Study On Biodegradation Technology Of Konjak Glucomannan Using Edible-medicinal Mushroom

Konjac Glucomannan component(KGM) has attracted great attention for its considerable potential in medical and health care application. In China, however, the traditional Konjac industry only focused on Konjac material and brief products manufacturing. The simple process technology made products in the market very similar. In order to improve the technical level and stimulate the development of Konjac industry, this study investigated bio-conversion and bio-degradation technology of KGM products with series of molecular weight, which was based on conversion capacity of edible and pharmacological fungi. The main results were as follows.?-glycosidase was the key enzyme involved in glucomannan degradation. First, the enzymatic activity of ?-glycosidase from selected three edible and pharmacological fungi was confirmed to be different. Then, optimization of ?-glycosidase production from Pleurotus ostreatus, Ganoderma lucidum and Irpex lacteus were investigated by single factor and orthogonal test(four factors, three levels). The maximum enzymatic activity of these three fungi showed a 1.19, 1.65 and 1.91 fold increase after optimization, respectively. The greatest improvement appeared in Irpex lacteus fermentation, whose optimized conditions were 1.25 g/L inorganic nitrogen and 2.5 g/L organic nitrogen mixed as nitrogen source, 0.3 g/L dried taro powder as carbon source, while fermentation temperature raised up to 30?. It was more suitable for industry application comparing with the other two strains since its lower carbon, lower nitrogen input and higher temperature requirement.Further, the degradation characteristics and molecular weight changes of glucomannan from the denatured crude Konjac powder or refined Konjac powder by enzymatic degradation or fungi degradation was investigated. The results showed that average molecular weight of enzymatic products were all significantly decreased after degradation with crude enzyme from these three fungi for 6 hours. Crude enzyme from Irpex lacteus seems to be most effective for Konjac powder degradation, since it could produce a homogeneous 4.53 w molecular weight glucomannan residue. The gradual decrease of molecular weight was significantly correlated with the enzymatic time. All of these three fungi were suitable for bioconversion of KGM but the degradation rate of Irpex lacteus was higher than Pleurotus ostreatus and Ganoderma lucidum. A highly homogeneous low polymer glucomannan with a 0.51 w molecular weight could be obtained after 4 days of Irpex lacteus degradation. It revealed that the effective bio-conversion of target products from Konjac could be achieved through enzymatic hydrolysis and fermentation time control no matter what degradation method it would take.Finally, this study explored combination of fruit and vegetable functional products with the degraded KGM which had a series of different molecular weight. The results showed a good recovery. As a result, it provided a technique foundation for KGM bio-conversion and product development.