Application of ohmic heating for accelerating Pacific whiting fish sauce fermentation

Pacific whiting (PW) is an inexpensive, protease rich fish which makes it an excellent candidate as a source for fish sauce. However, fish sauce fermentation requires elevated ambient temperatures (20-35 degrees C) for 12-18 mo. Ambient temperature where PW is harvested ranges from 1 to 20 degrees C and therefore external heating would be required. To make fish sauce from PW economically feasible, both accelerated fermentation and a heat process that is not energy intensive would be required. Ohmic heating is an alternative heating process that uses less energy than conventional heating. This project evaluated fish sauce produced using step-wise thermal treatments with conventional indirect heating (water bath) or alternative direct heating (ohmic). Three parts whole PW was comminuted with 1 part salt then fermented using a step-wise thermal treatment protocol to target endogenous protease activity optimums: 25 degrees C, 1 wk; 35 degrees C, 1 wk; 55 degrees C, 6 wk. Ohmic heated samples had significantly higher brownness, taste value, and overall nitrogen content (p < 0.05). The difference was hypothesized to be due to electroporation and consistent heat. This study discovered that ohmic heating can be utilized for Pacific whiting fish sauce production as it not only provides heat cost effectively, but also significantly accelerates fermentation quality factors.