Effect of Acetylation on Physicochemical and Functional Properties of Commercial Pumpkin Protein Concentrate.

The purpose of the present study was to determine the effects of acetylation with different doses of acetic anhydride on the chemical composition and chosen functional properties of commercial pumpkin protein concentrate (PPC). The total protein content decreased as compared to unmodified samples. Electrophoretic analysis revealed that in the acetylated pumpkin protein, the content of the heaviest protein (35 kDa) decreased in line with increasing concentrations of modifying reagent. Acetylation of PPC caused a significant increase in water-binding and oil-absorption capacity and for emulsifying properties even at the dose of 0.4 mL/g. Additionally, an increase in foaming capacity was demonstrated for preparations obtained with 2.0 mL/g of acetic anhydride, whereas acetylation with 0.4 and 1.0 mL/g caused a decrease in protein solubility as compared to native PPC.

In vitro digestibility of proteins from historical and modern wheat cultivars.

BACKGROUND: Previous research has suggested that proteins and other quality parameters of wheats may have changed over a century of wheat breeding. These changes may affect protein digestibility. The in vitro protein digestibility of breads made with 21 cultivars of wheat introduced or released in the USA between 1870 and 2013 was therefore evaluated. RESULTS: Protein digestibility increased with release year, but was not normally distributed; three older cultivars had significantly lower digestibility than the other cultivars: 42.0 ± 0.3 mol% (primary amino N/total N) versus 34.7 ± 0.7 mol%; P < 0.001. High molecular weight (MW) protein fractions increased and low MW protein fractions decreased with release year, but these changes were not related to protein digestibility. Thus, other differences in protein composition or other flour components may contribute to diminished digestibility of the three older cultivars. CONCLUSIONS: This study identified differences in protein digestibility among wheat cultivars that may have important implications for human nutrition. Further investigation is required to determine the specific characteristics that differentiate high- and low-digestibility wheat cultivars. © 2020 Society of Chemical Industry.

The health benefits, functional properties, modifications, and applications of pea (Pisum sativum L.) protein: Current status, challenges, and perspectives.

In recent years, the development and application of plant proteins have drawn increasing scientific and industrial interests. Pea (Pisum sativum L.) is an important source of high-quality vegetable protein in the human diet. Its protein components are generally considered hypoallergenic, and many studies have highlighted the health benefits associated with the consumption of pea protein. Pea protein and its hydrolysates (pea protein hydrolysates [PPH]) possess health benefits such as antioxidant, antihypertensive, and modulating intestinal bacteria activities, as well as various functional properties, including solubility, water- and oil-holding capacities, and emulsifying, foaming, and gelling properties. However, the application of pea protein in the food system is limited due to its poor functional performances. Several frequently applied modification methods, including physical, chemical, enzymatic, and combined treatments, have been used for pea protein to improve its functional properties and expand its food applications. To date, different applications of pea protein in the food system have been extensively studied, for example, encapsulation for bioactive ingredients, edible films, extruded products and substitution for cereal flours, fats, and animal proteins. This article reviews the current status of the knowledge regarding pea protein, focusing on its health benefits, functional properties, and structural modifications, and comprehensively summarizes its potential applications in the food industry.

Changes in conformation and quality of vegetable protein during texturization process by extrusion.

Texturized Vegetable Protein (TVP), as meat analogs, has garnered attention due to the nutritional advantages it offers over conventional animal proteins. During the extrusion process of TVP, under the comprehensive effects of temperature, shear force, and pressure, complex conformational changes and molecular interactions amongst protein, carbohydrate, lipid, and other components occur, all of which influence the quality of TVP. Control of the extrusion process is still one of the largest challenges in its evolution. Therefore, this review aims to summarize the development and current status of food extrusion technology for TVP production and give detailed descriptions about the conformational changes of the main components during the extrusion process, focusing on the effects of barrel temperature, moisture content, feed rate and screw speed on TVP quality. Lastly, we discuss approaches to characterize the extrusion process and propose a new system analysis model.

Protein content and amino acid composition of commercially available plant-based protein isolates.

The postprandial rise in essential amino acid (EAA) concentrations modulates the increase in muscle protein synthesis rates after protein ingestion. The EAA content and AA composition of the dietary protein source contribute to the differential muscle protein synthetic response to the ingestion of different proteins. Lower EAA contents and specific lack of sufficient leucine, lysine, and/or methionine may be responsible for the lower anabolic capacity of plant-based compared with animal-based proteins. We compared EAA contents and AA composition of a large selection of plant-based protein sources with animal-based proteins and human skeletal muscle protein. AA composition of oat, lupin, wheat, hemp, microalgae, soy, brown rice, pea, corn, potato, milk, whey, caseinate, casein, egg, and human skeletal muscle protein were assessed using UPLC-MS/MS. EAA contents of plant-based protein isolates such as oat (21%), lupin (21%), and wheat (22%) were lower than animal-based proteins (whey 43%, milk 39%, casein 34%, and egg 32%) and muscle protein (38%). AA profiles largely differed among plant-based proteins with leucine contents ranging from 5.1% for hemp to 13.5% for corn protein, compared to 9.0% for milk, 7.0% for egg, and 7.6% for muscle protein. Methionine and lysine were typically lower in plant-based proteins (1.0 ± 0.3 and 3.6 ± 0.6%) compared with animal-based proteins (2.5 ± 0.1 and 7.0 ± 0.6%) and muscle protein (2.0 and 7.8%, respectively). In conclusion, there are large differences in EAA contents and AA composition between various plant-based protein isolates. Combinations of various plant-based protein isolates or blends of animal and plant-based proteins can provide protein characteristics that closely reflect the typical characteristics of animal-based proteins.

The α' subunit of ß-conglycinin and various glycinin subunits of soy are not required to modulate hepatic lipid metabolism in rats.

PURPOSE: This study examined the effect of soy proteins with depletion of different subunits of the two major storage proteins, ß-conglycinin and glycinin, on hepatic lipids and proteins involved in lipid metabolism in rats, since the bioactive component of soy responsible for lipid-lowering is unclear. METHODS: Weanling Sprague Dawley rats were fed diets containing either 20% casein protein in the absence (casein) or presence (casein + ISF) of isoflavones or 20% alcohol-washed soy protein isolate (SPI) or 20% soy protein concentrates derived from a conventional (Haro) or 2 soybean lines lacking the α' subunit of ß-conglycinin and the A1-3 (1TF) or A1-5 (1a) subunits of glycinin. After 8 weeks, the rats were necropsied and liver proteins and lipids were extracted and analysed. RESULTS: The results showed that soy protein diets reduced lipid droplet accumulation and content in the liver compared to casein diets. The soy protein diets also decreased the level of hepatic mature SREBP-1 and FAS in males, with significant decreases in diets 1TF and 1a compared to the casein diets. The effect of the soy protein diets on female hepatic mature SREBP-1, FAS, and HMGCR was confounded since casein + ISF decreased these levels compared to casein alone perhaps muting the decrease by soy protein. A reduction in both phosphorylated and total STAT3 in female livers by ISF may account for the gender difference in mechanism in the regulation and protein expression of the lipid modulators. CONCLUSIONS: Overall, soy protein deficient in the α' subunit of ß-conglycinin and A1-5 subunits of glycinin maintain similar hypolipidemic function compared to the conventional soy protein. The exact bioactive component(s) warrant identification.

Pretreatment of different food rest materials for bioconversion into fungal lipid-rich biomass.

Food rest materials have the potential to be used as media components in various types of fermentations. Oleaginous filamentous fungi can utilize those components and generate a high-value lipid-rich biomass, which could be further used for animal and human use. One of the main limitations in this process is the pretreatment of food rest materials, needed to provide homogenization, sterilization and solubilization. In this study, two pretreatment processes-steam explosion and enzymatic hydrolysis-were evaluated for potato and animal protein-rich food rest materials. The pretreated food rest materials were used for the production of fungal lipid-rich biomass in submerged fermentation by the oleaginous fungus Mucor circinelloides. Cultivation media based on malt extract broth and glucose were used as controls of growth and lipid production, respectively. It was observed that media based on food rest materials can support growth and lipid production in M. circinelloides to a similar extent as the control media. More specifically, the use of potato hydrolysate combined with chicken auto-hydrolysate resulted in a higher fungal total biomass weight than using malt extract broth. When the same C/N ratio was used for glucose and rest materials-based media, similar lipid content was obtained or even higher using the latter media.

[Biodegradation of proteins of grain raw materials for the production of new bakery products].

The effect of enzyme systems on the degree of protein destruction of grain crops to obtain new types of bakery products has been studied. Protein and amino acid composition of triticale grain crop in comparison with wheat and rye one has been studied. The high biological value of triticale proteins containing 38.75% of essential amino acids while in wheat - 34.93% has been shown. The influence of different enzyme systems (ES) with proteolytic action on the efficiency of catalytic modification of triticale proteins has been investigated. It was found that the highest activity was shown by the enzymatic system ES-1, synthesized by the mycelial fungus Aspergillus oryzae, as a result of which at a concentration of 5 u/g, the level of accumulation of amine nitrogen in triticale enzymatic hydrolysates was 125 mg%; the degree of hydrolysis of proteins was 90%. Enzyme preparations of bacterial origin, as well as alkalase and papain had a lower ability to hydrolyze triticale proteins. The fractional composition of modified proteins obtained by ES-1 showed a decrease in their molecular weight (to 35 kDa). Analysis of amino acid composition in grain enzymatic hydrolysates showed that as a result of exposure to FS-1, about 50% of the total number of amino acids passed into the free state, of which 38.8 to 43.6% were essential amino acids. The recipes of breads, containing composition of wheat flour and fermentolizates of the whole-grain triticale flour in the ratio 1:1 have been tested. The amino acid composition of the bread showed that the test samples contained 6.2 fold more free amino acids than the control. The use of fermented triticale in the recipes of bread allowed to increase the content of essential amino acids such as methionine, valine, isoleucine, leucine, phenylalanine, threonine, tryptophan and lysine in 2.0-5.0 times. It was shown that the developed technology allowed baking bread containing peptides with reduced molecular weight and free amino acids, which by its organoleptic and physic-chemical parameters corresponded to classic bakery products.

Meat analogues: Health promising sustainable meat substitutes.

There is a scarcity of protein of high biological value due to rapid increase in the world population and limited natural resources. Meat is a good source of protein of high biological value but converting the vegetable protein into animal protein is not economical. There is a trend of production of healthy and delicious meat free food for satisfaction of vegetarian and personal well beings. This resulted in increasing use of low cost vegetable protein such as textured soy protein, mushroom, wheat gluten, pulses etc as a substitute for animal-protein. These simulated meat-like products, with similar texture, flavor, color, and nutritive value can be substituted directly for meat to all sections of the society.

Effects on functional groups and zeta potential of SAP1<MW<3kDa treated by pulsed electric field technology.

BACKGROUND: SAP1

Extraction, composition, and functional properties of dried alfalfa (Medicago sativa L.) leaf protein.

BACKGROUND: Alfalfa is considered a potential feedstock for biofuels; co-products with value-added uses would enhance process viability. This work evaluated dried alfalfa leaves for protein production and describes the functional properties of the protein. RESULTS: Dried alfalfa leaves contained 260 g kg-1 dry basis (DB) crude protein, with albumins being the major fraction (260 g kg-1 of total protein). Alkali solubilization for 2 h at 50 °C, acid precipitation, dialysis, and freeze-drying produced a protein concentrate (600 g kg-1 DB crude protein). Alfalfa leaf protein concentrate showed moderate solubility (maximum 500 g kg-1 soluble protein from pH 5.5 to 10), excellent emulsifying properties (activity 158-219 m2 g-1 protein, stability 17-49 min) and minimal loss of solubility during heating at pH ≥ 7.0. CONCLUSIONS: It is technically feasible to extract protein with desirable emulsifying and heat stability properties from dried alfalfa leaves; however, the dried form may not be a practical starting material for protein production, given the difficulty of achieving high yields and high-purity protein product. © 2016 Society of Chemical Industry.

Stabilization of red fruit-based smoothies by high-pressure processing. Part A. Effects on microbial growth, enzyme activity, antioxidant capacity and physical stability.

BACKGROUND: Non-thermal pasteurization by high-pressure processing (HPP) is increasingly replacing thermal processing (TP) to maintain the properties of fresh fruit products. However, most of the research on HPP-fruit products only partially addresses fruit-pressure interaction, which limits its practical interest. The objective of this study was to assess the use of a mild HPP treatment to stabilize red fruit-based smoothies (microbial, enzymatic, oxidative and physical stability). RESULTS: HPP (350 MPa/10 °C/5 min) was slightly less effective than TP (85 °C/7 min) in inactivating microbes (mesophilic and psychrophilic bacteria, coliforms, yeasts and moulds) in smoothies kept at 4 °C for up to 28 days. The main limitation of using HPP was its low efficacy in inactivating oxidative (polyphenol oxidase and peroxidase) and hydrolytic (pectin methyl esterase) enzymes. Data on antioxidant status, colour parameters, browning index, transmittance, turbidity and viscosity confirmed that the HPP-smoothies have a greater tendency towards oxidation and clarification, which might lead to undesirable sensory and nutritional changes (see Part B). CONCLUSION: The microbial quality of smoothies was adequately controlled by mild HPP treatment without affecting their physical-chemical characteristics; however, oxidative and hydrolytic enzymes are highly pressure-resistant, which suggests that additional strategies should be used to stabilize smoothies. © 2016 Society of Chemical Industry.

Differential responses of the gut transcriptome to plant protein diets in farmed Atlantic salmon.

BACKGROUND: The potential for alternative plant protein sources to replace limited marine ingredients in fish feeds is important for the future of the fish farming industry. However, plant ingredients in fish feeds contain antinutritional factors (ANFs) that can promote gut inflammation (enteritis) and compromise fish health. It is unknown whether enteritis induced by plant materials with notable differences in secondary metabolism is characterised by common or distinct gene expression patterns, and how using feeds with single vs mixed plant proteins may affect the gut transcriptome and fish performance. We used Atlantic salmon parr to investigate the transcriptome responses of distal gut to varying dietary levels (0-45%) of soy protein concentrate (SPC) and faba bean (Vicia faba) protein concentrate (BPC) following an 8-week feeding trial. Soybean meal (SBM) and fish meal (FM) were used as positive and negative controls for enteritis, respectively. Gene expression profiling was performed using a microarray platform developed and validated for Atlantic salmon. RESULTS: Different plant protein materials (SPC, BPC and SBM) generated substantially different gut gene expression profiles, with relatively few transcriptomic alterations (genes, pathways and GO terms) common for all plant proteins used. When SPC and BPC were simultaneously included in the diet, they induced less extensive alterations of gut transcriptome than diets with either SPC or BPC singly, probably due to reduced levels of individual ANFs. The mixed plant protein diets were also associated with improved body composition of fish relative to the single plant protein diets, which may provide evidence for a link between the magnitude of changes in gut transcriptome and whole-animal performance. CONCLUSIONS: Our results indicate that gut transcriptomic profiling provides a useful tool for testing the applicability of alternative protein sources for aquaculture feeds and designing diets with reduced impact of ANFs on fish health. Ultimately, understanding diet-gut interactions and intestinal homeostasis in farmed fish is important to maximise performance and to ensure that aquaculture continues to be a sustainable source of food for a growing world population.

Correlation between different markers for the assessment of red chilli pepper powders stability during shelf-life.

Pungency and red colour of Capsicum powders deteriorate during processing and storage, resulting in a decrease in market value. Two varieties of pepper with different pungencies were monitored for capsaicinoids, colour and furosine. Aliquots were stored at room and at low temperature during one year. At low temperature all indicators were stable in both varieties, while at room temperature, redness and capsacinoids decreased significantly, while furosine increased. High correlation was found between those markers. The more pungent variety exhibited higher stability in terms of all parameters. Differences observed suggest a potential protective effect exerted by capsaicinoids on powder stability. The decrease in capsaicinoids and redness accompanied by furosine increase showed a linkage between those markers never reported before. Considering that capsaicinoids and furosine occurrence have strong impact on the nutritional profile, the findings of this work show relevant changes in the nutritional value of chilli pepper powder after storage.

Effect of high pressure processing on dispersive and aggregative properties of almond milk.

BACKGROUND: A study was conducted to investigate the impact of high pressure (450 and 600 MPa at 30 °C) and thermal (72, 85 and 99 °C at 0.1 MPa) treatments on dispersive and aggregative characteristics of almond milk. Experiments were conducted using a kinetic pressure testing unit and water bath. Particle size distribution, microstructure, UV absorption spectra, pH and color changes of processed and unprocessed samples were analyzed. RESULTS: Raw almond milk represented the mono model particle size distribution with average particle diameters of 2 to 3 µm. Thermal or pressure treatment of almond milk shifted the particle size distribution towards right and increased particle size by five- to six-fold. Micrographs confirmed that both the treatments increased particle size due to aggregation of macromolecules. Pressure treatment produced relatively more and larger aggregates than those produced by heat treated samples. The apparent aggregation rate constant for 450 MPa and 600 MPa processed samples were k450MPa,30°C = 0.0058 s(-1) and k600MPa,30°C = 0.0095 s(-1) respectively. CONCLUSIONS: This study showed that dispersive and aggregative properties of high pressure and heat-treated almond milk were different due to differences in protein denaturation, particles coagulation and aggregates morphological characteristics. Knowledge gained from the study will help food processors to formulate novel plant-based beverages treated with high pressure. © 2015 Society of Chemical Industry.

Enhancement of umami taste of hydrolyzed protein from wheat gluten by ß-cyclodextrin.

BACKGROUND: Wheat gluten was hydrolyzed by Flavourzyme and Neutrase at pH 7.0 and 50 °C for 8 h with ß-cyclodextrin (ß-CD) employed in the reaction. The hydrolysates were enzyme deactivated, cooled and centrifuged at 1500 × g for 15 min. RESULTS: Sensory and chemical characterization of wheat gluten hydrolysates WGH-1 (reaction conducted without ß-CD), WGH-2 (reaction conducted with ß-CD) and WGH-3 (ß-CD added to WGH-1) was performed. WGH-2 revealed enhanced umami taste and higher hydrolyzing degree, total free amino acid amount, protein yield and umami taste amino acid (Glu + Asp) amount. High-performance liquid chromatography showed that the proportion of molecular weight 180-500 Da in WGH-2 was 11.5% higher than that in WGH-1. Further research indicated that ß-CD had multiple effects on the hydrolysis. It could not only increase the solubility of wheat gluten but also form inclusion complexes with resultants. This can both promote the hydrolysis and protect oligopeptides from degradation. CONCLUSION: ß-CD was found to have the ability to increase the umami taste of enzyme-hydrolyzed vegetable protein from wheat gluten. The reasons analyzed were that ß-CD could take part in the hydrolysis process by improving the solubility of wheat gluten and form inclusion complexes with resultants. © 2016 Society of Chemical Industry.

Rheology and microstructure of binary mixed gel of rice bran protein-whey: effect of heating rate and whey addition.

BACKGROUND: Rice bran protein (RBP) is a valuable plant protein which has unique nutritional and hypoallergenic properties. Whey proteins have wide applications in the food industry, such as in dairy, meat and bakery products. RESULTS: Whey protein concentrate (WPC), RBP and their mixtures at different ratios (1:1, 1:2, 1:5 and 1:10 w/w) were heated from 20 to 90 °C at different heating rates (0.5, 1, 5 and 10 °C min(-1) ). The storage modulus (G') and gelling point (Tgel ) of WPC were higher than those of RBP, indicating the good ability of WPC to develop stiffer networks. By increasing the proportion of WPC in mixed systems, G' was increased and Tgel was reduced. Nevertheless, the elasticity of all binary mixtures was lower than that of WPC alone. Tgel and the final G' of RBP-WPC blends were increased by raising the heating rate. The RBP-WPC mixtures developed more elastic gels than RBP alone at different heating rates. RBP had a fibrillar and lentil-like structure whose fibril assembly had smaller structures than those of WPC. CONCLUSION: The gelling structure of the mixed gel of WPC-RBP was improved by adding WPC. Indeed, by adding WPC, gels tended to show syneresis and had lower water-holding capacity. Furthermore, the gel structure was produced by adding WPC to the non-gelling RBP, which is compatible with whey and can be applied as a functional food for infants and/or adults. © 2015 Society of Chemical Industry.

Production of the natural iron chelator deferriferrichrysin from Aspergillus oryzae and evaluation as a novel food-grade antioxidant.

BACKGROUND: Deferriferrichrysin (Dfcy) is a siderophore found in foods fermented by Aspergillus oryzae and is a promising candidate for an antioxidant food additive because of its high binding constant toward iron. However, the Dfcy concentration is typically low in foods and cultures. RESULTS: We optimised culture conditions to improve Dfcy production to 2800 mg L(-1) from 22.5 mg L(-1) under typical conditions. Then, we evaluated the potential of Dfcy as a food additive by measuring its safety, stability, and antioxidant activity. Dfcy was sufficiently stable that over 90% remained after pasteurisation at 63 °C for 30 min at pH 3-11, or after sterilisation at 120 °C for 4 min at pH 4-6. Dfcy showed high antioxidant activity in an oil-in-water model, where inhibition of lipid oxidation was measured by peroxide value (PV) and thiobarbituric acid reactive substances (TBARS) assays. Dfcy decreased PV and TBARS by 83% and 75%, respectively. Antioxidant activity of Dfcy was equal to or higher than that of the synthetic chelator EDTA. CONCLUSION: Our study provides the first practical method for production of Dfcy. Dfcy can be a novel food-grade antioxidant and the first natural alternative to the synthesised iron chelator EDTA. © 2015 Society of Chemical Industry.

Selection of lactic acid bacteria strains for the hydrolysis of allergenic proteins of wheat flour.

BACKGROUND: Wheat flour is one of the most common causative agents of food allergy. The study presents the selection and characterization of lactic acid bacteria (LAB) strains capable of hydrolyzing/modifying allergenic proteins of wheat flour. Hydrolysis of wheat proteins was determined with sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblotting with sera from patients with food allergy to gluten. RESULTS: The analysis of electrophoretic profiles of protein extracted from sourdough shows the capability of selected LAB strains for proteolytic degradation of wheat proteins that belong to two factions: albumin/globulin (hydrolysis of 13 polypeptides with a molecular weight between 103 and 22 kDa); and gliadin (seven polypeptides with a molecular weight between 39 and 24 kDa). All analyzed strains were capable of hydrolyzing some IgE-binding epitopes of wheat allergens. The lack of such changes in control samples indicates that they were induced rather by the proteolytic activity of bacterial strains than endogenous enzymes of wheat flour. The gluten proteins were susceptible to hydrolysis by sequential digestion with pepsin and trypsin. CONCLUSION: The selected strains exhibit proteolytic activity, which leads to a reduction in allergenicity of wheat sourdoughs. These strains may be applied as specific starter cultures to prepare bakery products of special nutritional use. © 2015 Society of Chemical Industry.