Study On The Process And Quality Improvement Of Fermented Brown Rice Steam Sponge Cake

Brown rice is rich in nutrition,and contains a variety of physiologically active substances which are effective in disease prevention and improvement of human health.But its poor taste and flavor and other defects make it not acceptable to most consumers,and cause a low consumption of BR.Fermented rice cake is known as Chinese traditional rice product,its special flavor and taste make it popular to many people.In order to improve the taste of BR and enhance the nutritive value of BR cake,this thesis took advantage of the characteristic of BR to study the process of BR steam sponge cake based on the traditional rice cake,from the aspects of raw material selection,fermentation condition optimization,quality improvement,etc.At the same time,the storage stability of quick-frozen fermented rice cake products was studied on account of the short shelf life and unstable quality of fermented rice cake products.This study used 7 different kinds of brown rices as raw material.Amylose content,pasting properties,thermal properties of BR flour and texture properties of fermented BR cake were tested to analyze the correlation between material properties and texture quality.The results showed that the amylose content had great impact on BR cake's quality,the lower amylose content,the higher viscosity and poorer taste of the fermented BR cake.The higher peak and through viscosity value,the lower viscosity and better quality of fermented BR cake.Setback associated with the aging rate of BR cake,the speed of aging was fast with a high setback.Gelatinization temperature and enthalpy affected the steaming time of the sample,the lower gelatinization temperature and enthalpy,the shorter steaming time.Among raw materials,the texture quality of fermented BR cake produced by Zhuhai indica rice is the best,which amylose content was 24.36%,peak viscosity,through viscosity,setback was 3475 cP,2121 cP,1300 cP,respectively,and the gelatinization enthalpy was 8.89 J/g.Designed single factor test to study the effect of lactic acid bacteria(LAB)species,LAB addition amount,LAB pre-fermentation time,LAB pre-fermentation temperature,LAB and yeast mixed fermentation time,LAB and yeast mixed fermentation temperature and the amount of yeast on the flavor,sensory quality and texture characteristics of fermented BR cake.The results showed that the addition of LAB mainly affect the flavor of fermented BR cake and had little effect on texture quality of BR cake,the flavor substances produced by the fermentation of commercially available 8 strains mixed lactic acid bacteria were more abundant than produced by Lactobacillus plantarum fermentation alone.Adding 1.2% mixed LAB powder into BR pulp and fermented 4 hours at 28?,and then adding 2% yeast continue to ferment 2.5 hours at 32?,the texture properties and sensory quality of fermented BR steam sponge cake were greatest.On the basis of single factor tests,orthogonal experiment was carried out to determine the optimal ratio of LAB and yeast mixed fermentation temperature,LAB and yeast mixed fermentation time and yeast additive amount to achieve proper characteristic of hardness,adhesiveness,springness and cohesiveness of fermented BR cake,score the fermented BR cakes made under different conditions with the fuzzy comprehensive evaluation,the highest score was 85.4 points,and the fermentation conditions was adding 2.5% yeast fermented 2 hours at 32?.In order to improve the quality of fermented BR cakes,xanthan gum,gluten flour,cassava starch were chosen as the modifier.The improvement effect and the optimum dosage of each modifier were determined by single factor test,and the optimal ratio of the three modifiers was determined by orthogonal test.The results showed that when the composition of the improver is xanthan gum 0.3%,gluten flour 9%,cassava starch 3%,the sensory achieve the best with lower hardness and adhesiveness and higher springiness and cohesiveness.The modified fermented brown rice cakes were stored at 4 ? and-18 ?,determined the moisture content,hardness and retrogradation enthalpy of improved BR cakes of different storage time,and then tessted the quality of secondary steaming fermented BR cakes stored at-18? in different days.Results showed that BR cakes aging faster at 4? than at-18?.Fermented BR cake stored at-18 ? for 60 days was re-steamed,the texture quality and sensory quality were good.However,when the storage time was 180 days,the color of the rice cake changed to yellow,and the surface viscosity became larger and the edible quality decreased.