Process optimisation for the preparation of sorghum incorporated composite probiotic dairy spread

Response surface methodology (RSM) was employed to optimize the formulation of a nutri-cereal incorporated probiotic dairy spread and to evaluate the effects of key ingredients on product quality. Five major ingredients - milk protein concentrate (MPC-80), sorghum malt, probiotic curd, butter, and sodium tripolyphosphate (STPP) - were studied within selected ranges of 8–12%, 5–8%, 35–45%, 15–25%, and 0.5–1.5%, respectively. These ingredients significantly influenced sensory, textural, and rheological properties of the product through linear, quadratic, and interaction effects. Texture and spreadability were particularly affected by ingredient interactions. The optimized formulation consisted of 39% probiotic curd, 14% butter, 13.03% MPC-80, 5% sorghum malt, 0.5% stabilizer, 4% cheese, 0.75% salt, and 30% water, heat processed at 85 °C for 2 min. The final product contained 55.59% moisture, 44.41% total solids, 16.29% carbohydrates, 15.70% fat, 10.02% protein, 2.93% ash, and 272 mg/100 g dietary fibre, with a viable probiotic count of 10.36 log₁₀ cfu/g of Lactiplantibacillus plantarum and Lacticaseibacillus casei. The developed spread demonstrated excellent sensory acceptability and functional potential as a probiotic food.