Development of Fermented Taro as a Food Preservative Ingredient in Intermediate Moisture Products

Abstract : This study focuses on the functionality of fermented taro as an antibacterial ingredient for intermediate moisture (IM) products being developed by the military. The taro is cooked and then inoculated with a food-grade bacterium, Lactococcus lactis ssp. lactis, which produces a bacteriocin, nisin, forming a fermented taro product. The fermented taro has antibacterial activity against various bacteria and is freeze-dried for eventual incorporation as a food preservative ingredient in an IM product. L. lactis yielded nisin concentrations in a range of 15,000-19,000 AU/g of taro. Challenge studies were conducted in which the fermented taro was incorporated into an IM product, the burrito sandwich. The challenge organisms consisted of three strains of Staphylococcus aureus. The burrito samples with 600 AU/g of fermented taro showed no increase in bacterial counts after 7 days. However, after 14 days the bacterial counts increased to 3 X 107 CFU/g. The burrito samples treated with 1200 AG/u of fermented taro showed no increase in growth from the original inoculum (2 X 105 CFU/g) during the challenge study. The last sampling time was at 56 days with a slight decrease in the S. aureus counts. It appears that fermented taro can be a good food preservation ingredient in IM products, though further studies will have to be done to optimize product.