Effect of lotus-seed starch quality on lotus-seed juice's rheological property and shelf life

Starch quality is one of the important factors of starchy food quality. In order to ensure the quality of lotus-seed products, optimizing lotus-seed with low-content amylose content is the key to the processing of lotus-seed products. Twenty-two representative wild or cultivated varieties of lotus-seed in China were collected and their amylose contents(AC) were determined, then seven varieties of lotus-seed were chosen to produce lotus-seed juice according to AC. Rheology of lotus-seed juice and its changes in the storage were studied. The mathematical model of the AC, shelf life of lotus-seed juice and the retrogradation deposition content of starch was constructed by stepwise regression analysis. The results were as follows: AC of lotus-seed differed largely among all varieties, lotus-seed juice belonged to pseudoplastic liquid, starch viscosity decreased during retrogradation, and the viscosity decreased faster at the beginning of storage while the AC was bigger. The mathematical model was: Y=0.5107exp(0.020T-7.562×10^-5T²+9.955×10^-8T³+0.05C-0.001C²), in which Y was the starch retrogradation deposition content; T was storage time; and C was amylose content. The model provided basis for forecasting the shelf life of lotus-seed juice and high-quality breeding of lotus-seed, meanwhile the study offered valuable reference for the processing of starchy products.