Nutritional value, Anti-nutrient Level and Effect of Processing on Hyptis spicigera Lamiaceae seed (Black beniseed) as Human Food

Abstract

Civil conflicts have aggravated the situation of food security in South Sudan and the problem reached record levels in 2016 and 2017.Wild plant seeds constitute an important part of human diet. Hyptis spicigera has some attributes that could make it a suitable candidate to address the problem of food insecurity in South Sudan. Although, the plant is well known for its insecticidal, herbal and medicinal properties, its seed could be used as food, because of its high nutritional content. The state of art of nutritional value, anti-nutrient value and effect on processing content of the seed is lacking in the literature. The objectives of the present study were to determine the nutritional composition of the seed; to determine the anti-nutrient levels of the seed; to evaluate the effect of processing on the nutrient composition of the seed and to evaluate the effect of processing on the anti-nutrient content of the seed. Ten kilograms of Hyptis spicigera seeds collected from local farmers in South Sudan and transported in closed box to Jomo Kenyatta University of agriculture and technology laboratory then kept in a cold room at 10⁰C until analysis was done. Standard methods (AOAC, 1995) were used for proximate analysis; anti-nutrients, oxalic acid was determined by HPLC; phytic acid by HPLC and tannins was determined by the Folin-Denis colorimetric method. The samples of Hyptis seeds were treated for different time periods for the soaked; soaked and germinated or boiled and roasted. Raw seed served as control. The treated and untreated seeds were milled into flour and their proximate composition and anti-nutrient content were analyzed. Data were subjected to analysis of variance; means were separated by Duncan multiple range tests at 5% significance level using Genstat Release 14.1 Software. The nutrient composition and anti-nutrient analysis were reported on dry weight basis. The nutritional composition of the untreated seed were: moisture 4.71%;ash 2.82; fat 34.1%; crude fibre 18.2%; protein 16.0%; carbohydrate 24.1%; iron 2.72 mg/100g; calcium 252.6 mg/100g; zinc 2.52 mg/100g and magnesium 297.9 mg/100g. The anti-nutrient content of the untreated seeds were: tannins 332.0 mg/100g; oxalates 434.8 mg/100g and phytates 390.4 g/100g. Different processing techniques significantly (p≤0.05) increased the nutrient content of the seed but at the same time significantly reduced the ant-nutrient content of the seeds. Germination and roasting improved the nutritional content of the seed (carbohydrates, fat and fibre) when compared to soaking and boiling treatments. Hence, anti-nutrient treatments reduced the anti-nutrient content (tannins, oxalates, and phytates) of the seed, with germination registering the best reduction in tannins and oxalates. In conclusion, roasting and germination appears to be a promising processing method of enhancing the proximate composition of Hyptis spicigera Lam seed and reducing its anti-nutrient level. Its utilization could be recommended to fight against micronutrient deficiencies in the community.