Inactivation of Escherichia coli ATCC 25922 and Saccharomyces cerevisiae IMR-R-L 962 in grapefruit Citrus paradisi (Macf.) juice by UV-C light : changes in bioactive compounds and quality characteristics

La Cava E., . and Sgroppo S., . Inactivation of Escherichia coli ATCC 25922 and Saccharomyces cerevisiae IMR-R-L 962 in grapefruit Citrus paradisi (Macf.) juice by UV-C light : changes in bioactive compounds and quality characteristics. pp. 580-588. ISSN 2231-7546

The viability of UV-C treatment (0.0-2.36 J/cm) at 254 nm as a non-thermal preservation process for grapefruit juice on microbial inactivation the organic acids and individual flavonoids as well as the quality characteristics (pH Brix titratable acidity colour total phenolics and antioxidant capacity) was evaluated. Additionally pectin methylesterase (PME) activity was also measured. The effects of UV-C on microbial inactivation were assessed by kinetic studies on the inactivation of inoculated grapefruit juice with one strain of Escherichia coli ATCC 25922 and one strain of Saccharomyces cerevisiae IMR-R-L 962. The suitability of Weibull distribution and modified Gompertz models was analysed to characterise the UV-C inactivation kinetics for E. coli and S. cerevisiae in freshly squeezed grapefruit juice. Likewise the changes after UV-C treatment in citric (CA) malic (MA) ascorbic (AA) and tartaric (TA) acids as well as naringin (NAR) hesperidin (HES) and neohesperidin (NEO) were quantified by HPLC whereas the total phenolics and antioxidant capacity (DPPH and ABTS) were quantified by spectrophotometric methods. Nonlinear inactivation curves were successfully fitted with Weibull-type and modified Gompertz models. However the Gompertz model allowed a better fit and more accurate estimation of the parameters. UV-C treatment at 1.83 J/cm achieved a 5.18 0.01 and 2.7 0.15 log CFU/mL reduction in E. coli and S. cerevisiae respectively whereas no significant changes occurred in CA MA TA NAR HES NEO total phenolics ABTS pH Brix titratable acidity and colour of the grapefruit juices (p0.05). However PME was partially inhibited and the AA level and DPPH decreased significantly after treatment with losses up to 15.9 and 8 (at 1.83 J/cm) respectively which were associated with the UV-C dose intensity.

Full text available from: Official URL: http://www.ifrj.upm.edu.my/25%20(02)%202018/(18).p...

Abstract

The viability of UV-C treatment (0.0-2.36 J/cm) at 254 nm as a non-thermal preservation process for grapefruit juice on microbial inactivation the organic acids and individual flavonoids as well as the quality characteristics (pH Brix titratable acidity colour total phenolics and antioxidant capacity) was evaluated. Additionally pectin methylesterase (PME) activity was also measured. The effects of UV-C on microbial inactivation were assessed by kinetic studies on the inactivation of inoculated grapefruit juice with one strain of Escherichia coli ATCC 25922 and one strain of Saccharomyces cerevisiae IMR-R-L 962. The suitability of Weibull distribution and modified Gompertz models was analysed to characterise the UV-C inactivation kinetics for E. coli and S. cerevisiae in freshly squeezed grapefruit juice. Likewise the changes after UV-C treatment in citric (CA) malic (MA) ascorbic (AA) and tartaric (TA) acids as well as naringin (NAR) hesperidin (HES) and neohesperidin (NEO) were quantified by HPLC whereas the total phenolics and antioxidant capacity (DPPH and ABTS) were quantified by spectrophotometric methods. Nonlinear inactivation curves were successfully fitted with Weibull-type and modified Gompertz models. However the Gompertz model allowed a better fit and more accurate estimation of the parameters. UV-C treatment at 1.83 J/cm achieved a 5.18 0.01 and 2.7 0.15 log CFU/mL reduction in E. coli and S. cerevisiae respectively whereas no significant changes occurred in CA MA TA NAR HES NEO total phenolics ABTS pH Brix titratable acidity and colour of the grapefruit juices (p0.05). However PME was partially inhibited and the AA level and DPPH decreased significantly after treatment with losses up to 15.9 and 8 (at 1.83 J/cm) respectively which were associated with the UV-C dose intensity.

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Item Type:	Article
AGROVOC Term:	Escherichia coli
AGROVOC Term:	Saccharomyces cerevisiae
AGROVOC Term:	Grapefruits
AGROVOC Term:	Grape juice
AGROVOC Term:	Fruit juices
AGROVOC Term:	Microbial culture
AGROVOC Term:	Organic acids
AGROVOC Term:	Flavonoids
AGROVOC Term:	Quality
AGROVOC Term:	Processing quality
Depositing User:	Ms. Suzila Mohamad Kasim
Last Modified:	24 Apr 2025 06:29
URI:	http://webagris.upm.edu.my/id/eprint/24683

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