Investigating the impact of milk protein, inulin, and honey on quality attributes of goat milk yoghurt

In this present study, a three-factor Box–Behnken, response surface methodology (RSM) design was employed to optimize the skimmed milk powder (SMP)/whey protein concentrate (WPC) ratio (0.25–0.75%w/v) as a source of milk protein, inulin (1–2%w/v), and honey (4–6%w/v) for production of high-quality goat milk yoghurt (GMY). The resulting ANOVA and response surface equations revealed the significant effect ( p < 0.05) of these variables on the various attributes such as total solid (%), pH, titratable acidity [(LA) % by weight], syneresis (%), DPPH (% inhibition), viscosity (m.Pa⋅s), whiteness index (WI), and overall acceptability (OA). The coefficient of determination (R 2 ) for all response variables ranged from 0.88 to 0.99. Lack-of-fit tests resulted in non-significant F-values. The optimal conditions were determined as SMP/WPC at 0.36%w/v, inulin at 1.00%w/v, and honey at 6.00%w/v. The optimum values for total solid, pH, titratable acidity, syneresis, DPPH, viscosity, WI, and OA were 22.03, 4.46, 0.77, 6.34, 25.20, 182.30, 76.29 and 8.37, respectively with desirability value of 0.95.