Study On Quality Changes Of Konjac Tuber In Low Temperature

Amorphophallus Konjac,a kind of Araceae perennial endogen angiosperms,is commonly grown in humidity and low latitudes at an altitude of 250?2500 m mountainous area,and has been cultivated,processed and consumption in our country for 2000 years history.Konjac tuber is the only economic crops containa lot of Konjac Glucomannan(KGM).In recent years,KGM industry is developing rapidly,and with an increasingly number of process konjac glucomannan and its tuber.However,Konjac tuber body contain plenty of water content that is not resistant to storage and easily influenced by bacteria,fungi,etc.it is not only affect the product appearance,but also nutritional value.How to improve the quality of raw konjac tuber during storage,has become a problem to be solved in konjac plant industry.There is little research pay attention to konjac tuber storage.Based on these information,in this paper,three storage temperature(4? and 0?,-4?)were selected to storage konjac tuber and the change of biological character,chemical composition and its mechanism has been discussed.This research will provide a reference and theoretical basis for konjac tuber storage tactics.The main contents and conclusions were as follows:(1)Fresh konjac tuber has high moisture content and POD activity that prone to Browning and it is difficult to maintain quality at room temperature storage conditions.Compared to 4? and 0? low temperature storage conditions,konjac tuber can effectively reduce soluble sugar content,POD activity decreased at-4? storage conditions,delay the increase trend of soluble protein,starch content,MDA content and electric conductivity.Meanwhile,it also inhibits the respiration of tuber tissue,and reduces its cell metabolic activity,membranous oxidation and weightlessness rate during storage.It indicates-4? storage conditions is suitable for konjac tuber in low temperature storage that can effective postpone the aging process of tubers and hold a better original quality.(2)The KGM is extract form konjac tuber before and after storage by using ethanol precipitation method,and it found that the KGM(G1)content in fresh konjac tuber was similar to KGM(G2)content that storage at-4? for 3 months but is higher than that KGM(G3)content in konjac tuber storage at 4? for 3 months.Form color analysis of KGM power,G2 and G3 are fainter than G1 and W value are lower than G1 sample,but the W value of G2 is significantly higher than the G3 sample.Form swelling and freeze-thaw stability analysis of KGM solution,the swelling and freezing and thawing of G1 are higher than G2 and G3,but G2 is also better than G3,indicating-4? storage is a better storage method than 4? storage.At the same time,rheological properties of G1,G2 and G3 solution are similarly,which are verified by infrared spectrum analysis,X-ray diffraction spectra and DSC analysis results,it suggesting that there is no change of KGM in konjac tuber before and after storage.This proves the rationality and feasibility of this test.