Process optimisation and quality evaluation of passion fruit based probiotic drinks

Abstract

The functions of food has extended from satisfying hunger and providing nutrients to body, to health maintenance, wellness and prevention of diseases. Probiotics are such functional foods which when incorporated to foods helps to improve its nutritional profile and therapeutic value. Hence, the study entitled “Process optimisation and quality evaluation of passion fruit based probiotic drink” was undertaken with the objective of standardising probiotic fruit drinks with different combinations of fruits with passion fruit and also to evaluate the nutritional, organoleptic and shelf life qualities of these developed passion fruit based probiotic drinks. Passion fruit probiotic drinks were developed in combination with mango, pineapple and tomato. The proportion of ingredients were standardised with three sets of treatments, and from each set, one fruit drink combination with maximum organoleptic scores were selected. The fruit drink containing 50 per cent passion fruit juice (PFJ) and 50 per cent mango juice (MJ) (T5) was selected from set 1, whereas fruit drink containing 70 per cent passion fruit juice and 30 per cent pineapple juice (PJ) and tomato juice (TJ) (T3) was selected from set 2 and 3 respectively. Total scores for the selected combinations were 50.06, 51.16 and 49.01 respectively for T5 (PFJ+MJ) and T3 of PFJ+ PJ and PFJ+ TJ. For all the selected fruit drinks, the conditions were optimised for attaining the maximum viable count of L. acidophilus. The fruit drink (25 ml) fermented with 4 μl of inoculum for 1 hour at 370 C gave the maximum viable count of L. acidophilus ranging from 13.27 to 13.38 log cfu/g. The selected fruit drinks from each set along with their respective control (non probiotic samples) were analysed for their nutritional and organoleptic qualities. Titratable acidity ranged from 1.60 to 3.02 per cent in non probiotic drinks, where as in probiotic drinks it ranged between 1.98 to 3.18 per cent. Protein content ranging between 0.36 to 0.61 g/100 g was observed in non probiotic drinks and increased protein content was observed in probiotic drinks (0.62 to1.37 g/100g). Significant decrease in TSS was observed in probiotic drinks (12.3 to 12.80 brix) compared to non probiotic drinks (13.10 to 140 brix). Total sugar and reducing sugar of probiotic drinks were in the range of 14 to 16.66 g/ 100g and 3.08 to 4.08 g/ 100g respectively and a significant increase was observed in non probiotic drink, 15.20 to 17.10 g/ 100g and 3.57 to 4.53 g/ 100g respectively. With respect to mineral content, maximum phosphorus content was observed in PFJ+PJ probiotic and non probiotic drinks, whereas the highest potassium content was for PFJ in both probiotic and non probiotic. Iron and calcium of probiotic drinks ranged from 0.22 to 0.29 mg/ 100g and 2.04 to 2.65 mg/ 100g respectively and that of non probiotic drinks were 0.20 to 0.28 mg/ 100g and 2.02 to 2.64 mg/ 100 g respectively. The probiotic fruit drinks were packed in food grade plastic bottles and kept for storage studies under refrigerated condition for a period of 15 days and a decrease in the sensory attributes were observed. Initially, the overall acceptability of probiotic and non probiotic PFJ drinks were 8.16 and 8.15 respectively which reduced to 8.14 and 8.13 respectively after storage. Similar reduction was observed in every set of samples. The total score of probiotic PFJ, PFJ+MJ, PFJ+PJ and PFJ+TJ were 48.76, 50.14, 50.97 and 49.32 and that of non probiotic drinks were 48.71, 49.95, 50.94 and 49.27 respectively. The viable count of L. acidophilus decreased on storage from 13.27 to 13.39 log cfu/ ml to 13.26 to 13.37 log cfu/ ml. The cost of production of probiotic fruit drinks were in the range of Rs. 25.5 to Rs. 33.5 per 200 ml. The study revealed that passion fruit can be a suitable substrate for probiotic fermentation and probiotic drinks can be successfully developed. Further research can be done for the development of innovative probiotic products from passion fruit.