91E-23 |
Cold pasteurization of peach nectar using pulsed electric fields |
L. E. GUTIERREZ-BECERRA1, S. Q. Li2, Q. H. Zhang2, and E. Ortega-Rivas1. (1) Graduate Program of Food Science, University of Chihuahua, Division de Posgrado, a.p. 5142-C, Chihuahua, Chih., Mexico, (2) Department of Food Science and Technology, the Ohio State University, 2015 Fyffe Road, Columbus, OH 43210 Conventional pasteurization of peach nectar can lead to loss of flavor and color change, which can affect overall sales. Pulsed electric field (PEF) is a nonthermal food processing technology alternative to traditional processing. Application of PEF technology in peach nectar processing can avoid the detrimental changes in the quality attributes of the product. The purpose of the research was to assess the efficacy of PEF on inactivation of E. coli 8739 in peach nectar under various conditions. A major part of this study involved addressing undesirable color changes during processing as well. OSU-4H PEF unit was used with co-field flow chambers to provide PEF treatment conditions in 0 – 35 kV/cm and 200 – 600 pps at 2 microseconds pulse width. E. coli 8739 in Tryptic Soy Broth was incubated at 35°C for 8 hrs. Harvested by centrifuging at 5000 RPM for 5 minutes, the cells were inoculated into the fresh peach nectar. Samples before and after PEF treatments were collected for further analyses. The samples were plated on violet red brilliant agar plates and then incubated at 35°C for 48 hr. Color, pH, etc. were measured accordingly. PEF treatment at 35 kV/cm electric field strength for 30 microseconds with bipolar square waveform resulted in about 7-log reduction in E. coli 8739 population. Higher electric field strength results in a higher inactivation effect. Increased treatment time does increase the inactivation effects. Increasing treatment temperature from 10°C to 40°C did not show significant change in the inactivation efficacy. No significant change in pH, color and other main attributes of peach nectar was observed before and after PEF treatment. This work demonstrates that PEF cold pasteurization may be an effective technology for peach nectar processing to reduce microbial loads and to protect sensory attributes such as flavor and color.
Session 91E, Nonthermal Processing: Nonthermal processing of foods
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