Development of Spray-dried Probiotic Powder from Ultrasound-assisted Enzymatically Extracted Sohiong (Prunus nepalensis) Juice

Abstract

Consumer interest in non-dairy based functional foods has significantly increased due to lactose intolerance, casein allergy, and associated cholesterol risks with dairy products. Fruit-based products could be an excellent alternative option. Sohiong (Prunus nepalensis) fruit is widely available in the north-eastern part of India and is nutritious. However, due to lack of proper value addition techniques, the fruit remains underutilized. There is a need to develop a process to utilize Sohiong fruit. For the present work, Sohiong fruit was explored to develop a process for a possible fruit-based probiotic product. Various physical attributes and their relationships with mass (all, small, medium, and large groups) were modeled using linear, quadratic, S-curve, and power models. Textural and biochemical properties of Sohiong fruit were also determined. The results of physicochemical characterization and mass modeling of the fruit would add information to the scientific knowledge base. It would help in the design and development of storage, handling, processing and value-addition protocols and equipment for better utilization of the fruit. The Sohiong juice was extracted using ultrasound and pectinase enzyme. The process variables in juice extraction were modeled and optimized by Box-Behnken design. The ultrasound pretreatment increased the juice yield by 20% and reduced the juice extraction time significantly compared to enzyme treatment alone. The juice recovery and the quality of juice were found to be optimum at 90% ultrasound amplitude with an ultrasound treatment time of 9.95 minutes, enzyme concentration of 0.03% w/w, and incubation time of 57.44 minutes. The extracted juice was then fermented with probiotic Lactobacillus plantarum ssp. plantarum MCC 2974. The fermented juice was analyzed for physical and phytochemical properties. During fermentation, the number of viable probiotic cells increased up to 10 Log CFU/ml. The juice was then spray dried with additives for encapsulation, and the process was optimized to make probiotic Sohiong powder. The spray-dried powder yield was 57.68% (w/w) with a moisture content of 3.95% (w.b.). The encapsulation efficiency was 85.75%, with a probiotic cell count of 7.00 Log CFU/g. The cost of producing probiotic Sohiong powder was ₹10.54 INR per gram. The powder was characterized for various quality parameters such as particle morphology (FESEM), rehydration time, hygroscopicity, density, crystallinity (XRD), glass transition temperature, and probiotic viability. The storage stability of the powder was determined through moisture sorption isotherm modeling. Peleg model fitted best with highest R2adj. and lowest RMSE. The effects of storage time on probiotic viability, physicochemical, and sensory properties of the Sohiong powder were investigated and were found to be acceptable for consumption. The powder could be stored up to 36 days at 25oC and 50% RH with an acceptable probiotic cell count of 6.12 Log CFU/g. With proper packaging and storage conditions, the probiotic Sohiong powder could be stored for an extended period. The results are promising and suggest the feasibility of producing non-dairy based probiotic Sohiong powder at an industrial scale.