Ultrasound viscous reduction effects on the proteolysis of soy protein isolate at a limited degree of hydrolysis: Changes in the functional characteristics and protein structure

High-concentration soy protein isolate was subjected to ultrasonication for viscosity reduction to assist the process of limited enzymatic hydrolysis. Ultrasonication (20 kHz, 10 min, 160 W/L) effectively reduced the viscosity of soy protein isolate at a comparatively high concentration of 14 % (w/v) and promoted the limited enzymatic hydrolysis (controlled degree of hydrolysis of 12 %) with a higher peptide yield than that of the conventional method. The correlations between substrate viscosity and peptide yield, as well as the viscosities of the resulting hydrolysates, were studied. The findings revealed positive correlations between the viscosities of the substrate and hydrolysate, underscoring the potential impact of altering substrate viscosity on the final product. Furthermore, the utilization of ultrasonic viscosity reduction-assisted proteolysis has shown its capability to improve the functional and physicochemical properties, as well as the protein structure of the hydrolysate, while maintaining the same level of hydrolysis. It is worth noting that there were significant alterations in particle size (decrease), β-sheet content (increase), β-turn content (increase), and random coil content (increase). Interestingly, ultrasonication unexpectedly impeded the degradation of molecular mass in proteins during proteolysis, while increasing the hydrophobic properties of the hydrolysate. These findings aligned with the observed reduction in bitterness and improvement in emulsifying properties and water-holding capacity.

Impact of ultrasonicated Lactobacillus delbrueckii subsp. bulgaricus, Streptococcus thermophilus and Lactiplantibacillus plantarum AF1 on the safety and bioactive properties of stirred yoghurt during storage

In this study, the effects of ultrasonicated Lactobacillus delbrueckii subsp. bulgaricus, Streptococcus thermophilus and Lactiplantibacillus plantarum AF1 (100 W, 30 kHz, 3 min) on the safety and bioactive properties of stirred yoghurt during storage (4 °C for 21 days) were investigated. The results showed that sonicated cultures were more effective in reducing pathogens than untreated ones. The highest antioxidant activity (DPPH and ABTS), α-glucosidase and α-amylase inhibition capacity were found in yoghurt containing sonicated probiotic + sonicated yoghurt starter cultures (P + Y + ). The highest amount of peptides (12.4 mg/g) was found in P + Y + yoghurts at the end of the storage time. There were not significant differences between the exopolysaccharide content of P + Y+ (17.30 mg/L) and P + Y- (17.20 mg/L) yoghurts, although it was significantly (P ≤ 0.05) higher than the other samples. The use of ultrasonicated cultures could enhance the safety of stirred yoghurt and improve its functional and bioactive properties.

Ultrasound-Assisted Enzymatic Protein Hydrolysis in Food Processing: Mechanism and Parameters

Ultrasound has been widely used as a green and efficient non-thermal processing technique to assist with enzymatic hydrolysis. Compared with traditional enzymatic hydrolysis, ultrasonic-pretreatment-assisted enzymatic hydrolysis can significantly improve the efficiency of enzymatic hydrolysis and enhance the biological activity of substrates. At present, this technology is mainly used for the extraction of bioactive substances and the degradation of biological macromolecules. This review is focused on the mechanism of enzymatic hydrolysis assisted by ultrasonic pretreatment, including the effects of ultrasonic pretreatment on the enzyme structure, substrate structure, enzymatic hydrolysis kinetics, and thermodynamics and the effects of the ultrasonic conditions on the enzymatic hydrolysis results. The development status of ultrasonic devices and the application of ultrasonic-assisted enzymatic hydrolysis in the food industry are briefly described in this study. In the future, more attention should be paid to research on ultrasound-assisted enzymatic hydrolysis devices to promote the expansion of production and improve production efficiency.

Sustainable emerging high-intensity sonication processing to enhance the protein bioactivity and bioavailability: An updated review

High-intensity ultrasound (HIU) is considered one of the promising non-chemical eco-friendly techniques used in food processing. Recently (HIU) is known to enhance food quality, extraction of bioactive compounds and formulation of emulsions. Various foods are treated with ultrasound, including fats, bioactive compounds, and proteins. Regarding proteins, HIU induces acoustic cavitation and bubble formation, causing the unfolding and exposure of hydrophobic regions, resulting in functional, bioactive, and structural enhancement. This review briefly portrays the impact of HIU on the bioavailability and bioactive properties of proteins; the effect of HIU on protein allergenicity and anti-nutritional factors has also been discussed. HIU can enhance bioavailability and bioactive attributes in plants and animal-based proteins, such as antioxidant activity, antimicrobial activity, and peptide release. Moreover, numerous studies revealed that HIU treatment could enhance functional properties, increase the release of short-chain peptides, and decrease allergenicity. HIU could replace the chemical and heat treatments used to enhance protein bioactivity and digestibility; however, its applications are still on research and small scale, and its usage in industries is yet to be implemented.

Impact of cavitation on the structure and functional quality of extracted protein from food sources - An overview

Increasing protein demands directly require additional resources to those presently and recurrently available. Emerging green technologies have witnessed an escalating interest in "Cavitation Processing" (CP) to ensure a non-invasive, non-ionizing and non-polluting extraction. The main intent of this review is to present an integrated summary of cavitation extraction methods specifically applied to food protein sources. Along with a comparative assessment carried out for each type of cavitation model, protein extraction yield and implications on the extracted protein's structural and functional properties. The basic principle of cavitation is due to the pressure shift in the liquid flow within milliseconds. Hence, cavitation emerges similar to boiling; however, unlike boiling (temperature change), cavitation occurs due to pressure change. Characterization and classification of sample type is also a prime candidate when considering the applications of cavitation models in food processing. Generally, acoustic and hydrodynamic cavitation is applied in food applications including extraction, brewing, microbial cell disruption, dairy processing, emulsification, fermentation, waste processing, crystallisation, mass transfer and production of bioactive peptides. Micro structural studies indicate that shear stress causes disintegration of hydrogen bonds and Van der Waals interactions result in the unfolding of the protein's secondary and/or tertiary structures. A change in the structure is not targeted but rather holistic and affects the physicochemical, functional, and nutritional properties. Cavitation assisted extraction of protein is typically studied at a laboratory scale. This highlights limitations against the application at an industrial scale to obtain potential commercial gains.

Ultrasound-assisted limited enzymatic hydrolysis of high concentrated soy protein isolate: Alterations on the functional properties and its relation with hydrophobicity and molecular weight

The effects of power ultrasound (US) pretreatment on the preparation of soy protein isolate hydrolysate (SPIH) prepared at the same degree of hydrolysis (DH) of 12 % were measured. Cylindrical power ultrasound was modified into mono-frequency (20, 28, 35, 40, 50 kHz) ultrasonic cup coupled with an agitator to make it applicable for high density SPI (soy protein isolate) solutions (14 %, w/v). A comparative study of the alterations of the hydrolysates molecular weight, hydrophobics, antioxidants and functional properties change as well as their relation were explored. The results showed that under the same DH, ultrasound pretreatment decelerated the degradation of protein molecular mass and the decrease rate of the degradation lessened with the increase of ultrasonic frequency. Meanwhile, the pretreatments improved the hydrophobics and antioxidants properties of SPIH. Both surface hydrophobicity (H0) and relative hydrophobicity (RH) of the pretreated groups increased with the decrease of ultrasonic frequency. Lowest frequency (20 kHz) ultrasound pretreatment had the most improved emulsifying properties and water holding capacities, although decrease in the viscosity and solubility were found. Most of these alterations were correspondence toward the change in hydrophobics properties and molecular mass. In conclusion, the frequency selection of ultrasound pretreatment is essential for the alteration of SPIH functional qualities prepared at the same DH.

Advanced Processing of Giant Kelp (Macrocystis pyrifera) for Protein Extraction and Generation of Hydrolysates with Anti-Hypertensive and Antioxidant Activities In Vitro and the Thermal/Ionic Stability of These Compounds

In this study, giant kelp was explored under various conventional and ultrasound-assisted extraction (UAE) conditions for the extraction of protein, its hydrolysis, and ultrafiltration to generate multiple fractions. The amino acid composition of all the fractions and their biological activities in vitro, including angiotensin-converting enzyme I (ACE) inhibitory activity and antioxidant activities (2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging, reducing power (RP), and ferrous chelating (FC) activities) were tested by storing the compounds for 2 weeks at various temperatures (-20-60 °C) and pHs (2-11) to elucidate their thermal and ionic stability, respectively. The yield of protein extraction using the conventional method was lower (≈39%) compared to the use of UAE (150 W, 15 min), which achieved protein recoveries of approximately 60%. After enzymatic hydrolysis and ultrafiltration, low-molecular-weight (MW) hydrolysates had the highest levels of ACE inhibitory (80%), DPPH (84%), RP (0.71 mM trolox equivalents), and FC (81%) activities. Amino acids associated with peptides of high biological activities, such as Val, Ala, Asx, Gly, Lys, Met, Leu, and His, were at higher levels in the low MW fraction compared to any other sample. The biological activities in vitro of all the samples fluctuated under the multiple storage conditions studied, with the highest stability of all the samples appreciated at -20 °C and pH 7. This study shows for the first time the use of giant kelp as a promising source of bioactive peptides and indicates the optimum processing and storing conditions for the use of these compounds as nutraceuticals or functional foods that could help in the prevention of cardiovascular disorders and multiple chronic diseases associated with oxidative damage.

Influence of the Enzymatic Hydrolysis Using Flavourzyme Enzyme on Functional, Secondary Structure, and Antioxidant Characteristics of Protein Hydrolysates Produced from Bighead Carp (Hypophthalmichthys nobilis)

In the current study, bighead carp fish were used in conjunction with the flavourzyme enzyme to obtain (FPH) fish protein hydrolysates. The optimum conditions of the hydrolysis process included an enzyme/substrate ratio of 4% and a temperature of 50 °C and pH of 6.5. The hydrolysis time was studied and investigated at 1, 3, and 6 h, and the (DH) degree of hydrolysis was recorded at 16.56%, 22.23%, and 25.48%, respectively. The greatest yield value was 17.83% at DH 25.48%. By increasing the DH up to 25.48%, the crude protein and total amino acid composition of the hydrolysate were 88.19% and 86.03%, respectively. Moreover, more peptides with low molecular weight were formed during hydrolysis, which could enhance the functional properties of FPH, particularly the solubility property ranging from 85% to 97%. FTIR analysis revealed that enzymatic hydrolysis impacted the protein's secondary structure, as indicated by a remarkable wavelength of amide bands. Additionally, antioxidant activities were investigated and showed high activity of DDPH radical scavenging, and hydroxyl radical scavenging demonstrated remarkable activity. The current findings demonstrate that the functional, structural, and antioxidant characteristics of FPH might make it an excellent source of protein and suggest potential applications in the food industry.

Dietary-Nutraceutical Properties of Oat Protein and Peptides

Oats are considered the healthiest grain due to their high content of phytochemicals, dietary fibers, and protein. In recent years, oat protein and peptides have gained popularity as possible therapeutic or nutraceutical candidates. Generally, oat peptides with bioactive properties can be obtained by the enzymatic hydrolysis of proteins and are known to have a variety of regulatory functions. This review article focused on the nutraceutical worth of oat proteins and peptides and also describes the application of oat protein as a functional ingredient. Outcomes of this study indicated that oat protein and peptides present various therapeutical properties, including antidiabetic, antioxidant, antihypoxic, antihypertensive, antithrombotic, antifatigue, immunomodulatory, and hypocholestrolaemic. However, most of the conducted studies are limited to in vitro conditions and less data is available on assessing the effectiveness of the oat peptides in vivo. Future efforts should be directed at performing systematic animal studies; in addition, clinical trials also need to be conducted to fully support the development of functional food products, nutraceutical, and therapeutical applications.

Enhancing the Biological Activities of Food Protein-Derived Peptides Using Non-Thermal Technologies: A Review

Bioactive peptides (BPs) derived from animal and plant proteins are important food functional ingredients with many promising health-promoting properties. In the food industry, enzymatic hydrolysis is the most common technique employed for the liberation of BPs from proteins in which conventional heat treatment is used as pre-treatment to enhance hydrolytic action. In recent years, application of non-thermal food processing technologies such as ultrasound (US), high-pressure processing (HPP), and pulsed electric field (PEF) as pre-treatment methods has gained considerable research attention owing to the enhancement in yield and bioactivity of resulting peptides. This review provides an overview of bioactivities of peptides obtained from animal and plant proteins and an insight into the impact of US, HPP, and PEF as non-thermal treatment prior to enzymolysis on the generation of food-derived BPs and resulting bioactivities. US, HPP, and PEF were reported to improve antioxidant, angiotensin-converting enzyme (ACE)-inhibitory, antimicrobial, and antidiabetic properties of the food-derived BPs. The primary modes of action are due to conformational changes of food proteins caused by US, HPP, and PEF, improving the susceptibility of proteins to protease cleavage and subsequent proteolysis. However, the use of other non-thermal techniques such as cold plasma, radiofrequency electric field, dense phase carbon dioxide, and oscillating magnetic fields has not been examined in the generation of BPs from food proteins.

Ultrasonication as a novel processing alternative to pasteurization for camel milk: Effects on microbial load, protein profile, and bioactive properties

Ultrasonic technology presents a promising novel tool in the food industry for the processing of milk and dairy products. In this study, we investigated the effects of ultrasonication (US) as an alternative to thermal pasteurization for stabilization of the bioactive properties of camel milk. Camel and bovine milk samples were subjected to US at 6 different power levels (US1-US6), and 1 set of each type of milk was concurrently subjected to flash heat pasteurization (FHP) for comparative analysis (100 mL; n = 4). The microbiological and bioactive parameters of the samples were analyzed during 7 d of storage at 4°C. In both milk types subjected to US ≥ 140 W (US3), the bacterial load was reduced by almost 4 log cycles and complete reduction of microbial load was achieved with US = 170 W and US = 210 W (US5 and US6 treatments, respectively). No significant changes in protein patterns were observed with either FHP or US treatment. In addition, bioactive properties (cholesteryl esterase and pancreatic lipase inhibition) were either enhanced or retained at US3 or higher. 2,2'-Azino-bis-3-ethylbenzthiazoline-6-sulfonic acid and ferric reducing antioxidant power activities in camel milk were decreased after FHP treatment but increased or retained upon US, particularly at US3 and US4 (160 W). Overall, under our experimental conditions, US4 was effective in completely reducing the microbial count, while concomitantly retaining different bioactive properties of both camel and bovine milk. These outcomes highlight the potential of US at 160 W as an efficient nonthermal alternative processing method for milk.

Recent application of protein hydrolysates in food texture modification

The demand for clean labels has increased the importance of natural texture modifying ingredients. Proteins are unique compounds that can impart unique textural and structural changes in food. However, lack of solubility and extensive aggregability of proteins have increased the demand for enzymatically hydrolyzed proteins, to impart functional and structural modifications to food products. The review elaborates the recent application of various proteins, protein hydrolysates, and their role in texture modification. The impact of protein hydrolysates interaction with other food macromolecules, the effect of pretreatments, and dependence of various protein functionalities on textural and structural modification of food products with controlled enzymatic hydrolysis are explained in detail. Many researchers have acknowledged the positive effect of enzymatically hydrolyzed proteins on texture modification over natural protein. With enzymatic hydrolysis, various textural properties including foaming, gelling, emulsifying, water holding capacity have been effectively improved. It is evident that each protein is unique and imparts exceptional structural changes to different food products. Thus, selection of protein requires a fundamental understanding of its structure-substrate property relation. For wider applicability in the industrial sector, more studies on interactions at the molecular level, dosage, functionality changes, and sensorial attributes of protein hydrolysates in food systems are required.

Plant-derived proteins as a sustainable source of bioactive peptides: recent research updates on emerging production methods, bioactivities, and potential application

The development of novel protein sources to compensate for the expected future shortage of traditional animal proteins due to their high carbon footprint is a major contemporary challenge in the agri-food industry currently. Therefore, both industry and consumers are placing a greater emphasis on plant proteins as a sustainable source of protein to meet the growing nutritional demand of ever increasing population. In addition to being key alternatives, many plant-based foods have biological properties that make them potentially functional or health-promoting foods, particularly physiologically active peptides and proteins accounting for most of these properties. This review discusses the importance of plant-based protein as a viable and sustainable alternative to animal proteins. The current advances in plant protein isolation and production and characterization of bioactive hydrolysates and peptides from plant proteins are described comprehensively. Furthermore, the recent research on bioactivities and bioavailability of plant protein-derived bioactive peptides is reviewed briefly. The limitations of using bioactive peptides, regulatory criteria, and the possible future applications of plant protein-derived bioactive peptides are highlighted. This review may help understand plant proteins and their bioactive peptides and provide valuable suggestions for future research and applications in the food industry.

Ultrasound-assisted alkaline proteinase extraction enhances the yield of pecan protein and modifies its functional properties

To enhance the extraction yield of pecan protein and modify its functional properties, this study investigated whether both ultrasound and enzyme have a synergistic impact on the extraction of pecan (Carya illinoinensis (Wangenh.) K. Koch) protein. The highest protein extraction rate (25.51%) was obtained under the conditions of 1415.43 W.cm-2, 15 min, pH 10.0, 50 °C, and 1% (w/w) alkaline proteinase. Owing to its high shear, mechanical energy and cavitation, the ultrasound process increased the solubility of the substrate making it readily accessible to the enzyme, thereby accelerating the chemical reaction and improving the yield of the protein. The optimized ultrasound-assisted enzymatic method (400 W, 20 kHz, 5 s/3s) effectively changed the secondary and tertiary structure of the pecan protein. The results of surface hydrophobicity, intrinsic fluorescence spectra, sulfhydryl content and scanning electron microscopy all indicated the unfolding of protein and exposure of hydrophobic groups and sulfhydryl groups. Moreover, the protein obtained by this method showed higher solubility (70.77%), higher emulsifying activity (120.56 m2/g), smaller particle size (326.7 nm), and better dispersion (0.305) than single ultrasound and non-ultrasound methods (p < 0.05). To conclude, ultrasound-assisted enzymatic method could be an appropriate technique to improve the yield and quality of the pecan protein. The study also provides a theoretical basis for the application of pecan protein in food processing.

A Review on the Extraction and Processing of Natural Source-Derived Proteins through Eco-Innovative Approaches

In addition to their nutritional and physiological role, proteins are recognized as the major compounds responsible for the rheological properties of food products and their stability during manufacture and storage. Furthermore, proteins have been shown to be source of bioactive peptides able to exert beneficial effects on human health. In recent years, scholarly interest has focused on the incorporation of high-quality proteins into the diet. This fact, together with the new trends of consumers directed to avoid the intake of animal proteins, has boosted the search for novel and sustainable protein sources and the development of suitable, cost-affordable, and environmentally friendly technologies to extract high concentrations of valuable proteins incorporated into food products and supplements. In this review, current data on emergent and promising methodologies applied for the extraction of proteins from natural sources are summarized. Moreover, the advantages and disadvantages of these novel methods, compared with conventional methods, are detailed. Additionally, this work describes the combination of these technologies with the enzymatic hydrolysis of extracted proteins as a powerful strategy for releasing bioactive peptides.

Extraction of protein from food waste: An overview of current status and opportunities

The chief intent of this review is to explain the different extraction techniques and efficiencies for the recovery of protein from food waste (FW) sources. Although FW is not a new concept, increasing concerns about chronic hunger, nutritional deficiency, food security, and sustainability have intensified attention on alternative and sustainable sources of protein for food and feed. Initiatives to extract and utilize protein from FW on a commercial scale have been undertaken, mainly in the developed countries, but they remain largely underutilized and generally suited for low-quality products. The current analysis reveals the extraction of protein from FW is a many-sided (complex) issue, and that identifies for a stronger and extensive integration of diverse extraction perspectives, focusing on nutritional quality, yield, and functionality of the isolated protein as a valued recycled ingredient.

Antidiabetic Food-Derived Peptides for Functional Feeding: Production, Functionality and In Vivo Evidences

Bioactive peptides released from the enzymatic hydrolysis of food proteins are currently a trending topic in the scientific community. Their potential as antidiabetic agents, by regulating the glycemic index, and thus to be employed in food formulation, is one of the most important functions of these peptides. In this review, we aimed to summarize the whole process that must be considered when talking about including these molecules as a bioactive ingredient. In this regard, at first, the production, purification and identification of bioactive peptides is summed up. The detailed metabolic pathways described included carbohydrate hydrolases (glucosidase and amylase) and dipeptidyl-peptidase IV inhibition, due to their importance in the food-derived peptides research field. Then, their characterization, concerning bioavailability in vitro and in situ, stability and functionality in food matrices, and ultimately, the in vivo evidence (from invertebrate animals to humans), was described. The future applicability that these molecules have due to their biological potential as functional ingredients makes them an important field of research, which could help the world population avoid suffering from several diseases, such as diabetes.

Ultrasound-assisted modification of functional properties and biological activity of biopolymers: A review

In this review, the recent applications of power ultrasound technology in improving the functional properties and biological activities of biopolymers are reviewed. The basic principles of ultrasonic technology are briefly introduced, and its main effects on gelling, structural, textural, emulsifying, rheological properties, solubility, thermal stability, foaming ability and foaming stability and biological activity are illustrated with examples reviewing the latest published research papers. Many positive effects of ultrasound treatment on these functional properties of biopolymers have been confirmed. However, the effectiveness of power ultrasound in improving biopolymers properties depends on a variety of factors, including frequency, intensity, duration, system temperature, and intrinsic properties of biopolymers such as macromolecular structure. In order to obtain the desired outcomes, it is best to apply optimized ultrasound processing parameters and use the best conditions in terms of frequency, amplitude, temperature, time, pH, concentration and ionic strength related to the inherent characteristics of each biopolymer. This will help employ the full potential of ultrasound technology for generating innovative biopolymers functionalities for various applications such as food, pharmaceuticals, and other industries.