Tony Blakeney 1, Laun'e Lewin 2 and Russell Reinke2 Quality rice for North Asia 1 Cereal Solutions, Sydney, form erly Despite the rele ase of new varieties in Japan, BRI Australia Ltd Koshihikari remains the most important variety 2 NSW Agn'culture, Yanco Agn'cultura/ Institute (Figure 1). Japan has an estimated 200 or mo re rice breeders, many of whom aim at producing rices equal in taste and quality to Ko shihikari. Varieties such as Hitomebore , which were considered potential replacements have increased in planting area very slowly and not challenged the dominance of Koshihikari. This is despite lodging susceptibility and lower yield potential of the older variety. Akitakomachi and Kirara 397 have significant planting areas because they are able to grow in areas that do not favour Rice sales to North Asia, particularly Koshihikari production. It is clear then, that any Korea and Japan have remained difficult variety for North Asia, and Japan in particular, in the past year. There are still long-term must have quality characteristics that closely possibilities for sales into this region but resemble those of Koshihikari . the consumers are particular about the type of rice they buy. 1. TESTING FOR JAPANESE QUALITY The project "Quality Rice for North Asia" Taste has traditionally been measured in concluded in 2000 and results from the final Japan by the use of expert tasters or expert year indicated that taste evaluation by NIR (near taste panels. Rice is often traded in small infrared spectroscopy) as carried out in Japan, quantities and is sold in the brown state by can indicate acceptability but some factors can grower cooperatives or storage companies, or influence the results from these machines. from Government stockpiles. Unlike any other Comparisons of Opus with Koshihikari for taste region of the world, the cold storage of brown value indicated that quality of Opus would be rice is common. Individual mills commonly acceptable in Japan. Continued testing of employed a taste expert who evaluated all Hitomebore however, indicated that this variety incoming rice and advised on its taste value. It would not be suitable for cultivation in NSW. is well known within Japan that the individual evaluation of lots by this subjective method Figure 1 gives quite variable results and that some tasters are much more discriminating than others. 600 .------~ In 1988, the Satake Corporation, Japan's biggest suppliers of rice milling equipment 60 0 ---.- Koshihikari patented an NIR apparatus for evaluating rice ..-. ··O • Nipponbare ~ Sasanishiki grain taste (US Patent 4 752 689). This ~ 40 0 ----<:J • Akitakomach1 technique has been refined since the first 0 ---- Kinuhikari 0 ---G , - Klrara 397 0 Hinohikari patent, when these formula based instruments ;_... 300 -+ - -o-- Hltomebore were replaced by scanning NIR instruments that ca +4, Haenuki <11 .. -1'::r- Mutsuhomare correlated average taste values determined by

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Figure 2 100 Influence of protein content • Opus (r2=0,98) 90 Two varieties (Koshihikari and Opus) were o Koshihikari (r2=0,99) Q) analysed for the relationship between protein ::::, 80 content and taste analysis result. Samples were ~ extracted from a variety x nitrogen rate trial to f;l 70 represent a range in protein content. These ~ samples were analysed for both protein (Leico 60 nitrogen) and taste analysis (NIRECO 50 Corporation) (Figure 2). All samples were under­ 5 6 7 8 9 10 milled with a yellowness index of 33-35. Protein content (%) Taste value is clearly related to protein content in Japanese style rices. Lower protein rice is more acceptable and has higher taste Figure 2. Taste value (TV) vs protein content in Koshihikari and Opus. (For Opus, taste value= 146.7 - 10.04 * protein; for value. This is very important in the marketing of Koshihikari, taste value= 150.89 - 10.35 * protein.) softer cooking rices to Japan. Should a market warrant it, Opus could be segregated into higher Figure 3 and lower protein grades at receival, using the 95 .------~ NIT instruments (Grainspecs) that are currently 90 used for moisture. eo-8~ o Opus •c;99 0• Koshihikari 85 0 Q) Influence of degree of milling ::, '4 cii > 80 ~ One method of determining degree of milling Q) .o U) .o 0 is by measuring the yellowness index of the 0 ~ 75 • milled sample. When samples of Opus and • 0 Koshihikari were milled to varying degrees, 70 samples with different degrees of milling were • 65 subjected to taste analysis. Clearly, degree of 28 30 32 34 36 38 40 milling was important in determining the Yellowness index acceptability of the milled rice. More highly milled rice had higher taste value and was therefore more acceptable. The relationship is Figure 3. Taste value vs yellowness index for Koshihikari and Opus. not linear but despite this, the linear regression for each variety explains 94% of the variation in varieties could clearly be influence'd by taste value (Figure 3). important factors such as protein content and Non-linearity is probably associated with the degree of milling. Understanding these factors change in milling degree. The NIR taste analyser could influence taste value and the acceptability is calibrated at Japanese levels of milling and as of rice from Australia in North Asian markets. milling level increases, the defined relationship between NIR and subjective taste assessment may vary. The increased decline of Opus at low milling levels (yellowness index greater than 34) probably indicates that Koshihikari has some taste advantages as brown rice and this aspect of taste analysis requires further investigation.

2. COMPARISON OF KOSHIHIKARI AND OPUS FOR TASTE VALUE There were differences between Koshihikari and Opus for taste value in both comparisons. In each case, the taste value of Koshihikari was greater and this indicates superior quality (to the Japanese). The differences were very small however, and Opus was consistently rated as very high quality on this basis. The quality of all

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3. PERFORMANCE OF HITOMEBORE Table 1: Grain yield (t/ha at 14% moisture) of four varieties in district trials in 1999-2000. Hitomebore had been considered a potentially important variety in NSW for North Asian rice Variety markets. It was compared with standard Australian cultivars (particularly Opus) in 1999-2000 in a Leeton Griffith Coleambally Deniliquin Barham Mean ------series of district trials. Grain yield of Hitomebore Namaga 12.6 10.9 ---9.1------10.9 9.6 12.6 was well below that of the Australian commercial Millin 9.0 9.3 9.8 11.7 11.9 10.4 cultivars (Table 1). Opus 9.6 12.7 12.7 10.5 8.4 10.5 These varieties were also compared for quality Hitomebore 5.8 7.2 5.2 9.1 9.1 7.3 attributes on serial harvests from one trial at the lsd (p<.05) 1.0** 1.3** 1.5** 0.8** 0.8** 0.5** Leeton Field Station. Hitomebore compared favourably for milling. quality and milled grain colour. Its grains were significantly longer than those of Koshihikari, which may be a small 2: Table Grain quality results from serial harvest of the Leeton Field disadvantage, but it had significantly more chalk Station site. (Each value is the mean of four harvests.) than either Koshihikari or Opus (Table 2} . Variety % Whole Yellowness % Chalkb Lengthc WidthC It is apparent that Hitomebore cannot compete grain indexa with Opus, either on the basis of productivity or Namaga 73 34.1 3.7 5.68 2.75 quality. It is recommended that it not be Millin___ 64 35 .8 6.4 5.55 2.83 considered further for commercial production in Opus 75 36.5 1.7 5.02 2.92 NSW. Hitomebore 73 36.8 3. 1 5.28 2.86 Koshi hikari-- 74 38.0 1.0 4.98 2.82 Acknowledgements lsd (p<.05) 3.0** 1. 0** 1.5** 0.11 * * 0.08* * We thank the R&D and marketing staff of a Yellowness index is a measure of milled grain colour where a lower value is whiter Ricegrowers' Co-operative Limited for their b % Chalk is the area of chalk in a milled sample as a percentage of milled grain area c Length and width (mm) are measured on brown rice perception of market requirements. Part of this st udy was completed while Tony Blakeney was located at BRI Australia and their contribution is acknowledged. Many growers have supported the field evaluations reported in this article. Their help and that of the Rice Improvement program staff is acknowledged. We particularly thank Anne Sheldrick for her contribution to this project.

RIRDC Project BRE-1A CONTACT: Tony Blakeney Cereal Solutions, Lane Cove, NSW Tel: 02 9427 1449 Laurie Lewin NSW Agriculture, Yanco Agricultural Institute Tel: 02 6951 2713 Email: [email protected] Russell Reinke NSW Agriculture, Yanco Agricultural Institute Tel: 02 6951 2516 Email: [email protected]

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