Measuring Head Rice Recovery in Rice.

Head rice recovery (HRR) is a milling quality attribute that is highly influential toward the market price of rice. It is defined as the proportion of paddy rice that retains 75% of its length after milling. For a new rice variety to be accepted and adopted by farmers, the new variety's HRR should satisfy consumer requirements of at least 55% or above. Hence, HRR is a crucial attribute by which new varieties are selected for release. Although the amount of head rice recovered depends on the genetic background of a rice variety, HRR is also highly affected by postharvest processing conditions that the variety goes through. To determine the maximum HRR, therefore, one must ensure that the processing conditions are as optimal as possible. This book chapter outlines how paddy rice is processed into head rice and how HRR is measured. It also proposes an improved laboratory-scale means for postharvest drying to minimize head rice losses.

Method Development of Near-Infrared Spectroscopy Approaches for Nondestructive and Rapid Estimation of Total Protein in Brown Rice Flour.

Rice varietal development and improvement programs are constantly seeking means to shorten the breeding cycle in order to deliver new, consumer-acceptable rice varieties to farmers and to consumers. Advances in molecular biology technologies have enabled breeders to use high-throughput genotyping to screen breeding lines. However, current phenotyping technologies, particularly for rice cooking and eating properties, have yet to match the efficiency of genotyping methodologies. A high-throughput and cost-effective phenotyping suite is essential because without phenotype, the value of genotypic information cannot be maximized. In this book chapter, we explore the application of near-infrared spectroscopy (NIRS), a high-throughput and nondestructive approach in characterizing rice grains, primarily describing method development and validation, instrument calibration, upgrading, and maintenance. We then focus on estimating protein content (PC) in brown rice as a case study because (1) PC is an attribute that contributes to the cooking behavior and the eating properties of cooked rice; and (2) proteins contain chemical bonds that can easily be detected by NIRS.

Determination of Macronutrient and Micronutrient Content in Rice Grains Using Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES).

The rice grain endosperm is mostly composed of starch , which serves as the major source of calories for more than half of the world's population. Macro and micronutrients make a minor proportion of the rice grain, which particularly gets accumulated in outer aleurone layer, which are in general eliminated upon milling. Because rice is the major staple, it is seen as an efficient mechanism for delivering both macro- and micronutrients, particularly for the poor who do not have ample access to diversified diets. Enriching micronutrient and macronutrient concentrations in milled rice of endosperm and/or in brown rice, is an important dietary intervention to create health benefits of rice consumers. Efforts are underway to increase the nutritional content of rice through bio/fortification approaches. The plant takes up these same elements from the soil, redirect the transport of these elements into the grain. Thus besides biofortification strategies, scientists can also use the knowledge to design proper soil nutrient management to enrich micronutrients in the grains. Therefore, it is important to be able to determine the macro- and the micronutrient composition of the vegetative parts of the rice plant and of the rice grain. In this chapter, nitric-perchloric acid digestion and inductively coupled plasma-optical emission spectrometry (ICP-OES) methods routinely used in IRRI's Grain Quality and Nutrition Services Laboratory (GQNSL) to determine the concentrations of various macro- and micronutrients found in the rice grain and the rice plant, are described.

Determination of Cadmium Concentration in Milled and Brown Rice Grains Using Graphite Furnace Atomic Absorption Spectrometry.

Heavy metal pollution is a growing public health concern since it poses a food risk to public health via metal transfer. Cadmium is of particular concern because it is a potential carcinogen if exceed tolerable limits in the grain. Hence, it is important to monitor the cadmium content of rice before it reaches the market to ensure public healthy safety, especially in areas known to have high cadmium levels in soil. In this chapter, the method used to determine the concentration of cadmium in milled and brown rice grain samples is described. This method involves sample digestion with concentrated nitric acid and hydrogen peroxide and analysis of cadmium by Graphite Furnace Atomic Absorption Spectrometry (GF-AAS). Because cadmium concentrations are low in rice grains, quantification of cadmium content requires the use of a more sensitive instrument, such as GF-AAS.