Development of Spray-dried Probiotic Powder from Fruit Peel Waste: Physicochemical, Functional and Microbiological Evaluation

Fruit peel waste is an underutilized resource that contains bioactive compounds and dietary fiber for use in functional foods. The objective of this research was to produce a spray-dried probiotic powder with fruit peel waste as carrier matrix and then evaluate its physicochemical, functional and microbiological properties. The peels of banana, citrus and apple were homogenized into fine slurry mixed with Lactobacillus plantarum, spray-dried under optimized conditions (inlet temperature 140 -160°C, feed flow rate 5 mL/min) with maltodextrin as carrier. The obtained powders showed low moisture (≤4.2%) and low water activity (0.30). The encapsulation efficiency was more than 92%, and the particle sizes were between 15 and 35 μm. The total phenolic content, as well as antioxidant activity after drying, were retained at a high level, indicating a good protection of the peel matrix. Viability of probiotics showed >8.5 log CFU/g after spray drying, >7 log CFU/g following 60 days at 4 °C for storage stability and that fruit peel waste could be effectively valorized as a functional probiotic powder using spray drying with potential implementation to enable the sustainable, low-cost development of shelf-stable nutraceuticals and functional food materials.