Effect of additives on the thermo-mechanical behaviour of dough systems at sub-freezing temperatures

The aim of this study was to examine the effects of different additives, ascorbic acid, α-amylase, protease, hemicellulase, gluten, and gum guar, on thermo-mechanical dough properties at sub-freezing temperatures as measured by differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMA). The DSC thermograms showed that dough with a combination of ascorbic acid and hemicellulase had greater amount of water unable to crystallize and a lower co-operativity in ice-melting transition, indicating more polymer–water interactions. DMA studies permitted identification of three peaks, which were related to the ice melting, α-relaxation and β-relaxation. α-transition occurred over a temperature range of ∼40 °C and the ascorbic acid and their combination with hemicellulase, amylase, protease and gum guar increased temperature transition. An increment of the matrix viscosity due to higher number of inter- and intra-molecular interaction caused by oxidation of gluten proteins (ascorbic acid), and the increment of aggregated solid or generated molecules in the unfrozen phase could explain the increment in this transition.     

Technical note: Effect of low pH preservation on the colour and consistency of tomato juice

The changes in colour and consistency are reported for tomato juice produced by low pH preservation and stored under ambient conditions. The juice preserved under acid conditions showed higher consistency, probably due to the higher concentration of pectin and the presence of low methoxyl pectin. The furfural and hydroxymethyl-furfural which were detected in the juice indicated that darkening of the juice colour was due to non-enzymic browning involving both ascorbic acid and sugars (hexoses). Although the retention of ascorbic acid was higher under low pH conditions, it led to a significant darkening of the juice colour due to non-enzymic browning involving mainly ascorbic acid.     

Effects of trypsin‐hydrolyzed wheat gluten peptide on wheat flour dough

BACKGROUND: Gluten peptide was prepared by trypsin hydrolysis and characterized by high‐performance liquid chromatographic analysis. The effects on non‐frozen and frozen doughs of trypsin‐hydrolyzed gluten peptide (THGP) and its combination with ascorbic acid or KBrO₃ were investigated. RESULTS: Molecular analysis of THGP showed a decrease in the high‐molecular‐weight and an increase in the low‐molecular‐weight sodium dodecyl sulfate‐soluble fractions, compared with those of control wheat gluten. The addition of 8% THGP decreased the mixing time and tolerance of the dough, both with and without ascorbic acid or KBrO₃. However, the maximum resistance and extensibility of the rested dough containing 8% THGP, with and without ascorbic acid or KBrO₃, were not significantly different from those of the control dough. The addition of 8% THGP significantly increased the loaf volume of bread baked from non‐frozen dough when combined with 60 ppm ascorbic acid or 30 ppm KBrO₃, but it had a significant effect both with and without ascorbic acid or KBrO₃ on frozen‐dough bread. A large difference in volume was observed between breads made with and without THGP at the oven‐spring, rather than at proofing. CONCLUSION: The addition of 8% THGP increased the loaf volume of bread made from freeze‐damaged dough and this effect increased when THGP was combined with 60 ppm ascorbic acid. Copyright © 2008 Society of Chemical Industry     

EFFECTS OF GLUCOSE OXIDASE, HEMICELLULASE AND ASCORBIC ACID ON DOUGH AND BREAD QUALITY

ABSTRACT

In this study, glucose oxidase alone or its combinations with hemicellulase or ascorbic acid were used in bread making. Glucose oxidase alone mainly decreased dough extensibility. It produced stiffer and less extensible dough. Combinations of glucose oxidase–hemicellulase presented lower extensibility and were more resistant to extension than glucose oxidase alone. When glucose oxidase–ascorbic acid combinations were used, the softening degree significantly decreased, regardless when added the lowest glucose oxidase in combination with ascorbic acid. Glucose oxidase–ascorbic acid combinations significantly modified dough resistance. The glucose oxidase alone significantly increased specific loaf volume. The Dallman value of loaves made with glucose oxidase alone was found higher than for control. The most dramatic effect of additives on specific loaf volume was observed when glucose oxidase–hemicellulase combinations were added. This effect has been ascribed to redistribution of water from the hemicellulose to gluten, which would render the gluten more extensible. Specific loaf volume showed a significant enhancement when glucose oxidase–ascorbic acid combinations were added, but this effect was not as good as glucose oxidase–hemicellulase. The effects of glucose oxidase and its combinations with ascorbic acid and hemicellulase on dough rheology and bread quality are highly dependent on the amount of enzyme and the original wheat flour quality.

PRACTICAL APPLICATION

In practice, appropriate combinations of glucose oxidase with hemicellulase can be used as improvers in bread making, depending on their combination levels. This study will show the way to new research about glucose oxidase, ascorbic acid and hemicellulose.

     

Effect of additives on the quality and microstructure of vermicelli made from<Emphasis Type="Italic"> Triticum aestivum</Emphasis>

The effects of various additives [xylanase (0.06, 0.012, and 0.018%), gluten (1.5 and 3.0%), ascorbic acid (0.01 and 0.02%), glycerol monostearate, sodium stearoyl-2-lactylate (SSL) (0.25, 0.50%) and glucose oxidase (0.1%)] on the quality of vermicelli made from Triticum aestivum was studied. The results revealed that xylanase at 0.012% produced an improved quality product in terms of increase in cooked weight, expansion in volume of strands, and firm texture without stickiness. The micrograph of vermicelli exhibited a uniform, continuous protein matrix. The yellow index values improved with addition of gluten (3%) and ascorbic acid (0.01%). The gluten added appeared as a prominent strong network in micrographs, imparting strength to the vermicelli as evidenced by higher shear values. SSL (0.5%) gave a firm, discrete product and the protein fibrils displayed a massive network, owing to the strengthening effect. At the level of glucose oxidase used (0.1%), it exerted an adverse effect on the product quality. In general, the additives lowered the cooking loss and the leaching of solids in vermicelli when compared to the control.     

D-Erythroascorbic Acid in Bakers'Yeast and Effects on Wheat Dough

Extraction of hydrated and freeze-dried bakers’yeast yielded ～ 50 μg erythroascorbic acid (EAA) and 5 μg ascorbic acid (AA)/g dry yeast as determined by HPLC with electrochemical detection. D-EAA (82 ppm based on flour) slightly increased the flow of dough as rest time increased. Gluten isolated from a flour-water dough containing 82 ppm D-EAA or 100 ppm Lcysteine stretched at a faster rate than control gluten. EAA like AA did not change dough development time. Unlike AA, EAA showed neither oxidizing effect on dough and gluten nor improving effects on bread.     

氧化酶复合乳化剂在馒头中的应用研究

利用正交试验研究了氧化酶复合乳化剂对面团流变学特性和馒头质量的影响。确定了适量的葡萄糖氧化酶、抗坏血酸、硬酯酰乳酸钠一钙,增强了面粉的筋力,改善了馒头的内部组织结构、增大了体积、表面更光亮。     

Functional,nutritional and conformational changes from deamidation of wheat gluten with succinic acid and citric acid

Changes in deamidation degree, hydrolysis degree, nitrogen soluble index, the foaming and emulsification properties, the tertiary and secondary conformation and nutritional property of wheat gluten deamidated with succinic acid and citric acid were identified. Succinic acid and citric acid were found to effectively deamidate the amides in wheat gluten proteins into carboxyl groups, which resulted in a significant increase of the nitrogen soluble index of wheat gluten. Deamidation of wheat gluten by succinic acid was found to be more efficient than that with citric acid, although wheat gluten treated with succinic acid exhibited less improvement in the foaming capacity and stability and experienced inhibition in the emulsification activity compared with the gluten treated with citric acid. Wheat gluten deamidated with citric acid exhibited more flexible protein molecules, greater changes in the tertiary and secondary structures and better nutritional characteristics. These results may be useful to the food processing industry.     

Changes in glutathione content (reduced and oxidised form) and the effect of ascorbic acid and potassium bromate on glutathione oxidation during dough mixing

During dough mixing, reduced glutathione (GSH) is rapidly oxidised to the disulphide without change in the total glutathione content. The flour improvers potassium bromate and dehydroascorbic acid enhance the oxidation rate of GSH. The intensity of the acceleration caused by various diastereomeric ascorbic acids parallels the improvement of loaf volume, found by Maltha in baking experiments. The data support the assumption that oxidation of GSH by the improvers competes with a SH/SS-interchange reaction of GSH with the gluten proteins.     

Interactions between forage and wet corn gluten feed as sources of fiber in diets for lactating dairy cows

Twelve early lactation Holstein cows (4 fistulated) were used in replicated 4x4 Latin squares with 4-wk periods to determine the effective neutral detergent fiber (NDF) content of wet corn gluten feed and to measure the effect of forage particle size on ruminal mat consistency and passage rate of wet corn gluten feed. Diets were 1) 23.3% NDF (17.4 percentage units of NDF from alfalfa silage), 2) diet 1 plus 11.1 additional percentage units of NDF from alfalfa silage, 3) diet 1 plus 10.7 percentage units of NDF from wet corn gluten feed, and 4) 8.6 percentage units of NDF from alfalfa silage plus 8.9 percentage units of NDF from coarsely chopped alfalfa hay and 10.7 percentage units of NDF from wet corn gluten feed. The calculated effective NDF factor for wet corn gluten feed, using change in milk fat concentration per unit change in NDF, was 0.74 compared with an assumed 1.0 for alfalfa silage. Rumination activity was measured to calculate a physically effective NDF factor for wet corn gluten feed, which was only 0.11 compared with 1.0 for alfalfa silage. Physically effective NDF also was determined for wet corn gluten feed by wet sieving; 22% of the particles were retained on the 3.35-mm screen or greater. Ruminal mat consistency increased and passage rate of wet corn gluten feed decreased with added hay. The inclusion of chopped alfalfa hay to a diet containing wet corn gluten feed increased ruminal mat consistency, rumination activity, and slowed passage rate, resulting in greater ruminal digestion of NDF from wet corn gluten feed. Depending on the response variable, the effectiveness of NDF from wet corn gluten feed varied from 0.11 to 0.74.     

氧化淀粉对小麦面团品质变化影响研究

通过对面筋强度、巯基和二硫键含量测定、面筋蛋白电泳观察分析及面团流变学特性变化,研究氧化淀粉对小麦面团品质特性影响。结果表明,氧化淀粉能增加面筋乳酸溶涨值和透光率,提高面筋强度;对面筋蛋白具有氧化作用,增加大分子麦谷蛋白亚基含量,对面团粉质特性影响不显著;但能改善面团拉伸性能,其中以羧基含量为0.27%至0.40%氧化度氧化淀粉对面团品质变化影响最为显著。     

番茄汁加工工艺的研究

在番茄汁加工中分别给予85℃、65℃冷榨及100℃热烫的预热处理,并对不同预热处理的番茄汁进行了均质和不均质对比,结果发现:预热对出汁率、粘稠度及清液粘度均有显著影响,而均质主要影响番茄汁的维生素C(Vc)含量;预热和均质对粘稠度的交互作用显著;番茄汁的浆液分离和粘稠度呈高度负相关,而和清液粘度无任何相关;不同的预热温度与不同的均质处理相结合均有可能生产出品质良好的番茄汁。     

Understanding high pressure-induced changes in wheat flour–water suspensions using starch–gluten mixtures as model systems

The effect of high pressure (HP) on wheat flour–water suspensions was investigated. Suspensions were treated for 10 min at 200–600 MPa. HP-treatment significantly increased the consistency of the flour suspensions, as studied by frequency sweep tests. Temperature sweeps revealed that HP-induced starch gelatinisation, with a sigmoidal-shaped correlation between degree of gelatinisation and treatment pressure. Analysis of protein solubility in different buffers indicated the HP-induced formation of urea-insoluble complexes and/or disulphide bonds. Furthermore, the effects of HP on the isolated components wheat starch and gluten were studied, and starch–gluten mixtures were used as a model system for flour. A negative effect of gluten on the consistency increase of starch suspension was observed. Comparing the rheological parameters of HP-treated wheat flour suspensions to those of starch suspensions, confirmed the weakening effect of gluten. However, the presence of gluten in flour could not fully explain the differences between starch and flour suspension.     

Influence of whey protein concentrate, additives, their combinations on the quality and microstructure of vermicelli made from Indian T. Durum wheat variety

Effect of whey protein concentrate (5%, 7.5%, 10%) and additives on the quality of vermicelli made from Indian durum wheat was studied. The results revealed that with increase in whey protein concentrate (WPC) from 0% to 10%, cooked vermicelli weight increased from 82.5 to 88 g/25 g, cooking loss increased from 6.0 to 8.4%, L values indicating lightness increased (47.42–52.9); b values indicating yellowness decreased (7.0–3.80) and shear force decreased (66–45 g). Sensory evaluation of vermicelli with 5%, 7.5%, 10% WPC showed that addition of above 5% WPC resulted in whitish colour vermicelli with mashy strand quality and sticky mouthfeel. Studies on the effect of additives namely ascorbic acid (0.01% and 0.015%), gluten (1.5% and 3.0%) and glycerol monostearate (GMS) (0.25% and 0.5%) individually as well as in combination on the quality of vermicelli with 5% WPC indicated that combination of 0.01% ascorbic acid, 3% gluten and 0.5% GMS resulted in vermicelli having lower cooking loss, creamy yellow colour, firm, discrete strands and non-sticky mouthfeel. The protein content of vermicelli with 5% WPC and combination of additives was 16% as against 11.5% of control vermicelli. Scanning electron microscopy study of control vermicelli, vermicelli with 5% WPC and vermicelli with 5% WPC and combination of additives revealed that vermicelli with 5% WPC showed a rough surface with a prominent rupture while vermicelli with 5% WPC and combination of additives showed a continuous, rupture free structure.     

抗坏血酸对猴头菇β-葡聚糖表观黏度及结构特征的影响

采用碱提醇沉法制备猴头菇 β-葡聚糖(Hericium erinaceus alkali-extracted polysaccharide,HEAEP),系统研究了不同条件(抗坏血酸浓度、金属离子、温度、pH值等)下抗坏血酸对HEAEP表观黏度的影响,并深入分析了抗坏血酸对HEAEP结构特征的影响.研究结果表明:猴头菇...     

Impact of endogenous constituents from different flour milling streams on dough rheology and semi-sweet biscuit making potential by partial substitution of a commercial soft wheat flour

A flour fractionation-reconstitution procedure was used to study the substitution of a commercial soft wheat flour with gluten, water extractables, prime starch and starch tailing fractions isolated from patent and clear flour streams on dough rheology and semi-sweet biscuit characteristics. Substitution of soft wheat flour with increasing levels of the native patent and clear flour streams raised the dough consistency, hardness and elastic properties as well as the biscuit textural attributes (density, hardness). The dough stickiness of the base flour was also reduced and the biscuits were free of cracks. Gluten isolated from the patent flour had a greater impact on dough consistency, hardness and elastic properties than gluten obtained from the clear flour, likely due to the superior protein quality of the former. Additionally, with increasing gluten levels in the fortified flour there were moderate increases in biscuit density, hardness, and lower crunchiness. The addition of starch tailings produced the largest impact on consistency and hardness of the dough. This fraction also exerted a pronounced effect on biscuit density and hardness, while it lowered crunchiness, presumably due to its higher pentosan content. Overall, the dough rheological properties and biscuit characteristics were controlled by the amount-nature of the fractions added; i.e., besides gluten (amount and quality), other constituents such as pentosans and the overall composition of the flour blends can largely affect the quality of the semi-sweet biscuits.     

Effect of ascorbic acid on the foaming and gelling of globular proteins

Foam expansion and foam stability of plasma and egg albumen proteins were enhanced in the presence of increasing concentrations of ascorbic acid (0.1–1.0%). BSA showed the greatest improvement in foaming properties following treatment with ascorbic acid, whilst foaming properties of egg albumen were improved to a limited extent. A combination of partial acid hydrolysis and treatment with 1% ascorbic acid was required to dramatically improve the foaming properties of bovine blood plasma. In the presence of sucrose, foam expansion of both native and ascorbic acid-treated blood plasma was decreased. In contrast the foam expansion of ascorbic acid-treated egg albumen was greater although this effect decreased slightly on incubation. the gelation of ascorbic acid treated proteins increased with increasing temperatures over 80–90°C, particularly for BSA and blood plasma, and with increasing concentrations of ascorbic acid. Ascorbic acid-treated proteins exhibited enhanced surface and exposed hydrophobicity and reduced numbers of sulphydryl groups indicating the involvement of these factors in foam and gel formation.     

Physicochemical Properties of Wheat Gluten Proteins Modified by Protease From Sierra (Scomberomorus sierra) Fish

The effect of semi-purified trypsin on the physicochemical properties of durum and bread wheat flour and gluten protein fractions was evaluated. Trypsin was partially isolated from sierra (Scomberomorus sierra) guts extracts by affinity chromatography. Treatment with enzyme caused hydrolysis of 1.16–1.40% in both durum and bread wheat gluten and gluten fractions. The effect of hydrolysis on the isoelectric point was more evident in durum that bread wheat gluten. Addition of the trypsin-like enzyme at three different concentrations induced a decrease in the gluten index. The dough consistency fell after 1.5 h of incubation. It was possible to modify wheat flour proteins by varying S. sierra trypsin-like enzyme concentration and incubation time, depending on the wheat species.     

Effect of fortification of drinking water with iron plus ascorbic acid or with ascorbic acid alone on hemoglobin values and anthropometric indicators in preschool children in day-care centers in Southeast Brazil

BACKGROUND: Iron-deficiency anemia currently is the most frequently occurring nutritional disorder world-wide. Previous Brazilian studies have demonstrated that drinking water fortified with iron and ascorbic acid is an adequate vehicle for improving the iron supply for children frequenting day-care centers. OBJECTIVE: The objective of this study was to clarify the role of ascorbic acid as a vehicle for improving iron intake in children in day-care centers in Brazil. METHODS: A six-month study was conducted on 150 children frequenting six day-care centers divided into two groups of three day-care centers by drawing lots: the iron-C group (3 day-care centers, n = 74), which used water fortified with 10 mg elemental iron and 100 mg ascorbic acid per liter, and the comparison group (3 day-care centers, n = 76), which used water containing only 100 mg ascorbic acid per liter. Anthropometric measurements and determinations of capillary hemoglobin were performed at the beginning of the study and after six months of intervention. The food offered at the day-care centers was also analyzed. RESULTS: The food offered at the day-care center was found to be deficient in ascorbic acid, poor in heme iron, and adequate in non-heme iron. Supplementation with fortified drinking water resulted in a decrease in the prevalence of anemia and an increase in mean hemoglobin levels associated with height gain in both groups. CONCLUSIONS: Fortification of drinking water with iron has previously demonstrated effectiveness in increasing iron supplies. This simple strategy was confirmed in the present study. The present study also demonstrated that for populations receiving an abundant supply of non-heme iron, it is possible to control anemia in a simple, safe, and inexpensive manner by adding ascorbic acid to drinking water.     

Influence of Calcium Treatment on'Golden Delicious'Apple Quality

The use of a CaCl₂ treatment in the storage of apples improved the keeping quality of fresh apples in prolonged cold storage and did not deter from the quality of the processed product. The fresh market apples in controlled atmosphere storage were firmer with more ascorbic acid than CaCl₂ treated apples in standard cold storage. However, fresh market CaCl₂ treated apples had less green color, were firmer, with a high titratable acidity and ascorbic acid content, than untreated apples in standard cold storage. The processed products made from CaCl₂ treated apples had better color and firmness than those made with apples from standard cold storage and better consistency and less weep than those made with apples from controlled atmosphere storage.