Quality improvement and preservation of rice flour bread

Preference test result show medium high acceptance of the high substitution level rice bread (50 percent). Substitution of wheat flour with rice flour in bread was possible in laboratory scale. Application of this research result need further study about market, cost, and consumer acceptance. For quality and shelf-life improvement of gluten free rice bread, the effect of alpha-amylase on the quality and staling extension of bread was studied by using rice flours having 16 and 25 percent amylase content. Experiments were undertaken to extend shelf-life of the bread by adding preservatives, UV radiation and using packaging materials in combination with oxygen absorber (Ageless) and/or modified atmosphere. Nutritional analysis was also included. The use of alpha-amylase in the examined bread formulas supplemented with and without pre-gelatinized flour showed that the one having both supplemented enzyme and pre-gelatinized flour had bread crumb structure similar to wheat bread and also had higher specific volume. The addition of 0.05 and 0.07 percent of alpha-amylase was found to give optimum level to retard firmness of bread prepared from 16 and 25 percent amylose flours during 6 day-storage at 30+- 2 deg C. Storage at -25 deg C was found to retard firmness at least 6 weeks. In the comparative study of packaging materials consisting of multilayer (ML) and metallized (MZ, type oriented polypropylene) films against PP under various conditions of storage. No change were observed for moisture and a sub(w) values (average 0.954) of rice bread packed with various films at all conditions while the texture had been found changing. Packaging with MZ film under atmosphere the increase of firmness rate was slower than the other two type of films, the taste panelists accepted the product with 4 days-storage in MZ film. The effect of packaging methods on microbial quality of rice bread suggested that at atmospheric keeping conditions the quality could be accepted within 4 storage days with PP film. But the samples packed at MAP+Ageless condition with MZ film and had subjected to UV radiation microbial growth was not found for 8 days. However yeast growth of 10**(3) CFU/ g was found in 12 days but without fermented odor.