Effects of conventional food processing methods on the mineral and anti- nutrient composition of sunflower (Helianthus annuus) Seeds

Abstract

This study evaluated the effects of processing on the mineral and anti-nutrient components of sunflower (Helianthus annuus) seeds using boiling, roasting, solvent extraction and mechanical extraction. Mineral and anti-nutrient concentrations of differently processed meal samples were determined using standard analytical procedures and parameters were subjected to statistical analysis. Mineral content analysis revealed the following concentrations: Calcium (0.17 – 0.38 mg/g), Iron (0.25 – 0.52 μg/g), Sodium (0.10 – 0.25 mg/g), Potassium (1.87 – 2.12 mg/g), Phosphorus (1.57 – 1.72 mg/g), Magnesium (0.13 - 0.37 mg/g), Manganese (0.13 – 0.15 mg/kg), Copper (0.01 – 0.04 mg/kg) and Zinc (0.09 – 0.14 mg/kg). These values were statistically different (p<0.05) except for sodium and manganese. Phytochemical screening of the meal samples revealed the presence of some bioactive compounds including tannin, oxalate and phytate and their observed values were statistically different (p<0.05) except for oxalate and phytate. Tannin was highest in the raw undehulled meal (0.45 mg/g) and least (0.21 mg/g) in the boiled meal. Oxalate content was least (0.11 mg/g) in the roasted and boiled meals and highest (0.15mg/g) in the raw dehulled meal. Phytate content was highest (0.16 mg/g) in the raw undehulled meal and least (0.10mg/g) in the boiled meal. Boiled sunflower seed meal had statistically (p<0.05) lower values of anti-nutrients, higher percentage reductions in the levels of these anti-nutrients and appreciable amounts of macro- and micro-minerals. Therefore, in view of its considerably lower values of anti-nutrients, higher percentage reductions of anti-nutrients and appreciable amounts of minerals, the study recommends boiled sunflower seed meal as a viable alternative to soybean meal and groundnut cake in feed formulations for fish and livestock.

Keywords: Sunflower seed, processing techniques, phytochemical screening, mineral content, anti-nutrients