Identification of Filamentous Fungi Isolated from Aseptic Filling System for Tea Beverages and Their Microbiological Characteristics.

Abstract

Two filamentous fungi isolated from contaminated samples which were thought to have occurred stochastically in the medium fill test in the aseptic filling production line for tea beverage were identified and studied their microbiological characteristics. The test strains were identified as Arthrinium sacchari (Speg.) Ellis and Chaetomium funicola Cooke. The optimum growth temperature was 20-25°C for A. sacchari M001 and 25°C for C. funicola M002. A. sacchari was able to grow at 5°C. The optimum growth pH was 4.0-8.0 for A. sacchari M001 and 5.0-8.0 for C. funicola M002. Because both strains had low heat resistance, it was suggested that the contamination had occurred after the UHT sterilization process in the medium fill test. When growth behavior was examined in green tea, oolong tea, barley tea and blended tea, both strains showed a delayed or inhibited growth in the catechin-containing green and oolong teas. It was suggested that tea catechin in the beverages could inhibit growth of filamentous fungi for a certain period of time. On the other hand, both strains grew rapidly in barley tea and blended tea that were low in tea catechin content.