Determination of Mineral Content and Anti-Nutritional Factors in Soybean Flour Processed by Different Methods in Kwara State

Soybean is an important leguminous crop with high protein and mineral content, but its nutritional quality and anti-nutritional profile are significantly influenced by processing methods. This study evaluates the mineral content and anti-nutritional factors of soybean flour prepared by four processing methods, including raw grinding, boiling, roasting, and fermentation, in Kwara State, North Central Nigeria. Flour samples were prepared from locally grown soybeans and analysed for calcium, iron, zinc, phosphorus, and potassium by atomic absorption spectrophotometry. Anti-nutritional factors assessed include phytate, oxalate, tannin, and trypsin inhibitor activity, determined using established colorimetric and enzymatic methods. Results show that fermentation significantly reduced phytate and tannin content while marginally improving iron and zinc bioaccessibility, as estimated by in vitro dialysis methods. Roasting reduced trypsin inhibitor activity by approximately 80 percent compared to raw flour. Boiling produced intermediate reductions in most anti-nutritional factors. Iron and zinc concentrations were highest in fermented flour, consistent with phytate reduction improving micronutrient retention. The study provides practical, evidence-based guidance for households and food processors in Kwara State seeking to optimise the nutritional value of soybean-based foods, and recommends integration of traditional fermentation practices into community nutrition programmes. Keywords: soybean flour, anti-nutritional factors, mineral content, processing methods, Kwara State