Development of angkak fermentation and production of food colour for small scale industries
1990
Napha Lotong | Poonpilai Suwanarit (Kasetsart Univ., Bangkok (Thailand). Faculty of Science. Dept. of Microbiology)
Method of producing ang-kak (Chinese red rice) in plastic bags by Monascus sp. NP1 was developed. Advantages of the procedure over that of the traditional ones were : 1) Preparations of inoculum and substrate were easier 2) fermentaion could be performed at low initial moisture content without further addition of water, 3) Aggregation of rice kernels could be overcomed by external manipulation of the bags, 4) contamination could be completely eliminated. The ang-kak obtained was good in appearance that all kernels remained unbroken but were soft in texture sectioning of the graams showed that they impregnated throughout by the pigment. Spectrophotometric measurement of the extract revealed that it contained pigment of the same absorption spectra as those of the market products. The experimental products were superior to the commercial ones in respect of intensity of the pigment. Fermentation of rice of various moisture contents gave results that agreed with previous findings that ang-kak could be produced only at a relatively low initial moisture level. The mechanism by which the initial substrate moisture content regulated pigmentation was clasified. Glucoamylase activity increased with increase in initial substrate moisture content, Therefore at high moisture content, as high enzyme activity was produced, glucose was rapidly liberated in amounts that inhibited pigmentation. The sugar was then transformed to ethenol. Addition of various amounts of glucose to rice of low moisture content before fermentation confirmed that the sugar at certain concentration had an inhibitory effect on pigmentation.
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