Combined effects of limited enzymatic hydrolysis and high hydrostatic pressure on the structural and emulsifying properties of rice proteins

Tailoring soy protein/corn zein mixture by limited enzymatic hydrolysis to improve digestibility and functionality

This study aimed to modify plant protein mixture to improve their functionality and digestibility by limited hydrolysis. Soy protein isolate and corn zein were mixed at the ratio of 5:1 (w/w), followed by limited hydrolysis using papain from 15 to 30 min. The structural characteristics, in vitro digestibility, and functional properties were evaluated. Also, DPPH radical scavenging activity was determined. The results indicated that the molecular weight of different modified samples was largely reduced by limited hydrolysis, and the proportion of random coil was significantly increased. Furthermore, the solubility, foaming, emulsifying and water-holding capacity of hydrolyzed protein mixture were significantly improved, which were close to those of whey protein isolate. In vitro digestibility after 30-min limited hydrolysis was remarkably elevated. In addition, the hydrolyzed protein mixture exhibited a higher antioxidant activity than those of untreated proteins. Overall, limited hydrolysis of protein mixture led to improved digestibility, functionality and antioxidant activity.

Effects of probiotics fermentation on physicochemical properties of plum (Pruni domesticae semen) seed protein-based gel

The plum seed protein isolates (PSPI) were used to prepare a gel by probiotics fermentation. The effects of fermentation time (from 0 to 12 h) on the physicochemical properties of PSPI gel were evaluated. The results showed that PSPI started to form a gel after 6 h of fermentation, as evidenced by a decrease in pH from 6.6 to 5.2, an increase in particle size from 10 μm to 40 μm, appearance of a new peak with retention time of 10 min in gel filtration high-performance liquid chromatography, and formation of aggregation and porous structure observed by fluorescence and scanning electron microscope. The PSPI gel from 9 h of fermentation exhibited the highest viscosity (318 Pa.s), storage modulus (18,000 Pa), water holding capacity (37 %), and gel strength (21.5 g) due to stronger molecular interactions such as hydrogen bond, electrostatic, hydrophobic interaction and disulfide bond. However, increasing fermentation time over 9 h led to disrupture of PSPI gel. Furthermore, the subunit around 15 kDa of PSPI disappeared after fermentation, indicating that the formation of PSPI gel was induced by both acidification and partial hydrolysis. Our results suggest that PSPI can provide an alternative for developing plant-based gel products.

Insight into the solubilization mechanism of wheat gluten by protease modification from conformational change and molecular interaction perspective

The low solubility limits the utilization of other functional characteristics of wheat gluten (WG). This study effectively improved the solubility of WG through protease modification and explored the potential mechanism of protease modification to enhance the solubility of WG, further stimulating the potential application of WG in the food industry. Solubility of WG modified with alkaline protease, complex protease, and neutral protease was enhanced by 98.99%, 54.59%, and 51.68%, respectively. Notably, the content of β-sheet was reduced while the combined effect of hydrogen bond and ionic bond were increased after protease modification. Meanwhile, the reduced molecular size and viscoelasticity as well as the elevated surface hydrophobicity, thermostability, water absorption capacity, and crystallinity were observed in modified WG. Moreover, molecular docking indicated that protease was specifically bound to the amino acid residues of WG through hydrogen bonding, hydrophobic interaction, and salt bridge.

Use of olive and sunflower protein hydrolysates for the physical and oxidative stabilization of fish oil-in-water emulsions

BACKGROUND

Olive and sunflower seeds are by-products generated in large amounts by the plant oil industry. The technological and biological properties of plant-based substrates, especially protein hydrolysates, have increased their use as functional ingredients for food matrices. The present study evaluates the physical and oxidative stabilities of 50 g kg-1 fish oil-in-water emulsions where protein hydrolysates from olive and sunflower seeds were incorporated at 20 g kg-1 protein as natural emulsifiers. The goal was to investigate the effect of protein source (i.e. olive and sunflower seeds), enzyme (i.e. subtilisin and trypsin) and degree of hydrolysis (5%, 8% and 11%) on the ability of the hydrolysate to stabilize the emulsion and retard lipid oxidation over a 7-day storage period.

RESULTS

The plant protein hydrolysates displayed different emulsifying and antioxidant capacities when incorporated into the fish oil-in-water emulsions. The hydrolysates with degrees of hydrolysis (DH) of 5%, especially those from sunflower seed meal, provided higher physical stability, regardless of the enzymatic treatment. For example, the average D [2, 3] values for the emulsions containing sunflower subtilisin hydrolysates at DH 5% only slightly increased from 1.21 ± 0.02 μm (day 0) to 2.01 ± 0.04 μm (day 7). Moreover, the emulsions stabilized with sunflower or olive seed hydrolysates at DH 5% were stable against lipid oxidation throughout the storage experiment, with no significant variation in the oxidation indices between days 0 and 4.

CONCLUSION

The results of the present study support the use of sunflower seed hydrolysates at DH 5% as natural emulsifiers for fish oil-in-water emulsions, providing both physical and chemical stability against lipid oxidation. © 2024 Society of Chemical Industry.

Rice proteins: A review of their extraction, modification techniques and applications

Rice protein is highly nutritious and easy to digest and absorb. Its hydrolyzed peptides have significant effects on lowering blood pressure and cholesterol. First, a detailed and comprehensive explanation of rice protein extraction methods was given, and it was found that the combination of enzymatic and physical methods could improve the extraction rate of rice protein, but it was only suitable for laboratory studies. Second, the methods for improving the functional properties of rice protein were introduced, including physical modification, chemical modification, and enzymatic modification. Enzymatic modification of the solubility of rice protein to improve its functional properties has certain limitations due to the low degree of hydrolysis, the long time required, the low utilization of the enzyme, and the possible undesirable taste of the product. Finally, the development and utilization of rice protein was summarized and the future research direction was suggested. This paper lists the advantages and disadvantages of various extraction techniques, points out the shortcomings of existing extraction techniques, aims to fill the gap in the field of rice protein extraction, and then provides a possible improvement method for the extraction and development of rice protein in the future.

Multifunctional apple seed protein hydrolysates: Impact of enzymolysis on the biochemical, techno-functional and in vitro α-glucosidase, pancreatic lipase and angiotensin-converting enzyme inhibition activities

The work was designed to assess the amelioration effect of papain hydrolysis on the biochemical, techno-functional, and biological properties of apple seed protein isolate (API) after 0-90 min of hydrolysis. Hydrolysis significantly enhanced the nutritional value (protein content ˃ 90 %) while decreasing the average particle size. With increasing hydrolysis time, FTIR analysis revealed a transition from α-helix to β-turn structure, indicating the unfolding of protein structure. This structural alteration positively influenced the functional characteristics, with samples hydrolyzed for 90 min exhibiting excellent solubility, higher water and oil absorption capacity, foaming capacity, and increased emulsifying activity index. Moreover, samples hydrolyzed for 90 min displayed the highest α-glucosidase (29.62-57.43 %), pancreatic lipase inhibition (12.87-31.08 %), and ACE inhibition (25.32-62.70 %) activity. Interestingly, the inhibiting ability of protein hydrolysates against α-glucosidase and ACE was more effective than pancreatic lipase, suggesting their usefulness as a functional ingredient, particularly in type II diabetes and hypertension management.

Modification and Solubility Enhancement of Rice Protein and Its Application in Food Processing: A Review

Rice protein is a high-quality plant-based protein source that is gluten-free, with high biological value and low allergenicity. However, the low solubility of rice protein not only affects its functional properties such as emulsification, gelling, and water-holding capacity but also greatly limits its applications in the food industry. Therefore, it is crucial to modify and improve the solubility of rice protein. In summary, this article discusses the underlying causes of the low solubility of rice protein, including the presence of high contents of hydrophobic amino acid residues, disulfide bonds, and intermolecular hydrogen bonds. Additionally, it covers the shortcomings of traditional modification methods and the latest compound improvement methods, compares various modification methods, and puts forward the best sustainable, economical, and environmentally friendly method. Finally, this article lists the uses of modified rice protein in dairy, meat, and baked goods, providing a reference for the extensive application of rice protein in the food industry.

Effects of ultrasound assisted cell wall disruption on physicochemical properties of camellia bee pollen protein isolates

Camellia bee pollen protein isolates were extracted by cell wall disruption using ultrasonication, freeze-thawing, enzymatic hydrolysis, and their combinations. The effects of these methods on microstructure of cell wall, protein release, protein yield, physiochemical properties and structure of proteins were investigated. As compared with physical treatments (ultrasonication, freeze-thawing and their combination), the enzymatic hydrolysis significantly improved the yield of proteins, because it not only promoted the release of proteins from the inside of pollen, but also released proteins in pollen wall. The proteins extracted by enzymatic hydrolysis method also exhibited better solubility, emulsifying and gelation properties due to the partial hydrolysis of proteins by protease. In addition, when ultrasound was combined with freeze-thawing or enzymatic hydrolysis, it could further improve the yield of proteins and the functional properties of proteins, which was mainly related to the changes of protein structure induced by cavitation effect of ultrasound.

Effect of Enzymatic Hydrolysis on Solubility and Emulsifying Properties of Lupin Proteins (Lupinus luteus)

Solubility and emulsifying properties are important functional properties associated with proteins. However, many plant proteins have lower techno-functional properties, which limit their functional performance in many formulations. Therefore, the objective of this study was to investigate the effect of protein hydrolysis by commercial enzymes to improve their solubility and emulsifying properties. Lupin protein isolate (LPI) was hydrolyzed by 7 commercial proteases using different E/S ratios and hydrolysis times while the solubility and emulsifying properties were evaluated. The results showed that neutral and alkaline proteases are most efficient in hydrolyzing lupin proteins than acidic proteases. Among the proteases, Protamex® (alkaline protease) showed the highest DH values after 5 h of protein hydrolysis. Meanwhile, protein solubility of LPI hydrolysates was significantly higher (p < 0.05) than untreated LPI at all pH analyzed values. Moreover, the emulsifying capacity (EC) of undigested LPI was lower than most of the hydrolysates, except for acidic proteases, while emulsifying stability (ES) was significantly higher (p < 0.05) than most LPI hydrolysates by acidic proteases, except for LPI hydrolyzed with Acid Stable Protease with an E/S ratio of 0.04. In conclusion, the solubility, and emulsifying properties of lupin (Lupinus luteus) proteins can be improved by enzymatic hydrolysis using commercial enzymes.

A Narrative Review on Rice Proteins: Current Scenario and Food Industrial Application

Rice, Oryza sativa, is the major staple food that provides a larger share of dietary energy for more of the population than other cereal crops. Moreover, rice has a significant amount of protein including four different fractions such as prolamin, glutelin, globulin, and albumin with different solubility characteristics. However, these proteins exhibit a higher amino acid profile, so they are nutritionally important and possess several functional properties. Compared with many other cereal grains, rice protein is hypoallergic due to the absence of gluten, and therefore it is used to formulate food for infants and gluten-allergic people. Furthermore, the availability makes rice an easily accessible protein source and it exhibits several activities in the human body which discernibly affect total health. Because of these advantages, food industries are currently focusing on the effective application of rice protein as an alternative to animal-based and gluten-containing protein by overcoming limiting factors, such as poor solubility. Hence, it is important to gain an in-depth understanding of the rice protein to expand its application so, the underlined concept of this review is to give a current summary of rice protein, a detailed discussion of the chemistry of rice protein, and extraction techniques, and its functional properties. Furthermore, the impact of rice protein on human health and the current application of rice protein is also mentioned.