A brief profiling of microbes of freshly squeezed pineapple juices in Kolkata city, India and reduction of microbial load following thermal and non-thermal methods

Abstract

Fruit juices are popular drinks as they contain various nutrients like vitamins, minerals, antioxidants which are very helpful for healthy life especially to combat several diseases. For being so nutritious they support a lot of microorganisms to grow in it. In this study, an effort has been made to know the microbial profile of the most demanding freshly squeezed Pineapple Juices collected from street vendors of different areas and branded pineapple juice was also monitored. All samples were found to be acidic in nature. A total of 9 juice samples (8 fresh and 1 branded/packaged) were examined for their microbiological analysis, after being collected in sterile containers. Total Viable Count (TVC) was high ranging from 2.45×105 - 28×105 CFU/ml, and hence not safe for human consumption. Coliform count ranged from 0.8×104 - 9.8 ×104 CFU/ml. Alicyclobacillus count varied from 0.20×104 - 9.6×104 CFU/ml with few being numerous in count. Vibrio (0.3×104- 5.2×104 CFU/ml), Salmonella-Shigella (0.1×104 – 12.5×105 CFU/ml), Yeast (0.10×104 -2.5×104 CFU/ml) with few being numerous in count, molds (1.1×104- 6.8 ×104) with 1 being numerous were also detected. Sensitivity of the isolated colonies were checked for 8 antibiotics. One species of Alicyclobacillus and Salmonella were found to be resistant in Ampicillin which may pose health challenge whereas others being sensitive towards most or all antibiotics.The attempt was taken to reduce the microbial load in the juice samples using non thermal (UC-C radiation and Ultrasonication) as well as thermal methods (Low temperature long time and high temperature short time treatment). Both thermal and non thermal methods were effective to reduce the microbial load to a great extent. Though thermal methods were most effective but they may compromise the nutritional value and organoleptic properties of the fruit juice samples. So the non thermal methods are recommended for healthy processing of the fruit juice samples