Status : Verified
| Personal Name | Ancog, Ma. Mikhaila |
|---|---|
| Resource Title | Effects of implicit microbial physiology and intrinsic juice properties on ultraviolet-C susceptibility of listeria monocytogenes |
| Date Issued | 15 June 2016 |
| Abstract | The study was conducted to evaluate the effects of prior exposure to physicochemical stress conditions on the susceptibility of Listeria monocytogenes to ultraviolet-C inactivation in coconut water and apple juice.Individual strains of the microorganism were exposed to gradual acidification (final pH 4.5), desiccation stress (aw = 0.96), heat stress (40 ºC), and their combinations before homogenization. Inoculated, turbulent-flowing juice samples (V = 250 ml) underwent UV-C inactivation.Inactivation curves displayed log-linear curves for all physicochemical ecologies. Unit time (D) and dose (DUV-C) needed to reduce microbial load by 1 log (90%) varied across physicochemical stress conditions, per juice system. Greatest resistance against UV-C for coconut water was observed in cells with previous exposure to acid-heat stress (D-value 21.95 s, DUV-C 37.32 mJ/cm2), acid-desiccation stress for apple juice (D-value 427.51 s, DUV-C 726.76 mJ/cm2).These values differed significantly (p > 0.05) with other stress conditions especially for systems that exhibited least resistance to UV-C: heatstressed (D-value 14.94 s, DUV-C 25.40 mJ/cm2) for coconut water, acid-heat-stressed (Dvalue 175.77 s, DUV-C 298.81 mJ/cm2) for apple juice.A D ratio (D stressed/D control) > 1.00 indicated increased resistance against UV-C inactivation. Cells with the lowest D-values were the only ones unable to exhibit heterologous adaptation. D and DUV-C values for coconut water and apple juice varied significantly, indicating that, in addition to implicit microbial physiology, intrinsic suspending medium properties affect efficacy of UV-C treatment. |
| Degree Course | Bachelor of Science in Food Technology |
| Language | English |
| Keyword | Apple juice--Microbiology; Coconut water--Microbiology |
| Material Type | Thesis/Dissertation |
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Access Permission : Limited Access