44E-24 |
Inactivation of natural flora in a functional food derived from fruit juice and milk |
S. Q. LI and Q. H. Zhang. Dept. of Food Science & Technology, The Ohio State Univ., 2015 Fyffe Ct., Columbus, OH 43210 Pulsed Electric Field (PEF) pasteurization is a newly developed, nonthermal food processing technology. Particularly for functional foods, PEF may help avoid the detrimental influences of thermal processing on the flavor and nutraceutical properties. To investigate the possibility of applying PEF to functional food processing. OSU-4A pulse generator, together with a six co-field flow tubular PEF chambers and an automatic syringe pump fluid handling system provided selected treatments. System back-pressure was maintained at 30 psi. The fruit juice carton was open and mixed with milk one week prior to treatment. PEF parameters, electric field strength, pulse duration time and total treatment time were investigated. Samples were diluted and plated on PCA and PDA agars, incubated at 37oC for 2 days or incubated at room temperature for 6 days, respectively. PEF treatments on the fruit juice and milk mix showed significant microbiological inactivation effects against the natural flora existing in the samples. About 5 logs reduction in PCA counts was reached at 35.62 kV/cm for 55 microseconds. In this case the temperature changes after a pair of chambers treatment was 19oC and the maximum temperature during treatment was 37oC. No influence of pulse duration time was observed in the range of 2 to 4 microseconds on PCA counts. PCA counts for PEF treated samples were too low to count, indicating that the inactivation might be higher than 5 logs. This work helps to understand the inactivation of natural flora in juice and milk mix. Since milk proteins are not very stable when mixed with fruit juice, avoiding the exposure of this kind of food products to thermal pasteurization but keeping it microbiologically stable is important for a successful processing of thermally sensitive products.
Session 44E, Nutraceuticals & Functional Foods
|