Innovative food processing technologies on the transglutaminase functionality in protein-based food products: Trends, opportunities and drawbacks

Integrated ultrasonic-transglutaminase modification of lesser mealworm protein isolate: A pioneering cobalamin delivery vehicle in gluten-free breads

A combined approach of microbial transglutaminase (MTGase) crosslinking and high-intensity ultrasound (HIU) was implemented to improve the physicochemical, rheological, structural, and thermal properties, as well as the targeted release of vitamin B12 of lesser mealworm protein isolate (LMPI)-based gels. Prolonging HIU to 60 min significantly reduced LMPIs' size, polydispersity, zeta-potential, and fluorescence intensity while increasing surface hydrophobicity, free amino (FAGs), and sulfhydryl (FSGs) groups. The MTGase-catalyzed LMPI gels effectively decreased the content of FAGs and FSGs. LMPI gels from 60 and 75 min HIU and MTGase catalysis exhibited a shear-thinning flow behavior, superior thermal stability, and improved water retention and gel strength with the most controlled release of vitamin B12 during in vitro simulated gastrointestinal digestion. Incorporating freeze-dried gel powders from 60 min HIU-treated MTGase-catalyzed LMPI and pea protein isolate into the dough of a new gluten-free bread improved physicochemical, textural, and sensory properties, with notable vitamin B12 retention rate.

A comparative study of the impacts of preparation techniques on the rheological and textural characteristics of emulsion gels (emulgels)

A subtype of soft solid-like substances are emulsion gels (emulgels; EGs). These composite material's structures either consist of a network of aggregated emulsion droplets or a polymeric gel matrix that contains emulsion droplets. The product's rheological signature can be used to determine how effective it is for a specific application. The interactions between these structured system's separate components and production process, however, have a substantial impact on their rheological imprint. Therefore, rational comprehension of interdependent elements, their structural configurations, and the resulting characteristics of a system are essential for accelerating our progress techniques as well as for fine-tuning the technological and functional characteristics of the finished product. This article presents a comprehensive overview of the mechanisms and procedures of producing EGs (i.e., cold-set and heat-set) in order to determine the ensuing rheological features for various commercial applications, such as food systems. It also describes the influence of these methods on the rheological and textural characteristics of the EGs. Diverse preparation methods are the cause of the rheological-property correlations between different EGs. In many ways, EGs can be produced using various matrix polymers, processing techniques, and purposes. This may lead to various EG matrix structures and interactions between them, which in turn may affect the composition of EGs and ultimately their textural and rheological characteristics.

Structural and textural properties of walnut protein gels induced by ultrasound and transglutaminase: encapsulation and release of tea polyphenols

This study investigated the synergy of ultrasonic and transglutaminase (TGase) treatment on the structural, physicochemical, rheological, gelation properties and controlled release properties of dehulled walnut proteins (DWP). The results showed that after ultrasonic-TGase treatment, the surface hydrophobicity was decreased, indicating the involvement of disulfide bonds in gel formation. Scanning electron microscopy (SEM) showed that ultrasonic-TGase treatment resulted in a more uniform and denser microstructure of DWP gels. Ultrasonic-TGase treatment changed the secondary structure of the DWP gels as determined by Fourier transform infrared spectroscopy, with an increase in α-helix, β-turn and random coils and a decrease in β-sheets. In addition, in vitro drug release profiles showed that ultrasonic-TGase treatment promoted the cross-linking of protein molecules and formed a dense network to embed tea polyphenols (TP), thereby slowing down the digestion of TP in simulated gastric fluid and achieving the purpose of slow-release in simulated intestinal fluid. Thus, the synergy of ultrasonic and TGase treatment might be an effective method to improve gel properties and expand the application of protein gels in the food industries.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13197-023-05756-6.

Effects of high-pressure homogenization on physicochemical and functional properties of enzymatic hydrolyzed soybean protein concentrate

This paper investigates the effect on the physicochemical and functional properties of soybean protein concentrate (SPC) by using Alcalase protease and high-pressure homogenization (HPH) (0, 20, 40, 60, 80, and 100 MPa) for the combined modification. The results showed that the degree of hydrolysis of SPC was 4.1% and the antigen protein was degraded after Alcalase hydrolysis, when the homogenization pressure (HP) was 6 0Mpa, the particle size of the SPC was the smallest, the zate potential absolute value up to 33.45 mV, the secondary structure has the lowest β-sheet content, the highest random coil content, and the highest surface hydrophobicity (H0), the size of protein fragments on the microstructure surface is the smallest, the lowest denaturation temperature (T d ) and enthalpy (△H) are 72.59°C and 1.35 J/g, the highest solubility is 80.54%, and the highest water and oil holding capacities are 7.73 g/g and 6.51 g/g, respectively. The best emulsifying activity and emulsifying stability were 43.46 m2/g and 190.35 min, the most even distribution of emulsion droplets. This indicates that the HPH treatment destroys the structure of enzymatic hydrolyzed SPC, changes its physicochemical properties, and improves its functional properties. In this study, SPC was modified by HPH and enzyme combined treatment, in order to improve the functionality and application range of SPC, and provide a theoretical basis for its high-value utilization in the food field.

Bioactive and health-promoting properties of enzymatic hydrolysates of legume proteins: a review

This study comprehensively reviewed the effect of controlled enzymatic hydrolysis on the bioactivity of pulse protein hydrolysates (PPHs). Proteolysis results in the partial structural unfolding of pulse proteins with an increase in buried hydrophobic groups of peptide sequences. The use of PPHs in a dose-dependent manner can enhance free radical scavenging and improve antioxidant activities regarding inhibition of lipid oxidation, ferric reducing power, metal ion chelation, and β-carotene bleaching inhibition. Ultrafiltered peptide fractions with low molecular weights imparted angiotensin-I converting enzyme (ACE) inhibitory effects during in vitro simulated gastrointestinal digestion and in vivo conditions. Ultrasonication, high-pressure pretreatments, and glycosylation as post-treatments can improve the antiradical, antioxidant, and ACE inhibitory activities of PPHs. The electrostatic attachment of pulse peptides to microbial cells can inhibit the growth and activity of bacteria and fungi. Bioactive pulse peptides can reduce serum cholesterol and triglycerides, and inhibit the formation of adipocyte lipid storage, allergenic factors, inflammatory markers, and arterial thrombus without cytotoxicity. The combination of germination and enzymatic hydrolysis can significantly increase the protein digestibility and bioavailability of essential amino acids. Moreover, the utilization and enrichment of bakery and meat products with functional PPHs ensure quality, safety, and health aspects of food products.

Hydrogels as promising carriers for the delivery of food bioactive ingredients

The burden of public health challenges associated with the western dietary and living style is growing. Nutraceuticals have been paid increasing attentions due to their effects in promotion of health. However, in the gastrointestinal (GI) tract, the nutraceuticals suffer from not only the harsh acidic environment of the stomach and a variety of digestive enzymes, but also the antibacterial activity of intestinal bile salts and the action of protease from the gut microbiota. The amount of the nutraceuticals arriving at the sites in GI tract for absorption or exerting the bioactivities is always unfortunately limited, which puts forward high requirements for protection of nutraceuticals in a certain high contents during oral consumption. Hydrogels are three-dimensional polymeric porous networks formed by the cross-linking of polymer chains, which can hold huge amounts of water. Compared with other carries with the size in microscopic scale such as nanoparticle and microcapsules, hydrogels could be considered to be more suitable delivery systems in food due to their macroscopic bulk properties, adjustable viscoelasticity and large spatial structure for embedding nutraceuticals. Regarding to the applications in food, natural polymer-based hydrogels are commonly safe and popular due to their source with the appealing characteristics of affordability, biodegradability and biocompatibility. Although chemical crosslinking has been widely utilized in preparation of hydrogels, it prefers the physical crosslinking in the researches in food. The reasonable design for the structure of natural polymeric hydrogels is essential for seeking the favorable functionalities to apply in the delivery system, and it could be possible to obtain the enhanced adhesive property, acid stability, resistant to bile salt, and the controlled release behavior. The hydrogels prepared with proteins, polysaccharides or the mix of them to deliver the functional ingredients, mainly the phenolic components, vitamins, probiotics are discussed to obtain inspiration for the wide applications in delivery systems. Further efforts might be made in the in situ formation of hydrogels in GI tract through the interaction among food polymers and small-molecular ingredients, elevation of the loading contents of nutraceuticals in hydrogels, development of stomach adhesive hydrogels as well as targeting modification of gut microbiota by the hydrogels.

Transglutaminase-Induced Free-Fat Yogurt Gels Supplemented with Tarragon Essential Oil-Loaded Nanoemulsions: Development, Optimization, Characterization, Bioactivity, and Storability

There is a high demand for designing healthy-functional dairy gels with a newly structured protein network in the food industry. Non-fat yogurt gels enriched with stable tarragon essential oil-nanoemulsions (TEO-NEs) using crosslinking of microbial transglutaminase (MTGase) were developed. The gas chromatography-mass spectrometry analysis showed that methyl chavicol (85.66%) was the major component in TEO extracted by the hydrodistillation process. The storage-dependent droplet size and physicochemical stability data of samples at room temperature for 30 days revealed that the TEO-NE containing 0.5% tween-80 and 1:2 TEO/sunflower oil had the lowest peroxide value and droplet growth ratio. The response surface methodology-based formulation optimization of free-fat yogurt gels using MTGase (0.15–0.85 U/g) and the best TEO-NE (0.5–3.02%) using the fitted second-order polynomial models proved that the combination of 0.87% TEO-NE and 0.70 U/g MTGase led to the desired pH (4.569) and acidity (88.3% lactic acid), minimum syneresis (27.03 mL/100 g), and maximum viscosity (6.93 Pa s) and firmness (0.207 N) responses. Scanning electron microscopy images visualized that the MTGase-induced crosslinks improved the gel structure to increase the firmness and viscosity with a reduction in the syneresis rate. The optimal yogurt gel as a nutritious diet not only provided the highest organoleptic scores but also maintained its storage-related quality with the lowest mold/yeast growth and free-radical oxidation changes.

Whey Protein Hydrolysates Improved the Oxidative Stability and Water-Holding Capacity of Pork Patties by Reducing Protein Aggregation during Repeated Freeze–Thaw Cycles

The effects of whey protein hydrolysates (WPH) on myofibrillar protein (MP) oxidative stability and the aggregation behavior and the water-holding capacity of pork patties during freeze–thaw (F–T) cycles were investigated. During F–T cycles, the total sulfhydryl content and zeta potential of MP decreased, while peroxide value, surface hydrophobicity, particle size, pressure loss and transverse relaxation times increase. The oxidative stability and the water-holding capacity of pork patties were enhanced by the addition of WPH in a dose-dependent manner, whereas the MP aggregation decreased. The addition of 15% WPH had the most obvious effects on the pork patties, which was similar to that of the 0.02% BHA. After nine F–T cycles, the POV, surface hydrophobicity, particle size and pressure loss of the pork patties with 15% WPH were reduced by 17.20%, 30.56%, 34.67% and 13.96%, respectively, while total sulfhydryl content and absolute value of zeta potential increased by 69.62% and 146.14%, respectively. The results showed that adding 15% WPH to pork patties can be an effective method to inhibit lipid and protein oxidation, reducing protein aggregation and improving the water-holding capacity of pork patties during F–T cycles.

Transglutaminase-Catalyzed Bottom-Up Synthesis of Polymer Hydrogel

Enzyme catalysis has attracted increasing attention for application in the synthesis of polymer hydrogel due to the eco-friendly process and the devisable catalytic reaction. Moreover, bottom-up approaches combining enzyme catalysts and molecular self-assembly have been explored for synthesizing hydrogel with complex architectures. An enzyme widely distributed in nature, transglutaminase (TGase) has been confirmed to catalyze the formation of isopeptide bonds between proteins, which can effectively improve the gelation of proteins. In this mini-review, TGase-catalyzed synthesis of polymer hydrogels, including fibrin hydrogels, polyethylene glycol hydrogels, soy protein hydrogels, collagen hydrogels, gelatin hydrogels and hyaluronan hydrogels, has been reviewed in detail. The catalytic process and gel formation mechanism by TGase have also been considered. Furthermore, future perspectives and challenges in the preparation of polymer hydrogels by TGase are also highlighted.

Role of Food Hydrocolloids as Antioxidants along with Modern Processing Techniques on the Surimi Protein Gel Textural Properties, Developments, Limitation and Future Perspectives

Texture is an important parameter in determining the quality characteristics and consumer acceptability of seafood and fish protein-based products. The addition of food-based additives as antioxidants (monosaccharides, oilgosaccharides, polysaccharides and protein hydrolysates) in surimi and other seafood products has become a promising trend at an industrial scale. Improvement in gelling, textural and structural attributes of surimi gel could be attained by inhibiting the oxidative changes, protein denaturation and aggregation with these additives along with new emerging processing techniques. Moreover, the intermolecular crosslinking of surimi gel can be improved with the addition of different food hydrocolloid-based antioxidants in combination with modern processing techniques. The high-pressure processing (HPP) technique with polysaccharides can develop surimi gel with better physicochemical, antioxidative, textural attributes and increase the gel matrix than conventional processing methods. The increase in protein oxidation, denaturation, decline in water holding capacity, gel strength and viscoelastic properties of surimi gel can be substantially improved by microwave (MW) processing. The MW, ultrasonication and ultraviolet (UV) treatments can significantly increase the textural properties (hardness, gumminess and cohesiveness) and improve the antioxidative properties of surimi gel produced by different additives. This study will review potential opportunities and primary areas of future exploration for high-quality surimi gel products. Moreover, it also focuses on the influence of different antioxidants as additives and some new production strategies, such as HPP, ultrasonication, UV and MW and ohmic processing. The effects of additives in combination with different modern processing technologies on surimi gel texture are also compared.

Vegan Egg: A Future-Proof Food Ingredient?

Vegan eggs are designed with the aim to provide a healthier and more sustainable alternative to regular eggs. The major drivers of this industry are the increasing prevalence of egg allergies, awareness towards environmental sustainability, and the shift to vegan diets. This study intends to discuss, for the first time, the vegan egg market, including their formulation, nutritional aspects, and some applications (i.e., mayonnaise and bakery products). Recreating the complete functionality of eggs using plant-based ingredients is very challenging due to the complexity of eggs. Current, but scarce, research in this field is focused on making mixtures of plant-based ingredients to fit specific food formulations. Nutritionally, providing vegan eggs with similar or higher nutritional value to that of eggs can be of relevance to attract health-conscious consumers. Claims such as clean labels, natural, vegan, animal-free, gluten-free, and/or cholesterol-free can further boost the position of vegan eggs in the market in the coming year. At present, this market is still in its infancy stages, and clear regulations of labeling, safety, and risk assessment are deemed mandatory to organize the sector, and protect consumers.

Enhancing the functional characteristics of soy protein isolate via cross-linking catalyzed by Bacillus subtilis transglutaminase

BACKGROUND

Although Streptomyces mobaraense transglutaminase (MTG) has been extensively applied to enhance the functional characteristics of soy protein isolate (SPI) through cross-linking, various transglutaminases (TGs) in nature may provide more choice in the food industry. Previous research reported that TG derived from Bacillus subtilis (BTG) exhibited better pH stability and thermostability than MTG.

RESULTS

An attempt was made to study the influence of BTG induced cross-linking on the properties of SPI. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) results indicated that almost all protein constituents (α', α, β, AS, and BS) in SPI could be cross-linked with BTG treatment. The BTG treatment also resulted in a significant increase (*P < 0.05) in SPI mean particle size. Emulsifying activity and stability were improved from 0.11535 m²  g^-1 and 48.3% for native SPI to 0.13252 m²  g^-1 and 83.9% for SPI treated with BTG at 6 h. Similarly, the modified SPI showed better foam activity (1.32 mL) and stability (87.6%) than the original SPI (0.93 mL and 56.8%). The water-holding capacity of SPI gel was found to increase with time, with a value of 95.43% at 6 h. Furthermore, SPI gel's texture profiles were greatly improved by adding BTG (*P < 0.05).

CONCLUSION

The results of the present study indicated that BTG could be a promising cross-linking agent for improving the functional characteristics of SPI. As a substitute for MTG, BTG could thus potentially be used for food structure engineering to enhance the functional characteristics of multiple proteins to advance the development of food chemistry. © 2020 Society of Chemical Industry.

A brief review of the science behind the design of healthy and sustainable plant-based foods

People are being encouraged to consume more plant-based foods to reduce the negative impacts of the modern food supply on human and global health. The food industry is therefore creating a new generation of plant-based products to meet this demand, including meat, fish, egg, milk, cheese, and yogurt analogs. The main challenge in this area is to simulate the desirable appearance, texture, flavor, mouthfeel, nutrition, and functionality of these products using healthy, affordable, and sustainable plant-derived ingredients, such as lipids, proteins, and carbohydrates. The molecular and physicochemical properties of plant-derived ingredients are very different from those of animal-derived ones. It is therefore critical to understand the fundamental attributes of plant-derived ingredients and how they can be assembled into structures resembling those found in animal products. This short review provides an overview of the current status of the scientific understanding of plant-based foods and highlights areas where further research is required. In particular, it focuses on the chemical, physical, and functional properties of plant ingredients; the processing operations that can be used to convert these ingredients into food products; and the science behind the creation of some common plant-based foods, namely meat, egg, and milk analogs.

Effect of ultrasound pretreatment on structural, physicochemical, rheological and gelation properties of transglutaminase cross-linked whey protein soluble aggregates

A solution (10%, w/v) of whey protein soluble aggregates (WPISA) was pretreated with high-intensity ultrasound (HUS, 20 kHz) for different durations (10-40 min) before incubation with transglutaminase (TGase) to investigate the effect of HUS on the structural, physicochemical, rheological, and gelation properties of TGase cross-linked WPISA. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) results showed that HUS increased the amounts of high-molecular-weight polymers/aggregates in WPISA after incubation with TGase. HUS significantly increased (P < 0.05) the degree of TGase-mediated cross-linking in WPISA, as demonstrated by a reduction in free amino group contents. HUS significantly increased (P < 0.05) the particle size, intrinsic fluorescence intensity, and surface hydrophobicity of TGase cross-linked WPISA, but had no significant impact (P > 0.05) on the zeta-potential or total free sulfhydryl group content of TGase cross-linked WPISA. The apparent viscosity and the consistency index of TGase cross-linked WPISA were significantly increased by HUS (P < 0.05), which indicated that HUS facilitated the formation of more high-molecular-weight polymers. HUS significantly increased (P < 0.05) the water holding capacity and gel strength of glucono-δ-lactone (GDL)-induced TGase cross-linked WPISA gels. The results indicated that HUS could be an efficient tool for modifying WPISA to improve its degree of TGase-mediated cross-linking, which would lead to improved rheological and gelation properties.

The science of plant-based foods: Constructing next-generation meat, fish, milk, and egg analogs

Consumers are increasingly demanding foods that are more ethical, sustainable and nutritious to improve the health of themselves and the planet. The food industry is currently undergoing a revolution, as both small and large companies pivot toward the creation of a new generation of plant-based products to meet this consumer demand. In particular, there is an emphasis on the production of plant-based foods that mimic those that omnivores are familiar with, such as meat, fish, egg, milk, and their products. The main challenge in this area is to simulate the desirable appearance, texture, flavor, mouthfeel, and functionality of these products using ingredients that are isolated entirely from botanical sources, such as proteins, carbohydrates, and lipids. The molecular, chemical, and physical properties of plant-derived ingredients are usually very different from those of animal-derived ones. It is therefore critical to understand the fundamental properties of plant-derived ingredients and how they can be assembled into structures resembling those found in animal products. This review article provides an overview of the current status of the scientific understanding of plant-based foods and highlights areas where further research is required. In particular, it focuses on the chemical, physical, and functional properties of plant-derived ingredients; the processing operations that can be used to convert these ingredients into food products; and, the science behind the formulation of vegan meat, fish, eggs, and milk alternatives.

Enzymatic modifications of gluten protein: Oxidative enzymes

Oxidative enzymes treat weak flours in order to restore the gluten network of damaged wheat flour and reduce the economic and technological losses. The present review concentrates on oxidative exogenous enzymes (transglutaminase, laccase, glucose oxidase, hexose oxidase) and oxidative endogenous enzymes (tyrosinase, peroxidase, catalase, sulfhydryl oxidase, lipoxygenase, lipase, protein disulfide isomerase, NAD(P)H-dependent dehydrogenase, thioredoxin reductase and glutathione reductase) and their effects on the rheological, functional, and conformational features of gluten and its subunits. Overall, transglutaminase is used in wheat-based foods through introducing isopeptide bonds (ε-γ glutamyl-lysine). Glucose oxidase, hexose oxidase, peroxidase, sulfhydryl oxidase, lipase, and lipoxygenase form disulfide and nondisulfide bonds through producing hydrogen peroxide. Laccase, tyrosinase, and protein disulfide isomerase form cross-links between tyrosine and cysteine residues by generating radicals. Thioredoxin reductase and glutathione reductase create new inter disulfide bonds. The effect of oxidative enzymes on the formation of covalent cross-linkages were substantially more than non-covalent bonds in gluten structure.

An Integrated Approach for the Valorization of Cheese Whey

Taking into account the large amount of whey that is produced during the cheese production process and the constant demand by society for more sustainable processes, in accordance with Sustainable Development Goals (SDGs) and the circular economy concept, it is necessary to adapt two-unit operations into a single process, allowing us to not only valorize a part of the whey but the whole process, which is known as bioprocess integration. In this sense, the adaptation of different processes, for example, physicochemical (micro, ultra and nanofiltration) and fermentation, that are commonly used to obtain proteins, lactose and other compounds with different activities (antioxidant, antifungal, etc.) could be integrated to achieve a complete recovery of the cheese whey. Likewise, keeping in mind that one of the main drawbacks of cheese whey is the great microbial load, some innovative processing technologies, such as high hydrostatic pressures, electrotechnologies and ultrasound, can allow both the development of new foods from whey as well as the improvement of the nutritional and organoleptic properties of the final products prepared with cheese, and thus reducing the microbial load and obtaining a safe product could be incorporated in the cheese whey valorization process.

Legume proteins are smart carriers to encapsulate hydrophilic and hydrophobic bioactive compounds and probiotic bacteria: A review

Encapsulation is a promising technological process enabling the protection of bioactive compounds against harsh storage, processing, and gastrointestinal tract (GIT) conditions. Legume proteins (LPs) are unique carriers that can efficiently encapsulate these unstable and highly reactive ingredients. Stable LPs-based microcapsules loaded with active ingredients can thus develop to be embedded into processed functional foods. The recent advances in micro- and nanoencapsulation process of an extensive span of bioactive health-promoting probiotics and chemical compounds such as marine and plant fatty acid-rich oils, carotenoid pigments, vitamins, flavors, essential oils, phenolic and anthocyanin-rich extracts, iron, and phytase by LPs as single wall materials were highlighted. A technical summary of the use of single LP-based carriers in designing innovative delivery systems for natural bioactive molecules and probiotics was made. The encapsulation mechanisms, encapsulation efficiency, physicochemical and thermal stability, as well as the release and absorption behavior of bioactives were comprehensively discussed. Protein isolates and concentrates of soy and pea were the most common LPs to encapsulate nutraceuticals and probiotics. The microencapsulation of probiotics using LPs improved bacteria survivability, storage stability, and tolerance in the in vitro GIT conditions. Moreover, homogenization and high-pressure pretreatments as well as enzymatic cross-linking of LPs significantly modify their structure and functionality to better encapsulate the bioactive core materials. LPs can be attractive delivery devices for the controlled release and increased bioaccessibility of the main food-grade bioactives.

New insights into food hydrogels with reinforced mechanical properties: A review on innovative strategies

Enhancement on the mechanical properties of hydrogels leads to a wider range of their applications in various fields. Therefore, there has been a great interest recently for developing new strategies to reinforce hydrogels. Moreover, food gels must be edible in terms of both raw materials and production. This paper reviews innovative techniques such as particle/fiber-reinforced hydrogel, double network, dual crosslinking, freeze-thaw cycles, physical conditioning and soaking methods to improve the mechanical properties of hydrogels. Additionally, their fundamental mechanisms, advantages and disadvantages have been discussed. Important biopolymers that have been employed for these strategies and also their potentials in food applications have been summarized. The general mechanism of these strategies is based on increasing the degree of crosslinking between interacting polymers in hydrogels. These links can be formed by adding fillers (oil droplets or fibers in filled gels) or cross-linkers (regarding double network and soaking method) and also by condensation or alignment of the biopolymers (freeze-thaw cycle and physical conditioning) in the gel network. The properties of particle/fiber-reinforced hydrogels extremely depend on the filler, gel matrix and the interaction between them. In freeze-thaw cycles and physical conditioning methods, it is possible to form new links in the gel network without adding any cross-linkers or fillers. It is expected that the utilization of gels will get broader and more varied in food industries by using these strategies.

Oxidized Oligosaccharides Stabilize Rehydrated Sea Cucumbers against High-Temperature Impact

Small-molecule crosslinkers could diffuse into and stabilize protein hydrogels without damaging their appearance, but they are absent from the food industry due to the high safety and efficacy requirements for foods. Oxidized oligosaccharides are non-toxic small polyaldehydes previously found capable of crosslinking proteins by premixing. In this study, we managed to diffuse various oxidized oligosaccharides into the protein wall of rehydrated sea cucumbers, and the texture profile analysis, total soluble material assay and SEM (scanning electron microscope) images all suggested the treated sea cucumbers acquired significantly enhanced stability against high-temperature-promoted deterioration. The stabilization was positively correlated with the aldehyde content of oxidized oligosaccharides but negatively correlated with molecular size. The mechanism of stabilization was found to include both covalent and hydrogen bond crosslinking. These results have demonstrated that oxidized oligosaccharides could enter food protein hydrogel by free diffusion and stabilize the 3D network effectively and thereby has great potential in food-related industry.

Role of chitosan and transglutaminase on the elaboration of gluten-free bread

The increasing sensitivity to gluten has aroused interest in gluten-free products like bread. However, one of the biggest challenges of producing gluten-free bread is to get a good quality structure. We hypothesize that using chitosan along with transglutaminase, a network of crosslinks would be generated, guaranteeing a better structure. Thus, in the present work, we produced gluten-free bread using red rice flour and cassava flour, transglutaminase, and chitosan at concentrations of 0%, 1%, and 2%. Loaves of bread were characterized, and the instrumental texture properties during five days were determined. Bread produced with chitosan and transglutaminase presented lighter brown coloration due to incomplete Maillard reaction and low specific volumes varying from 1.64 to 1.48 cm3/g, possibly due to chitosan interfering with yeast fermentation. Rheological tests revealed increases in viscosity before and after fermentation when chitosan was used. Bread with chitosan presented high initial firmness but a lower rate of staling, possibly due to water retention. According to results, a possible network involving chitosan and other proteins promoted by transglutaminase was formed and after optimization could yield better gluten-free bread.

Utilization of agro-industrial waste for production of Transglutaminase from Streptomyces mobaraensis

This work studied the production of Transglutaminase (TGase) using wheat bran as carbon source. The medium components and culture conditions were optimized by statistical Box-Behnken response surface methodology. The release of active Transglutaminase was enhanced by adding (i) protease to remove pro-region to make inactive enzyme to active form, (ii) Cetyl trimethyl ammonium bromide (CTAB) which facilitated more secretion. Under finally optimized conditions viz. 5 g wheat bran, protease: 39.14 U, magnesium chloride (MgCl₂): 0.10 M, CTAB: 0.08% and inoculation size: 2% led to 4-fold (12.949 ± 0.061 IU/g) increased TGase production over that of un-optimized conditions. The application of TGase was shown to be useful in effective casein cross-linking.

Microbial transglutaminase: A new potential player in celiac disease

Microbial transglutaminase is heavily used in the food processing industries to improve food qualities. Being a protein's glue, by cross-linking it creates neoepitope complexes that are immunogenic and potentially pathogenic in celiac disease. Despite low sequence identity, it imitates functionally its family member, the endogenous tissue transglutaminase, which is the autoantigen of celiac disease. The present comprehensive review highlights the enzyme characteristics, endogenous and exogenous intestinal sources, its cross-talks with gluten and gliadin, its immunogenicity and potential pathogenicity and risks for the gluten induced conditions. If substantiated, it might represent a new environmental inducer of celiac disease. The present findings might affect nutritional product labeling, processed food additive policies and consumer health education.

Innovative processing techniques for altering the physicochemical properties of wholegrain brown rice (Oryza sativa L.) - opportunities for enhancing food quality and health attributes

Rice is a globally important staple consumed by billions of people, and recently there has been considerable interest in promoting the consumption of wholegrain brown rice (WBR) due to its obvious advantages over polished rice in metabolically protective activities. This work highlights the effects of innovative processing technologies on the quality and functional properties of WBR in comparison with traditional approaches; and it is aimed at establishing a quantitative and/or qualitative link between physicochemical changes and high-efficient processing methods. Compared with thermal treatments, applications of innovative nonthermal techniques, such as high hydrostatic pressure (HHP), pulsed electric fields (PEF), ultrasound and cold plasma, are not limited to modifying physicochemical properties of WBR grains, since improvements in nutritional and functional components as well as a reduction in anti-nutritional factors can also be achieved through inducing related biochemical transformation. Much information about processing methods and parameters which influence WBR quality changes has been obtained, but simultaneously achieving the product stabilization and functionality of processed WBR grains requires a comprehensive evaluation of all the quality changes induced by different processing procedures as well as quantitative insights into the relationship between the changes and processing variables.