β-Lactoglobulin nanofibrils: The long and the short of it

The bovine whey protein β-lactoglobulin will self-assemble into amyloid-like nanofibrils when heated at pH ≤ 3 and temperatures ≥75 °C. These fibrils have diameters <10 nm and lengths that can exceed 10 μm. The length and stiffness of fibrils depends on ionic strength; heating at low ionic strength produces long semi-flexible fibrils, whereas heating with added salts produces highly flexible ‘worm-like’ fibrils that are an order of magnitude shorter. Over the last two decades there has been a substantial research effort focused on imaging fibrils, manipulating conditions to accelerate fibril formation, and characterising microstructural and rheological properties of fibril dispersions. Here we review the major mechanistic findings, explore potential applications for fibrils as food ingredients, and highlight the major gaps in knowledge surrounding these intriguing self-assembled structures.     

Production,structure–function relationships,mechanisms, and applications of antifreeze peptides

Growth of ice crystals can cause serious problems, such as frozen products deterioration, road damage, energy losses, and safety risks of human beings. Antifreeze peptides (AFPs), a healthy and effective cryoprotectant, have great potential as ice crystal growth inhibitors for a variety of frozen products. In this review, methods and technologies for the production, purification, evaluation, and characterization of AFPs are comprehensively summarized. First, this review describes the preparation of AFPs, including the methods of enzymatic hydrolysis, chemical synthesis, and microbial fermentation. Next, this review introduces the major methods by which to evaluate AFPs’ antifreeze activity, including nanoliter osmometer, differential scanning calorimetry, splat-cooling, the biovaluation model, and novel technology. Moreover, this review presents an overview of the molecular characteristics, structure–function relationships, and action mechanisms of AFPs. Furthermore, advances in the application of AFPs to frozen food, including frozen dough, meat products, fruits, vegetable products, and dairy, are summarized and holistically analyzed. Finally, challenges of AFPs and future perspectives on their use are also discussed. An understanding of the production, structure–function relationships, mechanisms and applications of AFPs provides inspiration for further research into the use of AFPs in food science and food nutrition applications.     

Wheat gluten–based coatings and films: Preparation,properties, and applications

Effective food packaging that can protect foodstuffs from physical, chemical, and biological damage and maintain freshness and quality is essential to the food industry. Wheat gluten shows promise as food packaging materials due to its edibility, biodegradability, wide availability, low cost, film-forming potential, and high resistance to oxygen. The low mechanical properties and poor water permeability of wheat gluten coatings and films limit their wide applications; however, some inferior properties can be improved through various solutions. This work presents a comprehensive review about wheat gluten–based coatings and films, including their formulation, processing methods, properties, functions, and applications. The mechanical and water resistance properties of coatings and films can be reinforced through wheat gluten modification, combinations of different processing methods, and the incorporation of reinforcing macromolecules, antioxidants, and nanofillers. Antioxidants and antimicrobial agents added to wheat gluten can inhibit microbial growth on foodstuffs, maintain food quality, and extend shelf life. Performances of wheat gluten–based coatings and films can be further improved to expand their applications in food packaging. Current research gaps are identified. Future research is needed to examine the optimal formulation and processing of wheat gluten–based coatings and films and their performance.     

β-Lactoglobulin nanofibrils: Effect of temperature on fibril formation kinetics, fibril morphology and the rheological properties of fibril dispersions

Almost all published studies of heat-induced β-lactoglobulin self-assembly into amyloid-like fibrils at low pH and low ionic strength have involved heating at 80 °C, and the effect of heating temperature on self-assembly has received little attention. Here we heated β-lactoglobulin at pH 2 and 75 °C, 80 °C, 90 °C, 100 °C, 110 °C or 120 °C and investigated the kinetics of self-assembly (using Thioflavin T fluorescence), the morphology of fibrils, and the rheological properties of fibril dispersions.Self-assembly occurred at all temperatures tested. Thioflavin T fluorescence increased sigmoidally at all temperatures, however it decreased sharply with >3.3 h heating at 110 °C and with >5 h heating at 120 °C. The sharp decreases were attributed partly to local gelation, but destruction of fibrils may have occurred at 120 °C. Thioflavin T fluorescence results indicated that maximal rates of fibril formation increased with increasing temperature, especially above 100 °C, but fibril yield (maximum Thioflavin T fluorescence) was not affected by temperature.At 100 °C and 110 °C, fibrils were slightly shorter than at 80 °C, but otherwise they looked very similar. Fibrils made by heating at 120 °C for 1 h were also similar, but heating at 120 °C for 8 h gave predominantly short fibrils, apparently the products of larger fibrils fragmenting. Heating at 100 °C gave consistently higher viscosity than at 80 °C, and heating for >2 h at 120 °C decreased viscosity, which may have been linked with fibril fragmentation seen in micrographs.     

β-Lactoglobulin heat denaturation: A critical assessment of kinetic modelling

Bovine whey protein β-lactoglobulin (β-lg) will denature above 70 °C. Denaturation may contribute positively or negatively to food functionality, so it is important to control the degree of denaturation during milk processing. This work critically examined the kinetic modelling of β-lg denaturation in water, buffer or milk at 70–150 °C using the general rate law for a single-species reaction and the Arrhenius equation. Several published datasets, originally analysed in linearised form, were re-analysed with nonlinear regression, which preserves the error structure of data and estimates the precision of parameters. This work discusses statistical best practice for modelling the heat denaturation of β-lg, explores the criteria for using 2- or 3-parameter regression equations, and proposes new approaches for modelling the concentration- and temperature-dependence of denaturation rates. These new approaches improved the accuracy and precision of kinetic parameter estimates, and revealed new details of how solution conditions influence β-lg denaturation rates.     

β-Lactoglobulin conformation and mixed sugar beet pectin gel matrix is changed by laccase

Sugar beet pectin (SBP) and β-lactoglobulin (BLG) contain ferulic acid and tyrosine, respectively, potential substrates for laccase. Dispersions of BLG were treated with laccase and/or heat and SBP to assess potential for ferulic acid in SBP to influence laccase conjugation of BLG. Changes were investigated by size exclusion chromatography combined with multi angle laser light scattering (HPSEC-MALLS), refractive index (RI) and UV detector, particle size and ζ-potential analysis. Molecular weight (MW) of BLG decreased from 3.7 × 10⁴ to 2.9 × 10⁴ and root mean square (RMS) decreased from 41 to 36 after laccase treatment. The slope of a conformation plot increased from 0.35 to 0.72, indicating a change in shape in laccase treated BLG to more random coil. While laccase did not affect MW of BLG, MW of BLG increased after sequential heat and laccase treatment to 2.9 × 10⁶ and 4.4 × 10⁶, respectively. Free thiol (SH) increased by heat and laccase treatment of BLG; tyrosine in BLG increased only by heat. An increased MW and decreased ferulic acid in SBP was observed in the presence of BLG and laccase. The increase in MW was attributed to entrapment of BLG in SBP cross-linked matrix catalyzed by laccase.     

Exudate gums: chemistry,properties and food applications – a review

Gums are complex carbohydrate molecules which have the ability to bind water and form gels at low concentration. These carbohydrates are often associated with proteins and minerals in their structure. Gums are of various types such as seed gums, exudate gums, microbial gums, mucilage gums, seaweeds gums, etc. Exudate gums are plant gums which ooze out from bark as a result of a protection mechanism upon injury. Exudate gums have been used by humans since ancient times for various applications due to their easy availability. The main characteristics which make them fit for use in various applications are viscosity, adhesive property, stabilization effect, emulsification action and surface-active property. Major applications of these gums are in food products, the paper, textile, cosmetics and pharmaceutical industries, oil-well drilling, etc. In the present paper, the chemistry, properties, processing and applications of commercially available exudate gums such as acacia gum or gum arabic, karaya gum, ghatti gum and tragacanth gum are discussed. Recent literature reveals that apart from the above mentioned applications, these gums also have nutritional properties which are being explored. Other gums cannot replace them because of their certain unique characteristics. © 2020 Society of Chemical Industry     

Thermal Properties of Yak α-Lactalbumin and β-Lactoglobulin: a DSC Study

A differential scanning calorimetry (DSC) method was used to investigate the denaturation temperature of yak α-lactalbumin (α-La), β-lactoglobulin (β-Lg), and a mixture of two proteins and the thermal properties of α-La and β-Lg in the presence of glucose, lactose, sucrose, NaCl, CaCl₂, and at various pH (4.0–10.0). The denaturation temperature (T _d) of α-La increased from 52.1 °C in the absence of β-Lg to 53.9 °C in the presence of β-Lg, while the T _d of β-Lg decreased from 81.4 °C in the absence of α-La to 79.9 °C in the presence of α-La. α-La was thermal stable in the range of pH 4.0–10.0, while β-Lg was more thermal stable in acidic pH than in alkaline pH. Sugars, Na⁺, and Ca²⁺ influenced the stabilization of the two proteins against thermal denaturation with greatly influenced for β-Lg. α-La kept reversibility in the presence of sugars, NaCl, CaCl₂, and over a wide pH range (4.0–10.0), with most of the reversibility values being greater than 90%. In contrast, β-Lg was completely irreversible whether in its native state or in the presence of the additives.     

β-Lactoglobulin genetic variants in Brown Swiss breed and its association with compositional properties and rennet clotting time of milk

β-Lactoglobulin (β-Lg) polymorphism of Holstein Friesian and Brown Swiss breeds were studied by applying native polyacrylamide gel electrophoresis. In addition, total solids, protein, fat ash, lactose and solid non-fat contents, rennet clotting time and major minerals (potassium, calcium, phosphorus and magnesium) of milk from Brown Swiss breed were examined. Phenotype and allele frequencies of β-Lg in both breeds were estimated and the association of the β-Lg genetic variants with the examined properties of Brown Swiss milk was studied. As a result of the study, β-Lg AA, AB and BB phenotypes were found in both Holstein Friesian and Brown Swiss breeds. The gene frequencies of β-Lg A and B were 0.27 and 0.73 in Holstein Friesian and 0.44 and 0.56 in Brown Swiss breeds, respectively. Therefore, β-Lg B allele gene was found more common in both breeds. In addition, significant differences were observed in β-Lg genotypes between two breeds. Also, significant relationships were found between β-Lg genetic variants and total solids (p<0.05), fat (p<0.01), calcium (p<0.05) and phosphorus (p<0.05), while no relationship was obtained for the other parameters studied in the milk of Brown Swiss breed.     

Green tea extract: Chemistry,antioxidant properties and food applications – A review

Green tea is one of the most popular and extensively used dietary supplement in the United States. Diverse health claims have made for green tea as a trendy ingredient in the growing market for nutraceuticals and functional foods. Green tea extract contains several polyphenolic components with antioxidant properties, but the predominant active components are the flavanol monomers known as catechins, where epigallocatechin-3-gallate and epicatechin-3-gallate are the most effective antioxidant compounds. Additional active components of green tea extract include the other catechins such as epicatechin and epigallocatechin. Among these, epigallocatechin-3-gallate is the most bioactive and the most scrutinized one. Green tea polyphenols are also responsible for distinctive aroma, color and taste. Green tea extract can also be used in lipid-bearing foods to delay lipid oxidation and to enhance the shelf-life of various food products. This review outlines the chemistry, flavour components, antioxidant mechanism, regulatory status, food applications, and stability of green tea extract in food.     

Fungal β-1,3-1,4-glucanases: production,proprieties and biotechnological applications

β-1,3-1,4-glucanases (or lichenases; EC 3.2.1.73) comprise one of the main enzymes used in industry during recent decades. These enzymes hydrolyze β-glucans containing β-1,3 and β-1,4 linkages, such as cereal β-glucans and lichenan. The β-1,3-1,4-glucanases are produced by a variety of bacteria, fungi, plants and animals. A large number of microbial β-1,3-1,4-glucanases have potential application in industrial processes, such as feed, food and detergent industries. The present review summarizes the available studies with respect to β-1,3-1,4-glucanases production conditions, enzyme biochemical properties and potential industrial application. © 2018 Society of Chemical Industry     

Synthesis and controlled-release properties of chitosan/β-Lactoglobulin nanoparticles as carriers for oral administration of epigallocatechin gallate

A nano-sized double-walled carrier composed of chitosan and β-lactoglobulin (β-Lg) for oral administration of epigallocatechin gallate (EGCG) was developed to achieve a prolonged release of EGCG in the gastrointestinal tract. Carboxymethyl chitosan (CMC) solution was added dropwise to chitosan hydrochloride (CHC) containing EGCG to form a primary coating by ionic complexation. Subsequently, β-Lg was added to create a secondary layer by ionic gelation. The obtained EGCG-loaded chitosan/β-Lg nanoparticles had sizes between 100 and 500 nm and zeta potentials ranging from 10 to 35mV. FT-IR spectroscopy revealed a high number of hydrogen-bonding sites in the nanoparticles, which could incorporate EGCG, resulting in high encapsulation efficiency. EGCG incorporated in the primary coating was released slowly over time by diffusion from the swollen CMC-CHC matrix after the outer layer of β-Lg was degraded in the intestinal fluid. The sustained-release property makes chitosan/β-Lg nanoparticles an attractive candidate for effective delivery of EGCG.     

Composition,industrial processing and applications of rice bran γ-oryzanol

Rice bran oil (RBO) (20–25 wt% in rice bran) is a unique rich source of commercially-important bioactive phytochemicals, most of them of interest in nutrition, pharmacy and cosmetics. The unsaponifiable constituents of RBO include mainly tocols (vitamin E, 0.10–0.14%) and γ-oryzanol (esters of trans-ferulic acid with sterols and triterpenic alcohols, 0.9–2.9%). The following topics concerning γ-oryzanol are reviewed: analytical methods for characterisation and determination; influence of genetic and environmental factors on the composition of rice bran; extraction approaches, including supercritical CO₂ and subcritical water; and biomedical and industrial applications, including food and pharmaceuticals. Concentration ranges of γ-oryzanol, tocopherols and tocotrienols found in rice bran and RBO from different varieties and geographical areas are summarised. This review focuses on the 2003–2008 period, where an average of 13–14 references per year were published; however, some relevant work reported during the 1998–2002 period is also briefly commented upon.     

Bioactive polysaccharides and oligosaccharides from garlic (Allium sativum L.): Production,physicochemical and biological properties,and structure–function relationships

Garlic is a common food, and many of its biological functions are attributed to its components including functional carbohydrates. Garlic polysaccharides and oligosaccharides as main components are understudied but have future value due to the growing demand for bioactive polysaccharides/oligosaccharides from natural sources. Garlic polysaccharides have molecular weights of 1 × 10³ to 2 × 10⁶ Da, containing small amounts of pectins and fructooligosaccharides and large amounts of inulin-type fructans ((2→1)-linked β-d -Fruf backbones alone or with attached (2→6)-linked β-d -Fruf branched chains). This article provides a detailed review of research progress and identifies knowledge gaps in extraction, production, composition, molecular characteristics, structural features, physicochemical properties, bioactivities, and structure–function relationships of garlic polysaccharides/oligosaccharides. Whether the extraction processes, synthesis approaches, and modification methods established for other non-garlic polysaccharides are also effective for garlic polysaccharides/oligosaccharides (to preserve their desired molecular structures and bioactivities) requires verification. The metabolic processes of ingested garlic polysaccharides/oligosaccharides (as food ingredients/dietary supplements), their modes of action in healthy humans or populations with chronic conditions, and molecular/chain organization–bioactivity relationships remain unclear. Future research directions related to garlic polysaccharides/oligosaccharides are discussed.     

Formation and characterisation of food protein–polysaccharide thermal complex particles: effects of pH,temperature and polysaccharide type

The objective of this study was to prepare and characterise the thermal complex particles (TCPs) based on heating food grade protein–polysaccharide electrostatic complexes. The soybean protein isolate (SPI), cationic polysaccharide (chitosan, CS) and anionic polysaccharide (carboxymethyl cellulose, CMC) were used. Turbidity, particle size, ζ-potential and morphology of TCPs were measured. The results showed that SPI-CS and SPI-CMC soluble complexes were obtained at specific pHs and kept at high electrostatic repulsive force. The particle size and polydispersity index of stable SPI-CS (pH 4.55/80 °C) and SPI-CMC (pH 6.15/95 °C) TCPs were 286.6 nm/0.282 and 171.5 nm/0.298, respectively. We inferred that the re-assembly of SPI after thermal denaturation resulted in the formation of TCPs. The pH and ionic strength sensitivity tests indicated that the TCPs with different properties can be controlled by pH, temperature and polysaccharide type during heating. These TCPs could be used to encapsulate food functional components which were thermal insensitive.     

Formation of conjugates between β-lactoglobulin and allyl isothiocyanate: Effect on protein heat aggregation,foaming and emulsifying properties

Whey proteins are widely used food ingredients due to their nutritional and functional properties (gelling, emulsifying, foaming). Owning to their structure (free thiol group, lysine residues, hydrophobic pocket), they can also be used as carriers for bioactives. In this study, conjugates between β-lactoglobulin (β-lg), and a bioactive metabolite from Brassicaceae vegetables, allyl isothiocyanate (AITC) were formed. Heat aggregation behavior (85 °C, 15 min), foaming and emulsifying properties of conjugates, at pH 4.0 and 7.1, were evaluated.     

Preparation and potential applications of casein–polysaccharide conjugates: a review

Glycation of casein and caseinates with polysaccharides via Maillard reaction is a simple and environmentally safe way to prepare new food ingredients of improved functional properties. Sodium caseinate has been used mainly to prepare conjugates with several polysaccharides particularly maltodextrins and dextrans. The functional properties of these conjugates are influenced by the used polysaccharides and heating conditions. Under optimal heating conditions substantial improvements have been evident in their emulsification and foam properties of these conjugates. Casein–polysaccharide conjugates have several potential applications in food processing and microencapsulation. This article gives an overview on their formation and potential uses. © 2019 Society of Chemical Industry     

Green-based active packaging: Opportunities beyond COVID-19, food applications,and perspectives in circular economy—A brief review

The development of biodegradable packaging, based on agro-industrial plant products and by-products, can transform waste into products with high added value and reduce the use of conventional nonrenewable packaging. Green-based active packaging has a variety of compounds such as antimicrobials, antioxidants, aromatics, among others. These compounds interact with packaged products to improve food quality and safety and favor the migration of bioactive compounds from the polymeric matrix to food. The interest in the potential hygienic–sanitary benefit of these packages has been intensified during the COVID-19 pandemic, which made the population more aware of the relevant role of packaging for protection and conservation of food. It is estimated that the pandemic scenario expanded food packaging market due to shift in eating habits and an increase in online purchases. The triad health, sustainability, and circular economy is a trend in the development of packaging. It is necessary to minimize the consumption of natural resources, reduce the use of energy, avoid the generation of waste, and emphasize the creation of social and environmental values. These ideas underpin the transition from the emphasis on the more subjective discourse to the emphasis on the more practical method of thinking about the logic of production and use of sustainable packaging. Presently, we briefly review some trends and economic issues related to biodegradable materials for food packaging; the development and application of bio-based active films; some opportunities beyond COVID-19 for food packaging segment; and perspectives in circular economy.