Proteins In Food Industry Research Articles

Raman spectroscopy and molecular dynamics simulations of protein microgels at the oil-water interface

The real-time structural changes of the molecular space conformation of myofibrillar protein microgels (MPM) after heat treatment (90 °C, 30 min) were analyzed by molecular dynamics simulation, and the structural properties and changes of MPM at the oil-water interface were analyzed by the combination of Raman spectroscopy and molecular dynamics simulation. The shift in the oil ratio had a major impact on the transformation of disulfide bonds within the protein molecule. Simultaneously, it caused tryptophan and tyrosine residues (I850 cm−1/ I850 cm−1 > 1) to become exposed, increasing the locations of amino acid residues in the protein that interact with the oil phase. HIPE with different oil phases influenced the change in spatial structural conformation of MPM, and there was a flexible structural change in the molecular space. The HIPE system, which was stabilized by 3.0 wt% MPM and 0.75 oil phase, exhibited a thixotropic recovery of >70 % and the highest elastic modulus G′ (822.14 Pa) based on the rheological behavior. It is expected to provide a theoretical basis for the development and utilization of high internal phase emulsion stabilized by microgel protein in food industry.

Effects of enzymatic hydrolysis combined with glycation on the emulsification characteristics and emulsion stability of peanut protein isolate

Peanut protein isolate (PPI) has high nutritional value, but its poor function limits its application in the food industry. In this study, peanut protein isolate was modified by enzymatic hydrolysis combined with glycation. The structure, emulsification and interface properties of peanut protein isolate hydrolysate (HPPI) and dextran (Dex) conjugate (HPPI-Dex) were studied. In addition, the physicochemical properties, rheological properties, and stability of the emulsion were also investigated. The results showed that the graft degree increased with the increase of Dex ratio. Fourier transform infrared spectroscopy (FTIR) confirmed that the glycation of HPPI and Dex occurred. The microstructure showed that the structure of HPPI-Dex was expanded, and the molecular flexibility was enhanced. When the ratio of HPPI to Dex was 1:3, the emulsifying activity and the interface pressure of glycated HPPI reached the highest value, and the emulsifying activity (61.08 m2/g) of HPPI-Dex was 5.28 times that of PPI. The HPPI-Dex stabilized emulsions had good physicochemical properties and rheological properties. In addition, HPPI-Dex stabilized emulsions had high stability under heat treatment, salt ion treatment and freeze–thaw cycle. According to confocal laser scanning microscopy (CLSM), the dispersion of HPPI-Dex stabilized emulsions was better after 28 days of storage. This study provides a theoretical basis for developing peanut protein emulsifier and further expanding the application of peanut protein in food industry.

Effects of combined hot alkaline and pH-shift treatments on structure and functionality of legume protein-EGCG conjugates: Soybean-, pea-, and chickpea protein-EGCG systems

Legume proteins are appealing in the food industry for their nutrition and sustainability, but their low solubility due to the compact structure makes their applications in food industry limited. In this study, three commonly used legume proteins in food industry were selected as samples to be tested: soy protein (SP), pea protein (PP), and chickpea protein (CP). This study aims to improve the structural properties of these three proteins, so that it could promote effective grafting with epigallocatechin gallate (EGCG) through a combined hot alkaline and pH-shift treatments. Legume protein solutions were adjusted to pH 12 and heated at 80 °C for 30 min, resulting to a 13%–19% increase in free thiol content and a 59%–610% increase in surface hydrophobicity. This kind of change in structure leads to a 19%–46% increase in EGCG grafting degree. Treated protein-EGCG conjugates exhibited smaller and more uniform particle sizes, improved emulsification activity by 27%–218%, and additionally enhanced solubility, thermal stability, and antioxidant activity. Among all the tested proteins, pre-treated SP-EGCG conjugates showed the best solubility, emulsification, and thermal stability due to their highest surface hydrophobicity, highest EGCG grafting degree, and loose structure. These results indicate that combined hot alkaline and pH-shift treatment enhances the functional properties of legume proteins, expanding their potential applications as functional ingredients in the food industry.

Interactions of different polyphenols with wheat germ albumin and globulin: Alterations in the conformation and emulsification properties of proteins

In this study, chlorogenic acid (CA), piceatannol (PIC), epigallocatechin-3-gallate (EGCG) and ferulic acid (FA) was selected to explore the influence of polyphenol on the structural properties of wheat germ albumin (WGA) and wheat germ globulin (WGG). The emulsifying properties of the emulsions prepared by WGA-EGCG complex were also evaluated. The results indicated that all polyphenols could significantly enhance the antioxidant capacity of WGA and WGG. In particular, EGCG increased the ratio of random coil in WGA and WGG, resulting in protein unfolding and shifting from an order to disorder structure. In addition, lipid oxidation and protein oxidation of the soybean oil emulsion was significantly slowed down by WGA-EGCG. The stability of the emulsions under various environmental stress and the storage time was significantly improved by WGA-EGCG. These findings can provide a reference for expanding the application of wheat germ protein in food industry.

Recent processing of peanut protein in food industry: a molecular structure perspective

SummaryPeanuts produce millions of tons of high‐protein peanut meal (after oil extraction) annually that can be used for food. Peanut protein, as a plant‐based protein, is a great alternative to animal protein to address protein deficiencies and rising health problems in the world. It has a high nutritional value, while the globular structure results in poor functional properties, limiting its application. Better functional properties can be obtained through processing and modification. This paper elaborates the nutritional and functional properties of peanut protein and highlights the application of peanut protein in food industry in recent years. Applications for peanut protein include meat and milk substitutes, edible films, nanoparticles, and some new technologies such as electrostatic spinning and three‐dimensional (3D) printing in recent years. This paper could improve people's understanding of the molecular structure of peanut protein and the physicochemical properties associated with the structure changes during processing. It could also contribute to better utilisation of peanut protein, providing more varieties of peanut protein products for the food industry.

Analyzing changes in volatile flavor compounds of soy protein isolate during ultrasonic-thermal synergistic treatments using electronic nose and HS-SPME-GC-MS combined with chemometrics

The beany flavor of soy protein isolate (SPI) creates barriers to their application in food processing. This study investigated the effect of ultrasonic-thermal synergistic treatments, combined with vacuum degassing, on the removal of volatile compounds from SPI. The results revealed that ultrasonic-thermal synergistic treatments altered protein secondary structure and increased fluorescence intensity and surface hydrophobicity, which affected the flavor-binding ability of protein, resulting in reduced electronic nose sensor response values. At synergistic treatment (350 W, 120 ℃ and 150 s), the content of hexanal, (E)-2-hexenal, and 1-octen-3-ol reduced by 70.60 %, 95.60 % and 61.23 %. (E)-2-nonenal and 2-pentylfuran were not detected. Chemometric analysis indicated significant flavor differences between control and treated SPI. Furthermore, α-helix, β-sheet, β-turn, and surface hydrophobicity highly correlated with volatile compounds through correlation analysis, indicating that altered protein structure affected interactions with volatile compounds. The study reduced beany flavor and further expanded the range of applications of plant protein in food industry.

Fabrication and characterization of W1/O/W2 double emulsions stabilized with Pleurotus geesteranus protein particles via one-step emulsification

In this study, Pleurotus geesteranus protein isolate (PPI) with low solubility in water was fabricated into nanoparticle (PPIP) that can be uniformly dispersed in pH 7.0 aqueous solution using pH cycle method. PPIP with a zeta potential of −19.21 mV had a mean size of 250.53 nm and two main peaks in particle size distribution profile. This was consistent with the TEM results, which existed both as individual particles and as particle aggregates. The main force responsible for maintaining the structure of protein particles was hydrogen bonding. Interestingly, these protein particles were successfully utilized to fabricate W1/O/W2 double emulsions using one-step homogenous emulsification, and the formation and properties of PPIP-stabilized W1/O/W2 double emulsions were significantly influenced by the protein particle concentration, oil content, and salt concentration in W2 continuous phase. Specifically, higher particle concentration and salt concentration caused a reduction in the number of W1/O droplets and the size of oil droplets. Conversely, an increase in oil content increased the number of W1/O droplets primarily due to the augmentation in the size of oil droplets. The gel strength of double emulsions was enhanced with particle concentration and oil content, as this led to the formation of stronger particle networks and droplet networks. While an opposite phenomenon was found in increasing salt concentration in W2 continuous phase, possibly resulting from the disruption of the ordered gel network. These findings not only provide new food-grade emulsifiers for W1/O/W2 double emulsions, but also broaden the application of edible mushroom proteins in food industry.

Study on the quality of soybean proteins fermented by Bacillus subtilis BSNK-5: Insights into nutritional, functional, safety, and flavor properties

Microbial fermentation emerges as a promising strategy to elevate the quality of soybean proteins in food industry. This study conducted a comprehensive assessment of the biotransformation of four types of soybean proteins by Bacillus subtilis BSNK-5, a proteinase-rich bacterium. BSNK-5 had good adaptability to each protein. Soluble protein, peptides and free amino acids increased in fermented soybean proteins (FSPs) and dominant after 48–84 h fermentation, enhancing nutritional value. Extensive proteolysis of BSNK-5 also improved antioxidant and antihypertensive activities, reaching peak level after 48 h fermentation. Furthermore, excessive proteolysis effectively enhanced the generation of beneficial spermidine without producing toxic histamine after fermentation, and formed the flavor profile with 56 volatiles in 48 h FSPs. Further degradation of amino acids showed a positive correlation with off-flavors, particularly the enrichment of 3-methylbutanoic acid. These findings establish a theoretical foundation for regulating moderate fermentation by BSNK-5 to enabling the high-value utilization of soybean protein.

Recent advances, challenges and functional applications of antifreeze protein in food industry

SummaryFreezing is a common food preservation method that can extend the shelf life of food, but the ice crystals and recrystallisation during freezing, storage and transportation cause significant damage to frozen food. Antifreeze proteins are a class of proteins that widely exist in organisms living in cold conditions, such as fish, insects, plants and microorganisms in Antarctica and other cold regions. Antifreeze proteins can reduce the freezing point of water, inhibit recrystallisation effects, modify ice crystal morphology and effectively suppress the quality deterioration caused by ice crystals during food freezing. This review comprehensively introduces the source, antifreeze mechanism, application in food, influencing factors and regulating methods of antifreeze activity of antifreeze proteins, as well as the limitations of antifreeze proteins. It also looks forward to the future application of antifreeze proteins in food.

How the strength of proteins interactions affects the phase behavior of protein complexes

How the protein−protein interactions affect the phase behaviour of protein complexes can afford technical support for the application of egg white protein in food industry. Here the drawing of phase diagram of ovalbumin-lysozyme (Ova-Lys) complexes was reported, and the effect of interaction between Ova and Lys on the phase behaviour of three phases (co-soluble polymers, insoluble complexes and soluble complexes) was investigated by combining experimental and computational approaches. The soluble and insoluble complexes displayed an amorphous pattern, with the insoluble complexes manifesting a cross-linked conformation. Ova and Lys exhibited strong co-localization within heteroprotein complexes, where Ova being the predominant component on the surface of the complexes. Electrostatic and hydrogen bonding interactions were the main driving forces to afford co-soluble polymers, while electrostatic, hydrogen bonding and hydrophobic interactions existed in insoluble and soluble complexes. The strong force facilitated to yield insoluble complexes, while the weak force favoured to give co-soluble polymers.

Improvement of solubility, emulsification property and stability of potato protein by pH-shifting combined with microwave treatment and interaction with pectin

The application of potato protein (PP) in food industry has been limited due to its low water solubility, poor emulsification and stability. Herein, it was found that the pH-shifting combined with microwave heating significantly increased the solubility of PP (from 24.0% to 89.0%) and surface hydrophobicity (from 125 to 207). The particle size of PP was significantly reduced (from 249.95 ± 1.15 mm to 90.37 ± 1.03 nm). SDS-PAGE analysis indicated that the microwave treatment did not disrupt the primary structure of PP. A complex formation between modified potato protein (MPP) and pectin (PC) at the optimum mass ratio of MPP to PC of 4:1 and pH 5 was characterized by fluorescence spectroscopy, fourier transform infrared spectroscopy, scanning electron microscopy and transmission electron microscopy, which showed that MPP and PC had electrostatic interaction. Moreover, the effect of mass ratios of MPP to PC from 5:1 to 1:2 on the phase behavior of MPP-PC soluble complexes was evaluated by the phase diagram and ζ-potential measurement. These results showed that the dispersibility, emulsification and thermal stability of the protein were improved by forming MPP-PC complexes. This study provides a valuable reference for the improvement of physicochemical and functional properties of PP which is conducive to broaden the application of the protein in food industry.

Effects of different plant proteins on the quality and characteristics of heat induced egg white protein gel under freezing conditions

Eggs white is rich in protein, whose gel property is one of the most important functional characteristics during processing. The purpose of this study was to reveal the effect of different plant proteins (2% (w/w), 2.5% (w/w), 3% (w/w)) on the quality of heat induced egg white protein (EWP) gel after freezing. Gels were prepared by adding 2.5% soy protein isolates (SPI) or pea protein isolates (PPI), and then were frozen for 14 days. Compared with the control group (EWP without adding any plant proteins), the hardness, chewiness and gumminess of SPI-EWP gel were increased by 58.23%, 71.11% and 66.35%, respectively, which was better than PPI-EWP. The thawing loss rate of SPI-EWP and PPI-EWP gel decreased by 16.8% and 13.0%, respectively, and the centrifugal loss rate decreased by 13.2% and 11.8%, respectively. The addition of plant proteins resulted in a decrease in the proton signal intensity of the T23 peak. Hydrogen proton imaging and rheology results showed that water content of gels added with plant proteins after freezing was higher than control group and showed better viscoelasticity (SPI was better than PPI). The results of intermolecular forces indicated that with the increase of plant protein, the ionic bonds decreased, the contribution of disulfide bonds significantly increased (p < 0.05). Fourier Transform Infrared Spectroscopy (FTIR) indicated that the α-helix content decreased, β-sheet increased. In brief, this study provides valuable reference for the development and application of plant protein to improve the quality of egg white protein in food industry.

Study on Catalytic Mechanism of Microbial Transglutaminase in Protein Substrate

Transglutaminase (abbreviated as TG,EC2.3.2.13) can catalyze the acyl transfer reaction of peptides in protein, but it can only catalyze a certain acyl transfer reaction instead of every acyl group. Protein is widely used to modify protein in food industry because it is safe and non-toxic and the catalyzed product can be digested and absorbed by human body. In this paper, the catalytic mechanism of protein substrate for MTG (Microbial TG) was studied in order to provide theoretical basis for the follow-up research and application of MTG. The results show that within 1%~4%, the total amount of biopolymer produced increases linearly, and then it remains basically unchanged. The catalytic amount of MTG to substrate and catalytic efficiency are contradictory. Under the condition of fixed MTG concentration, the higher the substrate concentration, the smaller the catalytic efficiency, and it shows a linear downward trend. When the concentration is 10%, the gel strength is the highest, reaching 68.09g. When the concentration of protein is low, protein-solvent interaction is dominant, and the system is not easy to form gel. The lower the hydrophobicity of protein surface, the easier it is to be catalyzed by MTG. However, the surface hydrophobicity of soybean globulin is in the middle, and MTG has moderate catalytic activity for it.

Extraction and Isolation of Cricket Protein Isolate with Ammonium Sulfate Addition Method and Its Effect on The Functional Properties of The Proteins

Cricket insect contains a high quality of protein. To be able to use the proteins in food industry, extraction and isolation steps are necessary to elevate the protein content. The objective of this study was to extract and isolate protein of cricket insect and to assess its functional properties. The extraction and isolation steps were carried out by using alkaline extraction-acid precipitation (AEAP) with varying concentrations of ammonium sulfate (0, 20,40, and 60% w/v). It was found that extraction method with 60% ammonium sulphate inclusion showed the highest yield and obtained maximum protein content (92.41%), which could be characterized as cricket protein isolate (CPI). This extraction and inclusion of ammonium sulphate affected physicochemical properties, including water holding capacity, oil holding capacity, emulsifying properties, and foaming properties of CPI. In conclusion, the extraction, isolation, and addition of ammonium sulfate could be used for isolating the CPI containing high protein content and can be further used in food manufactures as an alternative protein in the future.

Chitosan and chitosan oligosaccharide influence digestibility of whey protein isolate through electrostatic interaction

Chitosan (CTS)/chitosan oligosaccharide (COS) and whey protein isolate (WPI) have been frequently used as food supplements, but notably, the interaction between the carbohydrate and the protein may affect the digestibility of protein. Thus, the present study focused on effects of the interaction between CTS/COS and WPI on the protein digestibility. A series of chemical and spectroscopic techniques including gel electrophoresis, gel permeation chromatography, Fourier transform-infrared (FT-IR) spectroscopy, intrinsic fluorescence (IF) spectroscopy, and circular dichroism (CD) spectroscopy were applied. According to the findings, both CTS and COS dramatically reduced intestinal digestibility of WPI, resulting in a decrease of DH by 43.33 % and 52.31 %, respectively. The substitution degree of WPI on CTS was 0.87 g WPI/g CTS, and the electrostatic interaction between amine groups of CTS and carboxyl groups of WPI caused changes in WPI's stability, microstructure, and fluorescence intensity. Notably, CTS affected the digestibility of WPI by precipitating protein and enzyme, whereas COS altered WPI's digestibility by decreasing or inactivating enzyme activity. The present study offered a solid scientific foundation for the rational formulations of carbohydrates and proteins in food industry.

The temporal evolution mechanism of structure and function of oxidized soy protein aggregates

The emulsifying activity of soy protein would decrease after long-term storage, which caused huge economic losses to food processing plants. This study explored the temporal evolution mechanism of oxidation on the structure and function of soy protein aggregates, which would improve the application of soy protein in food industry. Decreased α-helix and increased random coil were observed at the initial oxidation stage (0-4h), which induced increases in hydrophobicity and disulfide bond content. In addition, emulsibility increased significantly. However, when the oxidation time extended to 6-12h, the soluble aggregates transformed into insoluble aggregates with large particle size, low solubility, and molecular flexibility. Surface hydrophobicity and emulsifying activity were reduced, resulting in bridging flocculation of emulsion droplets. Mutual transformation between components is affected by factors that include spatial conformation and intermolecular forces, which eventually lead to functional changes in the protein molecules.

Bread Wheat Gluten and Its Health Effects

Glutens are the major constituents of bread wheat grain storage proteins and constituting 85% of the total. They are mainly responsible for the processing quality of wheat dough and were among the first proteins isolated and studied by human beings. Different compositions of wheat storage proteins confer different dough physical properties, which are required by different products. Gluten provides dough with unique extensibility and elasticity, which are essential for various wheat products. Gluten is one of the most commonly used proteins in food industry. Its characteristic properties make it an essential ingredient in the preparation of high quality dough, hence it is popular in the baking industry. Some wheat gliadin proteins are strong allergens that can cause various symptoms of food allergies and baker asthma. The most immune reactive ω-5 gliadin fractions are the main allergens in wheat dependent exercise induced anaphylaxis. Apart from their role in dough quality, gluten proteins can affect the health of genetically susceptible individuals. Many gluten proteins contain T-cell stimulatory epitopes that can cause celiac disease. The consumption of gluten proteins can trigger an immune response that damages the small intestine. Therefore, patients with celiac disease (CD) are restricted to a lifelong gluten-free diet

Characterization of structures and gel properties of ultra-high-pressure treated-myofibrillar protein extracted from mud carp (Cirrhinus molitorella) and quality characteristics of heat-induced sausage products

This study aimed to understand the effects of ultra-high pressure (UHP) treatment on the protein structures and gel properties of myofibrillar protein (MP), and the secondary structure and quality of sausage gels developed by Cirrhinus molitorella. MP was treated with 100, 200, and 300 MPa for 3, 9, and 15 min separately. Observations suggested that UHP treatment improved MP aggregation α-helix and β-Sheet converted to random coil in MP structures as pressure increased. Myosin heavy chain (180 kDa) and actin (48 kDa) are the most important protein bands in C. molitorella MP. When the pressure reached to 300 MPa for 9 min during UHP-thermal processing, the gel strength, water holding capacity, and the chewiness and hardness of fish sausage gels reached to the peak value of 1,296.8 g cm, 83.60%, 3864.02 g/mm and 2169.94 g, respectively. 300 MPa for 9 min was the optimum UHP condition to modify the conformation to improve gel properties of MP, and to improve the quality characteristics of heat-induced sausage gels. Collectively, UHP had the potential in expanding the application of fish protein in food industry by modifying MP structure, as well as in developing novel fish products.

Functional properties of Australian blue lupin (Lupinus angustifolius) protein and biological activities of protein hydrolysates

AbstractLupin is an undervalued legume despite its high protein content with known health benefits. In this research, Australian blue lupin protein was isolated and hydrolysed enzymatically to produce bioactive peptides with a view to assess their potential for nutraceutical and therapeutic applications. Pepsin, pancreatin and flavourzyme were used to enzymatically hydrolyse blue lupin protein, and the hydrolysates were subjected to molecular weight cut‐off (MWCO) fractionation. Measurement of biological activities led to the identification of angiotensin converting enzyme (ACE) inhibitory fractions in the molecular weight range of 2–3 and 3–5 kDa. For the most active fractions in this range, the ACE inhibitory activities were very significant with IC50 values from 450 to 600 μg/ml. Blue lupin protein‐derived MWCO fractions were significantly active against Gram‐positive bacteria and only a little inhibition was observed against Gram‐negative bacteria. Pancreatin hydrolysed fractions showed the best antimicrobial activities with several fractions exhibiting ≥85% inhibition against Bacillus cereus and Staphylococcus aureus. These properties reveal the potential of lupin protein hydrolysates for developing antihypertensive and host defence agents. In order to demonstrate the potential of isolated blue lupin protein in food industry, functional properties including water and oil absorption capacity, gelling properties, solubility and emulsifying properties were evaluated and found to be extremely suitable for developing functional foods with enhanced health benefits.

Modification of myofibrillar protein functional properties prepared by various strategies: A comprehensive review.

Today, both consumers and food industry producers have exhibited an ever-growing interest in improving and broadening the functional performance of proteins in food industry. Myofibrillar protein (MP) is mainly responsible for texture, yield and organoleptic characteristics of final meat products. To increase functional properties of MP, technological and nutritional improvement of MP is needed to modify its structure and functionalities. Considerable approaches, including additives, oxidation treatments, and novel food processing technologies, have been utilized to modify its functional properties to manufacture acceptable meat products with lower cost and more desirable nutritional characteristics. However, a comprehensive summary of structural and functional changes of MP in response to different modification strategies is still lacking. Hence, in this review paper, our main goal is first to provide an overview of the functional characteristics of MP. Then, this review will mainly discuss the current knowledge on the functional changes of MP caused by various modification methods and will present some examples of previous works and recent progress. Finally, future outlooks are presented to tailor the manufacture of functionality enhanced and value-added muscle-based products and enable modified MP can be applied as a novel meat ingredient in food industry.