Effect of Amino Acids and Peptides on Mixing and Frozen Dough Properties of Wheat Flour

Free amino acids, peptides, and vital wheat gluten were investigated to determine their effect on the mixing and frozen dough baking properties of wheat flour. Addition of 1% cysteine and aspartic acid decreased and glutamic acid, histidine, arginine, and lysine increased the mixing tolerance of flour. Cystine, methionine, tryptophan, and phenylalanine increased but isoleucine, histidine, glycine, arginine, glutamic acid, aspartic acid, and lysine decreased loaf volume of nonfrozen dough breads. However cystine, methionine, tryptophan, and phenylalanine did not increase loaf volume of bread prepared from frozen dough. Vital wheat gluten increased mixing tolerance and bread loaf volume only for the nonfrozen dough. However, wheat gluten hydrolysate, corn, and bonito peptides decreased mixing tolerance after optimum mixing time and were effective in increasing loaf volume for both frozen and nonfrozen dough. As the amount of corn and bonito peptide increased, specific loaf volumes also increased. Addition of 2.5% corn peptide was most effective in increasing loaf volume of frozen dough bread. Crust browning and crumb stickiness increased, whereas crumb softness decreased with addition of peptides. Addition of less than 1% peptide did not adversely affect the aftertaste and off‐flavor of bread. These results suggest that addition of peptides are effective for improving the baking quality of frozen dough, whereas amino acids and gluten have no effect.     

Effect of phenolic acids on the rheological properties and proteins of hard wheat flour dough and bread

BACKGROUND: The effects of different phenolic acids on the rheological properties and gluten proteins of hard wheat flour dough and bread were investigated. Caffeic, ferulic, syringic and gallic acids were each blended with hard wheat flour at a concentration of 4.44 µmol L^?1 g^?1 flour. RESULTS: Mixing time and tolerance were reduced with the addition of phenolic acids. The phenolic acids reduced the maximum resistance to extension (R_max) and increased the extensibility of dough, with effects in the following order: gallic < syringic < ferulic < caffeic acid. The effect on R_max was more pronounced in overmixed dough. Loaf volume was most significantly decreased with the addition of caffeic acid. Extraction of sodium dodecyl sulfate‐soluble high‐molecular‐weight proteins was increased in both mixed and fermented doughs by the addition of ferulic and caffeic acids. The order of influence of the phenolic acids on the rheological properties and protein structure of dough and bread was consistent with that of their antioxidant activity. CONCLUSION: The addition of caffeic and ferulic acids reduced R_max and increased the extensibility of hard wheat flour dough by modifying the high‐molecular‐weight gluten, which resulted in decreased bread volume. Copyright © 2011 Society of Chemical Industry     

Antioxidant activity of hard wheat flour, dough and bread prepared using various processes with the addition of different phenolic acids

BACKGROUND: The purpose of this study was to evaluate the effect of baking process on the antioxidant activity of different phenolic acids. Antioxidant potential was determined using the β‐carotene‐bleaching activity assay, and free phenolic acid levels were determined by high‐performance liquid chromatography. Four phenolic acids, caffeic acid, ferulic acid, syringic acid and gallic acid, were mixed with wheat flour at a concentration of 4.44 µmol/g of flour. RESULTS: Type of phenolic acid and processing affected antioxidant activity. Of the phenolic acids, caffeic acid had the most pronounced antioxidant effect. The ranking of phenolic acids in terms of their antioxidant activity in fermented dough and bread was similar to that before processing, i.e. syringic acid < gallic acid < ferulic acid < caffeic acid. The content of ferulic acid was greater than that of the other phenolic acids after baking. Antioxidant activity and free phenolic acid content were reduced by mixing but recovered after fermentation and baking. Phenolic acid recovery after baking was 74–80%. CONCLUSION: Phenolic acids retain their antioxidant activity after the baking process, which has potential health benefits for consumers. Elucidation of interactions between the baking process and phenolic acids is important for the development of functional foods. Copyright © 2010 Society of Chemical Industry