| Coix is the dry and mature seed of Adlay, named Coix lacrym- jobi Linn. As a grass crop, it is commonly used as traditional Chinese medicine with the pharmacological activities such as immune regulation, antitumor, antiviral, hypoglycemic effect, hypocalcemic effect, antihypertensive, inhibited trypsin and induced ovulation. At the same time, Coix is also an important minor crop with the functions of nutrition, health protection and medicine. So it has a vast developing prospective. Shell and Coix seed bran need to be removed and Coix seed broken rice is generated during the processing of Coix seeds products. The by-products which contributes about 10-15% of the total Coix seeds production is usually used as feed material, its value has not been fully exploited. At present, it has become one of the new domains of food research by using microbial fermentation to transform vegetal material for achieving higher nutritional and organoleptic qualities of product. However, Coix Monascus tea has not been reported at home and abroad. Therefore, in order to develop the new kind of Coix seed tea which is particularly rich in bioactivity compound, increase value-added of by-products and extend the chain of Coix industry with new products and technology, this paper used Monascus purpureus 3.4629 to ferment the by-products(Coix seed broken rice and bran) and optimize process parameters. The main conclusions are as follows:1. The physicochemicaland effective properties of five kinds of materials such as polishing Coix seed(PCS), coarse Coix seed(CCS), broken Coix seed(BCS), bran(CSBr) and extruded bran(CSEBr) were analysised. BCS was rich in starch(72.2%), crude polysaccharide(61.03%), protein(16.73%), crude fat(2.06%), ash(1.10%), reducing sugar(0.81%) and vitamin C(0.2 mg/100g). Its starch and crude polysaccharidecontents were significantly higher than PCS and CCS(P<0.01). And its protein was significantly higher than that of PCS too(P < 0.05). CSBr was also rich in starch(49.85%), crude polysaccharide(36.57%), protein(13.40%), ash(8.11%), crude fat(4.37%), reducing sugar(1.98%) and vitamin C(0.48 mg/100g). Its reducing sugar and ash contents were higher than others at the most significant difference level(P<0.01). On the other hand, Coix seed by-products were rich in efficacy component, for example, the contents of flavonoid in BCS and CSBr was significantly higher than that of PCS(P<0.05). What’s more, Coix polyester content of BCS can reach 4.04g/100 g, and that of bran can reach 3.61g/100 g. The content of Coixol in BCS was determined by R-HPLC, and it can reach 16.16mg/kg. Analysis of fatty acid compositions by GC-MS found that unsaturated fatty acids in BCS account for 71.9% and that in bran account for 62.7%. The results suggested that by-products of Coix seed can be intensively processed to increase added value.2. Culture medium and condition of Monascus seed were optimized. In order to expand culture of Monascus, BCS and CSBr were compounded and optimized. The result showed that maltose was the best carbon source, and ammonium chloride was the best nitrogen source. The optimum culture medium and condition were obtained by orthogonal test. And it was as followed: BCS 60g/L, bran 60g/L, maltose 50g/L, ammonium chloride 3g/L, magnesium sulfate 2g/L, inoculation 5%, initial pH 6, liquid medium 30mL/100 m L and temperature 34℃.Under these conditions, dried cell weight of Monascus seed was 75.38 g/L(living cell concentration ≥1.0×108cfu/mL), the mycelium pellets showed much better uniform structure and strong vigor, and the obtained seed met requirements.3. Fermentation process was studied. Uniform design was used to optimize the process of Coix solid- state fermentation by Monascus for the purpose of gathering various bioactivity compounds( such as Coixol, Coix polyester and Monacolin K). By the efficacy components were weighted to contrast analysis, optimal process was screened. That was initial pH 6.5, ratio of solid to liquid 1:0.34, solid medium 7.22g/100 m L, steamed time 6min, inoculation9%. Under these conditions, fermentation product contained Coixol 64.63 mg/kg, Coix polyester 17.75g/100 g and Monacolin K 1678.82 mg/kg, and its color value could reach 1058.34 U/g.4. Baking Coix material to age and increase fragrances and formula process were studied. With fuzzy mathematic sensory evaluation and reservation rate of flavonoid as index, the optimum baking conditions and formula processas were obtained respectively. The optimum baking conditions was baking temperature 130℃, baking time 40 min when the height of tiled material was 1cm.Under these conditions, aging rate was more than 98%, burnt rate was less than 1%, aging Coix material looked golden and smelt good, and its reservation rate of flavonoid could reach 77.59%. The best ratio of baking Coix material and fermentation product with various bioactivity compounds was 20:1. Electronic tongue detection and principal component analysis(PCA) showed that taste of Coix Monascus tea was harmonious. The produced Coix Monascus tea had red and bright color, aromatic bouquet, soft palate and its color and taste was still well after pouring 3 times with 85℃ hot water.5. The product quality was evaluated. The Coix Monascus tea which was produced by the optimum process met standards of GB/T13738.1-2008 and GB/T13738.2-2008. It had water 6.13%, ash 0.77%, crude fibre 0.349%, water soluble ash 0.52%, water insoluble ash 0.29%, acid insoluble ash 0.016%, water soluble extractive 32.10%. Furthermore, it was rich in nutrients and efficacy components, such as protein 16.6g/100 g, fat 0.038g/100 g, free amino acid 223mg/kg, Coixol 18.19mg/kg, Coix polyester 4.61g/100 g and Monacolin K 824.61 mg/kg. These results indicated that the processing technology of solid fermented tea by Monacus was viable and Coix Monascus tea had highly development value for its good quality. |
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