PHYSICO-CHEMICAL'ANALYSIS OF DEGERMED FLOURS OF SELECTED CEREALS

Abstract

The flours of degermed grains of rice (!\) iOry:a sativa). millet (8) iElcuslne coracanai. wheat (C) (Triticin, (I('.\'li\'III11). white maize (D) (Zeo I1IOV\'). )'eIIO\\ maize (L) (L('u 11I00's). red sorghum (F) (Sorghlllll bicolour L. Moench) and white sorghum (G) (Sorghlllll bicolour L. Moench) were analyzed lor their proximate compositions. sugar compositions. starch contents. physicochemical properties, pasting properties and mineral compositions using standard chemical methods. These analyses were carried out with the view to evaluating the nutritional significance 01" the selected cereals in the production 01" weaning foods and possible suitability for other industrial purposes. The results of proximate analysis of the sample (p<O.05) revealed that the highest moisture content 01" whitc sorghum (G) /lour (I O.77±O.03%) made it least stable to microbial activity. The values of crude protein obtained ranged from 0.45±O.03% in rice flour to 15.66±O.05% in red sorghum. The values of ash content ranging from 1.48±O.02 to 2.12±O.02% were obtained. The highest fat content (3.11 ±O.02%) was obtained in red sorghum and the lowest (O.75±O.02%) in rice flour. Wheat flour appeared to be the richest flour in crude fibre (2.25±O.OS%) while the flour of white sorghum the poorest in crude fibre (I .62±O.04%). The values of carbohydrate by difference of the samples ranged from 66.96±O. I I to 84.7I±O.02%. The studies on sugar compositions ofthe samples showed that glucose contents ranged from 49.50±O.05 to SO.20±O.IO mg/lOOg while the contents of fructose were in the range S2.60±O: IO-S3.30±O.20 mg/lOOg. The peak value of maltose was 80.80±O.20 mg/lOOg in red sorghum flour and the least was 79.90±O.OS mg/lOOg in wheat /lour. The starch content of rice flour (79.24±O.04%) was the highest while that 01" red sorghum flour (61. IO±O.20%) the lowest. The results of physicochemical properties revealed that the pH of the samples varied from S.S8±O.O I to 6.33±O.O 1 and that their levels 01" acidity decreased in the order rice>mi Ilet>white maize>yellow maizc.-whcuc-whitc sorghurn--rcd sorghum. ;\11 the samples were gluten-free except the flour of wheat with gluten content 01" Il.20±O.OO(%, Yellow maize flour exhibited the highest valucx or hoth water absorption cupacitv (9X.50±O.O I(%) and least gelation concentration (25.00±O.O I%) while red sorghum flour had the lowest values or both water absorption capacity (85.60±O.O I(%) and least gelation concentration (15,OO±O.O I(Yo). Amylose and amylopectin contents were observed as an influence on the values or the swelling power and solubility of the samples. I ligh amylose content (or low amylopectin content) was revealed to be proportional to the 100v values or swelling power and solubility. All the samples were rich in energy with the' most energy-rich flour as red sorghum flour (341.7±0.OI Kcal) and the least cncruy-rich as rice Ilour (326.3±O.OI Kcal). The studies also revealed that the ability or the pastes or the samples to retrograde after cooling decreased in the order white sorghum>rice>millet>red sorghum>yellow maize>white maize>wheat. The most viscous paste of all the samples was whtte sorghum (120.67 RVU) with paste stability value or 26.83 R VU. which was lower I than that or millet (39.92 RVU) with paste viscosity or 95.42 R VU. The values of pasting temperature ranged between 80.40 and 83.40uC. All the samples studied were good sources or minerals with the abundant ones occurring as calcium. phosphorus and potassium. Potassium was the most predominant mineral with contents ranging from 34S.8±0.20 to 433.4±0.SO mglI OOg. The flour of rice had the highest contents or calcium (421.0±O.02 mg/ IOOg), phosphorus (266.2±,O.02 mg/! OOg) and sodium (22.4S±O.OS mg/! OOg). The values of zinc content were trace raging from O. I 7±O.O 1 rug/ I~Og in white sorghum to 2.61 ±0.02 mg/I OOg in wheat. The peak value of iron content was obtained in white maize flour (6.77±O.03 mg/IOOg) while the least in wheat flour (4.86±0.02 mg/lOOg). There

were no detectable amounts for lead. copper, cadmium and mercury in all the samples.