Review of Rice Quality under Various Growth and Storage Conditions and its Evaluation using Spectroscopic Technology

Abstract

Purpose: Grain quality is a general concept that covers many characteristics, ranging from physical to biochemical and physiochemical properties. Rice aging during storage is currently a challenge in the rice industry, and is a complicated process involving changes in all of the above properties. Spectroscopic techniques can be used to obtain information on the quality of rice samples in a non-destructive manner. Methods: The objective of this review was to highlight the factors that contribute to rice quality and aging, and to describe various spectroscopic modalities, particularly vibrational and hyperspectral imaging, for the assessment of rice quality. Results: Starch and protein are the main components of the rice endosperm, and are therefore key factors contributing to eating and cooking quality. While the overall starch, protein, and lipid content in the rice grain remains essentially unchanged during storage, structural changes do occur. These changes affect pasting and gel properties, and ultimately the flavor of cooked rice. In addition, grain quality is significantly affected by growing and environmental conditions, such as water availability, temperature, fertilizer application, and salinity stress. These properties can be evaluated using spectroscopic techniques, and rice samples can be discriminated by using multivariate statistical analysis methods. Conclusion: Hyperspectral imaging and vibrational spectroscopy techniques have good potential for determining rice quality properties in a non-invasive manner, i.e., not requiring the introduction of instruments into the rice grain.

Salt tolerance at vegetative stage is partially associated with changes in grain quality and starch physicochemical properties of rice exposed to salinity stress at reproductive stage

“…grain. 57,58 Grain starch comprises two main polymers, one of which is amylose. Amylose content plays an important role in the cooking time and texture of cooked milled rice, especially cooked rice hardness.…”

Yield, Grain Quality, and Starch Physicochemical Properties of 2 Elite Thai Rice Cultivars Grown under Varying Production Systems and Soil Characteristics

“…In addition to external appearance (i.e., grain size and grain shape), production system and soil physical and chemical characteristics also considerably affected the grain internal quality (i.e., reducing sugar and starch contents, crude protein content, and the amylose to amylopectin ratio), ultimately influencing eating and cooking quality of cooked rice grains [24,26,84,85]. Water-soluble carbohydrates (such as total reducing sugars) provide precursors (i.e., ADP glucose) for starch biosynthesis in the developing rice grain; therefore, changes in total reducing sugars leads to alteration of starch accumulation in the developing rice grain [86].…”

Effect of rice variety and milling fraction on the starch gelatinization and rheological properties of rice milk

“…According to Joshi et al (2015), rice exhibits a very wide range of rheological properties and cooking qualities depending on variety and type of rice, amylose content, and gelatinization temperature. Joshi et al (2015) also stated that amylose to amylopectin ratio varied among different rice varieties and greatly affected the functional properties of starch. Therefore, it is evident that varietal differences in raw rice can impact end product qualities of rice-based food products including rice milk.…”