Defining Rice Quality - What’s Important and Why

Introduction

Rice is one of the world's most important food crops. Current research suggests that half of the world's population consider rice to be a staple in their diets. As the global population continues to grow, it is vital to ensure continued cultivation of high-quality rice and the production of new and exciting rice-based products.

Rice is one of the world’s most important food crops. Current research suggest that half of the world's population consider rice to be a staple in their diets. As the global population continues to grow, it is vital to ensure continued cultivation of high-quality rice and the production of new and exciting rice-based products.

Globally, there are many different factors that define rice quality. For example, in Southeast Asia rice is defined by its nutritional benefits, softness and aroma, whereas other regions seek uniformity, slenderness and whiteness. With the globalization of the food industry, rice can now be rapidly transported and consumed all around the world.

However, a lack of international standards for rice quality can make it difficult for rice growers and processors to navigate the varying regulations. Furthermore, as rice is grown and traded globally, there is currently a huge need for reliable tools to predict the head rice yield and the quality of rice from the paddy husk.

Sticking Points

Rice crop undergoes a series of storage and processing steps to convert paddy rice into the supermarket product with which we are familiar. Each stage, from inside the paddy husk through to the final packaged product, has the potential to affect the quality of the rice. As such, it is vital that robust quality control procedures are put in place to ensure high-quality and safe rice reaches the consumer.

The quality of rice is dependent on a multitude of factors such as the variety, the methods of cultivation and the processing system. One of the key factors that can impact head rice yield, which is the weight of complete milled rice kernels compared to the weight of the total rough rice crop, is kernel cracks and breakage. Moisture content has a major impact on rice breakage and remains an important method of quality determination.

Ensuring the optimal moisture level can often be a challenging balancing act for producers. High levels of moisture typically result in a softer rice crop, which may not withstand the pressure caused by hulling. This can then result in the grains cracking and breaking, and the possible pulverization of the grain. Moisture can promote the growth of mold and increase the risk of self-heating, whereas rice crop that is overly dry runs the risk of cracking and creating dust, which could potentially result in in silo fires and great damage to expensive processing equipment.

These factors can greatly affect not only the cost of producing high-quality rice, but also the sale price of the rice crop. To keep profits high, sensitive and robust methods for moisture monitoring are vital throughout the entire production process.

Jagged Japonica

There are several other criteria that can also impact the final price of the harvest and regulate rice quality including texture, shape and, in some regions, head rice yield. In this instance, broken grains can have a large impact on the total value of rice, and with regulations evolving rapidly, there is a vital need for tools to ensure accurate approximations of head rice yield.

If part of the milled rice kernel is opaque rather than translucent, it is often characterized as "chalky". Although the color disappears upon cooking, it can affect the adhesive texture of the cooked rice and lead to a chewier product. This negatively impacts consumers’ perception of rice quality and confidence in a brand. Such chalkiness is most commonly caused by either high night temperatures throughout growing, rice maturity, or heat interruption during the final stages of grain filling. Detection of chalky rice is therefore a quality parameter of significance.

Rapid detection and categorization processes for chalky or abnormal-shaped rice crops are imperative, as is the need to identify rice that is considered immature. Immature grains can have a major impact on head rice yield and the overall quality. Immature kernels are very slender and chalky, which results in excessive production of bran, broken grains and "brewer’s rice". Although brewer’s rice (slightly broken grains) can be used in beer brewing and rice products such as flour and noodles, it is sold at a discounted rate.

The optimal moisture stage to harvest grain in many countries is about 30 days after flowering. If the harvest is too late, many grains are lost through shattering or drying out and are cracked during threshing, which again causes grain breakage during milling.

In order to produce premium rice and achieve maximum profits, there is a demand for sensitive methods for vigorous quality parameters throughout the entire measuring and production processes.

Pests in your Pilaf

Pesticides and other agrochemicals are widely applied to protect crops and maximize crop yields. As seen in current research, 30% of current global crop yields are due to the application of pesticides. Good soil nutrition also leads to a healthier crop. With the increased use of nitrogen fertilizers, which allow a higher assimilation of nitrogen into the grain, yields are improving and protein content is increasing.

Looking to the future, we can presume pesticides will continue to evolve and be relied upon to provide high quality grains to the growing global population. However, as consumers become growingly aware of the potential harm that chemical residues can cause, accurate technologies that can deduce the levels of different pesticides in rice are important to ensure consumer safety and confidence.

Heavy metal presence is also a key concern of consumers. Due to an increasing industrial development process, paddy rice harvests have been demonstrated to be contaminated by potentially carcinogenic and toxic heavy metals such as cadmium, arsenic and lead. These trace metals are believed to have adverse effects on the nervous, cardiovascular and respiratory systems.

As consumer concerns about environmental and chemical contaminants increase, so does the growing need for sensitive and robust tools to measure contaminant concentration in rice.

Going with the Grain

In a highly competitive industry, supplying premium produce can boost a brand’s reputation and help it to stand out amongst the competition.

Additionally, as the demand for rice-based foods continues to grow, it is vital that inventive solutions for improved analysis are developed, with advanced control to assist processors. This will aid the continuous cultivation of premium crops and the production of innovative rice-based products, safeguarding the high-quality produce for every plate.

REFERENCES

Gross, B. L. & Zhao, Z. Archaeological and genetic insights into the origins of domesticated rice. Proc. Natl. Acad. Sci. U. S. A. 111, 6190–6197 (2014).

Custodio, M. C. et al. Rice quality: How is it defined by consumers, industry, food scientists, and geneticists? Trends Food Sci. Technol. 92, 122–137 (2019).

Gaunt, N., Thomson, N., Padia, F., Seymour, M. & Moger, J. Advances in Analytical Capability to Power Agrochemical Product Design. Outlooks Pest Manag. 29, 104–110 (2018).

Khalifa, A. A. B. A. Evaluation of some rice varieties under different nitrogen levels. Adv. Appl. Sci. Res. 3, 1144–1149 (2012).

Fu, J. et al. High levels of heavy metals in rice (Oryza sativa L.) from a typical E-waste recycling area in southeast China and its potential risk to human health. Chemosphere 71, 1269–1275 (2008).