Production and optimization of probiotic-enriched breakfast cereals: A mixture augmented design approach

Abstract

Delivering probiotics in ready-to-eat breakfast cereals has potential in functional foods, but securing viability is challenging due to the high processing temperatures. This study aimed to deliver probiotics in ready-to-eat breakfast cereals and evaluate and optimise the formulation. A mixture centroid-augmented design was used to formulate the blends from sorghum, soybean flour, and fruit slurry (an equal mixture of mango and banana). Pure strains of Lactobacillus plantarum (NRRL B-787) were cultured and diluted to a 1.20 × 10⁹ CFU/ml solution using a 4 McFarland turbidity standard. The liquid was mixed with the component mixtures, cold-extruded, and dried at 50 °C for five hours. The samples underwent proximate, mineral, isoflavones, sensory, and microbial analysis, and the results obtained were analysed and optimised using a special quartic model, with significance accepted at p < 0.05. The protein, moisture, ash, fat, fibre, carbohydrate, and energy contents ranged from 15.20 % to 27.69 %, 7.77–13.17 %, 2.18–2.86 %, 2.41–3.395 %, 2.28–3.08 %, 543.93–68.32 %, and 336.53–364.70 Kcal, respectively. Soybean flour contributed to the high phosphorus, zinc, and isoflavones (daidzein, genistein, and glycitein). In contrast, sorghum contributed to the high iron, potassium, and manganese. Sensory attributes, especially overall acceptability, increased proportionally with the inclusion of fruit slurry. The total viable count ranged from 1.0 × 10⁶ to 8.9 × 10⁶, while lactic acid bacteria ranged from 1.0 × 10⁵ to 9.0 × 10⁵ CFU/g, with no coliforms detected. The optimum formulation was sorghum = 55.05 %, soybean flour = 26.42 %, and fruit slurry = 18.54 %, with a probiotic composition of 1.92 × 10⁵ CFU/g.