To investigate different contents of pu-erh tea polyphenol affected by abiotic stress, this research determined the contents of tea polyphenol in teas produced by Yuecheng, a Xishuangbanna-based tea producer in Yunnan Province. The study drew a preliminary conclusion that eight factors, namely, altitude, nickel, available cadmium, organic matter, N, P, K, and alkaline hydrolysis nitrogen, had a considerable influence on tea polyphenol content with a combined analysis of specific altitudes and soil composition. The nomogram model constructed with three variables, altitude, organic matter, and P, screened by LASSO regression showed that the AUC of the training group and the validation group were respectively 0.839 and 0.750, and calibration curves were consistent. A visualized prediction system for the content of pu-erh tea polyphenol based on the nomogram model was developed and its accuracy rate, supported by measured data, reached 80.95%. This research explored the change of tea polyphenol content under abiotic stress, laying a solid foundation for further predictions for and studies on the quality of pu-erh tea and providing some theoretical scientific basis.

This research prepared gelatinized waxy maize starch (WMS), low-amylose maize starch (LAS), and high-amylose maize starch (HAS) with different glutathione (GSH) content (5, 10, and 15 %) using high hydrostatic pressure (HHP) at 600 MPa. Scanning electron microscopy (SEM) revealed damaged morphology of WMS and complete swelled granules of LAS and HAS with different degree of gelatinization (DG) values, 92.86, 59.36, and 17.45 %, respectively. Fourier transform infrared spectroscopy (IR spectra), laser confocal micro-Raman (LCM-Raman) spectroscopy, and X-ray diffraction (XRD) results suggested that the crystallinity content of gelatinized WMS and HAS with addition of GSH was higher than that of LAS, and the gelatinized LAS and HAS were mainly of C type and V type, respectively. The resistant starch of LAS (25.15 %) and HAS (34.76 %) increased with GSH addition. The crosslinking between GSH and amylose/amylopectin caused changes in physicochemical properties. This study will provided theoretical basis for GSH usage in food industry.