184 The Open Nutraceuticals Journal, 2010, 3, 184-187 1876-3960/10 2010 Bentham Open Open Access Microbial Population Succession in Alcoholic Beverages Produced from Some Tropical Fruits Sanjay Mishra 1,2, * , Surabhi Nanda 2 , Nidhi Madaan 2 and Varsha Mudgal 2 1 Department of Biotechnology, College of Engineering & Technology, IFTM Campus, Delhi Road, Moradabad 244 001, U.P., India 2 Department of Biotechnology & Microbiology, Institute of Foreign Trade & Management, Lodhipur-Rajput, Delhi Road, Moradabad 244 001, U.P., India Abstract: In the present study, monoculture and mixed culture fermentation techniques were employed to produce certain alcoholic beverages from watermelon; watermelon-banana and watermelon-pineapple mixtures. Three yeast species, namely, Saccharomyces cerevisiae, Kleochera apicalata, Torulospora delbruckii and four bacterial species Leuconostoc oenos, Lactobacillus Sp, Micrococcus luteus and Streptococcus lactis were identified. The daily succession of these organisms in the various fermenting samples differed in cell mass and occurrence due to their different growth conditions and factors present. A higher bacterial load (3.9 + 0.2 - 4.4+ 0.3) log (cfu) ml -1 than yeast (2.8 + 00 - 4.6 + 0.4) log (cfu) ml -1 counts was observed in the mixed culture fermentation, while in the monoculture fermentation, a higher yeast load (4.3+ 0.3-4.7+ 0.2) log (cfu) ml -1 than bacterial loads (2.7+ 0.1-4.1+ 0.3) log (cfu) ml -1 counts was recovered. These results reflected that monoculture-fermented beverages were of better quality as compared to the mixed culture fermented ones, and the monoculture-fermented beverage from watermelon-pineapple mixture was ranked as the best alcoholic beverage. Keywords: Beverages, fermentation, microbiological quality, tropical fruits. INTRODUCTION Principally, distinctive flavours of wine originate from different types of raw materials during alcoholic and malolactic fermentation [1, 2]. All over the world, different raw materials are used for the production of alcoholic bever- ages traditionally. The forms of alcoholic beverage con- sumed in various regions of the world vary considerably in accordance to location and ingredients [3]. There has been some controversy over the relative merits of spontaneous fermentations with natural flora of the ‘must’ and fermentation carried out with selected yeast strains. While it was found that spontaneous fermentation produced a better rounded and more complex aromatic quality [4], a subsequent study concluded it a significant preference for wine produced with selected yeast [5, 6]. Seeding of the fermentation is undertaken with the as- sumption and expectation that the inoculated strain will out- compete and dominate over indigenous strains of Saccharo- myces cerevisiae and the non-saccharomyces yeasts. Al- though there is high probability that inoculated S. cerevisiae will dominate the fermentation, seeding will not necessarily guarantee the dominance of any particular strain or its exclu- sive contribution in the fermentation [7-10]. *Address correspondence to this author at the Department of Biotechnology & Dean (Research), College of Engineering & Technology, IFTM Campus, Lodhipur-Rajput, Delhi Road, Moradabad 244 001, U.P., India; Tel: +91-9837096059; E-mail: sanjaymishra66@gmail.com The present studies were undertaken in view of gathering information on microbial population succession in alcoholic beverage produced from some tropical fruits through mixed and monoculture fermentation, and the impact of fermenta- tion strategy and fruit mixture on the beverage quality. MATERIALS AND METHODS Tropical fruits, mainly, watermelon (Citrullus lunatus Thumb) banana (Musa sapientum) and pineapple (Ananas comosus) were procured from local farms in the close vicin- ity to Moradabad, U.P., India. All containers and appliances used in the study were properly sterilized and the fruits were processed under aseptic conditions. The first treatment set up involved a homogenate of 8000 g of watermelon. The 2 nd treatment contained 8000 g each of homogenized watermelon and banana while the 3 rd treatment was a homogenate of 8000 g each of watermelon and pineapple. However, each of the treatments was repli- cated for (monoculture and mixed culture) fermentations, simultaneously. The process fermentation was carried out at room temperature of 28+ 2 0 C. In the mixed culture fermenta- tion, indigenous microflora of the fruits were allowed for the fermentation while in the monoculture, the substrates were seeded with Saccharomyces cerevisiae of quantity 8.62 log cfu ml- 1 to overgrow the indigenous microflora of the fruits. All the treatments were allowed to ferment for one week. At every 24 h, the samples were aseptically withdrawn from the fermentors, serially diluted and 1ml each pure laced