. They were selected based on previously published multilinear stepwise regression results. Bioinformatic-assisted analyses covered the hydrolysis of five major soybean-originating protein sequences using bromelain, ficin, papain, and proteinase K. Verification of the results in experimental conditions included soy protein concentrate (SPC) hydrolysis, RP-HPLC (for monitoring the proteolysis), and identification of peptides using RP-HPLC-MS/MS. Discrepancies between in silico and in vitro results were observed when identifying parent peptide SPC hydrolysate samples. However, both analyses revealed that conglycinins were the most abundant sources of parent peptides likely to taste bitter. The compatibility percentage of the in silico and in vitro results was 3%. Nine parent peptides with the following sequences were identified in SPC hydrolysates: LSVISPK, DVLVIPLG, LIVILNG, NPFLFG, ISSTIV, PQMIIV, PFPSIL, DDFFL, and FFEITPEK (indicators are in bold). The fragmentomic idea of research might provide a supportive method for predicting the bitterness of hydrolysates. However, this statement needs to be confirmed experimentally.

Effect of Spray-Drying and Freeze-Drying on the Properties of Soybean Hydrolysates

The use of enzyme-assisted aqueous extraction to extract soybean oil will produce soy protein hydrolysates (SPH) that have good antioxidant properties but are bitter and hygroscopic. To microencapsulate these hydrolysates, soy protein isolate/maltodextrin mixtures were used as the carrier. The effects of spray-drying and freeze-drying on the bitterness, hygroscopicity, and antioxidant properties were compared. The properties of different dried samples were compared using solubility, hygroscopicity, moisture content, water activity, flowability, and glass transition temperature (Tg). The results showed that the spray-drying was more effective than freeze-drying. Hygroscopicity was reduced to 18.2 g/100 g, and the Tg value was raised to 80.8°C. The morphology was analyzed using scanning electron microscopy, and the antioxidant properties of the samples were measured using the ABTS˙+ radical scavenging activity. The results showed that spray-dried SPH had more carrier masking, which weakened bitterness, reduced moisture absorption, and had no significant negative impact on its oxidation resistance, solubility, and flowability, and spray-drying after carrier encapsulation of SPH improved the recovery rate.

Soybean soluble polysaccharides enhance bioavailability of genistein and its prevention against obesity and metabolic syndrome of mice with chronic high fat consumption

This study aimed to explore a novel strategy for the simultaneous consumption of soluble soybean polysaccharides (SSPS) and insoluble genistein to improve the bioavailability of genistein and its prevention against obesity and metabolic syndrome in high-fat diet (HFD)-induced obese mice. C57BL/6J mice were fed a normal diet and HFD supplemented or not (n = 8) with SSPS (2.5%), genistein (0.5%) and their mixture (S + G) for 12 weeks. The UPLC-qTOP/MS assay showed that SSPS observably enhanced the urinary concentration of genistein and its metabolites compared to that of single genistein in mice. Supplementation of SSPS, genistein or their combination prevented HFD-induced gain weight, dyslipidemia, oxidative stress and inflammation in obese mice. Interestingly, the combined S + G ingestion exhibited more effective alleviation of dyslipidemia by modulating hepatic FAS, ACC, SREBP-1C and ADRP expressions relative to that of individual SSPS or genistein. Furthermore, S + G activated the energy metabolism pathway AMPK in the liver, and the hepatic PPAR-α/PPAR-γ pathways were doubly activated to alleviate lipogenesis, inflammation, obesity and metabolic syndrome. Moreover, S + G supplementation dramatically modified the gut microbial species at the phylum level with a decrease in Firmicutes and increase in Bacteroidetes. These findings support that the combined supplementation of SSPS and genistein is a novel couple to prevent obesity and metabolic syndrome.

Controlled enzymatic hydrolysis of pollen protein as promising tool for production of potential bioactive peptides

In the present study, response surface method was used to optimize hydrolysis condition to generate potential bioactive peptides from pollen protein using pepsin (pepsin hydrolysated pollen-PHP) and trypsin (trypsin hydrolysated pollen-THP). Then PHP and THP prepared under optimized conditions were analyzed by size-exclusion chromatography. The fractions possessing the maximum ACE-inhibitory, DPPH radical scavenging, and ferric-reducing power were further purified by RP-HPLC. A heterogeneous composition of hydrophobic and hydrophilic peptides in both fractions was obtained. Finally, peptide sequences in active fractions of PHP and THP were identified by mass spectrometry in tandem. All the identified peptides had herbal protein origins. These were 6-21 amino acids in length, and Glycine and Alanine were two main hydrophobic amino acids present in their sequences. The results proved that using controlled enzymatic hydrolysis of pollen protein is possible to generate bioactive peptides with high ACE-inhibitory and antioxidant activity in final product. PRACTICAL APPLICATIONS: Pollen is well-known as an interesting protein source. Compared to other types of hydrolysis, enzymatic hydrolysis of vegetable proteins has few or no undesirable side reactions or products. In this study, controlled enzymatic hydrolysis of pollen protein was applied as a suitable method to produce bioactive peptide. The results proved that using controlled enzymatic hydrolysis of pollen protein is possible to generate bioactive peptides with high ACE-inhibitory and antioxidant activity in final product. This product can be used as functional and health promoting ingredient in different food formulations.

A Comprehensive Review on Kiwifruit Allergy: Pathogenesis, Diagnosis, Management, and Potential Modification of Allergens Through Processing

Kiwifruit is rich in bioactive components including dietary fibers, carbohydrates, natural sugars, vitamins, minerals, omega-3 fatty acids, and antioxidants. These components are beneficial to boost the human immune system and prevent cancer and heart diseases. However, kiwifruit is emerging as one of the most common elicitors of food allergies worldwide. Kiwifruit allergy results from an abnormal immune response to kiwifruit proteins and occur after consuming this fruit. Symptoms range from the oral allergy syndrome (OAS) to the life-threatening anaphylaxis. Thirteen different allergens have been identified in green kiwifruit and, among these allergens, Act d 1, Act d 2, Act d 8, Act d 11, and Act d 12 are defined as the "major allergens." Act d 1 and Act d 2 are ripening-related allergens and are found in abundance in fully ripe kiwifruit. Structures of several kiwifruit allergens may be altered under high temperatures or strong acidic conditions. This review discusses the pathogenesis, clinical features, and diagnosis of kiwifruit allergy and evaluates food processing methods including thermal, ultrasound, and chemical processing which may be used to reduce the allergenicity of kiwifruit. Management and medical treatments for kiwifruit allergy are also summarized.

The high expression of Aspergillus pseudoglaucus protease in Escherichia coli for hydrolysis of soy protein and milk protein

The hydrolysates of soy protein and milk protein are nutritional and functional food ingredients. Aspergillus pseudoglaucus aspergillopepsin I (App) is an acidic protease, including signal peptide, propeptide, and catalytic domain. Here, we cloned the catalytic domain App with or without propeptide in Escherichia coli. The results showed that the App without propeptide was not expressed or did not exhibit activity and App with propeptide (proApp) was highly expressed with a specific activity of 903 U/mg. Moreover, the denaturation temperature of proApp was 4.1 °C higher than App's. The proApp showed 104 U/mg and 252 U/mg hydrolysis activities towards soy protein and milk protein under acidic conditions. By RP-HPLC analysis, the peptides obtained from the hydrolysates of soy protein and milk protein were hydrophilic peptides. This work first demonstrates efficient proteolysis of soy protein and milk protein through the functional expression of full-length proApp, which will likely have valuable industrial applications.

Production of wheat gluten hydrolyzates by enzymatic process at high pressure

A novel process for producing wheat gluten enzyme hydrolyzates (WGEHs) was developed, using combinations of Flavourzyme 500MG, Alcalase 2.4L, Protamex, and Marugoto E at the high pressure of 300 MPa, and the resultant hydrolyzates were analyzed for electrophoretic and hydrolytic properties. It was found that multiple-enzyme treatments increased the proportion of the electrophoretic bands less than 5 kDa in the hydrolyzates greatly both at ambient pressure and 300 MPa compared with one-enzyme hydrolysis. The contents of total soluble solids in the WGEHs increased considerably up to 89.75% according to the increase in the number of enzymes used at 300 MPa compared with 79.37% found for the ambient-pressure hydrolysis. These characteristics together with the contents of soluble nitrogen and free amino acids clearly indicated that the high-pressure enzymatic process of this study is an efficient method for obtaining WGEHs with increased degree of hydrolysis.