Effect of ultrasound and microwave processing on the structure, in-vitro digestibility and trypsin inhibitor activity of soymilk proteins

Proteomic and peptidomic profiling of spirulina-fortified probiotic powder formulations during in vitro digestion

This study reports on the influence of lactic acid fermentation on the proteomic and peptidomic profiles of spirulina protein isolate (SPI)-fortified, freeze-dried powders containing living Lacticaseibacillus rhamnosus GG (LGG) cells during in vitro digestion. For comparison, powders fortified with whey protein isolate (WPI) and pea protein isolate (PPI) were also evaluated. Prior to freeze-drying, the powder precursors were either non-treated or fermented. Capillary SDS-PAGE electropherograms revealed a mild proteolytic effect due to fermentation. C-phycocyanin (SPI) and β-lactoglobulin (WPI) showed the highest resistance to pepsinolysis. All samples were responsive to pancreases, with fermented WPI showing the lowest responsiveness. Fermentation enhanced the degree of hydrolysis (DH) in gastric chymes, whereas in intestinal chymes, DH followed the order SPI > PPI > WPI, with fermentation showing no significant impact. A total of 6, 11, and 52 potential bioactive peptide sequences, associated with various beneficial activities, were identified in the SPI, PPI, and WPI digesta, respectively. The highest amino acid bioaccessibilities were observed for cysteine and methionine in SPI, isoleucine and arginine in PPI, and glycine in WPI. In conclusion, fortifying probiotic formulations with protein isolates offers secondary health benefits, stemming from the release of bioactive peptides and bioaccessible essential amino acids.

A comparative study on the protein digestion of four different soy beverages: effects of the composition, microstructure, and protein digestibility evaluation method

The increased consumption of soy-based products leads to the incentive for more sustainable soybean processing and more accurate nutritional evaluation. The protein structures and aggregation states of different components vary with different soy products, but their relationship with digestibility is unclear. In order to study the digestion of soy protein in complex food matrices, four soy-based beverages were carefully prepared, including whole component soy beverage (WS), soy beverage with insoluble soybean residue removed (DO-WS), soy beverage with lipids removed (DL-WS), and soy protein isolate beverage (HSPI). During digestion, the microstructure revealed that particles of all soy beverages were reduced and more evenly distributed, but striated fibres (in WS and DL-WS) still remained after digestion. Tricine-SDS-PAGE profiles showed that after in vitro gastrointestinal digestion of the four beverages, almost all the bands corresponding to the complete proteins from soy disappeared, leaving fewer visible bands with a low MW - below 12 kDa. In vitro protein digestibility analyzed by TCA precipitation (strategy B), which ranged from 64.24% to 68.70%, was more accurate, with peptides of MW <1 kDa accounting for over 84% for all the four digested fractions. Moreover, the highest values of in vitro DIAAS (96/80) and digestible protein (29.40/24.41 g per 100 g of soybeans) were achieved by WS. Characterization of the insoluble digesta further elucidated that peptides with a smaller MW (below 12 kDa) and a higher amount of hydrophobic amino acids aggregated more easily, resulting in the occurrence of precipitates and the relatively lower in vitro protein digestibility. This research contributes to the understanding of protein digestibility in whole legume-based diets, which in turn could aid in the development of new whole legume products and more efficient utilization of proteins.

A Comprehensive Review of Antinutrients in Plant-Based Foods and Their Key Ingredients

In recent years, the growing popularity of vegan and vegetarian diets, along with the rising demand for plant-based foods, has led researchers to concentrate on examining the presence and effects of antinutrients. While there are existing literature reviews focusing on antinutritional compounds, particularly on their reduction, this review aims to provide a comprehensive description of antinutrients for producers, food scientists, professionals, legislators and consumers, emphasising the complexity of the subject and the necessity for diverse approaches while identifying aspects that still require further research. Antinutrients, including protease inhibitors, amylase inhibitors, phytic acid, lectins, saponins, tannins, cyanogenic glycosides, oxalic acid, polyphenols, goitrogens and pyrimidine glycosides, are described, encompassing various aspects such as their structural characteristics, analytical detection methods, distribution, physiological impacts and strategies for mitigation or elimination. Specifically, our review concentrates on assessing the presence of antinutrients in plant-based food products and the primary ingredients, categorised into five distinct groups, cereals, pseudocereals, pulses, seeds and nuts, which are commonly used in their production. Among these categories, legumes are identified as the richest source of anti-nutritional compounds, followed by cereal grains. However, certain pseudocereals, seeds and nuts also demonstrate high levels of specific antinutrients. While antinutrients are generally regarded as harmful to nutrient absorption, recent studies have revealed some potential health benefits associated with them. Therefore, further in vivo research is essential to elucidate the behaviour of antinutritional compounds within the human body. Additionally, there is a significant lack of formal regulations and guidelines regarding antinutrients, and food products currently do not feature labelling related to these compounds.

Eco-friendly encapsulation: Investigating plant-based protein-alginate shells for efficient delivery and digestion of hemp seed oil encapsulated via supercritical CO2 dispersion

In this study, supercritical carbon dioxide solution-enhanced dispersion (SEDS) was used to encapsulate hemp seed oil (HSO) within matrices of hemp seed protein isolate (HPI), pea protein (PPI) and soy protein (SPI) (0.5 % w/v) in complex with alginate (AL) (0.01 % w/v). The effects of different pH levels (3-9), NaCl concentrations (0-200 mmol/L) and simulated gastrointestinal conditions on HSO release and digestion patterns were analyzed. The findings revealed that SPI/AL microcapsules effectively maintained structural integrity and controlled oil release across diverse pH levels and salt concentrations. During gastrointestinal phases, minimal oil release was observed during oral digestion (<25 % for all samples), while significant (P < 0.05) gastric release occurred in PPI/AL (55.4 %) and SPI/AL (78.1 %) microcapsules. Surprisingly, HPI/AL microcapsules exhibited delayed and sustained release (27.9 %), indicating their potential as ideal wall material for delivering sensitive food and pharmaceutical ingredients to the intestinal stage while minimizing damage in the harsh gastric environment.

A comprehensive review of effects of ultrasound pretreatment on processing technologies for food allergens: Allergenicity, nutritional value, and technofunctional properties and safety assessment

Many proteins are essential food components but also major allergens. Reducing protein allergenicity while preserving its nutritional value and technofunctional properties has always been the goal of the food industry. Ultrasound (US) is a green processing method for modifying proteins. In addition, US pretreatment combined with other processing techniques (USPCT) has been increasingly used in the food industry. Therefore, this review presents an overview of recent advances in the impact of US and USPCT (US-combined enzymatic hydrolysis [USCE], US-combined glycation [USCG], and US-combined polyphenol conjugation [USCP]) on the allergenicity, nutritional value, and technofunctional properties of food allergens. We discuss the potential mechanisms, advantages, and limitations of these technologies for improving the properties of proteins and analyze their safety, challenges, and corresponding solutions. It was found that USPCT can improve the efficiency and effectiveness of different methods, which in turn can be more effective in reducing protein allergenicity and improving the nutritional value and functional properties of processed products. Future research should start with new processing methods, optimization of process conditions, industrial production, and the use of new research techniques to promote technical progress. This paper is expected to provide reference for the development of high-quality hypoallergenic protein raw materials.

In vitro protein digestive properties and peptidomic characterization of five whole component plant protein beverages using a pepsin-pancreatin model

Plant protein has received great attention for its potential nutrition and health benefits. In this study, the digestive properties and peptidomics of whole component plant protein beverages from soybean, chick pea, pea, oat, and quinoa were characterized using an in vitro pepsin-pancreatin digestion model. The study found that quinoa beverage had a higher in vitro protein digestibility (80.49 %), followed by pea, soybean, chick pea, and oat beverage (79.25-70.89 %). Additionally, quinoa and soybean beverage showed comparably higher in vitro digestible indispensable amino acid score (DIAAS) of 81-97, while chick pea and pea beverage had lower in vitro DIAAS of 58-79 due to low concentration of sulfur-containing AA (SAA). Meanwhile, peptides with molecular weight (MW) below 1 kDa occupied more than 93 % of the digested fraction in quinoa beverage, which might result in its higher DPPH scavenging activity, ABTS scavenging activity and ACE inhibitory activity with the IC50 value of 2.80, 0.20 and 0.90 mg/mL, respectively. Peptidomics characterization combined with rapid screening by PeptideRanker and BIOPEP database further suggested that cereals, especially oat and quinoa, released potentially bioactive peptides with a higher percentage (30.89 % and 22.81 %, respectively) compared to legumes like soybean and chick pea (13.30-18.52 %). Additionally, the identified active peptides were more likely to be derived from globular proteins. The methods and data here provided a reference for a better understanding of the digestive properties and nutritional recommendations of whole component plant protein product.

Effect of sonoprocessing on the quality of plant-based analog foods: Compatibility to sustainable development goals, drawbacks and limitations

Sonoprocessing (US), as one of the most well-known and widely used green processing techniques, has tremendous benefits to be used in the food industry. The urgent call for global sustainable food production encourages the usage of such techniques more often and effectively. Using ultrasound as a hurdle technology synergistically with other green methods is crucial to improving the efficiency of the protein shift as well as the number of plant-based analog foods (PBAFs) against conventional products. It was revealed that the US has a significant impact when used as an assistant tool with other green technologies rather than being used alone. It increases the protein extraction efficiencies from plant biomasses, improves the techno-functional properties of food compounds, and makes them more applicable for industrial-scale alternative food production in the circular economy. The US aligns well with the objectives outlined in the UN's Sustainable Development Goals (SDGs), and Planetary Boundaries (PBs) framework, demonstrating promising outcomes in life cycle assessment. However, several challenges such as uncontrolled complex matrix effect, free radical formation, uncontrolled microbial growth/germination or off-flavor formation, removal of aromatic compounds, and Maillard reaction, are revealed in an increased number of studies, all of which need to be considered. In addition to a variety of advantages, this review also discusses the drawbacks and limitations of US focusing on PBAF production.

On the modification of plant proteins: Traditional methods and the Hofmeister effect

With increasing consumer health awareness and demand from some vegans, plant proteins have received a lot of attention. Plant proteins have many advantages over animal proteins. However, the application of plant proteins is limited by a number of factors and there is a need to improve their functional properties to enable a wider range of applications. This paper describes the advantages and disadvantages of traditional methods of modifying plant proteins and the appropriate timing for their use, and collates and describes a method with fewer applications in the food industry: the Hofmeister effect. It is extremely simple but efficient in some respects compared to traditional methods. The paper provides theoretical guidance for the further development of plant protein-based food products and a reference value basis for improving the functional properties of proteins to enhance their applications in the food industry, pharmaceuticals and other fields.

A comprehensive review on novel synthetic foods: Potential risk factors, detection strategies, and processing technologies

Nowadays, the food industry is facing challenges due to the simultaneous rise in global warming, population, and food consumption. As the integration of synthetic biology and food science, novel synthetic foods have obtained high attention to address these issues. However, these novel foods may cause potential risks related to human health. Four types of novel synthetic foods, including plant-based foods, cultured meat, fermented foods, and microalgae-based foods, were reviewed in the study. The original food sources, consumer acceptance, advantages and disadvantages of these foods were discussed. Furthermore, potential risk factors, such as nutritional, biological, and chemical risk factors, associated with these foods were described and analyzed. Additionally, the current detection methods (e.g., enzyme-linked immunosorbent assay, biosensors, chromatography, polymerase chain reaction, isothermal amplification, and microfluidic technology) and processing technologies (e.g., microwave treatment, ohmic heating, steam explosion, high hydrostatic pressure, ultrasound, cold plasma, and supercritical carbon dioxide) were reviewed and discussed critically. Nonetheless, it is crucial to continue innovating and developing new detection and processing technologies to effectively evaluate these novel synthetic foods and ensure their safety. Finally, approaches to enhance the quality of these foods were briefly presented. It will provide insights into the development and management of novel synthetic foods for food industry.

Optimizing Screw Speed and Barrel Temperature for Textural and Nutritional Improvement of Soy-Based High-Moisture Extrudates

Soy remains the legume protein of excellence for plant-based meat alternatives due to its fiber-forming potential. In this study, protein-rich powders from soy protein isolate (SPI), concentrate (SPC), and their mixture (SPM) were thoroughly characterized for their proximate composition, nutritional quality, and physicochemical properties to understand their structuring behavior during high-moisture extrusion. SPI presented higher degrees of protein denaturation and aggregation, least gelation concentration and lower essential amino acid contents. Thus, an SPI:SPC combination (1:9 ratio, 70% protein) was extruded at three different screw speeds (300, 350, and 400 rpm) and two temperature profiles (120 and 140 °C maximum temperature). The effects of the processing parameters on the extrudates were evaluated for their appearance (fibrousness), texture (TPA, cutting force, and anisotropy), color, protein structure (FTIR), and trypsin inhibitors. Higher temperatures resulted in softer and darker extrudates, with increased visual and instrumental anisotropy. Increasing screw speeds led to softer and lighter extrudates, without a clear fibrousness effect. β-sheet structures decreased and intermolecular aggregates (A1) increased after extrusion, especially at 140 °C, together with the formation of intramolecular aggregates (A2). Extrusion also significantly decreased the amount of trypsin inhibitors (>90%). This study demonstrates that extrusion parameters need to be carefully selected to achieve meat analogs with optimal textural and nutritional characteristics.

Technological challenges and future perspectives of plant-based meat analogues: From the viewpoint of proteins

The global demand for high-quality animal protein faces challenges, prompting a surge in interest in plant-based meat analogues (PBMA). PBMA have emerged as a promising solution, although they encounter technological obstacles. This review discusses the technological challenges faced by PBMA from the viewpoint of plant proteins, emphasizing textural, flavor, color, and nutritional aspects. Texturally, PBMA confront issues, such as deficient fibrous structure, chewiness, and juiciness. Addressing meat flavor and mitigating beany flavor in plant protein are imperative. Furthermore, achieving a distinctive red or pink meat color remains a challenge. Plant proteins exhibit a lower content of essential amino acids. Future research directions encompass (1) shaping myofibril fibrous structures through innovative processing; (2) effectively eliminating the beany flavor; (3) developing biotechnological methodologies for leghemoglobin and plant-derived pigments; (4) optimizing amino acid composition to augment the nutritional profiles. These advancements are crucial for utilization of plant proteins in development of high-quality PBMA.

Plant-based proteins: advances in their sources, digestive profiles in vitro and potential health benefits

Plant-based proteins (PBPs), which are environmentally friendly and sustainable sources of nutrition, can address the emerging challenges facing the global food supply due to the rapidly increasing population. PBPs have received much attention in recent decades as a result of high nutritional values, good functional properties, and potential health effects. This review aims to summarize the nutritional, functional and digestive profiles of PBPs, the health effects of their hydrolysates, as well as processing methods to improve the digestibility of PBPs. The diversity of plant protein sources plays an important role in improving the PBPs quality. Several types of models such as in vitro (the static and semi-dynamic INFOGEST) and in silico models have been proposed and used in simulating the digestion of PBPs. Processing methods including germination, fermentation, thermal and non-thermal treatment can be applied to improve the digestibility of PBPs. PBPs and their hydrolysates show potential health effects including antioxidant, anti-inflammatory, anti-diabetic, anti-hypertensive and anti-cancer activities. Based on the literature, diverse PBPs are ideal protein sources, and exhibit favorable digestive properties and health benefits that could be further improved by different processing technologies. Future research should explore the molecular mechanisms underlying the bioactivity of PBPs and their hydrolysates.

Technological and health properties and main challenges in the production of vegetable beverages and dairy analogs

Lactose intolerance affects about 68-70% of the world population and bovine whey protein is associated with allergic reactions, especially in children. Furthermore, many people do not consume dairy-based foods due to the presence of cholesterol and ethical, philosophical and environmental factors, lifestyle choices, and social and religious beliefs. In this context, the market for beverages based on pulses, oilseeds, cereals, pseudocereals and seeds and products that mimic dairy foods showed a significant increase over the years. However, there are still many sensory, nutritional, and technological limitations regarding producing and consuming these products. Thus, to overcome these negative aspects, relatively simple technologies such as germination and fermentation, the addition of ingredients/nutrients and emerging technologies such as ultra-high pressure, pulsed electric field, microwave and ultrasound can be used to improve the product quality. Moreover, consuming plant-based beverages is linked to health benefits, including antioxidant properties and support in the prevention and treatment of disorders and common diseases like hypertension, diabetes, anxiety, and depression. Thus, vegetable-based beverages and their derivatives are viable alternatives and low-cost for replacing dairy foods in most cases.

Techno-functional attributes of oilseed proteins: influence of extraction and modification techniques

Plant-based protein isolates and concentrates are nowadays becoming popular due to their nutritional, functional as well as religious concerns. Among plant proteins, oilseeds, a vital source of valuable proteins, are continuously being explored for producing protein isolates/concentrates. This article delineates the overview of conventional as well as novel methods for the extraction of protein and their potential impact on its hydration, surface properties, and rheological characteristics. Moreover, proteins undergo several modifications using physical, chemical, and biological techniques to enhance their functionality by altering their microstructure and physical performance. The modified proteins hold a pronounced scope in novel food formulations. An overview of these protein modification approaches and their effects on the functional properties of proteins have also been presented in this review.

In vitro protein digestibility of different soy-based products: effects of microstructure, physico-chemical properties and protein aggregation

This study investigates the effects of protein structure and food microstructure on the in vitro protein gastrointestinal digestibility of different soy-based products, such as soy drink, reconstituted soy drink powder, firm tofu, and yuba. The results of the chemical cross-linking analysis showed that hydrogen bonds and hydrophobic interactions were the main forces driving protein aggregation in (reconstituted) soy drink powder and firm tofu, whereas disulphide bonds were significantly more important for soy drink and yuba. The β-sheet content of soy drink (36.5%) was lower than that of yuba (43.3%), but significantly higher than those of soy drink powder (23.2%) and firm tofu (29.8%). The in vitro protein digestibility decreased in the order of firm tofu > reconstituted soy drink powder > yuba > soy drink. Principal component analysis showed that protein gastrointestinal digestibility was positively correlated with the surface SH content and soluble protein content released by SDS + urea (SB-SA) but negatively correlated with the disulphide bonds and β-sheet content for the four soybean products.

Redesign of air/oil-water interface via physical fields coupled with pH shifting to improve the emulsification, foaming, and digestion properties of plant proteins

The application of plant proteins in food systems is largely hindered by their poor foaming or emulsifying properties and low digestibility compared with animal proteins, especially due to the aggregate state with tightly folded structure, slowly adsorbing at the interfaces, generating films with lower mechanical properties, and exposing less cutting sites. Physical fields and pH shifting have certain synergistic effects to efficiently tune the structure and redesign the interfacial layer of plant proteins, further enhancing their foaming or emulsifying properties. The improvement mechanisms mainly include: i) Aggregated plant proteins are depolymerized to form small protein particles and flexible structure is more easily exposed by combination treatment; ii) Particles with appropriate surface properties are quickly adsorbed to the interfacial layer, and then unfolded and rearranged to generate a tightly packed stiff interfacial layer to enhance bubble and emulsion stability; and iii) The unfolding and rearrangement of protein structure at the interface may result in the exposure of more cutting sites of digestive enzymes. This review summarizes the latest research progress on the structural changes, interfacial behaviors, and digestion properties of plant proteins under combined treatment, and elucidates the future development of these modification technologies for plant proteins in the food industry.

Effects of aroma-taste interaction on the sensory attributes of rebaudiosides in soymilk and milk

BACKGROUND

Rebaudioside A (Reb-A) and rebaudioside M (Reb-M) are intense natural sweeteners but can also elicit bitterness and a bitter aftertaste. In this study, the effect of vanilla and chocolate flavorings on the sensory attributes of Reb-A and Reb-M applied to soymilk and milk was investigated to identify whether the addition of flavoring could enhance the sweetness via aroma-taste interactions.

RESULTS

Nine samples each of soymilk and milk were formulated by adding sucrose, Reb-A and Reb-M in three flavor conditions (no flavoring, vanilla, and chocolate). Descriptive analyses were conducted using nine panelists for the soymilk and eight panelists for the milk. Another descriptive analysis was conducted using the same samples with olfactory occlusion via the wearing of a nose clip to check whether the sweetness enhancement was due to olfactory input. The chocolate flavoring significantly enhanced the sweetness of Reb-A and Reb-M and reduced the bitterness, bitter aftertaste and astringency in both soymilk and milk. The vanilla flavoring was not as effective as the chocolate flavoring in enhancing sweetness. When the olfactory passage was closed with a nose clip, the sweetness enhancement and bitterness suppression were not detected in the samples.

CONCLUSION

The addition of chocolate flavoring could successfully improve the sensory profile of soymilk sweetened with Reb-A through aroma-taste interactions. © 2023 Society of Chemical Industry.

Comparison between hydrodynamic and ultrasound cavitation on the inactivation of lipoxygenase and physicochemical properties of soy milk

The effects of hydrodynamic cavitation (HC) and ultrasound cavitation (UC) on the lipoxygenase activity and physicochemical properties of soy milk were evaluated. The results revealed that both ultrasound cavitation and hydrodynamic cavitation significantly inactivated the lipoxygenase activity. After the exposure to ultrasound cavitation at 522.5 W/L and 70 °C for 12 min, the lipoxygenase activity was inactivated by 96.47 %. Meanwhile, HC treatment with the cavitation number of 0.0133 for 240 min led to the loss of 79.31 % of lipoxygenase activity. An artificial neural network was used to model and visualize the effects of different parameters after ultrasound cavitation treatment on the inactivation efficiency of soy milk. Turbiscan test results showed that hydrodynamic and ultrasound cavitation decreased the instability index and particle size of soy milk. Moreover, the total free amino acid content was significantly increased after hydrodynamic and ultrasound cavitation treatment. Gas chromatography-mass spectrometry showed that the total content of beany flavor compounds decreased after acoustic cavitation and HC treatment. Acoustic cavitation and HC affected the tertiary and secondary structure of soy milk, which was related to the inactivation of lipoxygenase. We aim to explore a potential and effective way of the application in soy milk processing by comparing the ultrasound equipped with heat treatment and hydrodymic cavitation.

A review of alternative proteins for vegan diets: Sources, physico-chemical properties, nutritional equivalency, and consumer acceptance

Alternate proteins are gaining popularity as a more sustainable and environmentally friendly alternative to animal-based proteins. These proteins are often considered healthier and are suitable for people following a vegetarian or vegan diet. Alternative proteins can be recovered from natural sources like legumes, grains, nuts, and seeds, while single cell proteins (mycoproteins), and algal proteins are being developed using cutting-edge technology to grow fungus, yeast and algal cells in a controlled environment, creating a more sustainable source of protein. Although, the demand for alternative protein products is increasing, there still happens to be a large gap in use among the general consumers mainly stemming from its lower bioavailability, lack of nutritional equivalency and reduced digestibility compared to animal proteins. The focus of the review is to emphasize on various sources and technologies for recovering alternative proteins for vegan diets. The review discusses physicochemical properties of alternative proteins and emphasise on the role of various processing technologies that can change the digestibility and bioavailability of these proteins. It further accentuates the nutritional equivalency and environmental sustainability of alternative protein against the conventional proteins from animals. The food laws surrounding alternative proteins as well as the commercial potential and consumer acceptance of alternative protein products are also highlighted. Finally, key challenges to improve the consumer acceptability and market value of plant-based proteins would be in achieving nutrient equivalency and enhance bioavailability and digestibility while maintaining the same physicochemical properties, taste, texture, as animal proteins, has also been highlighted.

Effect of pH treatment on egg white protein digestion and the peptidomics of their in vitro digests

The pH treatment significantly enhanced the functional properties of egg white protein (EWP), but little is known about the relationship between pH treatment and in vitro digestion of EWP. In this paper, we explored the effect of pH treatment (pH 2, pH 2-7, pH 12 and pH 12-7) on the digestibility of egg white protein and peptide profiling using the digestion kinetics and peptidomics methods, separately. The results implied that all pH treatment reduced the protein digestibility in gastric phase, while alkaline pH (pH 12 and pH 12-7) showed greater digestion level and more gastric peptides, and more importantly, produced a greater amount of potentially bioactive peptides than acid treated samples. Besides, the least number of potentially bioactive peptides was obtained at pH 2, but this could be improved by adjusting pH 2 back to 7. Notably, the unique bioactive peptides induced by pH were mainly relevant to DPP IV inhibitor. These differences of digestibility and peptide profiling might be attributed to the change of protein structure and the formation of molten sphere, altering cleavage sites of digestive enzymes. This work would give an enlightening insight into the digestive and nutritional characteristics of the pH-induced EWP to expand their application in the field of food and healthcare.

The influence of ionic polysaccharides on the physicochemical and techno-functional properties of soy proteins; a comprehensive review

Since the world's population has surged in recent decades, the need for sustainable as well as environmentally friendly protein sources is growing. However, there are daunting challenges in utilizing these protein sources in the food industry due to their poor techno-functional properties compared with animal proteins. Numerous procedures have been introduced to improve plant protein functionalities with related pros and cons. Among them, complexation with polysaccharides is considered a safe and effective process for modulating plant proteins' technological and industrial applications. Notwithstanding the nutritional value of soy protein (SP) as a "complete protein," it is a crucial protein commercially because of its rank as the highest-traded plant-based protein worldwide. The current review deals with SP complexation with ionic polysaccharides, including chitosan, alginate, carrageenan, and xanthan gum, and their effects on the physicochemical and techno-functional properties of SP. Accordingly, the structure of SP and the abovementioned polysaccharides have been considered for a better understanding of the possible interactions. Then, the changes in the physicochemical and functional properties of SP and their potential applications in the formulation of plant-based food products have been discussed. Overall, ionic polysaccharides at optimum conditions would improve the functional properties of SP by altering its secondary structure, making it suitable for a wide range of applications in the food industry.

Effect of ultrasound and microwave treatment on the level of volatile compounds, total polyphenols, total flavonoids, and isoflavones in soymilk processed with black soybean (Glycine max (L.) Merr.)

This study analyzed the effect of ultrasound treatment (up to 9 min, 20 kHz, 130 W) on the volatile compounds, total polyphenols, total flavonoids, and isoflavones (daidzein, genistein, daidzin, genistin, and glycitin) in soymilk processed with microwave-roasted (700 W for 270 s) black soybean (Glycine max (L.) Merr.). 1-Hexanol and 1-octen-3-ol, unpleasant soybean flavors, were found to decrease by up to 96.13% and 93.04%, respectively, in ultrasound-treated soymilk compared to the control. 2,3-Diethyl-5-methylpyrazine, a baked flavor, which exhibited the highest odor impact ratio in soymilk processed with microwave-roasted soybean, increased significantly during ultrasound treatment (p < 0.05). The content of total isoflavones, polyphenols, and flavonoids increased (p < 0.05) with the increase in ultrasound treatment time. Spearman's correlation analysis showed that browning was positively correlated (p < 0.01) with total phenols, total furans, total pyrazines, total polyphenols, and total isoflavones. This study discusses the applicability of microwave-roasted soybeans for improving the volatile profile and bioactive compounds in soymilk and provides information on the effects of ultrasound treatment on the volatile compounds, total polyphenols, flavonoids, and isoflavones in soymilk.

An Updated Review of Soy-Derived Beverages: Nutrition, Processing, and Bioactivity

The global market for plant-based drinks is experiencing rapid growth driven by consumer demand for more sustainable diets, including vegetarian and vegan options. Soy beverages in particular are gaining popularity among individuals with lactose intolerance and milk protein allergies. They are considered an excellent source of high-quality protein, vitamin B, unsaturated fatty acids, and beneficial phytochemicals such as phytosterols, soy lecithins, and isoflavones. This review presents a comprehensive market survey of fifty-two soy beverages available in Spain and other European countries. The predominant category among those evaluated was calcium and vitamin-fortified drinks, accounting for 60% of the market. This reflects the need to address the nutritional gap compared to cow's milk and meet essential dietary requirements. The review covers the technological aspects of industrial soy milk production, including both traditional methods and innovative processing techniques. Additionally, it analyzes multiple studies and meta-analyses, presenting compelling evidence for the positive effects of soy beverages on various aspects of health. The review specifically examines the contributions of different components found in soy beverages, such as isoflavones, proteins, fiber, and oligosaccharides. Moreover, it explores controversial aspects of soy consumption, including its potential implications for growth, puberty, fertility, feminization, and the thyroid gland.

Effect of Microwave Vacuum Freeze-Drying Power on Emulsifying and Structure Properties of Egg White Protein

The study investigated the effects of different microwave vacuum freeze-drying powers (100-500 W) on the emulsifying properties and structural characteristics of egg white protein, which is of great significance in enhancing the added value of EWP and promoting its application. Emulsification analysis revealed that the emulsification performance was significantly influenced by microwave power and reached its maximum at 300 W. Fourier-transform infrared spectroscopy (FT-IR) and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analyses showed that microwave vacuum freeze-drying treatment altered the secondary structure of EWP without changing its peptide structure. Fluorescence measurements indicated that the maximum fluorescence emission intensity decreased, and the maximum emission wavelength shifted towards blue as the power increased. Particle size, zeta potential, scanning electron microscopy (SEM), and differential scanning calorimetry (DSC) analyses showed that the average particle size of EWP reached the minimum value of 1203.66 nm, the absolute value of zeta potential reached the maximum value of 41.35 mV, and the thermal stability was strongest, with a more uniform and loose structure observed at 300 W. Texture profile analysis (TPA) showed that appropriate power treatment significantly enhanced the chewiness and viscoelasticity of egg white protein. Therefore, appropriate power treatment could effectively improve the emulsifying properties and stability.

Recent innovations and emerging technological advances used to improve quality and process of plant-based milk analogs

The worldwide challenges related to food sustainability are presently more critical than ever before due to the severe consequences of climate change, outbreak of epidemics, and wars. Many consumers are shifting their dietary habits toward consuming more plant-based foods, such as plant milk analogs (PMA) for health, sustainability, and well-being reasons. The PMA market is anticipated to reach US$38 billion within 2024, making them the largest segment in plant-based foods. Nevertheless, using plant matrices to produce PMA has numerous limitations, including, among others, low stability and short shelf life. This review addresses the main obstacles facing quality and safety of PMA formula. Moreover, this literature overview discusses the emerging approaches, e.g., pulsed electric field (PEF), cold atmospheric plasma (CAP), ultrasound (US), ultra-high-pressure homogenization (UHPH), ultraviolet C (UVC) irradiation, ozone (O3), and hurdle technology used in PMA formulations to overcome their common challenges. These emerging technologies have a vast potential at the lab scale to improve physicochemical characteristics, increase stability and extend the shelf-life, decrease food additives, increase nutritional and organoleptic qualities of the end product. Although the PMA fabrication on a large scale using these technologies can be expected in the near future to formulate novel food products that can offer green alternatives to conventional dairy products, further development is still needed for wider commercial applications.

Fabrication of icariin-soymilk nanoparticles with ultrasound-assisted treatment

Ultrasound is effective to fabricate nanocomplex. Soymilk is a natural nanocarrier with good compatibility. However, information about soymilk-nutraceuticals nanocomplex is limited. In this work, soymilk was used to encapsulate icariin, a well known nutraceutical with poor bioavailability. The effect of ultrasound on the quality of icariin-soymilk nanocomplexes (ISNCs) was investigated. Ultrasound could reduce the particle size, improve the surface hydrophobicity and change the microstructure of soymilk. With increasing ultrasound treatment time, an increased surface hydrophobicity was observed. The highest encapsulation efficiency (89.67 %) and loading capacity (28.92 µg/mg) were found for USI-20, whereas the smallest particle size (132.47 nm) was observed for USI-120. USI-60 showed the lowest ζ-potential (-31.33 mV) and the highest bioaccessibility (76.08 %). Ultrasound could enhance the storage stability of ISNCs. The data of NMR and fluorescence indicated that ISNCs were mainly stabilized by hydrophobic interaction.

Impact of ultrasound processing on alternative protein systems: Protein extraction, nutritional effects and associated challenges

Proteins from alternative sources including terrestrial and aquatic plants, microbes and insects are being increasingly explored to combat the dietary, environmental and ethical challenges linked primarily to conventional sources of protein, mainly meat and dairy proteins. Ultrasound (US) technologies have emerged as a clean, green and efficient methods for the extraction of proteins from alternative sources compared to conventional methods. However, the application of US can also lead to modifications of the proteins extracted from alternative sources, including changes in their nutritional quality (protein content, amino acid composition, protein digestibility, anti-nutritional factors) and allergenicity, as well as damage of the compounds associated with an increased degradation resulting from extreme US processing conditions. This work aims to summarise the main advances in US equipment currently available to date, including the main US parameters and their effects on the extraction of protein from alternative sources, as well as the studies available on the effects of US processing on the nutritional value, allergenicity and degradation damage of these alternative protein ingredients. The main research gaps identified in this work and future challenges associated to the widespread application of US and their scale-up to industry operations are also covered in detail.

Recent advances on the impact of novel non-thermal technologies on structure and functionality of plant proteins: A comprehensive review

The recent trend in consumption of plant-based protein over animal protein opens up a new avenue for sustainable agriculture practice, less environmental impact and greenhouse gas emission. The modification of plant-based proteins by novel non-thermal technologies includes the structural transformation followed by the modulation of their functional properties that are exploited to develop a protein ingredient system for application in food formulation. This review explores the impact of non-thermal process technologies on structural modification of plant proteins followed by improvement in protein's function in food formulation. Novel concepts articulating the impact of non-thermal technologies on structural and functional modification of plant proteins affecting it's digestibility and bioavailability are addressed. Limitations and prospects of applying non-thermal technologies in developing an alternative plant-based protein food system are also summarized. Non-thermal processes are considered as the emerging technologies that results in conformational changes in secondary, tertiary and quaternary structure of plant proteins which helps in modification of functional properties without jeopardizing the organoleptic properties and bioactivity of the protein. However, extensive future study is needed to optimize the non-thermal process parameters along with the finding of new protein sources to achieve healthy and sustainable plant-based food system.

Plant-Based Meat Analogues Weaken Gastrointestinal Digestive Function and Show Less Digestibility Than Real Meat in Mice

Real meat and plant-based meat analogues have different in vitro protein digestibility properties. This study aims to further explore their in vivo digestion and absorption and their effects on the gastrointestinal digestive function of mice. Compared with the real pork and beef, plant-based meat analogues significantly reduced the number of gastric parietal cells, the levels of gastrin/CCKBR, acetylcholine/AchR, Ca²⁺, CAMK II, PKC, and PKA, the activity of H⁺, K⁺-ATPase, and pepsin, the duodenal villus height, and the ratio of villus height to crypt depth and downregulated the expression of most nitrogen nutrient sensors. Peptidomics revealed that plant-based meat analogues released fewer peptides during in vivo digestion and increased the host- and microbial-derived peptides. Moreover, the real beef showed better absorption properties. These results suggested that plant-based meat analogues weaken gastrointestinal digestive function of mice, and their digestion and absorption performance in vivo is not as good as the real meat.

Effect of hybrid drying technique on non-traditional Chicory (Cichorium intybus L.) herb: Phytochemical, antioxidant characteristics, and optimization of process conditions

This research investigated the influence of microwave-assisted fluidized bed drying (MAFBD) on the antioxidant and phytochemical characteristics of Chicory. Microwave power, temperature, and air velocity were used as process variables varied between 180–540 W, 50–70 °C, and 15–20 m/s, respectively. The responses determined for deciding the optimal criteria were total phenolics content, ascorbic acid, DPPH radical scavenging activity, total chlorophyll, carotene content, total flavonoid content, tannin content, and saponin content of the dried chicory. Statistical analyses were done by using the response surface methodology, which showed that independent variables affected the responses to a varied extent. The design expert predicted 462.30 W microwave power, 70°C temperature, and 15 m/s air velocity as optimum conditions to obtain highest desirability for the dried chicory. Separate validation experiments were conducted, under optimum conditions, to verify the predictions and adequacy of the second-order polynomial models. Under these optimal conditions, the predicted amount of ascorbic acid content was 38.32 mg/100g DW, total phenolic content 216.42 mg/100g DW, total flavonoid content mg/100g DW, DPPH scavenging activity 36.10 μg/ml, total chlorophyll content 311.79 mg/100g, carotene content 7.30 mg/100g, tannin content 2.72 mg/100g, and saponin content 0.46 mg/100g. The investigated parameters had a significant effect on the quality of the dried chicory. Taking the aforesaid results into consideration, our study recommended MAFBD as a promising technique with minimum changes in antioxidant and phytochemical content of chicory.

Production and characterization of bioactive peptides in novel functional soybean chhurpi produced using Lactobacillus delbrueckii WS4

A novel soy chhurpi product was developed by fermentation of soymilk using proteolytic Lactobacillus delbrueckii strains isolated from traditional chhurpi production of Sikkim Himalaya. Soymilk fermentation by L. delbrueckii WS4 was associated with the hydrolysis of globulin proteins, with observed antioxidant, and ACE-inhibitory activity which further increased upon simulated in vitro gastrointestinal digestion. Peptidomics analysis of soy chhurpi and its gastrointestinal digest resulted in the identification of bioactive peptides with ACE-inhibitory and antioxidant properties. In silico antihypertensive property prediction followed by molecular docking study demonstrated strong binding affinity of selected peptides with ACE. The glycinin-derived peptide, SVIKPPTDE escaped gastrointestinal digestion and demonstrated strong non-bond interactions with ACE catalytic residues. QSAR models predicted an ACE-inhibitory IC50 of 21.29 µM for SVIKPPTDE. This is the first report on the production of novel functional soy chhurpi cheese using defined starter strains and the identification of bioactive peptides in undigested and gastrointestinal digested soy chhurpi.

Effect of radio frequency, ultrasound, microwave-assisted papain, and alcalase hydrolysis on the structure, antioxidant activity, and peptidomic profile of Rosa roxburghii Tratt. seed protein

Traditional enzymatic hydrolysis methods have defects such as low efficiency and poor bioactivity in the production of active peptides. In this study, radio frequency (RF) technology was innovatively used to assist the hydrolysis of Rosa roxburghii Tratt. seed protein (RTSP) by papain and alcalase. RF-assisted hydrolysis was compared with ultrasound-(US) and microwave (MW)-assisted techniques in terms of the degree of hydrolysis, structure, antioxidant properties, and changes in the peptidome of the hydrolysates to clarify the mechanism of functional change of physically-assisted hydrolysate. All three methods improved hydrolysis efficiency. The degree of hydrolysis (DH) of papain group increased from 6.38% to 7.97%, 9.97% and 8.37% after US-, MW- and RF-assisted hydrolysis, respectively, while the DH of alcalase-treated group increased from 21.13% to 25.66%, 26.03%, and 23.01%, respectively. The in vitro antioxidant capacity and intracellular antioxidant capacity of RTSP and its hydrolysates were measured and evaluated by fuzzy statistical evaluation, and MW-assisted alcalase hydrolysis had the highest in vitro and intracellular antioxidant activity scores of 0.713 and 0.820, respectively. Fourier transform infrared and amino acid composition analysis explained the enhanced antioxidant properties of the hydrolysates. Further peptide profiling showed the physical assistance led to an increase in the species and contents of small molecule antioxidant peptides compared to enzyme treatment alone. Pearson's linear correlation analysis showed that AY, LY, IY, PHW, SVL, LHL, YYV, VYY, and NHAV were significantly correlated with the antioxidant properties of hydrolysates. Our data suggested that physical assistance such as US, MW, and RF were effective to improve the efficiency of enzymatic hydrolysis and produce novel antioxidant peptides. PRACTICAL APPLICATION: In this study, it was found that electromagnetic wave-assisted enzymatic hydrolysis could improve the efficiency of hydrolysis and enhance the antioxidant activity of hydrolysates compared to unassisted means. Compared with MW treatment, RF has the comparable hydrolysis effect, but has the advantages of high penetration ability, good uniformity, and low energy consumption and has greater potential for the production of bioactive peptides.

Legume Seed Protein Digestibility as Influenced by Traditional and Emerging Physical Processing Technologies

The increased consumption of legume seeds as a strategy for enhancing food security, reducing malnutrition, and improving health outcomes on a global scale remains an ongoing subject of profound research interest. Legume seed proteins are rich in their dietary protein contents. However, coexisting with these proteins in the seed matrix are other components that inhibit protein digestibility. Thus, improving access to legume proteins often depends on the neutralisation of these inhibitors, which are collectively described as antinutrients or antinutritional factors. The determination of protein quality, which typically involves evaluating protein digestibility and essential amino acid content, is assessed using various methods, such as in vitro simulated gastrointestinal digestibility, protein digestibility-corrected amino acid score (IV-PDCAAS), and digestible indispensable amino acid score (DIAAS). Since most edible legumes are mainly available in their processed forms, an interrogation of these processing methods, which could be traditional (e.g., cooking, milling, extrusion, germination, and fermentation) or based on emerging technologies (e.g., high-pressure processing (HPP), ultrasound, irradiation, pulsed electric field (PEF), and microwave), is not only critical but also necessary given the capacity of processing methods to influence protein digestibility. Therefore, this timely and important review discusses how each of these processing methods affects legume seed digestibility, examines the potential for improvements, highlights the challenges posed by antinutritional factors, and suggests areas of focus for future research.

Impact of the Structural Modifications of Potato Protein in the Digestibility Process under Semi-Dynamic Simulated Human Gastrointestinal In Vitro System

The raising consumer demand for plant-derived proteins has led to an increased production of alternative protein ingredients with varying processing histories. In this study, we used a commercially available potato protein ingredient with a nutritionally valuable amino acid profile and high technological functionality to evaluate if the digestibility of a suspension with the same composition is affected by differences in the structure. Four isocaloric (4% protein, w/w) matrices (suspension, gel, foam and heat-set foam) were prepared and their gastrointestinal fate was followed utilizing a semi-dynamic in vitro digestion model. The microstructure was observed by confocal laser scanning microscopy, protein breakdown was tested by electrophoresis and free amino acids after intestinal digestion was estimated using liquid chromatography/triple-quadruple-mass spectrometry (LC-TQMS). The heat-treated samples showed a higher degree of hydrolysis and lower trypsin inhibitory activity than the non-heat-treated samples. An in vitro digestible indispensable amino acid score was calculated based on experimental data, showing a value of 0.9 based on sulfur amino acids/valine as the limiting amino acids. The heated samples also showed a slower gastric emptying rate. The study highlights the effect of the food matrix on the distribution of the peptides created during various stages of gastric emptying.

A review of thermosensitive antinutritional factors in plant-based foods

Legumes and cereals account for the vast proportion of people's daily intake of plant-based foods. Meanwhile, a large number of antinutritional factors in legumes and cereals hinder the body absorption of nutrients and reduce the nutritional value of food. In this paper, the antinutritional effects, determination, and passivation methods of thermosensitive antinutritional factors such as trypsin inhibitors, urease, lipoxygenase, and lectin were reviewed to provide theoretical help to reduce antinutritional factors in food and improve the utilization rate of plant-based food nutrition. Since trypsin inhibitors and lectin have been more extensively studied and reviewed previously, the review mainly focused on urease and lipoxygenase. This review summarized the information of thermosensitive antinutritional factors, trypsin inhibitors, urease, lipoxygenase, and lectin, in cereals and legumes. The antinutritional effects, and physical and chemical properties of trypsin inhibitors, urease, lipoxygenase, and lectin were introduced. At the same time, the research methods for the detection and inactivation of these four antinutritional factors were also summarized in the order of research conducted time. The rapid determination and inactivation of antinutrients will be the focus of attention for the food industry in the future to improve the nutritional value of food. Exploring what structural changes could passivation technologies bring to antinutritional factors will provide a theoretical basis for further understanding the mechanisms of antinutritional factor inactivation. PRACTICAL APPLICATIONS: Antinutritional factors in plant-based foods hinder the absorption of nutrients and reduce the nutritional value of the food. Among them, thermosensitive antinutritional factors, such as trypsin inhibitors, urease, lipoxygenase, and lectins, have a high proportion among the antinutritional factors. In this paper, we investigate thermosensitive antinutritional factors from three perspectives: the antinutritional effect of thermosensitive antinutritional factors, determination, and passivation methods. The current passivation methods for thermosensitive antinutritional factors revolve around biological, physical, and chemical aspects, and their elimination mechanisms still need further research, especially at the protein structure level. Reducing the level of antinutritional factors in the future food industry while controlling the loss of other nutrients in food is a goal that needs to be balanced. This paper reviews the antinutritional effects of thermosensitive antinutritional factors and passivation methods, expecting to provide new research ideas to improve the nutrient utilization of food.

Influence of Emerging Technologies on the Utilization of Plant Proteins

Protein from plant sources is claimed alternatives to animal sources in the human diet. Suitable protein sources need high protein digestibility and amino acid bioavailability. In terms of protein functionality and food applications, they also need high-quality attributes, such as solubility, gelling, water- and oil-holding capacities, emulsifying, and foaming. Thermal processing can improve the nutritional quality of plants with some disadvantages, like reducing the assimilation of micronutrients (vitamins and minerals). Emerging technologies-such as ultrasound, high-pressure, ohmic heating, microwave, pulsed electric field, cold plasma, and enzymatic processes-can overcome those disadvantages. Recent studies demonstrate their enormous potential to improve protein techno-functional properties, protein quality, and decrease protein allergenicity. However, the literature lacks a broader evaluation, including protein digestibility, industrial-scale optimization, and exploring applications to these alternative protein sources.

Bioactivities, Applications, Safety, and Health Benefits of Bioactive Peptides From Food and By-Products: A Review

Bioactive peptides generated from food proteins have great potential as functional foods and nutraceuticals. Bioactive peptides possess several significant functions, such as antioxidative, anti-inflammatory, anticancer, antimicrobial, immunomodulatory, and antihypertensive effects in the living body. In recent years, numerous reports have been published describing bioactive peptides/hydrolysates produced from various food sources. Herein, we reviewed the bioactive peptides or protein hydrolysates found in the plant, animal, marine, and dairy products, as well as their by-products. This review also emphasizes the health benefits, bioactivities, and utilization of active peptides obtained from the mentioned sources. Their possible application in functional product development, feed, wound healing, pharmaceutical and cosmetic industries, and their use as food additives have all been investigated alongside considerations on their safety.

Recent Advances in the Application of Enzyme Processing Assisted by Ultrasound in Agri-Foods: A Review

The intensification of processes is essential for the sustainability of the biorefinery concept. Enzyme catalysis assisted by ultrasound (US) may offer interesting opportunities in the agri-food sector because the cavitation effect provided by this technology has been shown to improve the efficiency of the biocatalysts. This review presents the recent advances in this field, focused on three main applications: ultrasound-assisted enzymatic extractions (UAEE), US hydrolysis reactions, and synthesis reactions assisted by US for the manufacturing of agri-food produce and ingredients, enabling the upgrading of agro-industrial waste. Some theoretical and experimental aspects of US that must be considered are also reviewed. Ultrasonic intensity (UI) is the main parameter affecting the catalytic activity of enzymes, but a lack of standardization for its quantification makes it unsuitable to properly compare results. Applications of enzyme catalysis assisted by US in agri-foods have been mostly concentrated in UAEE of bioactive compounds. In second place, US hydrolysis reactions have been applied for juice and beverage manufacturing, with some interesting applications for producing bioactive peptides. In last place, a few efforts have been performed regarding synthesis reactions, mainly through trans and esterification to produce structured lipids and sugar esters, while incipient applications for the synthesis of oligosaccharides show promising results. In most cases, US has improved the reaction yield, but much information is lacking on how different sonication conditions affect kinetic parameters. Future research should be performed under a multidisciplinary approach for better comprehension of a very complex phenomenon that occurs in very short time periods.

Plant Protein-Based Delivery Systems: An Emerging Approach for Increasing the Efficacy of Lipophilic Bioactive Compounds

The development of plant protein-based delivery systems to protect and control lipophilic bioactive compound delivery (such as vitamins, polyphenols, carotenoids, polyunsaturated fatty acids) has increased interest in food, nutraceutical, and pharmaceutical fields. The quite significant ascension of plant proteins from legumes, oil/edible seeds, nuts, tuber, and cereals is motivated by their eco-friendly, sustainable, and healthy profile compared with other sources. However, many challenges need to be overcome before their widespread use as raw material for carriers. Thus, modification approaches have been used to improve their techno-functionality and address their limitations, aiming to produce a new generation of plant-based carriers (hydrogels, emulsions, self-assembled structures, films). This paper addresses the advantages and challenges of using plant proteins and the effects of modification methods on their nutritional quality, bioactivity, and techno-functionalities. Furthermore, we review the recent progress in designing plant protein-based delivery systems, their main applications as carriers for lipophilic bioactive compounds, and the contribution of protein-bioactive compound interactions to the dynamics and structure of delivery systems. Expressive advances have been made in the plant protein area; however, new extraction/purification technologies and protein sources need to be found Their functional properties must also be deeply studied for the rational development of effective delivery platforms.

Mechanism of low-frequency and high-frequency ultrasound-induced inactivation of soy trypsin inhibitors

In this study, the effect of ultrasonic frequency and power on the inactivation of soy trypsin inhibitors (TIs) was investigated to explore the ultrasound-induced inactivation mechanism. It was observed that 20 kHz and 355 kHz ultrasound have better inactivation efficiency than 1056 kHz. First-order rate constants for the inactivation process were obtained, which increased with increasing ultrasonic power at both 20 kHz and 355 kHz. For 20 kHz ultrasound, the formation of TI aggregates resulting from the physical effects of acoustic cavitation decreased the interactions between the active sites of TIs and trypsin, thus reducing the TI activity. For 355 kHz ultrasound, most of the methionine in the TIs was oxidised within 5 mins, resulting in a faster reduction of TI activity. Subsequent aggregation of TIs resulted in further TI inactivation. SDS-PAGE showed that neither disulphide bonds nor CC coupling were involved in the formation of aggregates.