- Milled rice varieties from traditional and improved varieties were used:

・ Irrigated varieties: MR10734.7.2, MR10734 (Madera), MR10214, MR10253 (Marisika), MR10244 1.2.3, 1.1.1 MR10218, Mahasarika, X265 (Mailaka), 2067, X398 (Tsiresindrano), X372 (Kelimirefaka), X360 (Mahadigny), ON333 (Soafitsanga), Tox V5 (Vesainky), X1816 (FRX 92F3B-14F4BF6), X1818 (FRX 92F3B-6F4BF6), X1832 (IR 70422-99-1-5), X1833 (IR 70423-170-2-3), X1834 (IR 70444-87-2-1), X1842 (RPSC148), Basmati 370, Soameva, hybrid 914, 879 hybrid, hybrid 885, 27GM, 28GM, 18Br,Rojofotsy, Manjamena.

・ Rainfed varieties: FOFIFA63, FOFIFA133 (Kanto), FOFIFA152 (Meva), FOFIFA153, FOFIFA157 (Malaky), FOFIFA159 (Mahasoa).

- Rrigated varieties: Soameva, ON333 (Soafitsanga), X265 (Mailaka), X372 (Kelimirefaka), X360 (Mahadigny), ToxV5 (Vesainky), 27 GM, 28 GM, 18 BR, Rojofotsy, short and sticky rice Tsipala, plain Rojomena, parboiled Rojomena, plain Manjamena.

- Rainfed varieties: Varieties: plain FOFIFA159 (Mahasoa), parboiled FOFIFA 159 (Mahasoa), 4129 (Meva), FOFIFA157 (Malaky), plain FOFIFA172, parboiled FOFIFA172.

The test (Table 1) gives rice caryopsis hardness and its gelatinization temperature. The value was obtained from rice grains (N = 6) soaked in 10 ml of potassium hydroxide 1.7 (w/v) during 23 h at 30˚C in triplicates. Variation was observed with the naked eye according to the following scores [1] : 1 = unaffected grain, low alkali value; 2 = swollen grain, low alkali value; 3 = swollen grain, with narrow incomplete collar, intermediate alkali value; 4 = swollen grain with wide complete collar, intermediate alkali value; 5 = split grain with complete collar, intermediate to high alkali value; 6 = dispersed grain merging with collar, high alkali value; 7= completely dispersed and intermingled grain, high alkali value. Lower scores correspond to harder grains. When gelatinization temperature is low [55˚C - 69.50˚C], this agrees with high alkali value (score 6 or 7), the grains are soft. The next scale is [70˚C, 74˚C] for intermediate and [74.5˚C, 80˚C] for high gelatinization temperature which corresponds to hard grains.

The gel consistency was defined by the length of cold gel in a horizontally held test tube for one hour. This was obtained from 100 mg of thin 60 mesh flour put in a test tube 13 × 100 mm, added with 2 ml of 0.2N aqueous potassium and some drops of thymol blue. A glass marble with the test tube width was used to

cover the solution. The whole was boiled during 8 minutes, and then cooled in an ice bath during 10 minutes before laying the test tubes on millimeter paper.

The values were classified as follow [2] [3] : L > 61 mm, soft consistency; 60 > L > 41 mm: medium consistency; L < 40 mm: hard consistency.

Alkali digestibility reflects the tenderness of the caryopsis and its easiness to cook. The grains may be speedy or long to cook according to the strength of alkali digestibility. Our test showed a strong alkali digestibility with Marisika, Vesainky, 2067, hybrid 885, Mahasoa (greater than 5): grains were split with a comprehensive and broad collar; their gelatinization temperature is therefore low. These varieties were easy to cook.

Alkali Digestibility was found average with MR10244 1.2.3, MR10218 1.1.1, Mahasarika, hybrid 879, hybrid 914, Malaky, Kelimirefaka, FOFIFA153, Meva, FOFIFA63, Rojofotsy, (observed values between 4.70 and 3.70): grains swollen with wide complete collar. Most of rainfed analyzed varieties (Table 2) were noticed in this average digestibility (average values = 4.03), except the variety Mahasoa (score 5.87). Their pasting temperature was in the intermediate value.

Regarding to irrigated varieties, we remarked that the caryopsis were homogeneous translucent. Their milled rice benefited to sustainable conservation according to our experiment (more than 2 years). These were: Mahadigny, Tsiresindrano, X1816 (FRX 92F3B-14F4BF6), X1818 (FRX 92F3B-6F4BF6), X1832 (IR 70422-99-1-5), X1834 (IR 70444-87-2-1), X1842 (RPSC148), Soafitsanga, Madera, MR10214, Mailaka; their alkali digestibility was low (2 to 3.17): (Table 3),

therefore, they were with a high gelatinization temperature. These varieties were longer to cook too.

Interpretation

The general tendency of the digestibility values (Table 2 and Table 3) on the analyzed whitened rice was the intermediate digestibility (score 3 to 5). Few varieties were of high digestibility (score 5.83). The noted results confirmed the proportionality between the digestibility and the homogeneity of the caryopsis: when the rice caryopsis was homogenous, the digestibility with the potassium hydroxide solution 1.7% was weak (score 2 to 3); this fact made the rice sample in good state for much time storage. In the opposite, the heterogeneity gave high digestibility of the rice caryopsis (5 to 7). That referred to varieties difficult to preserve (weevil attack, broken rice, wet rice…). The digestibility was an indicator of the quality to storage of the whitened rice, and of the full rice grain also.

On the culinary option, the high digestibility of the rice caryopsis however meant that it was interesting in being quickly cooked. On the other side the homogeneous rice caryopsis was proved to give firm and elongated caryopsis on cooking [3] . So the alkali digestibility also provided an indirect index on the cooking and eating quality, similarly to the results obtained by Chemutai et al. [4] .

The advantage of the gel consistency is to get information about the quality of the cooked rice after cooling. Generally, a hard gel consistency variety hardened after being cooked.

Soameva, Soafitsanga, Malaky, Meva, X265 (Mailaka), X372 (KELIMIREFAKA), X360 (Mahadigny), Basmati 370, Tox V5 (Vesainky), short size Tsipala, FOFIFA 157 (Malaky) were found in this case. Their average values were 30 mm to 40 mm.

The major values were inferior to 60 mm as seen in Table 4 and Table 5. So most of the analyzed Malagasy rice varieties were of hard gel consistency; they hardened after cooking and cooling. Some varieties however were exceptions such as those from the Middle-East (27 GM, 28 GM, 18 BR: average value 83 mm), the red improved rice Manjamena (82 mm), the traditional rice Rojomena (65 mm), the traditional sticky rice Tsipala from the North-East (92 mm).

On the other side, the parboiled rice varieties (parboiled Rojomena, parboiled FOFIFA 159, and parboiled FOFIFA 172) gave an ameliorating cooking and eating quality according to our determination; their gel consistency became at least medium (score value: 70 mm - 60 mm). Parboiled rice got elsewhere enrichment of nutritional values (minerals, proteins, fibers) [5] [6] [7] [8] .

Interpretation

The medium gel consistency (60 mm - 65 mm) of the traditional varieties such as Rojomena and Rojofotsy was a value that would seem to explain the good taste of numerous traditional rice during the sensorial analysis [9] . Much more, the varieties 27 GM, 28 GM, 18 Br and Manjamena having values between 60 mm to 95 mm, were tasty and showed remarkably tender cooked rice after cooling. The Manjamena red variety within its soft gel consistency (value reaching 82 mm), confirmed its interest on culinary and nutritional point of view [5] . The parboiled varieties (Mahasoa, FOFIFA 172, Rojomena) gave a flow of medium to soft gel consistency (60 mm to 82 mm). This fact confirmed the improvement obtained in the cooking quality of parboiled varieties; the cooled rice after cooking was expected fairly to have moderate or low hardening.

The soft and medium gel consistency varieties were then interesting index on the culinary aspect and were characterizing elite rice to be developed. Especially when the amylose content was high (≥24%), the soft gel consistency softened the cooked and cooled rice.