Shelf-life Extension of Thai Green Papaya Salad Dressing by Hurdle Technology

Green papaya salad or Som Tum is the most popular spicy mixed salads in Thailand due to its unique rich flavor. Green papaya salad dressing (GPSD) is made from various ingredients such as fresh chili pepper, fresh garlic, rind tamarind, fish sauce and lime oil, including the limitation in controlling the taste and flavor of salad dressing and its poor shelf-life. In this study, a convenient ready-to-eat GPSD was developed. Hurdle technology was applied to extend shelf-life of the GPSD based on monitoring of microbial contamination and food pathogens throughout the process. Hurdle technology able to decrease total plate count (TPC) from 5.6±0.2 to 1±0.3 log CFU/g and yeast and mold (Y&M) from 4.2±0.3 to <1 log CFU/g. After 12 weeks of storage at 5±2 ºC, slightly increase of TPC was detected as 1.5±0.2 log CFU/g and no changes were found for Y&M and other pathogens. At week 12, GPSD stored at 32±2 ºC was found to have higher TPC and Y&M (3.7±0.3 and 2.4±0.3 log CFU/g, respectively). Therefore, a combination of hurdles that combines low aw, low pH, heat treatment, low temperature after hot filling, and chilled storage could extend the shelf-life of GPSD with satisfy sensorial test result and be suitable for minimally processed salad dressing.