Food Sci. Technol. Res., 15 (3), 299–306, 2009

Textural Properties and Structures of Starches from Indica and Japonica with

Similar Amylose Content

1* 2 3 4 Sonoko Ayabe , Midori Kasai , Kyoko Ohishi and Keiko Hatae

1 Department of Health and Nutrition, Takasaki University of Health and Welfare, Takasaki, Gunma 370-0033, Japan 2 Department of Nutrition and Food Science, Ochanomizu University, Bunkyo-ku, Tokyo 112-8610, Japan 3 Department of Home Economics, Seitoku University, Matsudo, Chiba 102-8357, Japan 4 Department of Home Economics, Wayo Women’s University, Ichikawa, Chiba 272-8533, Japan

Received July 24, 2007; Accepted February 6, 2009

The difference in stickiness between cooked Nipponbare (Japonica rice) and Khao Dawk Mali (In- dica rice) that have similar apparent amylose content was investigated, and the fine structure of starch in both and extract from the surface of cooked rice was analyzed. Non-sticky high-amylose rice (Indica rice) was also studied for comparison. The solid content and amount of amylopectin in the ex- tract from the surface of cooked Nipponbare were the highest, followed by cooked Khao Dawk Mali, and cooked high-amylose rice. This difference in solid content and the amount of amylopectin contributed to the stickiness of cooked Nipponbare. This suggests that the stickiness of cooked rice is less when less amy- lopectin is dissolved into cooking water, even when the amylose content and fine structure of the starch in the rice grains is similar. Thus, cooked Khao Dawk Mali is less sticky than cooked Nipponbare, despite having similar amylose content.

Keywords: Indica rice, Japonica rice, texture, stickiness, amylose

Introduction ality, such as pasting behavior of three long-grain cultivars, There are two general categories of rice grain, Indica (long even though the apparent contents of amylose, crude protein grain) and Japonica rice (short grain), and cooked Japonica and crude fat of milled rice flours were comparable (Patindol rice is considered to be more sticky than cooked Indica rice. and Wang, 2002). It was also found that there are differences It is known that the higher the amylose content of raw rice, in the relative portion of starch components in these raw the harder and less sticky the cooked rice becomes. Apparent rice types. In the case of Japonica rice, Isono et al. (1994) amylose content of non- is classified into four reported that there were differences in hardness and sticki- groups: very low, 5-12%; low, 12-20%; intermediate, 20- ness between two short-grain cultivars, even though amylose 25%; and high, 25-33% (Kongseree and Juliano, 1972). Al- content was similar. However, there have been no reports most all Japonica rice falls under the low apparent amylose comparing Indica and Japonica rice strains that exhibit simi- content, while in the case of Indica rice, some cultivars have lar amylose content. To investigate the causes of stickiness in low apparent amylose content, but most cultivars fall under cooked rice, it is important to analyze starch structure in both high amylose content. Khao Dawk Mali 105 is an aromatic raw rice and cooked rice, as well as that in extracts from the Indica rice () having low apparent amylose con- surface of cooked rice (Ikeda, 2001). tent, 13.8-16.0% (Kongseree and Juliano, 1972). We focused In this study, we focused on the differences in textural on Khao Dawk Mali in order to investigate the differences in properties between Nipponbare (Japonica rice) and Khao texture between this Indica rice and Japonica rice. Dawk Mali (Indica rice) having similar amylose content, It has been reported that there are differences in function- and analyzed the fine structure of starch in both cooked rice and extracts from the surface of cooked rice. For a better un- *To whom correspondence should be addressed. derstanding of the causes of stickiness, we also used a high- E-mail: [email protected] amylose rice that is not sticky for comparison. 300 s. ayabe et al.

Materials and methods (Nelson, 1944; Somogyi, 1952). Glucose was used as a stan- Materials Two cultivars of Indica, L. var. dard for the measurement of total sugar and reducing sugar. Indica, cv. Khao Dawk Mali 105 and high-amylose milled Protein content was determined by Lowry’s method using rice, obtained from Thailand (2001) were used. These were bovine serum albumin as a standard. stored at 4℃ in plastic bags. Japonica rice, Oryza sativa L. Degree of gelatinization of cooked rice The degree Japonica cv. Nipponbare, grown in Shiga Prefecture, Japan of gelatinization of cooked rice was determined by the (2001) was used. Brown Nipponbare rice was stored at 4℃ β-amylase-pullulanase method (Kainuma, 1981). An aqueous in kraft paper bags and milled to 90% in a polishing machine solution containing β-amylase and pullulanase (Hayashibara (MC-90A, Toyoseiki Co., Tokyo, Japan) on the day of the Biochemical Laboratories, Japan) was added to 80 mg of de- experiment. hydrated powder of cooked rice and kept at 40℃ for 30 min. Preparation of starch Milled rice grains were ground The reducing sugar content of this mixture was measured by with an electric miller (DM-6, Yochi machine, Taiwan), Somogyi-Nelson’s method (Nelson, 1944; Somogyi, 1952). and the resulting flour was sifted through a 100-mesh sieve. The degree of gelatinization was calculated from the ratio of Starch was isolated from milled by using a cold reducing sugar content of the mixture to that of the fully ge- 0.2% sodium hydroxide (NaOH) solution according to the latinized by alkali treatment with 2 N NaOH solution. alkali method of Yamamoto et al. (1973), with some modifi- Textural properties of cooked rice Cooked rice was cation. Precipitates were washed with distilled water until the kept at 20℃ for 1 h after cooking in a rice cooker, and the pH decreased to 7.0. After rinsing with ethyl alcohol, starch textural properties of cooked rice grains were measured was dried in the air and passed through a 100-mesh sieve. with a texturometer (GTX-2, General Foods) using the three Cooked rice samples and extracts from surface of cooked grains method (Okabe, 1977). Measurement was carried out rice Milled rice grains were washed three times with dis- ten times and the average and standard deviation were calcu- tilled water, and were then soaked in distilled water at 20℃ lated. for 1 h. The weight ratios of rice grains to soaking water Iso-amylase treatment of starch and extracts from surface were 1:1.4 or 1:1.9, which are typically used for Japonica of cooked rice Debranching of starch in both rice flour and rice and Indica rice, respectively. After soaking, the rice extracts from the surface of cooked rice by iso-amylase was grains were cooked with an electric rice cooker (RC-74, performed according to Inouchi’s method (Inouchi et al., Toshiba Co., Tokyo, Japan). Ten grams of cooked rice was 1983). Briefly, 2 N NaOH solution (0.25 mL) and distilled removed from the middle part of the rice cooker and placed water (0.25 mL) were added to starch (15 mg) and stored in a beaker, to which 50 mL of cold distilled water (4℃) was overnight at 4℃. Distilled water (3.5 mL) was then added added, followed by stirring for 5 min, and the mixture was to the solution, and this was neutralized with 0.5 N acetic strained with a strainer. The liquid part of the mixture was re- acid. Next, 5 mL of 60 mM acetic acid buffer (pH 3.5) and garded as extract from the surface of cooked rice. The extract 25 μL of 1475 U Pseudomonas amyloderamosa iso-amylase was centrifuged at 12000 rpm at 4℃ for 10 min and the pre- (Hayashibara Biochemical Laboratories, Japan) were added cipitate of this extract was treated with ethyl alcohol and ac- to the solution, and this solution was reacted at 40℃ for 24 etone, and then dried in the air. The dry matter obtained was h. To stop the reaction, ethanol was added to a final concen- called solid content. Dehydrated powder samples of cooked tration of 80%, and was evaporated completely. The residue rice and extract from surface of cooked rice were prepared was then stored at 4℃. as follows: cooked rice was homogenized with ethyl alcohol Gel permeation chromatography (GPC) of starch hydro- three times. After rinsing with acetone, the sample was dried lysates after iso-amylase treatment GPC of starch hydro- in the air at room temperature and passed though a 100-mesh lysates after iso-amylase treatment was performed based on sieve. This extract was then freeze-dried. Ito’s method (Ito et al., 1994). 1 N NaOH (1 mL) was added Chemical composition of milled rice flour Moisture, to the debranched sample, and this was stored for 1 h to crude protein, crude fat and ash contents of milled rice flours gelatinize. Water (1 mL) was added, followed by centrifuga- were determined by the Approved Methods 44-15A, 46- tion at 3000 rpm for 10 min at room temperature. Next, 1.5 13, 30-25 and 08-01, respectively (AACC, 2000). Apparent mL of the hydrolysate was applied to a column (Toyopearl amylose content was determined by the method of Juliano et HW-50SF; 2.5 cm ID × 100 cm) (Tosoh Co., Ltd., Japan), al. (1981). Total sugar content of supernatant of extract from and was eluted with 0.05 N NaOH-0.2% NaCl-NaN3 solu- the surface of cooked rice was determined by phenol sulfuric tion using a peristaltic pump at a flow rate of 0.44 mL/min. acid method (Dubois, 1944), and reducing sugar content of Carbohydrates in each fraction (5 mL) were estimated by the supernatant was determined by Somogyi-Nelson’s method phenol-H2SO4 method, and the elution pattern was obtained. Textural Properties and Structures of Starches from Indica and Japonica Rice with Similar Amylose 5 Content 301

The reducing sugar content was measured using a modified Fr. Ⅲ, 525 nm > λmax. Park-Johnson method (Hizukuri et al., 1981). Moreover, the Statistical Analyses All measurements were performed polymerization level of each fraction was obtained by the in triplicate. Data were subjected to analysis of variance fol- following expression: lowed by the least significant difference test (LSD) in order Degree of polymerization = amount of total sugar/amount to compare means at p < 0.05 using SPSS v.10 software. of reducing sugar Measurement of maximum absorption spectrum A 50- Results and Discussion μL aliquot of aqueous 1% iodine - 10% potassium iodide so- Chemical composition of rice flour Table 1 summarizes lution was added to each fraction. The maximum absorption the chemical composition of flours prepared from three types spectrum was obtained with a spectrophotometer (UV-2200, of milled raw rice. The samples differed slightly in moisture Shimadzu, Japan). The eluted fractions were classified into and crude protein contents. The moisture content followed four types (Fr. Ⅰ, intermediate Fr., Fr. Ⅱ and Fr. Ⅲ) accord- the rank order of Nipponbare > Khao Dawk Mali > high- ing to the Iouchi et al. method: Fr. Ⅰ, λmax ≥ 620 nm; Int. amylose rice, and crude protein followed the reverse order.

Fr., 620 nm > λmax ≥ 600 nm; Fr. Ⅱ, 600 nm >λmax ≥ 525 nm; The differences in the content of crude protein may have an

Table 1. Physicochemical properties of rice flour1)

Nipponbare Khao Dawk Mali high amylose rice Moisture (%) 14.48a2) 14.19b 13.37c Crude protein (%) 5.34c 6.04b 7.62a Crude fat (%) 1.85a 1.83a 1.40a Ash (%) 0.27a 0.22a 0.26a Apparent amylose (%) 16.95b 16.77b 27.64a

1) Average of three measurements. 2) Mean values with different letters in each row are significantly different at P < 0.05.

Table 2. Quality parameters of cooked rice

Nipponbare Khao Dawk Mali high-amylose rice Textural properties (kgf) At water ratio of 1.4 Hardness 2.19b 2.45b 3.74a Stickiness 0.34a 0.10b 0.03c At water ratio of 1.9 Hardness 1.98b 2.18b 3.17a Stickiness 0.41a 0.14b 0.04c

Degree of gelatinization(%) At water ratio of 1.4 98.6a1) 96.7a 78.1b At water ratio of 1.9 99.8a 99.3a 86.4b

1) Values with different letters in each row are significantly different at P < 0.05. 302 s. ayabe et al. affect on the textural properties of cooked rice. It is gener- water was added. This suggests that the degree of gelatiniza- ally thought that the more protein content, the harder and tion does not fully account for the texture of cooked rice. less sticky the cooked rice is. There were no significant dif- Solid and saccharide contents in supernatants of extracts ferences in crude fat and ash among the samples. It was also from surface of cooked rice Solid and saccharide contents confirmed that the apparent amylose content of Khao Dawk in supernatants of extract from the surface of cooked rice are Mali was similar to that of Nipponbare, while the amylose summarized in Table 3. The solid content of extracts from content of high-amylose rice (Indica rice) was the highest of the surface of rice cooked at a water ratio of 1.4 differed the three samples. substantially in the three rice samples. It was largest for Nip- Textural properties and degree of gelatinization Textur- ponbare and smallest for high-amylose rice. These values did al properties and degree of gelatinization of the rice cooked not vary when more water was added to rice. The rank order at rice to water ratios of 1.4 and 1.9 are presented in Table 2. of solid content was the similar to that of the stickiness of For rice cooked at water ratios of 1.4 and 1.9, there were no cooked rice, as shown in Table 2; the higher the solid con- significant differences in hardness between cooked Nippon- tent, the more sticky the cooked rice. These results confirmed bare and Khao Dawk Mali. It was reported that Khao Dawk earlier findings that solid content of extract from the surface Mali showed a similar texture as Japonica rice (Kobayashi of cooked rice is correlated positively with the stickiness of et al., 1998). However, the stickiness of Nipponbare was cooked Japonica rice (Shibukawa, 1976; Ikeda, 2001). significantly higher than that of Khao Dawk Mali. This sug- The total sugar, reducing sugar and protein contents of gests that apparent amylose content of raw rice is not directly supernatant of the three cultivars followed a similar rank related to the stickiness of cooked rice. High-amylose rice order as the solid contents: Nipponbare > Khao Dawk Mali differed from these two samples, being the hardest and the > high-amylose rice. With regard to total sugar, these values least sticky. It was thus confirmed that high-amylose rice has corresponded with those of solid content. In contrast, the the typical textural properties of Indica rice. rank order of reducing sugar content in supernatant from The degree of gelatinization of both Nipponbare and Nipponbare and Khao Dawk Mali was the reverse as that of Khao Dawk Mali was near 100% when cooked at water ra- total sugar. The total amount of sugar may thus be directly tios of 1.4 and 1.9. This indicates that the degree of starch linked to the stickiness of cooked rice. On the other hand, the gelatinization in the cooked rice cannot completely account order of protein content in supernatant was similar to that of for the difference in stickiness between Nipponbare and solid content, although this order was the reverse as that of Khao Dawk Mali. On the other hand, in the case of high-am- raw rice. This means that the protein of Nipponbare was eas- ylose rice, the degree of gelatinization was the lowest (78.1%) ily eluted into the cooking water when compared with Khao at a water ratio of 1.4, but increased to 86.4% when more Dawk Mali. This suggests that both the lower protein content

Table 3. Solid and saccharide contents of extracts from the surface of cooked rice1)

Nipponbare Khao Dawk Mali high-amylose rice Precipitate Solid content (％ ) 1.0a 0.5b 0.1c

Supernatants solution Total sugar content (mg％ ) 597.5a2) 397.0a 40.7b Reducing sugar content (mg％ ) 91.7a 131.8a 26.8b Protein content(mg％ ) 6.4a 4.9b 2.8c

(At water ratio of 1.4) 1) Average of three measurements. 2) Mean values with different letters in each row are significantly different at P < 0.05. Textural Properties and Structures of Starches from Indica and Japonica Rice with Similar Amylose 5 Content 303 of raw rice and greater elution of protein into cooking water and Khao Dawk Mali rice are similar, but are slightly differ- is related to the stickiness of Nipponbare, due to its relation- ent in cooked rice, and are substantially different in extracts ship with the dissolution of starch in cooking water. This from the surface of cooked rice. The difference in the pat- interrelationship might come from the fact that the protein terns of gel permeation chromatography between cooked mostly exists in the form of protein bodies around the amylo- rice and extracts from the surface of cooked rice reflects plast and outer layers of rice grains. the distribution of starch in the rice grains. In the case of Gel permeation chromatography As mentioned above, extracts from the surface of cooked rice, as shown in Table the apparent amylose content of Nipponbare and Khao Dawk 4, the percentage of the amylose fraction (Fr. Ⅰ) of Khao Mali were similar, but the stickiness of cooked rice differed. Dawk Mali was significantly higher than that of Nipponbare. It was found that the amylose comprised very long chains Based on our findings, we assumed that the amylose in Khao in amylopectin (Takeda et al., 1987). Because the amount Dawk Mali is more abundant in the outer layer than in the of very long chains of amylopectin influences stickiness and inner layer. Therefore, the amylose of Khao Dawk Mali is hardness of the cooked rice (Mizukami and Takeda, 2000), it easily eluted into cooking water during cooking. As amylose is necessary to examine the structure of starch. is more abundant in the inner layer than in the outer layer of Figure 1 shows gel permeation chromatography pat- rice grains in the case of Japonica rice (Yamada et al., 1994, terns of starch, cooked rice, and extracts from the surface of Fukai et al., 1997), the small difference in the percentage of cooked rice, and Table 4 shows the calculated percentage of amylose (Fr. Ⅰ) between cooked rice and extracts for Nip- each fraction from Fig.1. As shown in Fig. 1, gel permeation ponbare might be ascribed to this amylose distribution in the chromatography patterns of the starch in raw Nipponbare rice grain. While the gel permeation chromatography pattern

Table 4. Chain length distributions of rice starch, cooked rice and extracts from the surface of cooked rice on Toyopeal HW-50Sa

Fr. Ⅰ Int. Fr. Fr. Ⅱ Fr. Ⅲ b Ratio of Chain length of peak (%) (%) (%) (%) Fr. Ⅱ /Fr. Ⅲ Fr. Ⅱ Fr. Ⅲ Starch Nipponbare 12.8b3) 3.8 25.0a 58.0a 2.3 28.2 13.3 Khao Dawk Mali 12.1b 3.2 24.7a 60.2a 2.4 26.5 14.1 High amylose rice 21.8a 4.9 21.2b 52.0b 2.5 37.9 11.3

Cooked rice Nipponbare 2.2b 1.8 24.8 71.0a 2.9 25.2 12.8 Khao Dawk Mali 3.2b 2.4 23.0 71.7a 3.1 23.0 13.1 High amylose rice 19.7a 3.2 23.1 51.5b 2.2 29.6 16.0

Extract from surface of cooked rice Nipponbare 5.7c 5.5 21.9 66.8a 3.1 28.6 16.6 Khao Dawk Mali 12.8b 5.2 19.5 62.5a 3.2 33.8 16.1 High amylose rice 25.8a 5.9 18.7 49.5b 2.6 37.5 14.7

1) Starch and Extracts were debranched by iso-amylase for 18 h at 40℃. 2) Each fraction (Fr.) was divided according to the λmax of iodine-starch complexes as follows.

Fr. I, λmax ≧ 620 nm, amylose; Intermediate Fr., 620 nm > λmax ≧ 600 nm ; Fr. Ⅱ 600 nm> λmax ≧ 525, nm long-chain amylopectin; Fr.

III, λmax < 525 nm, short-chain amylopectin. 3) Average values with different letters in columns for starch, cooked rice and extracts are significantly different at P < 0.05. 304 s. ayabe et al. of high-amylose rice starch was similar to those of the other short-chain amylopectin (Fr. Ⅲ) was lower than in the other two cultivars, except in the amylose fraction (Fr. Ⅰ), which two cultivars (Table 4). was significantly higher, those of cooked rice and extracts Extracts from the surface of cooked rice are thought to from the surface of cooked rice were significantly different, reflect the stickiness of cooked rice because they mainly as shown Fig. 1. The amylose percentage (Fr. Ⅰ) of high- contain starch eluted from rice grains (Shibukawa, 1976). amylose rice in the starch of raw rice, cooked rice, and ex- As shown in Table 3, the solid content of extracts from Nip- tracts from the surface of cooked rice was higher, and that of ponbare is much higher when compared with Khao Dawk

Fig. 1. GPC patterns (Toyopearl HW-50S) of starch, cooked rice and extracts from rice surface after iso-amylase treatment. Textural Properties and Structures of Starches from Indica and Japonica Rice with Similar Amylose 5 Content 305

Mali. As solid content is mostly composed of starch, the total 13. The Association: St. Paul, MN. amount of long- and short-chain amylopectin is higher in Dubois, M., Gilles, K. A., Hamilton, J. K., Rebers, P. A., Smith, F. Nipponbare than in Khao Dawk Mali, as seen in Table 5. We (1956). Colorimetic Method for Determination of sugar and re- found that Khao Dawk Mali is less sticky than Nipponbare lated substances. Anal. Chem., 28, 350-356 and confirmed that the high amount of amylopectin in extract Fukai, Y., Matsuzawa, T., and Ishitani, T. (1997). Physicochemi- from cooked rice is directly involved in the stickiness of cal properties and gelatinization characteristics of the starch of cooked rice. It was reported that stickiness of cooked Japoni- milled layer separated from rice grains. Nippon Shokuhin Kagaku ca rice can be attributed to the low amylose and high amylo- Kogaku Kaishi, 44, 102-111 (in Japanese) pectin contents in extracts from the cooked rice grains (Ikeda, Hizukuri, S., Takeda, Y., Yasuda, M., Suzuki, A. (1981). Multi 2001; Hanashiro, 2004). Our results were in agreement with Branched Nature of amylose and its action of debranching en- these reports. It was also suggested that short-chain amylo- zymes. Carbohydr. Res. 94, 205-213. pectin is related to the stickiness of Nipponbare. In the case Ikeda, H. (2001). Relationship between the saccharides extracted of high-amylose rice, the high percentage of amylose (Fr. Ⅰ) from rice grains during Cooking and the sensory taste of cooked and low amount of long- and short-chain amylopectin (Fr. Ⅱ rice. J. Home Eco. Jpn, 52, 401-409 (in Japanese) + Fr. Ⅲ) contributed to the non-stickiness. As the solid con- Inouchi, N., Glover, D.V., Takaya, T. and Fuwa, H. (1983). Devel- tent of extracts from the surface of cooked high-amylose rice opment changes in fine structure of starches of several endosperm is one tenth that of Nipponbare (Table 3), the total amount mutants of maize. Starch / Stärke, 35, 371-376 of long- and short-chain amylopectin is very low, as seen in Ito, T., Yoshio, N., Teranishi, K., Hisamatsu, M., Yamada, T. (1994). Table 5. Saccharides extracted from rice grain during cooking process and effect of monoglyceride on them. Nippon Shokuhin Kagaku Conclusion Kogaku Kaishi. 41, 871-877 (in Japanese) The higher the solid content and amount of amylopectin Juliano, B. O., Perez, C. M., Blakeney, A. B., Castillo, T., Kogseree, in the extracts from the surface of cooked rice, the more N., Laignelet, B., Lapis, E. T., Murty, V. V. S., Paule, C. M. and sticky the cooked rice is. In particular, the amount of short- Webb, B. D. (1981). International cooperative testing on the amy- chain amylopectin contributes to stickiness. The amylose of lose content of milled rice. Starch /_Stärke, 33, 157-162 Indica rice is easily eluted into cooking water when com- Kainuma, K., Mastunaga, A., Itagawa, M. and Kobayashi, S. (1981), pared with Japonica rice. It was concluded that the higher the New enzyme system-β-amylase-pullulanase to determine the total amount of long- and short-chain amylopectin, and the degree of gelatimization and retrogradation of starch or starch lower amylose in extracts from the surface of cooked rice, products. J. Jpn. Soc. Starch Sci., 28, 235-240 (in Japanese) the stickier the cooked rice is, even if the amylose content of Kobayashi, A., Suzuki, Y., Kobayashi, A., Miura, K., and Ohtsubo, two kinds of rice is similar. Especially, the amount of short- K., (1998), Grain Qualities of New-Characteristic- Devel- chain amylopectin in extracts from the surface of cooked rice oped in Hokuriku District, Nippon Shokuhin Kagaku Kogaku contribute to the stickiness of cooked rice. Kaishi. 45, 484-493 (in Japanese) Kongreseree, N. and Juliano, B. O., (1972). Physicochemical prop- References erties of rice grain and starch from lines differing in amylose con- American Association of Cereal Chemists. (2000). Approved Meth- tent and gelatinization temperature, J. Agr. Food Chem., 20, 714- ods of the AACC, 10th ed. Method 08-01, 30-25, 44-15A and 46- 718

Table 5. Amount of amylose and amylopectin in extracts from the surface of cooked rice*

Long chain Short chain Amylose (g) mylopectin (g) amylopectin (g) Nipponbare 0.057 0.219 0.688 Khao Dawk Mali 0.064 0.098 0.313 high amylose rice 0.026 0.019 0.050 * Each amount was calculated from the solid contents shown in Table 3, and percentage of each fraction shown in Table 4 306 s. ayabe et al.

Meizukami, H. and Takeda, Y., (2000). Chewing properties of Shibukawa, S. (1976). Quality of pressure cooked rice. J. Home cooked rice from new characteristic rice cultivars and their rela- Eco. Jpn 27, 92-99 (in Japanese) tion to starch molecular structures. J. Appl. Glycosci., 47. 61-65. Somogyi. (1952). Notes on sugar determination. J. Biol. Chem., (in Japanese) 195, 19-23 Nelson, N. J. (1944), A photometric adaptation of the Somogyi Takeda. Y., Hizukuri, S. and Juliano, B., O. (1987). Structures of method for the determination of glucose. J. Biol. Chem. 153, 375- rice amylopectins with low and high affinities for iodine, Carbo- 380 hydrate Res.,168, 79-88. Newell, G. J. and Mac Farlane, J. D. (1987). Expanded tables for multiple comparison procedures in the analysis of ranked data. J. Yamanda, T., Ito, T., Teranishi K. and Hisamatsu M. (1994), Char- Food Sci. 53, 1721-1725 acteristics of rice cooked with monoglyceride. Nippon Shokuhin Okabe, M. (1977), Beihan no syokumi ni kansuru kenkyu (sono1), Kagaku Kogaku Kaishi. 41, 251-258 (in Japanese) New Food Industry , 19, 66-71 (in Japanese) Yamamoto, K., Sawada, S., Onogaki, T. (1973). Properties of rice Patindol, J. and Wang, Y. (2002). Fine structures of starches from starch prepared by alkali method with various conditions. Den- long-grain rice cultivares with different functionality. Cereal pun Kagaku 20, 99-104 (in Japanese) Chem. 79, 465-469