Dispersion in the Presence of Acetic Acid or Ammonia Confers Gliadin‐Like Characteristics to the Glutenin in Wheat Gluten

Spray‐dried gluten has unique properties and is commercially available in the food industry worldwide. In this study, we examined the viscoelastic properties of gluten powder prepared by dispersion in the presence of acetic acid or an ammonia solvent and then followed by lyophilization instead of a spray drying. Mixograph measurements showed that the acid‐ and ammonia‐treated gluten powders had marked decreases in the time to peak dough resistance when compared with the control gluten powder. The integrals of the dough resistance and bandwidth for 3 min after peak dough resistance decreased in both treated gluten powders. Similar phenomena were observed when gliadin was supplemented to gluten powders. Basic and acidic conditions were applied to the acid‐ and ammonia‐treated gluten powders, respectively, and the viscoelastic behaviors were found to depend on the pH in the gluten dispersion just before lyophilization. These behaviors suggest that gluten may assume a reversible change in viscoelasticity by a fluctuation in pH during gluten dispersion. SDS‐PAGE showed that the extractable proteins substantially increased in some polymeric glutenins including the low molecular weight‐glutenin subunit (LMW‐GS) when the ammonia‐treated gluten powder was extracted with 70% ethanol. In contrast, the extractable proteins markedly increased in many polymeric glutenins including the high molecular weight‐glutenin subunit and/or the LMW‐GS when the acid‐treated gluten powder was extracted with 70% ethanol. It thus follows that the extractability of polymeric glutenin to ethanol increases similarly to gliadin when gluten is exposed to an acidic or a basic pH condition; therefore, glutenin adopts gliadin‐like characteristics.     

冻藏对面团中面筋蛋白分子结构及功能特性影响的研究进展

冷冻面团具有降低生产成本、提高产品质量和方便消费者优点,可用于加工生产面包、蛋糕和馒头等面制品。面团品质劣变是导致冷冻面团货架期缩短的主要原因,而冷冻面团品质下降的主要诱因是小麦面筋蛋白的品质劣变。本文综述了冷冻面团中面筋蛋白的分子组成、空间结构及功能特性等的变化,并对冷冻面团的未来发展方向进行了展望。     

柠檬酸处理对小麦面筋蛋白酶解特性的影响

以复合蛋白酶为水解酶,试验研究了小麦面筋蛋白酶解前柠檬酸预处理对其酶解特性的影响.通过单因素试验和正交试验确定柠檬酸预处理的最佳工艺条件为:柠檬酸浓度为0.1%(m/V),温度为50℃,处理时间为30min.同时研究了柠檬酸处理后小麦面筋蛋白在酶解过程中的水解度和蛋白提取率的变化规律.     

Laboratory‐scale Dry/Wet‐Milling Process for the Extraction of Starch and Gluten from Wheat

A laboratory‐scale process is presented for the manufacture of starch and gluten from wheat. Main feature of this process is that whole wheat kernels are crushed dry between smooth rolls prior to wet disintegration in excess water in such way that gluten formation is prevented and fibres can be removed by sieving. Centrifugation of the endosperm suspension yields a dough which can be separated into starch and gluten using an established batter process. The results suggest that starch recovery is increased in comparison to a conventional wheat flour process without a concomitant decrease in protein recovery. Although starch purification was omitted, a total starch with a low protein content is obtained. On the other hand, the protein content of the gluten fraction is rather low due to difficulties in removing the starch. Despite this, the effect on dough mechanical properties by the addition of gluten obtained from wet‐milled wheat is comparable to the effect of gluten from flour.     

Characterization of the Bread Made with Durum Wheat Semolina Rendered Gluten Free by Sourdough Biotechnology in Comparison with Commercial Gluten‐Free Products

Durum wheat semolina was fermented with sourdough lactic acid bacteria and fungal proteases aiming at a complete gluten hydrolysis. The gluten‐free (GF) semolina, added with naturally GF ingredients and structuring agents, was used to produce bread (rendered GF bread; rGFB) at industrial level. An integrated approach including the characterization of the main chemical, nutritional, structural, and sensory features was used to compare rGFB to a gluten‐containing bread and to 5 commercial naturally GF breads. High‐performance liquid chromatography was used for free amino acids (FAAs), organic acids, and ethanol analysis. A methanolic extract was used for determining total phenols and antioxidant activity. The bread characterization also included the analysis of dietary fibers, mycotoxins, vitamins, and heavy metals. Beyond chemical analysis, nutritional profile was evaluated considering the in vitro protein digestibility and the predicted glycemic index, while the instrumental texture profile analysis was performed to investigate the structure and the physical/mechanical properties of the baked goods. Beyond the huge potential of market expansion, the main advantages of durum wheat semolina rendered GF can be resumed in the high availability of FAAs, the high protein digestibility, the low starch hydrolysis index, and the better technological properties of bread compared to the commercial GF products currently present on the market. Vitamins, minerals, and dietary fiber profiles are comparable to those of gluten‐containing wheat bread. Also the sensory profile, determined by a panel test, can be considered the most similar to those of conventional baked goods, showing all the sourdough bread classic attributes.     

Effect of Molecular Weight,Acid, and Plasticizer on the Physicochemical and Antibacterial Properties of β‐Chitosan Based Films

Abstract: Effects of chitosan molecular weight (1815 and 366 kDa), type of acid (1% acetic, formic, and propionic acid, or 0.5% lactic acid) and plasticizer (0, 25% glycerol or sorbital w/w chitosan) on the mechanical, water barrier, and antibacterial properties of β‐chitosan films were investigated. Tensile strength (TS) of high molecular weight (Hw) films was 53% higher than that of low molecular weight (Lw) ones, acetate, and propionate films had the highest TS (43 and 40 MPa) among tested acids, and plasticizer‐reduced film TS 34%. Film elongation at break (EL) was higher in Hw films than in Lw ones, in which formate and acetate films were the highest (9% and 8%, respectively), and plasticizer increased the film EL 128%. Molecular weight of chitosan did not influence water vapor permeability (WVP) of the films. Acetate and propionate films had lower WVP than other acid types of films, and plasticizer increased film WVP about 35%. No difference was found between glycerol and sorbitol films in terms of film mechanical and water barrier properties. Lw β‐chitosan films showed significant antibacterial activity against E. coli and L. innocua. This study demonstrated that β‐chitosan films are compatible to α‐chitosan films in physicochemical properties and antibacterial activity, yet with simple sample preparation. Practical Application: β‐chitosan based edible films at molecular weight of about 300 kDa showed great antibacterial activity against Gram‐positive and Gram‐negative bacteria. The films have similar mechanical and water barrier properties to α‐chitosan based films at the similar molecular weight, but simple sample preparation procedures and more attractive color. The release of active chitosan fragment from the film matrix acts as an antibacterial agent, making β‐chitosan films suitable as intelligent food wraps or coatings for a wide range of food products to control moisture loss and prevent surface bacterial growth.     

High‐Throughput Isolation of Bacteriocin‐Producing Lactic Acid Bacteria,with Potential Application in the Brewing Industry

Lactic acid bacteria (LAB) were isolated from malted cereals by means of a high‐throughput screening approach and investigated for antimicrobial activity against a range of beer‐spoiling bacteria. Putative bacteriocin‐producing strains were identified by 16S rRNA analysis and the inhibitory compounds were partially characterized. Following determination of the inhibitory spectra of the strains, an unspeciated Lactobacillus sp. UCC128, with inhibitory activity against a range of beer‐spoiling strains was subjected to further characterization. A bacteriocin was purified from this strain and analyzed by mass spectrometry to determine the weight of the protein. The result indicated that the bacteriocin was highly similar to pediocin AcH/PA‐1 from Pediococcus acidilactici. The bacteriocin‐producers identified in this study have the potential to be used in the brewing industry to enhance the microbiological stability of beer in conjunction with hurdles already in place in the brewing process.     

Omega‐3 Fatty Acid Profile of Eggs from Laying Hens Fed Diets Supplemented with Chia,Fish Oil,and Flaxseed

The aim of this study was to investigate the effect of diets supplemented with fish oil, flaxseed, and chia seed on the omega‐3 fatty acid composition and sensory properties of hens’ eggs. No significant difference in yolk fat content was found between treatments. The fatty acid composition of egg yolk was significantly affected by the dietary treatments. Inclusion of chia at 300 g/kg into the diet produced eggs with the highest concentration of omega‐3 fatty acid. Eicosapentaenoic acid and docosahexaenoic acid were only detected in eggs from laying hens fed the diet supplemented with fish oil. Diet had a significant effect on color, flavor and overall acceptability of eggs. Types and levels of omega‐3 fatty acids in feed influence the level of yolk omega‐3 fatty acids in egg yolk. Inclusion of chia into the hens’ diet significantly increased the concentration of yolk omega‐3 fatty acid without significant change in sensory properties.     

Physicochemical Properties,Fatty Acid Profiles,and Sensory Characteristics of Fermented Beef Sausage by Probiotics Lactobacillus plantarum IIA‐2C12 or Lactobacillus acidophilus IIA‐2B4

Probiotics may be used to enhance the functionality and nutritional values of fermented sausages. This study aims to evaluate the physicochemical and sensory properties of beef sausages fermented by lactic acid bacteria of Lactobacillus plantarum IIA‐2C12 and L. acidophilus IIA‐2B4. These strains were isolated from beef cattle and have shown to display probiotic features. While the nutrient contents were not affected by the probiotics, the pH, texture, and color varied among the sausages. Further analysis on fatty acids showed different profiles of saturated (C14:0, C17:0, and C20:0) and unsaturated (C14:1, C18:1n9c, C18:2n6c, and C22:6n3) fatty acids in sausages with probiotics. Gas chromatography–mass spectrometry further revealed some flavor development compounds including acid, alcohols, aldehydes, aromatic, ketones, sulfur, hydrocarbons and terpenes, varied among the sausages. Hedonic test showed no difference in the preference toward aroma, texture, and color for untrained panelists.     

Total Phenolics,Carotenoids, Ascorbic Acid,and Antioxidant Properties of Fresh‐cut Mango (Mangifera indica L., cv. Tommy Atkin) as Affected by Infrared Heat Treatment

Abstract: Mango (Mangifera indica L.) is a major tropical fruit that has not been exploited for fresh‐cut or minimally processed products on a scale similar to apples, pineapples, or melons. The objective of this study was to investigate the effect of infrared (IR) treatment on total phenolics, carotenoids, ascorbic acid, and antioxidant properties of fresh‐cut cubes from ‘Tommy Atkin’ mangoes. Mango cubes were IR treated (5, 10, 15 min) and evaluated at 4‐d intervals during 16‐d storage at 4 ± 1 °C. Total phenolics, carotenoids, and ascorbic acid content in fresh‐cut control mango cubes were 43.33, 1.37, and 15.97 mg/100 g FW, respectively. IR treatments increased total phenolics (59.23 to 71.16 mg/100 g FW) and decreased ascorbic acid (12.14 to 15.38 mg/100 g, FW). Total carotenoids showed a mixed trend (1.13 to 1.66 mg/100 g, FW). The IR treatment showed a significant positive impact on antioxidant properties (μM TE/100 g, FW) of mango cubes, as assayed by ABTS (261.5 compared with 338.0 to 416.4), DPPH (270.5 compared with 289.4 to 360.5), and ORAC (6686 compared with 8450 to 12230). Total phenolics, carotenoids, ascorbic acid, and antioxidant capacity decreased over 16‐d storage. However, IR treated samples had consistently higher ABTS, DPPH, and total phenolics during storage. It was demonstrated that IR treatment can be effectively used in improving antioxidant properties of fresh‐cut mangoes with minimal effect on the visual appearance. Practical Application: Various methods/treatments are in use for extending the quality of fresh‐cut fruits, including mild heat treatment. This study explored the application of infrared (IR) heat for processing fresh‐cut mango cubes and evaluated its effect on vitamin C and antioxidant capacity during 16‐d storage. This is the first study reporting on the use of IR heat in fresh‐cut fruits. IR treatment was shown to be effective in retaining antioxidant properties of fresh‐cut mango cubes with minimal effect on the visual appearance.     

Identification of the Critical Amino Acid Residues of Immunoglobulin E and Immunoglobulin G Epitopes in α‐Lactalbumin by Alanine Scanning Analysis

α‐Lactalbumin represents one of the major allergens causing cow milk allergy. Few studies have clearly evaluated immunological relationships between immunoglobulin E (IgE) and immunoglobulin G (IgG)‐binding epitopes of α‐lactalbumin. IgE‐ and IgG‐binding epitopes were immunolabeled with individual sera from cow milk‐allergic patients. Alanine scanning of immunodominant epitopes was used to identify the critical amino acid (aa). Our initial data revealed Val⁸, Phe⁹, Arg¹⁰, Tyr¹⁰³, Leu¹⁰⁵, and His¹⁰⁷ were the critical aa for IgE‐binding epitope. The critical aa of IgG‐binding epitopes were Phe⁹, Leu¹⁵, Pro²⁴, Trp²⁶, and His³². This study will provide necessary information to alter the cDNA to encode a protein capable of activating milk‐specific T cells, but with reduced IgE‐ or IgG‐binding capacity.     

Quantitative Analysis of 10 Mycotoxins in Wheat Flour by Ultrahigh Performance Liquid Chromatography‐Tandem Mass Spectrometry with a Modified QuEChERS Strategy

A simple and sensitive analytical method for quantitative analysis of 10 mycotoxins was developed and validated by a combination of modified QuEChERS (quick, easy, cheap, effective, rugged, and safe) procedure with ultrahigh performance liquid chromatography‐tandem mass spectrometry (UHPLC‐MS/MS). Sample preparation involved QuEChERS with dispersive solid phase extraction for clean‐up, and analysis was performed by reversed‐phase UHPLC‐MS/MS using electrospray negative ionization and multiple reaction monitoring. Under optimized conditions, the calibration curves displayed good linear relationships with all coefficients of determinations (r²) higher than 0.998. The limits of quantification for all target mycotoxins were lower than 7 μg/kg. Trueness and precision for the analytes were 70% to 116% average recoveries and 2% to 13% relative standard deviations (RSDs). The validated method was used to analyze 46 wheat flour samples for the targeted mycotoxins. The method can be used as a rapid and robust tool for screening mycotoxin in cereal products.     

Method for Quantitative and Molecular Characterisation of Adsorbed Starch Polysaccharides on a Papermaking Pulp by SEC‐MALLS Measurements and Correlation with Paper Strength

A laboratory‐scale method for determining the molecularly dispersed amount of cationic starch adsorbed on a papermaking pulp was developed. The starch was molecularly dispersed by pressure cooking and was characterised by SEC‐MALLS (Size Exclusion with Multi‐Angle Laser Light Scattering) before and after the adsorption experiment. The adsorbed amount was calculated from the depletion of starch polymers in the starch‐fibre suspension. The molecular composition of the adsorbed starch product was determined from the difference in the SEC chromatograms before and after adsorption. In addition, handsheets were formed to correlate starch adsorption on the pulp with the resulting paper strength. The value of the method was demonstrated using the example of a low DS cationic potato starch derivative. This sample from a slurry process was adsorbed to a significantly higher extent in virtually electrolyte‐free deionised water (DW) than in water with a high electrolyte content (36 degrees German Hardness – 36 dGH). In DW, both amylopectin and amylose were adsorbed on the pulp, whereas in water of 36 dGH only the amylopectin‐rich fraction was adsorbed. A correlation between starch adsorption as a function of water quality and the resulting paper strength was found. The amount and molecular composition of the adsorbed starch product influenced paper properties.     

Effects of Fatty Acid Composition and β‐Carotene on the Chlorophyll Photosensitized Oxidation of W/O Emulsion Affected by Phosphatidylcholine

Abstract: Chlorophyll photosensitized oxidation of W/O emulsion consisting of oils with different fatty acid composition was studied and β‐carotene effects on the singlet oxygen oxidation affected by phosphatidylcholine were evaluated by determining peroxide value (PV) and conjugated dienoic acid (CDA) contents. An emulsion was composed of purified oil (sunflower, soybean, canola, or olive oil), water, and xanthan gum (50:50:0.35, w/w/w) with addition of phosphatidylcholine (0 or 250 ppm) and β‐carotene (0, 1, 5, or 10 ppm). PV and CDA content of oil in the emulsion were increased with time under chlorophyll photosensitized oxidation, and the oxidation rate was higher in the emulsion consisting of sunflower or soybean oil whose polyunsaturated fatty acids content was high compared to canola or olive oil. Addition of β‐carotene to the emulsion significantly decreased the oil oxidation under chlorophyll photosensitization, however, co‐addition of phosphatidylcholine decreased the antioxidant activity of β‐carotene, suggesting an antagonistic antioxidation between them. Practical Application: The results of this study can be applied to the area of emulsion foods such as salad dressing to have improved texture and stability by decreasing the oil oxidation and providing desirable color by use of β‐carotene with phosphatidylcholine as emulsifier.