PREFACE

Rice, a food staple in Japan, has gone through countless improvements in cultivation technology and growth environment in order to improve its yield. Today's improved rice hybred can be said to have reached the goal of higher yields per hectacre. Also, because of the Uruguay Round decisions that have liberalized parts of the rice trade, Japan no longer has to be concerned about securing necessary quantities of rice. The new food laws that recently passed have reduced many of the marketing restrictions and have brought the rice trade one step closer to a free market.

Under these new conditions, consumers are beginning to find higher quality and better tasting rice at lower cost. Kett Electric Laboratories, Inc. (Kett), responding to the demand for better quality, developed the "Rice Grain Identification Instrument, RN-500" that enables an objective measurement of external quality of rice (comparison of rice grain composition).

In addition, KETT recently introduced an analyzer that will measure the internal quality of rice to determine its palatability by analyzing the organic components that determine the taste of rice.

Recently, in the rice trade there has been many quasi-infrared devices introduced to analyze the ingredients and the taste of rice. But these instruments were barely an extension of a laboratory experimentation at best in terms of ease-of-operation, capability and price. They were grossly inadequate to be used at production, wholesale and retail sites for rice analysis.

When developing the "Rice and Wheat Composition Analyzer, ZX-800, the design concept was to come up with an inexpensive analyzer keeping the actual working site in mind. Something that would enable anyone to analyze the rice easily, quickly and accurately without crushing the sample. An analyzer that anyone could use with ease at any location, from research laboratory to production floor to elevator.

You will find the ZX-800 very useful in all aspects of agricultural operations: as soil to management indicator and as a taste and quality indicator for consumers and the processing industry.

1. INGREDIENTS AND TASTE OF RICE

As shown in Chart 1, rice consists of water, protein, carbohydrates (starch), fat, ash, etc. Of these, the main ingredients are protein, starch and water. These are all parts of rice that determine the taste, and it is said that the higher the protein content, the lower the taste quality index.

In terms of nutrition, it is generally thought that the higher the protein content, the more the nutrition, but in terms of taste, the lower protein appears to be desirable.

Next comes the amylose content in the starch which is also said to affect the taste of rice, and which determines its viscosity when cooked.

Then there is the water. It is said that when the moisture content of rice drops to below 14%, the taste drops as well.

In addition to these three main ingredients, there is the fat content that affects the taste of rice. When rice gets old, the fat turns to fat-acid and releases a peculiar odor which becomes an undesirable part to the taste.

Therefore, the taste of rice can be predicted by measuring its protein, starch, water and fatty-acid contents. However, in addition to the above, the taste itself involves physiological elements such as "touch and feel in the mouth," and perceptive elements such as "color and luster." Since all these elements are interacting in a complicated way, it becomes very difficult to reach a simple solution.

2. PRINCIPLES OF NEAR-INFRARED MEASUREMENT

Generally speaking, the near-infrared refers to spectrums from 800nm to 3,000nm. As shown in Chart 2, the near-infrared spectrum has wavelengths that absorb various organic elements compounds, most with several absorption wavelengths in this zone.

The most powerful absorption is for the combined 0-H molecule activities. For instance, there is a variance between water absorption degree of 1935nm and the non-absorption at l680nm. Thus we are able to express the water content by simply taking the results between 1935nm-1680nm.

The water content can be expressed by a simple projection of a curve: Water Content % = K0 + K1 x (OD1935 / OD1680). Thus the water contents can be determined by finding the coefficient of K0 and K1, then measuring the absorption at OD1935 and OD1680.

The same method could be applied to other ingredients. But in terms of grain, water content, protein, carbohydrates and fat, etc., they are mutually affecting each other and it becomes necessary to remove those influences. A typical method used is multiple linear regression (MLR),

3. PRINCIPLES AND FIXTURES USED IN NFAR-INFRARED ANALYSIS

Generally speaking, the absorption that takes place in the Near-infrared is very small. Therefore, in order to measure the absorption accurately, a highly sensitive spectrometer becomes necessary.

In the past, the wavelength range of 1000nm to 2500nm was used and the analyzer used PbS (lead Sulfide) detectors. PbS detectors have a wide detection capability, but limited sensitivity.

On the other hand, as shown in Chart #3, the absorption such as water exists between wavelength zones of 900nm to 1050nm. So, referring to the filtering formula as shown in Chart #4, the Ingredient Analyzer, ZX-800: uses a silicone detector in the spectrometer which has a much higher sensitivity in this range.

3-1: "GRAIN ANALYZER, ZX-800" USING THE NEAR-INFRARED ANALYSIS SYSTEM

When light is emitted from a Near-infrared diode and passes through the narrowband filter, it becomes a Near-infrared light at a specific wavelength.

The near-infrared light then passes through a scattering media that turns it into an evenly balanced light source. The energy then passes through and bounces around the grain with energy being absorbed and transmitted as it goes through the samples.

When the specific wavelength (the amount of light) and the filtering distance are determined, the amount of transmitted energy and absorbed energy reflect the ratio of density in the articles indexed. Thus, the ZX 8OO is able to do quantitative analysis to determine the ingredients in the samples.

In the real world where this instrument is used, properties other than known constituents (outer condition and color, etc.) need to be taken into consideration. Therefore, through repetitive testing and evaluation, we have adopted twelve wavelengths and the equation that best predicts the constituent values.

Chart #5 illustrates a more practical approach when an IRED is used. This is an instrument that measures when light is emitted from DARK to IRED12.

As shown above, IRED/Filter Matrix, which is the heart of this instrument, is a combination of multiple IREDs and narrow-band pass filters. This simple configuration generates the spectrum needed without resorting to the complicated moving parts that were required in the past; an enormous cost reduction and downsizing was possible.

3-2: METHODS OF DETERMINING THE "QUALITY EVALUATION DATA" FROM THE ZX-800

The "Quality Evaluation Data" is the relative ratio of various chemical components responsible for the taste of rice; component,% such as protein, water, and amylose, by indexing an average brand of Japanese rice such as "NihonBare" as 65. The relative ratio of other analyzed rice is then computed.

As a result, the "Quality Evaluation Data" does not necessarily coincide with the results of quality evaluation and sensual evaluation conducted in the past. The past tests included subjective values such as geographical regions and brand names. According to tests conducted, the "Quality Evaluation Data" indexed rice currently traded on the open market at somewhere between 60 to 75.

The "Quality Evaluation Data" is a KETT value established from analytic data and therefore, when compared to other food taste measurement techniques, may not necessarily be the same.

(1) PROTEIN % ... MEASUREMENT RANGE: 4 TO 10%

It is said that the lower this figure, the better is the taste. Depending on the breed of rice, you can have some with a higher protein content while others have less. The protein content is controllable by adjusting the amount of nitrogen fertilizers to obtain the right amount of protein content

There are two ways of displaying protein contents. One is to find the ratio of protein content against the overall weight when water content of the sample is stable (Constant Moisture basis). Rice protein CM is generally given on a dry basis (moisture content at 0%). The other way is to display the protein content (ASIS) in response to the water content at the time of evaluation. For purposes of the test, a dry basis is used.

(2) WATER CONTENT %.. MEASUREMENT RANGE: 10 TO 20%

(3) AMYLOSE % ... MEASUREMENT RANGE: 16 TO 25%

Amylose is related to the viscosity when cooked. Low figure means more viscosity, and higher figure means less viscosity.

(4) FATTY ACID ... MEASUREMENT SCOPE: 0 TO 100mgKOH/lOOg

When rice gets old, the fat disintegrates and turns into fatty acid which releases a peculiar odor. This odor has an adverse effect when rice is being cooked. Although our "Quality Evaluating Data" does not reflect the fatty-acid value, the newness and oldness as well as storage condition should be taken into consideration in the management index. It shows that the higher the figure, the older the rice is.

3-3: STRONG POINTS OF ZX-800

• The grain can be measured without grinding the grain.
• Simple operation and speedy measurement. (Analysis takes less than 40 seconds).
• All calibration data is self-contained in the instrument, thus no auxiliary computer is required, except for calibration.
• The light source is IRED which lasts almost forever.
• Small and light-weight.
• Low price.

The ZX-800 can be combined with the "Single Grain Rice Inspector, RN-500," to provide an internal quality control (ZX-800) and external quality control (RN- 500) to provide a comprehensive rice evaluation system.

3-4 RESULTS OF EVALUATION TESTS CONDUCTED ON THE ZX-800

In actual testing of 97 samples of unpolished rice and 99 samples of polished rice, the following results are obtained:

NOTE: Forced air oven at 105 degrees C was used for the moisture lab results. Kjeldahl method of nitrogen determination was used for the protein lab results.

CONCLUSION:

Using the above data, we can now select the best quality or rice, not only for color and external qualifications, but also for taste, nutrition and storage quickly, easily and accurately.

The ZX800 can provide quick and accurate analysis of polished and unpolished rice in less time than ever before possible and improve the taste and nutrition of rice for Japan.

3-5: SPECIFICATIONS OF ZX-800

TYPE: ZX-800

MEASURING METHODS: Near-infrared fixed filter 893-1045nm

OBJECT OF MEASUREMENT: Unpolished and polished rice, etc. Other whole grains and food products also may be analyzed.

INGREDIENT MEASURED: Moisture, protein, amylose, fatty-acid (except polished rice), etc. Other organic constituents can be analyzed.

SCOPE OF MEASUREMENT: In this paper:, our own test data curve: Water: 10 to 20% Protein: 4 to 10% Amylose: 16 to 25% (in starch) Fat-acid: 0-100mg (except polished rice) (mgKOfVlOOg)

MEASURING TIME: About 40 seconds

TEST ADJUSTMENT: None

AMOUNT OF TEST MATERIAL: About 80 grams

INTERNAL CALIBRATION Maximum 20 products, 4 constituents MEMORY: each. Max 4 ingredient x 20 varieties.

DISPLAY OF PRESENTATION: Large LCD display, optional printer

POWER SOURCE: 100-240 volts 50/60 Hz

VOLTAGE VARIATION LIMITS: tlO%

POWER CONSUMPTION: 60w

ENVIRONMENT TEMP.: 15 to 450C

WEIGHT: 15.Okg

CONTRIBUTION:

Near-infrared water measurement "Sensor Technology" by F. KUTSUKAKE, May 1986, Special issue (Vol. 6., No. 6)