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Effects of processing treatments on nutritional quality of raw almond (Terminalia catappa Linn.) kernels

Makinde Folasade M and Oladunni Subomi S

Almond (Terminalia catappa Linn) is one of the lesser utilized oil kernel distributed throughout the tropics including Nigeria ecosystem. In this research work, the effects of soaking, blanching, autoclaving and roasting on the proximate, mineral, vitamin and anti-nutritional concentrations of almond kernel were determined. The result of chemical composition revealed that raw almond kernel contained 11.93% moisture, 23.0% crude protein, 48.1% crude fat, 2.43% crude fiber, 2.69% ash, 12.0% carbohydrate, 0.35mg/100g thiamine, 0.15mg/100g riboflavin, 0.19mg/100g niacin and minerals among which the most important are potassium (9.87 mg/100g), calcium (4.66 mg/100g) and magnesium (4.45 mg/100g). Tannin, phytate and oxalate concentration in raw almond kernel were 0.15, 0.13 and 0.15mg/100g respectively. Increase in ash and fiber was noted for treated samples with time compared to raw almond. Compared to untreated kernels, soaking, blanching and autoclaving decreased fat content but there was increase during roasting of the kernels. Mineral concentrations were significantly increased by various treatments compared to raw kernel. However, roasting for 15 min resulted in highest increase in potassium (41.2 percent), calcium (45.1 percent), phosphorus (43.3 percent) and magnesium (43.6 percent). Vitamin content was significantly lowered upon processing. Vitamin loss was much pronounced during roasting (thiamine: 62.9-85.7 percent; riboflavin: 20-40 percent; niacin: 68.4-89.5 percent). A reduction trend was observed in the level of phytate, oxalate and tannin in the various samples with processing time, however, greatest reduction was observed in roasted samples compared to other treatments. Most importantly, the concentrations of these anti nutrients in raw and treated kernels were below the toxic level and therefore may not pose any effect on human. In overall, roasting in open pan for 15 min appears to be the recommended processing treatment to obtain nutritive almond flour, since it caused a minor decrease in nutritional value and the largest anti nutrient reduction.