Use of fermented glutinous rice as a natural enzyme cocktail for improving dough quality and bread staling

Abstract

Solid-state fermentation of glutinous rice by Rhizopus oryzae (rice wine or Jiu-niang in Chinese) is a traditional Chinese food as well as a natural enzyme cocktail with the potential to be used in bread making. The objective of this work was for the first time to study the enzyme activities of Jiu-niang and its effect on dough quality and bread staling. The results showed that the principal enzymes in Jiu-niang were amylase, protease and lipase. The Jiu-niang enzyme cocktail significantly improved the volume, texture, and shelf life of wheat breads. The use of an optimal enzyme concentration (addition of Jiu-niang at 10% on flour basis) increased specific volume (19%), reduced crumb hardness (50%), and reduced moisture migration rate and bread staling rate. Using low-field nuclear magnetic resonance (LF-NMR) analysis, proton mobility and starch retrogradation of Jiu-niang bread during storage were determined and discussed. These results indicated that Jiu-niang could be used as a natural quality improver for bread making.