Effect Of Cooking On Starch Structure And Digestibility Of Potato And Purple Yam

Carbohydrates are the main source of energy in people's daily diets and found mainly in the form of starch,which is closely related to human nutrition and health.Starch is the main component of tuber crops,and its structural changes during cooking have an important impact on the nutritional quality of tubers.However,related research have paid attention to the color,texture,nutrient loss and structural changes of cooking foods,and ignored the study of starch structure and digestibility in samples.In this study,we used potato and purple yam as raw materials and selecting different cooking methods(blanching,steaming and microwave heating)and time,in order to exploring the changes of structure and in vitro digestibility of starch after different treatments.The results of the study were as follows:For potatoes,the data of the thermodynamic properties,structural properties and in vitro digestibility of starch(the starch digestibility of potato was 97%after cooking)show that cooking destroyed completely the structure of starch in potato flour and increased greatly the in vitro enzymatic digestibility of starch.Cooking methods and time had little effect on the structural disruption and digestibility of starch in potato.From the results of paste viscosity properties,cooked potato flour(1413.7 cP-2153.3 cP)has a significantly higher peak viscosity than the raw potato flour(1172.0 cP),indicating that the cooking method and time have significant influence on the pasting properties of potatoes,which may be due to differences in the structure of the amorphous regions.For purple yam,the relative crystallinity of cooked purple yam flour decreased from 38.5%(raw pueple yam)to 17.5%(purple yam blanched for 5 min),and the fwhm at 480 cm-1 increased from 16.34(raw pueple yam)to 17.87(Purple yam heated in microwave for 10 min),indicating that the cooking caused a certain degree of damage to the structure of purple yam,and the relative crystallinity,paste viscosity and in vitro digestibility of starch in purple yam decreased gradually with the prolonging of cooking time.In addition,the microwave treatment of purple yam for 5 min in this experiment has the lowest digestibility,about 53.4%.