Journal of Yeast and Fungal Research Vol. 1(8), pp. 142 - 145, October 2010 Available online http://www.academicjournals.org/JYFR ISSN 2141-2413 ©2010 Academic Journals Full Length Research Paper Heat resistance of genus Byssochlamys isolated from bottled raphia palm wine E. I. Eziashi*, I. B. Omamor, C. E. Airede, C. V. Udozen and N. Chidi Nigerian Institute for Oil Palm Research (NIFOR), Plant Pathology Division, P. M. B. 1030, Benin City, Edo State, Nigeria. Accepted 14 August, 2010 Bottled raphia palm wine was cultured in a laboratory medium amended with 0.5% acetic acid (pH 4.8). Two cultures of identified heat resistant yeast (HRY) and one unidentified yeast species were isolated. Cultures of the isolates grown on potato dextrose agar for 10 days at 26°C, survived pasteurization temperature at 80°C for 20 min and 85°C for 15 min. Of these HRY identified were Byssochlamys nivea, Byssochlamys zollerniae and one unidentified yeast species. To determine the source of contamination, fresh un-pasteurized Raphia palm wine was cultured. Result revealed that, colonies of the three HRY were higher compared with the pasteurized Raphia palm wine. Frequencies of occurrence at 80°C, 85°C and in un-pasterurized raphia palm wine were B. nivea 15.2, 6.1 and 24.2%; B. zollerniae 6.1, 3.0 and 12% and yeast species 9.1, 6.1 and 18.2% respectively. The thermal destruction time were B. nivea 90°C for 15 min, B. zollerniae 90°C for 5 min and yeast species 90°C for 10 min. The result indicates they are acid tolerant and thermophilic yeasts with B. nivea having the highest frequency of occurrence. Key words: Culture, pasteurization, spoilage, identification, thermophilic. INTRODUCTION Raphia hookeri is the most economically important plant among the eight raphia species indigenous to Nigeria (Okolo, 2008; Otedoh, 1978). The exploitation of Raphia for the sap (palm wine) and other products of socio- economic importance such as pissava, fibre, oil edible grubs, poles, thatch etc are mainly from the wild (Udom, 2000). Wine is tapped from the panel which consists of the base of short spear leaves and the apical emerging terminal inflorescence axis (Tuley, 1965). The wine is rich in vitamins, carbohydrates and yeast (Obahiagbon, 2007). Filamentous fungi are morphologically complex micro- organisms exhibiting different structural forms through out their life cycles (Adrio and Demain, 2003). The life cycles of filamentous fungi starts and ends in the form of spores. In submerged cultures, these fungi have different morphological forms ranging from dispersal of mycelial *Corresponding author. E-mail: eziashius@yahoo.com. filaments to densely mycelial masses as pellets (Xu and Yank 2007). Microorganisms are an important part of our environment and are a principal cause of food spoilage. When food is contaminated by harmful microorganism, the products can cause severe human food-borne diseases, either due to the organisms themselves or the toxins released by them (Laplace-Buihe et al., 1993). The presence of these microorganisms in the products, even at low concentration may severely affect their quality (Laplace-Buihe et al., 1993). Fruit juices contain various concentration of sucrose, which constitutes a very important component of the me- dium for the growth of fungi (Palou et al., 1998). Microbial spoilage is a serious problem for the food industry as fungal contamination can occur during processing as well as handling of the end products. Since yeast can generally resist extreme conditions better than bacteria, they are often found in products with low pH and in those containing preservatives (Macrae et al., 1993). Especially yeast spoilage has increased in recent years as a result of lower doses of preservatives and milder preservation