Storage Stability and Performance of Fluid Bed Dried Solid State Fermented (SSF) Lactic Cultures

Aims: In addition to attempting to evaluate the performance of SSF cultures in heated milk, the current study aimed to investigate the impact of refrigeration temperature storage on the fluid bed dried powder of Solid State Fermented (SSF) lactic cultures, such as dahi, yoghurt, and probiotic cultures.

Duration and Place of study: The study was carried out in single season at Karnataka Veterinary, Animal and Fisheries Sciences University (KVAFSU, Bidar), Dairy Science College, Hebbal, Bangalore, Karnataka, India

Study design and Methodology: aerobic spore survival, the raw black gram dhal had the lowest spore count—1.52 log10cfu/g. The spores were killed by sterilizing the black gram dhal at 1210C for 30 minutes and then exposing it to a hot air oven at 1000C for one hour. Black gram dhal containing 1:0 was used to obtain the maximum viable starter counts of dahi (8.41 log10cfu/g), yoghurt (8.98 log10cfu/g), and probiotics (9.47 log10cfu/g) cultures during fermentation. Ash gourd, carrot, tomato, and skim milk powder liquids were added to the 8:1 moisture ratio at 1% level as growth-promoting agents. The fermented SSF cultures were dried on a fluid bed at room temperature (250C) for 1.5 hours. After fluid drying, the SSF culture viability of the probiotic, yoghurt, and dahi cultures dropped from (9.01 to 8.85, 8.65 to 8.33) and 9.65 to 9.34 log10cfu/g, respectively. 9.4% of the SSF cultures' moisture content was observed. Following inoculation of the heat-treated milk with these dried powders of SSF cultures of dahi, yoghurt, and probiotic cultures at 1,0.5, and 3%, the cultures took 5:00, 3:30, and 9:30 hours to establish the heat-treated milk with acidity of 0.68, 0.71, and 0.59% lactic acid, respectively.

Results: The dried SSF lactic cultures were viable for 40 days at 7±10C, or 6 log10cfu/g, when stored at that temperature. The absence of contaminants such as coliforms, aerobic spores, yeast, and molds in the stored fluid-dried SSF lactic cultures demonstrated the good hygienic practices used during the biomass production. The curdling period increased with the number of storage days at refrigeration temperatures in relation to the performance of stored SSF lactic cultures because of the decrease in viable lactic counts.

Conclusion: The minimum viable counts of probiotic, yoghurt, and dahi cultures on the 40th day of storage at refrigerator temperature were 6.45, 6.85, and 6.44 log10 cfu/g, respectively. Furthermore, none of the preserved samples had any coliforms, aerobic spores, yeast, or mould in them.