Study On The Improvement Of Produce Processing And Properties Of Inoculated Fermented Yin Rice

Yin rice is a kind of traditional naturally fermented rice food in south of China. As we known, waxy rice is usually used as raw material to produce yin rice. Through natural fermentation, the digestibility of waxy rice could be improved. So it could be used to cook soup, gruel for the special food of elderly, children, baby and other special people. The process of making naturally fermented yin rice was as follows:immersing the rice which was not washed for about 15 days, then, elutriation and draining, water steaming until every granule has no white section, and shade drying until it could be crushed with fingers.Inoculation fermentation hasn’t been used to make yin rice before. In this study, the method and conditions of making yin rice with inoculation fermentation were studied by means of the single factor experiment and orthogonal experiment in this paper. Then, the properties of native rice, naturally fermentated yin rice and inoculated fermented yin rice were measured to evaluate the usefulness of the inoculation fermentation. The conditions of making inoculated fermented yin rice cake were determined and the paper also studied on anti-retrogradation method for inoculated fermented yin rice cake. The main contents and results are as follow:1. Determining the optimum conditions of making inoculated fermented yin riceThrough the orthogonal experiment, it could obtain the optimum conditions of making inoculated fermented yin rice were as follows:adding 0.5%o LAB, 0.5%o yellow rice wine yeast and 2%o rice wine starter mixture strains, then fermented at 25℃ for 48h.2. The properties of native rice, naturally fermented yin rice and inoculated fermented yin riceThe chemical components, granular properties (particle size, water absorbing ability, solubility, swelling power), chroma, thermal properties, rheological properties, sensory characteristics of native rice, naturally fermented yin rice and inoculated fermented yin rice were measured. The results showed that the contents of protein and fat in inoculated feremented yin rice were lower than naturally fermented yin rice. And the contents of total sugar and protein in inoculated feremented yin rice had no significant differences with naturally fermented yin rice. The granular size of inoculated feremented yin rice was smaller than naturally fermented yin rice. To some extent, the change trend of the index of naturally fermented yin rice and inoculated fermented yin rice were the same, so it could obtain the result that inoculation fermentation could decrease the time of making yin rice.3. The volatile flavour compounds in native rice, naturally fermented yin rice and inoculated fermented yin riceThe volatile flavour compounds in native rice, naturally fermented yin rice and inoculated fermented yin rice were extracted by the "purge and trap’method and analysed by GC-MS (gas chromatography-mass spectrometry). Through the analysis, it could obtain the result that naturally fermented yin rice and inoculated fermented yin rice both has 16 kinds of main volatile flavor compounds, among them there are 9 species of them were the same. Inoculated fermented yin rice could produce other pleasant flavor,6-methyl-5-heptene-2-ketone, which was smell like flower. It was indicated that inoculation fermentation not only could maintain the the main volatile flavor components of naturally fermented yin rice but also could produce pleasant flavour. There were 10 kinds of volatile flavour compounds in inoculated fermented yin rice were produced by yellow rice wine yeast, nearly 7 kinds of volatile flavour compounds in inoculated fermented yin rice were produced by rice wine starter, about 2 kinds of volatile flavour compounds in inoculated fermented yin rice were produced by lactic acid bacteria. So yellow rice wine yeast was acted as a very important role in the inoculated fermentation.4. Determining the optimum conditions of making inoculated fermented yin rice cake and studied on the anti-retrogradation method for inoculated fermented yin rice cakeThrough the orthogonal experiment, it could obtain the optimum conditions of making inoculated fermented yin rice cake were as follows:40 mesh rice powder, water 80%, sugar 25% and steamed for 10 minutes. 0.6% glyceryl monostearate or 0.3% xanthan gum or 1.5%α-amylase or 2.5% cross-linked hydroxypropylated tapioca starch has an obvious effect on anti-retrogradation of inoculation fermentation yin rice cake.