Studies On The Texture Characteristics And Antimicrobil Compound Of Chinese Water Chestnets (Eleocharis Dulcis)

Chinese water chestnut (Eleocharis dulcis) is a kind of food which has special texture characteristics, high starch content and medical effects. The texture changes of Chinese water chestnuts during cooking and canning, as well as the antibacterial activity and application of puchiin extracting from the processed wastes of Chinese water chestnuts were investigated in the thesis.1. Cooking is the simplest and most common heating process. The thesis compared the texture changes of Chinese water chestnuts with those of potatoes during the cooking process. The results indicated that elastic nature (Fracturability, Hardness and Adhesiveness) and plastic nature (Cohesiveness and Resilience) of Chinese water chestnuts and potatoes have different responses to thermal processing. The elastic properties of Chinese water chestnuts and potatoes decreased during the cooking process, while the Adhesiveness of potatoes increased at the initial period. The plastic properties of Chinese water chestnuts assumed that the unidirectional change along with the heating time. With the increase of heating time, the cohesiveness decreased, while the resilience increased. The cohesiveness and resilience of potatoes increased after the initial decreasing. The correlation analyses of TPA parameters indicated that the correlation of parameters of Chinese water chestnuts and potatoes are different. The Chinese water chestnuts are dehydrating during the cooking process, however potatoes are absorbent. This difference may be an important reason for the texture thermal stability of Chinese water chestnuts.2. The texture changes of Chinese water chestnuts (Eleocharis dulcis) during canning and the relationship between texture and water content were studied through different processing periods. The texture parameters of Chinese water chestnuts were analyzed during pre-cooking, evaporation and sterilization, respectively. The results showed that elastic nature (Fracturability, Hardness and Adhesiveness) and plastic nature (Cohesiveness and Resilience) of Chinese water chestnuts have different responses to thermal processing. The elastic properties increased during evaporation processing. However, the plastic properties decreased during the whole processing. In the meanwhile, water content showed significant negative correlation with Adhesiveness, and correlated positively with all plastic parameters. The relationship between changes of Chinese water chestnuts texture and starch properties was analyzed to find the feasibility of good product texture by changing starch properties. It was observed that swell power and gel properties were significantly correlated with different texture parameters. The conclusion is that it is possible to obtain good product texture through controlling different thermal processing, especially pre-cooking, or by changing starch properties.3. The antibacterial activity and application of puchiin extracting from the processed wastes of Chinese water chestnut were studied. The results showed that puchiin has inhibition activity to the bacteria Escherichia coli, Staphylococcus aureus, Micrococcus luteus and Bacillus subtilis. Among the four bacteria, the inhibition activity to S. aureus was the highest. The inhibition activity was better than 1% potassium sorbate solution on E. coli, S. aureus and M. luteus except B. subtilis. Puchiin could effectively control the spoilage caused by Rhizopus nigrican and Alternaria alternate on Lycopersic on esculentum var.cevasiforme. However, the inhibition activity to A. alternata is better than that of R. nigrican.