Thesis
Equivalent processing for pasteurization of a juice blend by selected nonthermal technologies
Washington State University
Master of Science (MS), Washington State University
12/2019
DOI:
https://doi.org/10.7273/000004192
Handle:
https://hdl.handle.net/2376/125246
Abstract
A novel approach for food pasteurization provides an opportunity to develop pathogen free yet fresh-like food products. Nonthermal technologies such as high pressure processing (HPP), pulsed electric fields (PEF), and ultrasound (US) are promising tools as alternatives to thermal pasteurization. The objectives of this study were 1) to identify equivalent processing conditions for pasteurization of a pineapple-coconut (PC) juice blend using nonthermal technologies and 2) to evaluate and compare quality attributes of the juice blend under equivalent processing conditions. HPP, PEF, and US in combination with selected food preservation factors were studied in this research to reduce the number of E. coli and L. innocua cells by 5-log CFU/mL in the PC juice blend. The combined treatment of HPP with pH 4 and nisin (600 MPa, 5 min, 75-ppm of nisin) achieved 5-log reduction. The synergistic combination of PEF with pH 4, nisin and mild heat (18 kV/cm, 588 Hz, 50-ppm of nisin, 40°C) exhibited the greatest effectiveness in reaching the 5-log reduction. Thermosonication (120 [mu]m, 10 min, 45°C) also showed a synergistic effect resulting in 5-log reduction of the targeted microorganisms. The effects of HPP, PEF and US with the selected hurdle factors on the quality characteristics of the pasteurized juice blend were determined and compared. No significant changes were observed on the physico-chemical attributes of the PC juice blend by HPP, but there were significant impacts on color and ascorbic content by PEF and US (p < 0.05). Mathematical models were used to predict the inactivation kinetics of E. coli and L. innocua in the PC juice blend treated by the different treatments. The Weibull and biphasic models exhibited the best correlation for HPP inactivation curves. The Weibull model showed a good fit for inactivation kinetics by PEF. Double Weibull and biphasic models showed good agreement to E. coil inactivation kinetics by thermosonication. The first order, double Weibull and biphasic models were helpful to predict the inactivation kinetic of L. innocua by thermosonication. The determination of the three nonthermal technologies in terms of food safety and quality attributes demonstrated the promises and challenges of each technology. The results obtained in this study will support in developing and designing processes using nonthermal technologies.
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Details
- Title
- Equivalent processing for pasteurization of a juice blend by selected nonthermal technologies
- Creators
- Ga Young Shin
- Contributors
- Gustavo V Barbosa-Canovas (Advisor) - Washington State University, Biological Systems Engineering, Department of
- Awarding Institution
- Washington State University
- Academic Unit
- Biological Systems Engineering, Department of
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University
- Identifiers
- 99900896439401842
- Language
- English
- Resource Type
- Thesis