15B-5 |
High pressure destruction kinetics of common spoilage microorganisms in single strength and concentrated orange juice |
S. BASAK1, H. S. Ramaswamy1, and G. Piette2. (1) Dept. of Food Science, McGill Univ., Macdonald Campus, 21111 Lakeshore Rd., Sainte-Anne-de-Bellevue, QC H9X 3V9, Canada, (2) Agriculture & Agri-Food Canada, 3600 Casavant Blvd. W., Sainte-Hyacinthe, QC J2S 8E3, Canada Currently thermal pasteurization is considered to be the most common method for orange juice processing and preservation. This traditional method extends the shelf life with assured safety, but may have a detrimental effect on wholesomeness, aroma and flavor. Therefore, preservation technologies that offer prolong self-life without sacrificing the quality attributes of juices, are currently under investigation. In this regard, high pressure technology represents a novel method of food preservation. This emerging technology is gaining significant importance because its ability to destroy microorganisms, inactivate enzymes and denature of protein without deteriorating sensory and nutritional attributes. The objective of this research was to investigate the high pressure destruction kinetics of S. cereviseae and L. mesenteroids as influenced in single and concentrated orange juice. High pressure (HP) destruction of L. mesenteroids and S. cereviseae in single strength and concentrated orange juice by high hydrostatic pressure treatment (100-400 MPa) was evaluated at selected pressures (100-400 MPa) and holding times (0 – 120 min) at 20oC. Kinetic analysis of the microbial survivor data was evaluated based on the biphasic destruction behavior consisting of (i) instantaneous pressure kill (IPK) effect due to pressurization-depressurization with no hold-time (pressure-pulse) and (ii) subsequent semi-logarithmic destruction during the pressure hold-time. For both microorganisms and juices, IPK was enhanced at higher pressure level and was more pronounced with S. cereviseae than L. mesenteroids. During the pressure-hold, the associated D values decreased with an increase in pressure. However S. cereviseae had higher D values suggesting a higher pressure resistance than L. mesenteroids in concentrated juice. Pressure dependency of kinetic parameters was well described by the PDT model with associated zp values of 137 and 135 MPa in single strength orange juice and 251 and 287 MPa in concentrate, respectively, for L. mesenteroids and S. cereviseae. These studies suggest that high pressure processing might be an efficient nonthermal alternative for improving the quality and shelf life of single strength as well as concentrated orange juices.
Session 15B, Citrus
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