Biochemical and nutritional studies of lupin (Lupinus jermis) [Sudan]

Two lupin varieties (Rubatab and Dongola) purchased from the local market were used in this study. Physical properties showed that the weight and volume of cv. Dongola were higher than those of cv.Rubatab while thickness and density of cv.Rubatab were higher than those of cv.Dongola. Lupin varieties were debittered by cooking in water for 30 and 60 mins then steeped for three days in tap water for debittering. Proximate analysis showed that the moisture content ranged from 4.4 to 5.7. Fiber content ranged from 8.8 to 10.9 of whole seed and for kernels and testa it ranged from 0.9 to 1.8 and from 45 to 47 respectively. The ash content ranged from 1.3 to 1.9. Oil content ranged from 9.9 to 10.9 in whole seed (raw, debittered) and in kernels ranged from 11.5 to 12.0 while the testa had very low oil content (0.6- 1.1). Protein content ranged from 49.4 to 50.4 for raw whole seed and was 47.1 to 50.4 for debittered whole seeds. For kernels it ranged from 56 to 59. The protein content of testa ranged from 5.6 to 9.3. carbohydrates content was about 23 for raw whole seed and ranged from 25 to 26 for debittered whole seed. It ranged from 21 to 24 for kernels and increased to 39 in testa. Calorific value for 100 g of whole seed ranged from 381 to 433 kcal. It decreased in testa rangingfrom 187 to 193 kcal. In this study both varieties did not contain antinutritional factors e.g.trypsin inhibitors. The tannins content and phytate was very low presumably due to debittring. Fatty acid composition of lupin seed oil showed that it is composed of ten fatty acids. Oleic acid was the major fatty acid. It ranged from 52-60. Linoleic acid was about 16-19. Palmatic acid ranged from 10-11. Othe fatty acid of lupin oil were palmitoleic, lauric, myristeic, stearic, linolenic, and arashidic. The mineral content of lupin seed showed that Ca was 0.1, k ranged from 0.4-0.5 and was 0.7 in kernels. Mg content ranged from0.15-0.22. Fecontent was 0.03. P content ranged from 0.2 to 0.3. Zn content ranged from 82 to 127 ug/g for debittered whole seed, for kernels it ranged from 107 to 135 ug/g. Na content ranged from 56 to 72 ug/g. Mn content ranged from 4 to 6 ug/g. Pb content ranged from 9 to 10 ug/g. In this study lupin proteins were fractionated by two methods: Mendel-Osborne method and Landry and Moureaux. Protein fractions obtained by the first method were albumin which ranged from 3.1 to 24.8, globulin ranged from 1.9 to 3, glutelin ranged from 13.2 to 62. The Landry and Moureaux method gave globulins in the range of 24 to 66 albumin ranged from 1.1 to 3.2, glutelin (G lower2) ranged from 1.0 to 14.6, glutelin (G lower3) ranged from 5.3 to 63.1. Debittring increased glutelin and decreased albumin and globulin fractions. In vitro protein digestibility of total lupin proteins ranged from 73.9 to 81.0 for cv.Rubatab and from 73 to 80 for cv.Dongola.IVPD of the globulin fractions for cv.Rubatab ranged from 97 to 77 for whole seed and from 96.5 to 96.7 for kernels showing a significant (P 0.05) decrease as a result of debittring. For cv.Dongola it increased from 45 to 87.7 in whole seed (raw and debittered) and from 61.2 to 78.9 for kernels. IVPD of albumin decreased significantly (P 0.05) for cv.Rubatab ranged from78 to 33 for whole seed (raw and debittered) and 29 for kernels. For cv.Dongola it ranged from 96 to 76.6 for whole seed (raw and debittered), from 924 to 69.7 for kernels. IVPD of glutelin (G lower1) for whole seed (raw and debittered) decreased significantly (P 0.05) for cv.Rubatab it ranged from 64.4 to 53.5 and from 55 to 48.9 for kernels. For cv.Dongola it decreased significantly (P 0.05) from 94.2 to 48.5 for whole seed (raw and debittered) but for kernels it increased significantly (P 0.05) from 58.9 to 74.4. IVPD of glutelin (G lower2) of cv.Rubatab ranged from 74.6 to 79.7 for whole seed (raw and debittered) and for kernels it ranged from 61 to 57. For cv.Dongola increased significantly (P 0.05) from 63.7 to 91. IVPD of glutelin (G lower3) for cv.Rubatab increased significantly from 45.1 to 88.5 for whole seed. For kernels it decreased significantly (P0.05) from 94.0 to 78.7. For cv. Dongola for whole seed (raw and debittered) it was significantly increased from 35.5 to 76.7 and for kernels was decreased insignificantly (P 0.05) from 78.7 to 75. Results indicated that IVPD of globulin of cv.Rubatab and albumin and G lower1- glutelin for both cultivars decreased significantly (P0.05) due to debittering. The globulin, prolamin and G lower2- glutelin for cv.Dongola increased significantly (P 0.05). IVPD of G lower3- glutelin increased significantly (P 0.05) for both cultivars as a result of debittering.