Rice is one of the most important crops for feeding mankind. In 2013, rice was the world’s second largest grain crop, (corn being first), and half of the world’s population consumed rice. With the growth of the world population and accelerating global economic development, the demand for rice will continue to increase. To more efficiently supply this surging demand, it is important to improve rice varieties, quality, processing efficiency, and crop yield.
Since the 1950s, scientists have been searching for parameters that can define the cooking quality and processing characteristics of rice, as well as its chemical and physical testing methods. For example, amylose content and alkali diffusion values are widely used worldwide in rice breeding. Amylose content is related to water absorption, swelling, viscosity, and glossiness of rice. The alkali diffusion value is related to the gelatinization temperature of milled rice starch granules. The viscosity of rice paste during heating and cooling is often measured as an indicator of the milling properties of rice flour. Although the content of protein is not often used in rice breeding, it is nevertheless an important factor because it directly affects cooking time, texture, and nutritional value. The fat content is also an important nutrient of rice; it has a significant influence on the flavor, appearance, and quality. Additionally, the fat content in rice decreases with the extent of processing.
The traditional testing procedures for rice processing are very time consuming and cannot be used as online monitoring methods. For example, the iodine blue method is used to test the amylose content; it uses chemical agents, takes a long time, and has very poor reproducibility. Another example is the alkaline diffusion test which requires soaking the milled rice overnight in 1.5 or 1.7% KOH liquid. The viscosity property test takes over 1.5 hours.
Traditional Methods vs FT-NIR
In the last 20 years, near infrared spectroscopy has been used to identify the variety of rice and for quality control. Compared to the traditional analysis methods, near infrared has many advantages, such as:
• fast and accurate
• highly reproducible results
• non-destructive sampling
• no sample preparation
• multiple components analysis with a single measurement
NIR is widely used in the measurement of agricultural products. Fourier transform near infrared (FT-NIR) instruments, like Galaxy Scientific’s QuasIR series, have the additional advantages of high resolution, better reproducibility, and lower instrument drift with time.
Portable high-performance FT-NIR systems manufactured by Galaxy Scientific Inc., are lightweight, compact, rugged, and insensitive to vibration. With a wide operating temperature range, the QuasIR™ Series FT-NIR instruments are especially suitable for integration into rice processing.