| Coix Seed is the dried ripe kernel of Gramineae Coix lacryma-jobi, also known as pearl barley, semen coicis. Coix Seed is a kind of nutritionally rich and balanced cereal which could be used as food and medicine, its nutritional value and health value far exceeds that of other cereal, known as the "king of the world Gramineae". The unique value in health care making it the hotpot of recent research in the field of food industry. At present, the study about nutrient contents of coix seed have been reported, but the nutrients in various parts of Coix lacryma-jobi have rarely been reported, the same as the coix seed vinegar fermentation process and the fermentation traits in different fermentation stage.Using purebred small coix in Guizhou as raw material, detect the nutritive index of different position of Coix lacryma-jobi(seeds, shell, seed coat, root, stems and leaves); optimizing the coix seed vinegar fermentation process by the response surface method and have research on changes of nutrients, organic acids and aroma components during the fermentation process; full-automatic fermentor is used to carry out a mass production experiment, what’s more the coix seed vinegar product quality evaluation system would be established. All above are designed to provide experimental data for the production of coix seed vinegar. The conclusions are as follows:1) Nutritional compositions and functional components were analyzed in different tissues of coix lacryma-jobi grown in Guizhou. Results showed that the levels of different nutritional factors exhibited a difference among different tissues. Higher content of protein and polysaccharide were determined of coix seed kernel, which were separately up to19.33g/100g and2.26g/100g; the cotent of VE was86.61mg/kg. Higher content of total fiber were determined of coix coat and coix shell. Coix root had the highest content of VB1and VB2, which were separately up to0.61mg/kg and2.96mg/kg. Higher content of potassium, sodium, calcium and magnesium among minerals. Meanwhile,7essential amino acids and10non-essential amino acid were detected in coix seed kernel and coix leaf, in addition,7essential amino acids and9non-essential amino acid were detected in others’location. The contents of eoixol and polyphenols were highest in root, which were1.26mg/g and4.53mg/g; highest content of flavonoids was determined of coix seed kernel, which was2.26mg/g. The contents of unsaturated fatty acids were more than70%in coix coat, stem and leaf.(2) Adopted modern microbial fermentation technology, based on the single-factor test, optimization for vinegar acetic acid fermentation was done using response surface methodology. Result:Acetobacter AS1.41was selected as fermentation bacteria. The two polynomial model of coix seed vinegar fermentation conditions which was Y=6.62+037A+0.14B+0.36C+0.24D+0.19AB+0.19AC-0.49AD+0.17BC+0.39BD+0.65CD-1.29A2-1.52B2-1.53C2-0.97D2. The optimal fermentation conditions were volume of20%, fermentation temperature of30℃, fermentation time of5.34d, initial pH of4.19, initial alcohol degree of7.37%and acetic acid bacteria inoculation amount of.12.60%. Under these conditions, acetic acid content was6.76g/100mL in pearl barley vinegar. It has aromatic flavour, typical aroma of coix seed, and the taste soft and pure.(3) To study the changes in chemical composition of coix seed vinegar during primary fermentation and aging process. The result show that:The acetic acid content of coix seed vinegar gradually increased throughout the fermentation stage eventually stays stable; Flavonoid content was increased at first and then decreased in the main fermentation stage and a slow increase in the aging stage; Polyphenol content was first decline and then rising and it continues to increase in the aging process; The polysaccharide content showing fluctuations trend; Both in the primary fermentation stage and the aging stage amino acid nitrogen content continues to rise; The coixol content is fluctuating and declined slightly in the whole; In the entire fermentation phase organic acid content increases, specifically the content of acetic acid, lactic acid and succinic acid were increased significantly while malic acid decreased and oxalic acid, pyruvic acid, tartaric acid, citric acid almost remained unchanged. Acetic acid content decreased in the aging stage. There were totally86kinds of aroma components detected during the fermentation process, while63kinds of aroma components were detected in newly fermented vinegar,62kinds in aging for one month,68kinds in aging for two months and70kinds in aging for three months. And there are39kinds of aroma components in common which were mainly consist of esters, acids, alcohols, ketones and phenols.(4) Based on the fermentation parameters optimized by the response surface experiment, studying the method of coix seed vinegar fermentation using full-automatic fermenter. Fermentation parameters works out:fermentation temperature30℃, mixing speed200rpm, pH4.2, dissolved oxygen1.3%. Physicochemical indexes of coix seed vinegar fermented by full-automatic fermenter works out that:acetic acid content6.55g/100mL, amino acid nitrogen2.94g/100mL, flavonoids 133.47mg/L, polyphenol104.22mg/L, polysaccharide1.21g/L, coixol24.11mg/L. Total organic acids content are8276.05mg/100mL and8kinds of minerals. Aerobic bacterial count and coliform could meet the standard of national limits while pathogens were not detected. The production has a clarify pure smell and have the typical aromas of coix seed. |
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