Kazuhiro Takekura

Development of an automatic rice-quality inspection system

The need has arisen in rice-drying facilities in Japan for an automatic method to measure quality aspects of rice when it arrives at the drying facility. A near-infrared (NIR) transmission instrument was used to obtain NIR spectra of damp rough rice and damp brown rice. Calibration models were developed from the original spectra and reference analysis data to determine moisture and protein content of the samples. A visible light (VIS) segregator was used to determine sound whole kernel of brown rice. The precision and accuracy of the NIR instrument and the VIS segregator were found to be sufficiently high to determine moisture and protein content, and sound whole kernel ratio. An automatic rice-quality inspection system was consequently developed. The system consisted of a rice huller, a rice cleaner, an NIR instrument and a VIS segregator, and it was controlled by a computer. Based on the rice-quality information, this system enabled rough rice transported to a rice-drying facility to be classified into six qualitative grades.

Accuracy of Near-infrared Transmission Spectroscopy for Determining Rice Constituent Contents and Improvement in the Accuracy

The accuracy in determination of rice constituent contents using a commercial nearinfrared transmission (NIRT) instrument was validated. And the accuracy of measurements using this instrument was improved by modifying light filters and calibration equations used in the instrument. In the determination of moisture content, the coefficient of determination (r2) was 0.98, standard error of prediction (SEP) was 0.13%, and bias was -0.02%. In the determination of protein content, r2 was 0.90, SEP was 0.17%, and bias was 0.01%. These results show that the newly developed instrument is sufficiently accurate to be used instead of reference analysis for measuring moisture content and protein content of brown rice. An automatic rice-quality inspection system was designed. The system consisted of a rice huller, a rice cleaner, an NIRT instrument and a visible light (VIS) segregator. Based on rice-quality information, this system enables rough rice transported to a rice grain elevator to be classified into six qualitative grades.

Development of a System for Fine Cleaning of Rough Rice for High-Quality Storage

Bulk rough rice after drying consists of sound whole kernels, immature kernels, empty kernels, damaged kernels, hulled kernels and foreign materials such as straw, weed seed and dust. Fine cleaning of rough rice is an important step after drying to improve rough rice quality and to minimize quality deterioration of rough rice during storage. We developed a system for fine cleaning of rough rice. The system consists of a wind separator, gravity separator and indented cylinder separator. The wind separator removes straw, weed seed, dust and empty kernels by means of an air stream. The gravity separator discharges four streams of material: a mixture of sound whole kernels and hulled kernels; good rough rice product (mostly sound whole kernels); a mixture of sound whole kernels, damaged kernels and immature kernels, which is returned through the wind separator and gravity separator to achieve a complete separation; and a mixture of damaged kernels, immature kernels and empty kernels that is removed from the line. The indented cylinder separator removes hulled kernels from the mixture of sound wholekernels and hulled kernels discharged from the gravity separator. The sound whole kernels separated by the indented cylinder separator are mixed with the good rough rice product from the gravity separator. The fine cleaning system developed in this study enables separation and removal of immature kernels, empty kernels, damaged kernels and hulled kernels and therefore improvement in rough rice quality. The fine cleaning system has been in practical use in Japan.

Freezing Temperature and Freezing Injury of Rough Rice, and Quality of Rough Rice Stored at Temperatures between –50°C and 25°C for Four Years

A differential scanning calorimeter was used to determine freezing temperature of rough rice. Rice grains with a moisture content of 22.1% froze at about –35°C. Rice grains with a moisture content of less than 20.8% did not freeze at a temperature of –55°C. Incidence of freezing injury of rice grains was determined by germination rate because grains that suffered from freezing injury did not germinate. Rice grains with a moisture content of less than 17.8% germinated after being stored at –80°C for 11 days. Thus, no grain with a moisture content of less than 17.8% froze at a temperature of –80°C. Effects of temperatures between –50°C and 25°C on physiological properties and quality characteristics of rough rice during four-year storage were investigated. Low temperature maintained vitality of rice, minimized physiological activities, starch deterioration and rancidity in rice, and consequently preserved rice quality. Eating quality of rice stored at temperatures less than 5°C for four years was the same as that of newly harvested rice. These results indicate that preservation of rough rice quality for several years is possible by storing rice at an average temperature below 5°C during storage. A new on-farm rice storage technique at temperatures below ice point by using natural fresh chilly air in winter has been in practical use in Hokkaido, the northernmost island of Japan, in recent years. Twenty-six grain elevators have been constructed in Hokkaido since 1996. The storage capacity of rough rice in 2004 was 115,000 t.

Rice Storage Controlled at Temperature below ICE Point for Preserving High Quality

Abstract Rice with a moisture content of less than 17.8% did not freeze even at minus 80°C. In an on-farm storage experiment, 994 tons of rough rice was stored in two silos, and the rough rice was aerated for 91 hours in January 2000. The rough rice temperature fell down below ice point. At the end of storage, July 2000, the temperatures of rice grains in the center of the silos were kept still below ice point. A combination of rice storage at a temperature below ice point and utilization of ambient cold fresh air in winter therefore enables the quality of rice to be preserved at a high level without the requirement of a cooling unit or electricity.

Development of On-farm Storage Technique for Rice at Temperature below Ice Point Using Ambient Naturally Cold Air in Winter

The objective of this project was to develop a new on-farm storage technique for rice at a temperature below ice point using ambient naturally cold air in winter. In an on-farm storage experiment, 994 tons of rough rice was stored in two silos from the end of November 1999, and the rough rice was aerated from the bottom to the top of each silo for 91 hours in January 2000. The rough rice temperature in each silo fell down below ice point (minus 1.5 degrees Celsius on average). At the end of storage (end of July 2000), the temperature of rice grains in the center of each silo was kept still below ice point (minus 0.5 degrees Celsius). The quality of the rice stored in the silos was thereby preserved at a level similar to that of freshly harvested rice. A combination of rice storage at a temperature below ice point and utilization of ambient cold air in winter enables the quality of rice to be preserved at a high level without the requirement of a cooling unit or electricity.