Background Rice plays a significant role in providing basic energy and essential nutrients for humans. Its quality is of great concern to the agricultural industries and consumers. Due to the changes of external storage conditions and its own enzyme activity, rice undergoes the aging process, thus significantly decreasing its quality. Consequently, the development of a rapid, non-destructive, real-time detection method for rice quality inspection is urgently needed. Scope and approach In this article, the characteristics of volatile organic compounds (VOCs) that greatly contribute to aroma profiles of rice are introduced. Meanwhile, the working principles and applications of an electronic nose (E-nose) device as a reliable measurement in rice quality assessment based on the variation of aroma profiles are highlighted. Furthermore, comparisons between E-nose and traditional instrumental assessment methods, such as sensory evaluation, physical and chemical indicators, instrumental analysis, are made. In addition, this article also offers an insight into the challenges and future trends of the application of E-nose for rice quality inspection. Key findings and conclusion 2-acetyl-1-pyrroline (2-AP), aldehydes, heterocycles and alcohols have been identified as the major VOCs in rice aging. Through the comparison between E-nose and traditional instrumental measurements, E-nose has a huge potential for the rapid inspection of rice quality as it has numerous advantages in routine analysis. Furthermore, reducing the working temperature, utilizing appropriate pattern recognition methods and establishing new prediction models should be the future trends of E-nose employed as an effective detection method in rice quality inspection.

Electronic nose for volatile organic compounds analysis in rice aging

Background The global shift in food consumption patterns accompanied by a sedentary lifestyle has been driving the upsurge of non-communicable diseases, projected to remain as a global health challenge for the coming decades. Sustainable food-centric interventions should be developed and strengthened to mitigate the growing health concerns with huge socio-economic implications. Scope and approach Milled white rice is typically starch-rich, serves as the major daily caloric source for a majority of the world population especially in Asia. Most rice varieties are of high glycemic index (GI), a food quality inferenced to contribute to the health problems surrounding high-calorie intake and dysregulated glucose metabolism. Manipulation of GI through various approaches will significantly help in the fight against diabetes and related diseases. Key findings and conclusions A multidisciplinary approach of (a) introducing low to moderate GI property to modern varieties of rice through genetic manipulations, and (b) diet-based diversification solutions in a healthy plate of well-balanced portions of macronutrients with low GI food matrix together with elevated nutrient density and dietary fibre (DF) offers a sustainable solution to address the growing concern in meeting double burden nutritional challenges.

Low glycemic index rice—a desired trait in starchy staples

Metabolomic fingerprinting of volatile organic compounds for the geographical discrimination of rice samples from China, Vietnam and India.

Correlation of taste values with chemical compositions and Rapid Visco Analyser profiles of 36 indica rice (Oryza sativa L.) varieties

In rice (Oryza sativa), amylose content (AC) is the major factor that determines eating and cooking quality (ECQ). The diversity in AC is largely attributed to natural allelic variation at the Waxy (Wx) locus. Here we identified a rare Wx allele, Wxmw , which combines a favorable AC, improved ECQ and grain transparency. Based on a phylogenetic analysis of Wx genomic sequences from 370 rice accessions, we speculated that Wxmw may have derived from recombination between two important natural Wx alleles, Wxin and Wxb . We validated the effects of Wxmw on rice grain quality using both transgenic lines and near-isogenic lines (NILs). When introgressed into the japonica Nipponbare (NIP) background, Wxmw resulted in a moderate AC that was intermediate between that of NILs carrying the Wxb allele and NILs with the Wxmp allele. Notably, mature grains of NILs fixed for Wxmw had an improved transparent endosperm relative to soft rice. Further, we introduced Wxmw into a high-yielding japonica cultivar via molecular marker-assisted selection: the introgressed lines exhibited clear improvements in ECQ and endosperm transparency. Our results suggest that Wxmw is a promising allele to improve grain quality, especially ECQ and grain transparency of high-yielding japonica cultivars, in rice breeding programs.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/jipb.13010

A rare Waxy allele coordinately improves rice eating and cooking quality and grain transparency

Background Quality is a powerful engine in rice value chain upgrading. However, there is no consensus on how “rice quality” should be defined and measured in the rice sector. Scope and approach We adopt a Lancasterian definition of rice quality as a bundle of intrinsic and extrinsic attributes. We then review how rice quality is (i) perceived and defined by consumers and industry stakeholders in rice value chains in Southeast and South Asia; (ii) measured and defined by food technologists; and (iii) predicted through genetics. Key findings and conclusions Consumers are heterogeneous with respect to their perceived differentiation of rice quality among regions, countries, cities, and urbanization levels. Premium quality is defined by nutritional benefits, softness and aroma in Southeast Asia, and by the physical appearance of the grains (uniformity, whiteness, slenderness), satiety, and aroma in South Asia. These trends are found to be consistent with industry perceptions and have important implications for regional and national breeding programs in terms of tailoring germplasm to regions and rice varieties to specific local market segments. Because rice is traded internationally, there is a need to standardize definitions of rice quality. However, food technologists have not reached unanimity on quality classes and measurement; routine indicators need to be complemented by descriptive profiles elicited through sensory evaluation panels. Finally, because rice quality is controlled by multiple interacting genes expressed through environmental conditions, predicting grain quality requires associating genetic information with grain quality phenotypes in different environments.

Maria Lourdes Velasco

Papers

Rice quality: How is it defined by consumers, industry, food scientists, and geneticists?

Impact of access to capital and abiotic stress on production efficiency: Evidence from rice farming in Cambodia