Publication
Impact of pH on microbial behaviour in watermelon juice preservation by hyperbaric storage at room temperature
| Summary: | The systematic effect of pH (4.00, 5.00 and 6.50) on hyperbaric storage (HS, 25-100 MPa) at uncontrolled room temperature (RT, 18-23 °C) for up to 28 days was studied for the first time, using watermelon juice (WJ) as a case-study, due to its high perishability, focusing on Escherichia coli and Saccharomyces cerevisiae’s behaviour, along with RT and refrigerated controls at atmospheric pressure for comparison. Results showed that HS at RT could control E. coli and S. cerevisiae’s growth and that, during storage, inactivation also occurred, often reaching reductions over 5 log CFU/mL. HS’ effect varied according to the microorganism, the juice’s pH and storage pressure, and inactivation was observed regardless the pH and pressure level tested for both microorganisms. Higher pressures increased the inactivation rates of both microorganisms, while pH’s impact depended on the microorganism. E. coli showed greater inactivation at pH 4.0 whereas S. cerevisiae exhibited comparable or slightly higher reductions at pH 6.50. Microbial inactivation was well described by both first-order and Weibull kinetic models, with the latter generally providing a better fit. At pH 4.00, S. cerevisiae obtained lower zp-values than E. coli. This work showed HS’ potential for food preservation regardless of the pH (despite being influenced by it), without needing temperature control, which may lower energy costs and greenhouse gas emissions, being potentiality environmentally friendlier. |
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| Main Authors: | Lima, Vasco |
| Other Authors: | Pinto, Carlos A.; Saraiva, Jorge A. |
| Subject: | Food preservation Food safety Shelf-life extension Microbial growth control and inactivation Escherichia coli Saccharomyces cerevisiae Inactivation kinetics |
| Year: | 2026 |
| Country: | Portugal |
| Document type: | research article |
| Access type: | open access |
| Associated institution: | Universidade Católica Portuguesa |
| Language: | English |
| Origin: | Veritati - Repositório Institucional da Universidade Católica Portuguesa |
| Summary: | The systematic effect of pH (4.00, 5.00 and 6.50) on hyperbaric storage (HS, 25-100 MPa) at uncontrolled room temperature (RT, 18-23 °C) for up to 28 days was studied for the first time, using watermelon juice (WJ) as a case-study, due to its high perishability, focusing on Escherichia coli and Saccharomyces cerevisiae’s behaviour, along with RT and refrigerated controls at atmospheric pressure for comparison. Results showed that HS at RT could control E. coli and S. cerevisiae’s growth and that, during storage, inactivation also occurred, often reaching reductions over 5 log CFU/mL. HS’ effect varied according to the microorganism, the juice’s pH and storage pressure, and inactivation was observed regardless the pH and pressure level tested for both microorganisms. Higher pressures increased the inactivation rates of both microorganisms, while pH’s impact depended on the microorganism. E. coli showed greater inactivation at pH 4.0 whereas S. cerevisiae exhibited comparable or slightly higher reductions at pH 6.50. Microbial inactivation was well described by both first-order and Weibull kinetic models, with the latter generally providing a better fit. At pH 4.00, S. cerevisiae obtained lower zp-values than E. coli. This work showed HS’ potential for food preservation regardless of the pH (despite being influenced by it), without needing temperature control, which may lower energy costs and greenhouse gas emissions, being potentiality environmentally friendlier. |
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