Effect of different preservative treatments on the shelf-life of sorghum malt based fermented milk beverage.

Studies were conducted to extend the shelf life of sorghum based fermented milk beverage (referred to SSL) developed at our Institute. In the first approach preservatives namely nisin (N) @ 400RU/ml, MicroGARD (M) @ (1%), potassium sorbate (PS) @ (0.15%) were added to the beverage before packaging and in the second approach thermization (65 °C/5 min) of the packaged samples containing above mentioned preservatives was adopted. The shelf life was assessed on the basis of sensory, physico-chemical and microbiological parameters. Total plate count and lactic acid bacterial count increased till 7th day of storage and afterwards decreased significantly (p < 0.01). Yeasts and molds count increased significantly (p < 0.01) throughout the storage period and the rate of increase was lowest in samples containing PS. Samples containing PS, N and M were found sensorily acceptable up to 35, 28 and 21 days, respectively. Though the thermization treatment helped in improving the microbiological and chemical quality of the beverage, the sensory and physical quality was adversely affected. Addition of PS without thermization was found to be the best preservation technique for enhancing the shelf life of SSL at refrigeration conditions.