Rice grain quality: a comparison of local varieties with new varieties under study in Ghana

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1 Food Control 14 (2003) Rice grain quality: a comparison of local varieties with new varieties under study in Ghana E. Adu-Kwarteng a, W.O. Ellis b, *, I. Oduro b, J.T. Manful c a Crops Research Institute (CSIR), Fumesua, Kumasi, Ghana b Department of Biochemistry, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana c Food Research Institute (CSIR), P.O. Box M20, Accra, Ghana Received 18 October 2001; received in revised form 20 April 2002; accepted 22 April 2002 Abstract Studies were carried out to assess the grain quality of 10 new rice varieties (breeding lines) being evaluated by breeders compared to 10 local varieties grown by farmers. Physical parameters measured were grain size and shape, thousand grain weight, chalkiness, grain colour, total milling recovery (TMR) and broken fraction. The chemical parameters measured were total protein, watersoluble proteins (WSP), amylose, ash and minerals contents. The results of the study showed significant differences (p < 0:05) in all parameters monitored between the breeding lines and the local varieties. The breeding lines had good grain size and shape (L=W 3.12), good endosperm appearance, milling quality (TMR 67.2%) and higher amylose content ( %). The local varieties however, had lower levels of brokens (22.50%), higher protein ( %), WSP ( %), ash ( %) and minerals (K and Ca) contents. The local varieties had higher nutrient levels than the breeding lines and this needs requisite attention in future breeding programmes. Ó 2003 Published by Elsevier Ltd. Keywords: New varieties; Local varieties; Water-soluble proteins; Milling quality 1. Introduction Rice has become an important staple diet in Ghana. It accounts for 15% of the countryõs gross domestic product (GDP). Local production of rice in Ghana has been rising steadily in the last few years. Between 1990 and 1996 production levels have increased from 80,000 to 201,000 tonnes (GLG-SOFRENCO, 1997). In spite of this increase, large quantities are still imported into the country in order to meet consumer demand (MOFA, 1990). The increasing dependence of many families and communities on rice is reflected by a steady rise in per capita consumption levels. In 1972, it was estimated at 7.5 kg/year/person, in 1994, 13.3 kg/year/person and 1996, 20 kg/year/person (GLG-SOFRENCO, 1997). This increase has been attributed to the changes in our social structure as a result of increase in the number of working mothers. For most Ghanaians, preference is for imported rice over locally produced rice. This has been attributed to * Corresponding author. Tel.: ; fax: address: elliswo@yahoo.com (W.O. Ellis). several factors including variations in physical characteristics, nutritional quality and pasting and cooking behaviours. Studies have shown a higher demand for long-grain rice than for short, round grain types (GLG-SOFRENCO, 1997). Thus, rice research in the country has focused on the production of improved varieties with better production yields, and stress resistance. However, there is a paucity of data on physical properties, nutrient composition, sensory attributes and processing characteristics of the different rice varieties being cultivated by farmers in the country. The objective of this study was to assess the physical and nutrient variations between the new (improved) and the indigenous (local) varieties. 2. Materials and methods 2.1. Material source Twenty rice varieties were evaluated, ten (10) local collections and ten (10) from the breeding lines (Table 1). The new varieties (breeding lines) were obtained from /03/$ - see front matter Ó 2003 Published by Elsevier Ltd. doi: /s (03)00063-x

2 508 E. Adu-Kwarteng et al. / Food Control 14 (2003) Table 1 Lists of rice varieties Grouping Name Source Breeding lines ITA 318 a GRUG 7 ITA 92 TOX El TOX ITA 312 TOX E TOX TOX E4-2-2 WAR 100 Local varieties Emo Kokoo Abodom (Eastern region) Abibifoo Mo Kwaobaah (Eastern region) Emo Fitaa Oda Nkwanta (Eastern region) Mr. More Aframso (Ashanti region) Abodwese Senchi (Ashanti region) Mui Ixirie (Upperwest region) Long grain Akpafu Xeviwope (Volta region) Beta Jasikan (Volta region) Tema Jasikan (Volta region) Amavi Jasikan (Volta region) a VBRDP Valley Bottom Rice Development Project Crops Research Institute (CRI). the Valley Bottom Rice Development project at Ejisu- Besease in the Ashanti region of Ghana (Crops Research Institute (CSIR), Kumasi). These varieties (Crop year: 1996) were grown under identical agronomic conditions with fertilizer rates of kg/ha N P K. The local collections were obtained randomly from selected parts of the country where rice cultivation occurs Sample preparation Sufficient quantities of paddy of each variety, moisture content 14%, were dehusked in a Satake Testing Rice Husker (THU-34A, Satake Co. Ltd. Tokyo, Japan). The brown rice obtained was polished in a single pass rice pearler (BS08A Satake Co. Ltd. Tokyo, Japan). Degree of whiteness was set between low and medium. Samples were stored in plastic containers prior to analysis Physical measurements Grain size and shape The length and width of 10 whole polished grains were measured using a micrometer screw gauge with accuracy of 0.01 mm. Data obtained were interpreted based on the scale described by WARDA (1995) Thousand grain weight This was based on the method of Dorsey-Redding, Hurburgh, Johnson, and Fox (1991). It involved the counting and weighing of 100 randomly selected unmilled kernels. The weight obtained was multiplied by 10 to determine the thousand grain weight Total milling recovery (TMR) This is the weight of total milled rice obtained from a known weight of paddy expressed as a percentage after dehulling and polishing (WARDA, 1995) Broken fraction This was determined by weighing 100 g of polished rice and separating into broken and unbroken fractions. This was done manually using a perforated metal sheet combined with meticulous hand picking and re-picking. Each fraction was weighed and expressed as a percentage of initial weight of rice Endosperm appearance (chalkiness) Twenty gram samples were weighed into small flat trays mixed thoroughly and divided into four portions by means of a quartering device. Rice grains in each quarter were examined for presence of opaque or chalky portions. These were separated manually and weighed. The weight obtained was expressed as a percentage of the total weight within the quarter. The values obtained for each quarter were averaged and used to score for appearance description based on the IRTP system (1988) Grain colour The colour of bulked grains for each sample of polished rice was measured using the Chromameter (CR- 200, Minolta Co. Ltd. Japan). Measurement was based

3 E. Adu-Kwarteng et al. / Food Control 14 (2003) on the L a b colour system. The chromameter was calibrated with a standard white tile (L ¼ 100:01; a ¼ 0:01; b ¼ 0:02) Nutritional measurements Samples were ground into fine flour prior to analyses. Total protein and ash were measured based on the Official Methods of Analysis (AOAC, 1990) Water-soluble proteins Two grams of flour sample was dispersed in 80 ml distilled water for 2 h at room temperature by continuous stirring. The suspension was filtered using WhatmanÕs No. 42 filter paper after making volume to 100 ml. Twenty milliliters of filtrate was taken for protein determination by the Micro-Kjeldahl method (AACC, 1976) Amylose To 100 mg of flour sample was added 1 ml ethanol (95%) and 9 ml 1N NaOH. The sample was heated for 10 min in boiling water bath to gelatinize starch. Sample was cooled and transferred to 100 ml volumetric flask. 5 ml of starch solution and 1 ml 1 N acetic acid added. Two milliliters of iodine solution (0.2% of re-sublimed iodine in 2% potassium iodide) was added and volume made up to 100 ml. Flask was shaken and allowed to stand for 20 min. Percent transmittance was measured at 620 nm using an Ultraspec spectrophotometer (Ultraspec Plus, model 4054, Pharmacia LICB Biochrom Ltd., England). Total amylose content of sample was determine from a previously calibrated standard amylose (Potato, Sigma) curve (Juliano, 1971) Minerals Samples were ashed and the ash wetted with 1 2 drops of distilled water and dissolved in 20 ml 1 M HCl. They were then heated, cooled and transferred into 100 ml volumetric flask by filtering using Whatman No. 2 filter paper. Crucibles were washed twice with 5 ml distilled water and contents made to the 100 ml mark. Sodium, potassium and calcium contents in samples were determined using a flame photometer (model ANA-10 Kl, Ogawa Seiki Company Ltd., Tokyo, Japan). Concentrations for each element were determined from previously calibrated standard curves Statistical analysis Data obtained was analysed statistically (ANOVA, Regression analysis) using the Microsoft Excel program. All analyses were done in triplicates. 3. Results and discussion Length to width (L=W ) ratios are used in the classification of grain shape, a higher value indicating slender shapes and a lower value indicating medium, intermediate, bold or round shapes. The mean L=W was higher (3.12) for breeding lines and lower (2.51) for the local varieties. Based on the WARDA classification (1995) all the breeding lines had slender shapes except TOX 3108, which was medium. With the exception of Mui and Mr. More which were slender, the local varieties were medium shaped (Table 2). Total milling recovery (TMR) is a measure of milling quality and hence economic value. A 50% or less is undesirable since it means 50% of the rice is discarded as husk and bran after milling. The breeding lines had a mean TMR of 67.2% while the local varieties a mean of 63.5% (Table 3). All varieties gave appreciably higher milling recoveries (above 60%) except Abibifoo mo (TMR of 50%). It is interesting to note that among the breeding lines, there was a low and negative but significant correlation (r ¼ 0:40; p < 0:05) between grain length and TMR, indicating better milling quality with decreasing grain length. It also implies that other factors apart from grain length such as harvest timing determine TMR (IRTP, 1988). The breeding lines had higher levels of brokens than the local varieties (Table 3). However, the minimum level of brokens (22.50%) was observed in both TOX 3118 and Emo fitaa. The highest was observed in ITA 318. There was a significant correlation (r ¼ 0:52; p < 0:05) between grain size and shape and the level of brokens for the breeding lines, however, the low correlation coefficient implies other factors contribute to the effect. Inherent varietal differences, presence and extent of chalkiness, aging of the grain by storage, harvest timing and moisture content at harvest have been reported to affect the extent of breakage during milling (WARDA, 1995). The presence of chalkiness in rice grain has been described as a defect that affects milling, marketing and storage properties (Indudhara Swamy & Bhattacharya, 1982; Khush, Paule, & De la Cruz, 1979; Webb, Bollich, Johnston, & Mcllrath, 1979). Five varieties had no chalkiness (score: 0), three had moderately widespread chalky portions (score: 5; 10 20%) and the rest minimal incidence (score: 1; <10%). The extent of chalkiness was found to have a link with grain width. Varieties with no chalkiness had grain width below 2.3 mm. Similar observations have been reported by Bhashyam (1983) and Somrith (1974). Emo kokoo however had widespread chalky portions (score: 9; >20%) (Table 3). The thousand grain weights (TGW) of all the varieties was good. The local varieties had appreciably higher TGW. TGW is a measure of seed size and a range of g is acceptable. Below 20 g indicates the

4 510 E. Adu-Kwarteng et al. / Food Control 14 (2003) Table 2 Size and shape of rice varieties Grouping Variety Length (mm) Width (mm) L=W Size description Shape description Breeding lines ITA (0.35) 2.26 (0.12) 3.24 Long Slender GRUG (0.29) 2.28 (0.12) 3.17 Long Slender ITA (0.22) 2.14 (0.10) 3.16 Long Slender TOX (0.44) 2.21 (0.08) 3.37 Long Slender TOX (0.27) 2.29 (0.07) 2.90 Long Medium ITA (0.27) 2.17 (0.12) 3.31 Long Slender TOX (0.19) 2.29 (0.04) 3.13 Long Slender TOX (0.22) 2.23 (0.07) 3.17 Long Slender TOX (0.28) 2.18 (0.66) 3.44 Extra long Slender WAR (0.30) 2.59 (0.09) 2.34 Medium Medium Mean S.E. a Local varieties Emo kokoo 6.23 (0.40) 2.82 (0.27) 2.21 Medium Medium Mr. More 6.90 (0.30) 2.26 (0.08) 3.05 Long Slender Mui 7.28 (0.39) 2.41 (0.11) 3.02 Long Slender Abodwese 6.37 (0.40) 2.38 (0.11) 2.67 Medium Medium Long grain 6.76 (0.17) 2.26 (0.08) 2.99 Long Medium Beta 6.55 (0.39) 2.22 (0.09) 2.95 Medium Medium Tema 6.65 (0.29) 2.74 (0.18) 2.43 Long Medium Amavi 6.29 (0.32) 2.81 (0.13) 2.24 Medium Medium Emo fitaa 6.40 (0.26) 2.82 (0.10) 2.27 Medium Medium Abibifoo mo 6.65 (0.43) 2.35 (0.17) 2.82 Long Medium Mean S.E. a a (Standard error) within columns, differences between two means exceeding twice this value are significantly different at p < 0:05. Table 3 Milling and chalkiness qualities of rice varieties Grouping Variety TMR (%) a Broken fraction (%) Thousand grain Chalkiness score weight (g) Breeding lines ITA (0.90) 57.3 (0.68) 28.3 (0.52) 1 GRUG (1.03) 36.0 (0.92) 28.2 (0.66) 1 ITA (0.88) 42.7 (1.00) 22.2 (0.41) 1 TOX (1.12) 56.3 (0.96) 28.8 (0.34) 0 TOX (1.70) 25.4 (0.45) 25.3 (0.50) 0 ITA (1.10) 35.0 (0.82) 23.4 (0.72) 1 TOX (0.46) 22.5 (0.50) 26.1 (0.25) 1 TOX (0.95) 32.0 (0.75) 25.8 (0.61) 1 TOX (1.25) 44.0 (0.76) 28.7 (0.43) 0 WAR (0.54) 29.6 (0.53) 28.7 (0.43) 5 Mean S.E. b Local varieties Emo kokoo 63.2 (0.44) 29.0 (0.21) 30.0 (0.15) 9 Mr. More 65.4 (0.60) 25.2 (0.54) 27.0 (0.28) 0 Mui 63.7 (0.82) 34.7 (0.98) 29.2 (0.33) 1 Abodwese 66.5 (0.51) 46.2 (0.73) 27.3 (0.17) 1 Long grain 69.2 (0.40) 28.0 (0.60) 27.2 (0.47) 1 Beta 61.2 (0.35) 32.4 (0.42) 23.2 (0.22) 0 Tema 66.1 (0.28) 30.2 (0.40) 33.4 (0.15) 5 Amavi 64.1 (0.48) 25.5 (0.78) 30.0 (0.30) 5 Emo fitaa 65.6 (0.21) 22.5 (0.59) 30.2 (0.26) 1 Abibifoo mo 50.0 (0.50) 28.7 (0.62) 29.5 (0.29) 1 Mean S.E. b a TMR total milling recovery. b (Standard error) within columns, differences between two means exceeding twice this value are significantly different at p < 0:05.

5 E. Adu-Kwarteng et al. / Food Control 14 (2003) presence of immature, damaged or unfilled grains. The breeding lines were creamy-white while the local varieties ranged between creamy-white to reddish-brown. Degree of whiteness (L) was for the breeding lines and for the local varieties (Table 4). Varieties with higher red pigmentation also had higher yellow pigmentation with a corresponding decrease in the degree of whiteness. Grain colour is important as far as visual appeal is concerned and most consumers are of the perception that white rice is superior. Protein, a key factor influencing the eating quality of rice (Horino, Harakari, & Ae, 1983; Inatsu, 1988) was appreciably high (>7%) for all the varieties with the exception of GRUG 7, TOX 3142, WAR 100 and Emo kokoo (Table 5). Significant differences (p < 0:05) existed in the protein contents with the local varieties having higher levels ( %) relative to the breeding lines ( %). The ranges obtained for the varieties fall within that for polished rice (5 14%) (Damardjati, Soekarto, Nur, & Siwi, 1985). The variations observed may be due to varietal and environmental influences. Eggum and Juliano (1975) and Juliano (1985) reported of high levels of fertilizer increasing total protein content. Other factors such as short growth periods, soil salinity or alkalinity may also increase protein content of grain. Water-soluble proteins for varieties ranged between 0.16% and 0.49% with the local varieties having a higher mean value (0.33%) compared to the breeding lines (0.28%) (Table 5). There was a significant correlation between the extracted water-soluble proteins and total protein content for both the breeding lines (r ¼ 0:81) and the local varieties (r ¼ 0:90). This implies that water-soluble protein level varies correspondingly with protein content and agrees with the findings of Damardjati et al. (1985). Amylose levels were higher in the breeding lines ( %) compared to the local varieties ( %). TOX 3052 had the highest value and Tema the lowest (Table 5). About 70% of the local varieties were of the intermediate amylose classification (21 25%) while the same percentage of the breeding lines were of the high amylose classification (>25%). The intermediate amylose varieties are generally most preferred because they cook dry and fluffy retaining their soft texture even after cooling. The high amylose type cook dry and fluffy but become hard on cooling. This is due to retrogradation of the amylose molecules which tend to associate or bind strongly together with decreasing temperature. Amylose content is an important factor in determining the cooking and pasting behaviour of rice and its end use. Various workers have reported on the reliability of amylose content as a predictor of cooked rice stickiness (Juliano, Onate, & DelMundo, 1965; Hamaker & Griffin, 1993; Hamaker, Griffin, & Moldenhauer, 1991). Table 4 Chromameter indices for colour of rice varieties Grouping Variety L a b Breeding lines ITA (1.22) 0.07 (0.01) 9.95 (0.76) GRUG (2.01) 0.24 (0.04) 8.79 (0.51) ITA (1.50) 0.32 (0.02) 9.53 (0.40) TOX (1.85) 0.34 (0.04) 9.68 (0.85) TOX (2.39) 0.60 (0.05) (0.66) ITA (0.95) 0.23 (0.02) (0.82) TOX (1.03) 0.22 (0.01) 9.20 (0.74) TOX (0.76) 0.10 (0.02) 8.86 (0.50) TOX (2.00) )0.09 (0.03) 9.82 (0.71) WAR (1.55) 0.25 (0.06) (0.64) Mean S.E. a Local varieties Emo kokoo (1.13) (0.02) (0.46) Mr. More (2.40) )0.06 (0.01) 8.12 (0.51) Mui (1.20) (0.04) 9.42 (0.62) Abodwese (0.94) (0.01) (0.35) Long grain (0.86) (0.03) 8.40 (0.55) Beta (1.00) )0.09 (0.02) 7.75 (0.85) Tema (1.30) (0.06) 9.80 (0.83) Amavi (1.45) (0.05) (0.50) Emo fitaa (1.57) (0.08) 9.41 (0.77) Abibifoo mo (1.08) (0.07) (0.58) Mean S.E. a a (Standard error) within columns, differences between two means exceeding twice this value are significantly different at p < 0:05.

6 512 E. Adu-Kwarteng et al. / Food Control 14 (2003) Table 5 Some nutrient contents of rice varieties Grouping Variety Total protein (%) WSP a (%) Amylose (%) Ash (%) Breeding lines ITA (0.02) 0.32 (0.03) (0.31) 0.56 (0.06) GRUG (0.12) 0.25 (0.02) (0.04) 0.55 (0.04) ITA (0.02) 0.35 (0.08) (0.83) 0.45 (0.05) TOX (0.13) 0.21 (0.05) (0.03) 0.55 (0.02) TOX (0.85) 0.29 (0.01) (0.31) 0.59 (0.09) ITA (0.34) 0.48 (0.08) (0.95) 0.55 (0.05) TOX (0.13) 0.22 (0.04) (0.15) 0.46 (0.04) TOX (0.30) 0.16 (0.02) (0.41) 0.46 (0.03) TOX (0.12) 0.32 (0.05) (0.42) 0.55 (0.02) WAR (0.21) 0.19 (0.03) (0.63) 0.57 (0.05) Mean S.E. b Local varieties Emo kokoo 6.78 (0.83) 0.21 (0.08) (0.38) 0.53 (0.01) Mr. More 7.19 (0.23) 0.34 (0.02) (0.52) 0.48 (0.07) Mui 8.12 (0.27) 0.39 (0.05) (0.24) 0.54 (0.6) Abodwese 8.27 (0.45) 0.34 (0.04) (0.84) 0.58 (0.1) Long grain 7.26 (0.18) 0.23 (0.06) (0.21) 0.54 (0.05) Beta 7.91 (0.41) 0.25 (0.08) (0.03) 0.57 (0.04) Tema 8.12 (0.12) 0.33 (0.03) (0.60) 0.67 (0.01) Amavi (0.02) 0.48 (0.10) (0.50) 0.58 (0.02) Emo fitaa (0.90) 0.49 (0.07) (0.55) 0.56 (0.02) Abibifoo mo 7.32 (0.24) 0.24 (0.09) (0.07) 0.56 (0.03) Mean S.E. b a WSP water-soluble proteins. b (Standard error) within columns, differences between two means exceeding twice this value are significantly different at p < 0:05. Table 6 Potassium, calcium and phosphorus contents (mg/100 g) of rice varieties Grouping Variety Potassium Calcium Phosphorus Breeding lines ITA (0.99) (0.40) (1.25) GRUG (1.01) (0.32) (1.80) ITA (1.30) (0.66) (1.41) TOX (1.60) (0.72) (0.97) TOX (1.85) (0.45) (1.05) ITA (1.44) (0.90) (1.32) TOX (1.46) (0.50) (1.11) TOX (1.03) (0.88) (1.50) TOX (1.50) (0.54) (1.26) WAR (1.72) (0.41) (1.55) Mean (3.52) (0.41) (9.50) Local varieties Emo kokoo (0.82) (0.79) (1.50) Mr. More (1.00) (0.88) (2.00) Mui (1.50) (0.95) (1.20) Abodwese (1.20) (0.62) (1.45) Long grain (1.65) (0.73) (1.03) Beta (1.42) (0.49) (1.90) Tema (1.50) (0.90) (0.88) Amavi (1.72) (0.66) (0.98) Emo fitaa (1.20) (0.54) (1.60) Abibifoo mo (1.35) (0.90) (1.40) Mean (7.86) (0.46) (5.50)

7 E. Adu-Kwarteng et al. / Food Control 14 (2003) Significant differences (p < 0:05) existed in the total ash levels averaging 0.56% for the local varieties and 0.52% for the breeding lines (Table 5). The values obtained fall within the range reported by Juliano (1985) in milled rice grain ( %). The variations in ash content may be due to the degree of milling/polishing which is influenced by varietal effect. Rice bran contains much more minerals than the actual endosperm and the tendency of rice bran to stick to the grains during milling/ polishing (which is a varietal trait) influences ash content. Significant variations (p < 0:05) were observed in the mineral content of the varieties. Potassium content in the breeding lines was in the range mg/ 100 g and the local varieties, with the exception of Emo kokoo in the range mg/100 g (Table 6). Emo Kooko had very low potassium content of mg/100 g. These values were within the range reported by Matsuzaki, Takano, and Takeda (1991) in their work on 66 varieties of rice. The observed variations in potassium levels were more pronounced among the breeding lines than the local varieties. This may be due to varietal effect. Potassium plays an important role in human body metabolism thus foods with appreciable amounts are beneficial to health. The results of this study shows that TOX 3108, long grain, Tema and Abibifoo mo would be good contributors of potassium to the diet. For calcium levels which ranged between and mg/100 g for the 20 varieties (Table 6), the local varieties had appreciably higher levels relative to the breeding lines. Juliano (1985) and Pederson and Eggum (1983) reported ranges of mg/100 g for polished rice. Phosphorus content for samples was in the range mg/100 g (Table 6). Significant variations (p < 0:05) were more pronounced in the local varieties. These variations may be due to varietal effects, diverse soil fertility and growth conditions in the various localities. 4. Conclusion There were significant differences among both the breeding lines and local varieties for all the parameters studied. Grain size and shape, endosperm appearance and milling quality were better among the breeding lines than the local varieties. This is not surprising since breeding efforts are geared towards attaining grain physical characteristics that appeal to both consumers and commercial rice millers. However, the local varieties studied exhibited nutritional superiority especially potassium, calcium and protein contents. Many of them also had fairly acceptable milling qualities. Their amylose contents also fell within the preferred range (20 25%) with the exception of Tema. It is thus important that while breeding lines are screened for grain quality factors for effective selection and further cross-breeding, the local varieties must not be left out but given the requisite attention since they form a rich resource for incorporation into breeding programmes. References AACC (1976). American Association of Cereal Chemists. Cereal Laboratory Methods, St. Paul, MN, USA. AOAC (1990). Official methods of analysis. Association of Official Analytical Chemist, Washington, DC. Bhashyam, M. K. (1983). Structure of rice grain in relation to technological properties (193 pp). Ph.D. thesis. Mysore, India, University of Mysore. Damardjati, D. S., Soekarto, S. T., Nur, A., & Siwi, B. H. (1985). Evaluation of protein quality and properties in six varieties of Indonesian rice. Indonesian Journal of Crop Science, Dorsey-Redding, C., Hurburgh, C. R., Johnson, L. A., & Fox, S. R. (1991). Relationships among maize quality factors. Cereal Chemistry, 68, 6. Eggum, B. 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8 514 E. Adu-Kwarteng et al. / Food Control 14 (2003) Somrith, B. (1974). Genetic analysis of traits related to grain yield and quality in two crosses of rice (Oryza sativa L.) (p. 138). Ph.D. thesis, New Delhi, India. Indian Agricultural Research Institute. WARDA (1995). West Africa Rice Development Association. Grain quality laboratory database. WARDA, Bouake, Mali. Webb, B. D., Bollich, S. M., Johnston, T. H., & Mcllrath, W. O. (1979). Components of rice quality: Methodology of their identification and stage of application in United States breeding programmes. In Proceedings on the workshop on chemical aspects of rice grain quality (pp ). Manila, Philippines: IRRI.