Effect of glutamine peptide on baking characteristics of bread using experimental design

Glutamine is a conditionally essential amino acid as a deficit in this residue occurs during periods of catabolic stress. Glutamine-containing peptides can therefore be considered as potential functional food ingredients. The ubiquitous nature and low cost of bread makes it a potentially ideal vehicle for the delivery of glutamine peptide to the body. Glutamine-enriched peptide products were obtained following enzymatic hydrolysis of gluten. When glutamine peptide is incorporated into bakery products the processing variables considered optimal for standard bread result in dough with poor machinability. To optimize the production process a central composite design was chosen. Water addition, mix time, rest time and proof time were chosen as predictor variables. Each experiment was evaluated based on baking tests, color measurements and texture analysis. Production processes for standard bread and bread containing glutamine peptide at 3% w/w were compared. Mix time was a major influence on the baking characteristics of bread containing glutamine peptide and standard bread. Slight deviations from the optimum resulted in substantial increases in moisture loss and decreases in volume. Texture values in standard bread were strongly influenced by water addition. Using experimental design a production process resulting in high quality bread containing glutamine peptide was developed.