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Background and objectives This study aimed to determine the effect of xanthan gum on whole wheat dough and bread, especially dough rheological properties, gluten structures, loaf volume, and bread texture and staling. Findings Xanthan gum increased the water absorption and mixing time for whole wheat dough as determined by mixograph. Xanthan gum altered dough rheology as evaluated through the Kieffer extensibility test, Chen–Hoseney stickiness test, and compression test employed for extensional viscosity calculation. Gluten secondary structure was analyzed by FTIR spectroscopy. Changes to glutenin and gliadin extractability were measured by RP‐HPLC. Specific loaf volume increased from 3.74 to 4.38 cm3/g. Crumb hardness of fresh bread decreased more than twofold by xanthan inclusion. Hardness after 48 hr of bread storage was also lower than the control, but the rate of hardness increase was not reduced. Moisture loss over 48 hr decreased for 0.6% and 1.0% xanthan gum. DSC revealed that xanthan gum decreased amylose–lipid complexation, but did not affect amylopectin retrogradation. Conclusions Xanthan gum altered the rheological properties of whole wheat dough, increased whole wheat bread volume, and decreased the hardness of both fresh and stored bread. Future research could examine the effect of xanthan gum in combination with other crumb softeners and antistaling agents, in order to achieve both an increase in loaf volume and a decrease in staling for whole wheat bread. Significance and novelty This study may help improve the sensory appeal of whole wheat bread and ultimately increase whole grain consumption.

The objective of this research was to determine effects of five enzymes on whole wheat bread properties, particularly loaf volume, bread texture, and staling. Enzymes containing conventional α-amylase (α-amyl), cellulase (cel), glucose oxidase, maltogenic α-amylase (m amyl), and xylanase (xyl) were added at three levels. Vital wheat gluten (VWG) was added as an additional, separate treatment at 2.5% (flour weight basis). Enzymes had minimal effect on water absorption and mixing time. Each enzyme increased specific loaf volume for at least one of the usage levels tested (P < 0.01). Among the enzyme treatments, the greatest loaf volume was seen for xyl at the medium and high levels. No enzyme was as effective as VWG at increasing loaf volume. Overall, enzymes did not significantly change cell structure. The greatest reduction in fresh bread hardness was obtained for the high level of xyl. VWG, m amyl, and xyl reduced the rate of bread firming over 7 days. α-Amyl, cel, and m amyl decreased starch retrogradation at day 7 as measured by differential scanning calorimetry (P < 0.01). M amyl nearly eliminated the endothermic peak for recrystallized amylopectin. This study demonstrated the specific application of enzymes in whole wheat bread to increase loaf volume and decrease initial crumb hardness and bread staling.

Maillard reaction products (MRPs) can be an important dietary antioxidant source. Bread is the most popular bakery product; however, limited information is available on the antioxidant activities of MRPs generated during bread-baking. This paper reports the effect of different amino acids on bread properties, melanoidin formation and antioxidant activities. Totally six amino acids at four different levels were evaluated. Increasing the amount of amino acid led to darker bread crust, higher melanoidin content and stronger antioxidant activity. Among the six amino acids, bread with glycine had the highest melanoidin content and ABTS radical scavenging activity up to 1079.77 AE 8.43 lmol TE mg À1 . Bread with lysine had the highest DPPH radical scavenging activity up to 281.97 AE 10.52 lmol TE mg À1 . Bread with alanine had the highest crust metal chelating activity compared with others. Adding certain dietary amino acids is a potential approach to enhance the antioxidant capacity of bread products.

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