Nutritional Changes and Early Warning of Moldy Rice under Different Relative Humidity and Storage Temperature

Abstract

Processed unhusked rice is prone to mildew during storage. In this study, the storage conditions were simulated at temperatures of 20, 30, and 35 °C and a relative humidity of 40%, 60% and 80%, respectively. The water, fatty acid, and total starch content and the peak viscosity, mold colony number, protein secondary structure, and spatial structure of rice were monitored in order to propose the critical point of mildew during storage. In the process of rice from lively to moldy, the water content, fatty acid contents and the peak viscosity were increased. The total starch content decreased and then showed a slow increasing trend, while the microstructure of the powder particles changed from smooth and complete to loosen and hollow. With the increase in storage time, the vibration of the amide Ⅰ band of the rice samples decreased slightly, indicating that the total contents of β-fold, β-turn, α-helix, and random curl of the rice protein also changed. PCA (Principal Component Analysis) analysis showed that rice mildew index was closely related to temperature and humidity during storage. In our investigation, the best and most suitable temperature and relative humidity for rice storge is 20 °C and 40%, respectively. These results suggested that temperature and environmental humidity are vital factors affecting the physicochemical properties and nutrient changes, which provides a theoretical basis for the early warning of rice mildew during storage.

Rapid identification of adulterated rice using fusion of near-infrared spectroscopy and machine vision data: the combination of feature optimization and nonlinear modeling

“…During the moldy process of rice, mold forms a layer of hyphae and spores on the surface of the rice, causing small protrusions and pores, which affect the surface texture of the rice, making it irregular, rough, and uneven. The surface color also gradually darkens [34,35] . Although the rice has undergone treatments such as ridging, milling, and polishing, the resulting rice still differs from normal rice.…”

Real-Time Measurement of Moisture Content of Paddy Rice Based on Microstrip Microwave Sensor Assisted by Machine Learning Strategies

“…Moisture content is an important index that reflects the freshness, preservation state, and internal quality of agricultural products [1], and it is a key measurement and control parameter in the processes of purchasing, processing, storing, and transporting. High moisture content leads to grain mildew, shortened storage time, and effects on the food taste [2]. Grain moisture content is a crucial factor for the management of harvesting and postharvest operations and is a basis for pricing in the grain trade [3].…”

“…In general, very limited optimization work has been carried out regarding the realization of the on-line measurement of the moisture content of agricultural and food products. In this context, the aims of the present study are: (1) to develop a low-cost portable device for the real-time measurement of paddy rice with a moisture content range of generally 13-30%; (2) to determine the optimal measurement parameters according to experimental objects (microwave characteristics, phase shift, and temperature compensation); and (3) to develop an effective moisture content prediction model by comparing different regression algorithms. This work is expected to provide an important reference for the real-time in situ measurement of other agricultural products and to be of great significance for the development of intelligent agricultural equipment.…”