Effect of pre-treatment methods on the physicochemical and anti-nutritional properties of Bambara groundnut yoghurt

Abstract

Production of yoghurt from Bambara groundnut (BGN) had been reported to have some limitations on its stability and quality. This work was designed to determine the effect of pre-treatment methods on the physicochemical and anti-nutritional properties of Bambara groundnut yoghurt (BGNY). Seven yoghurt samples were made from BGN milk obtained from differently pre-treated BGN. The pre-treatment methods were germination (G), roasting (R), parboiling (P), germination and roasting (GR), roasting and parboiling (RP), germination and parboiling (GP), while untreated (U) served as the control. The viscosity, specific gravity (SG), Brix, total dissolved solids (TDS) and least gelation concentration (LGC) of both the pre-treated and untreated BGNY were 11.30-19.40 mpals, 1.02-1.05 g/mL, 2.0-6.90 (oBrix), 2350-3470 ppm and 6-12% respectively. Significant differences (P≤ 0.05) were obtained for viscosity except for U-BGN and GP-BGN, and none recorded for specific gravity. No significant differences (P≤ 0.05) were recorded for sedimentation stability and also LGC except for GR-BGN and G-BGN. Yoghurt produced from G-BGN had the best values in LGC, Brix, TDS, SG and sedimentation stability. Pre-treatments significantly decreased anti-nutritional properties, while lowest values were recorded for GR (40.36 mg/dL) in trypsin inhibitor, RP (12.23 mg/kg) in tannin and GP (4.64 mg/mL) in phytate reductions. It could be concluded that BGNY can be produced from pre-treated BGN, as pre-treatment significantly improved the stability of the yoghurt and reduced the anti-nutritional properties; and can be recommended that combined pre-treatment with GR-BGN should be adopted for large scale production of yoghurt since it had the best qualities.

Keywords

• pre-treatment methods, bambara groundnut yoghurt, physicochemical properties, anti-nutritional properties