Masters Theses

Date of Award

5-2019

Degree Type

Thesis

Degree Name

Master of Science

Major

Food Science

Major Professor

Mark Morgan

Committee Members

Doris H. D'Souza, Bonnie H. Ownley

Abstract

Botrytis cinerea (B. cinerea) is a soil borne fungus that produces airborne spores and causes serious damage to crops. Inactivation of B. cinerea has become a difficult challenge as it has become more resistant to fungicides, disinfectants, thermal, and non-thermal inactivation techniques, such as ultraviolet light and pulsed white light. Chlorine dioxide gas (ClO2) has proven to have promising and effective antifungal properties. The aim of this study is to determine the inactivation kinetics (D-value and z-value) of B. cinerea on stainless steel coupons (SS) using very low concentrations of chlorine dioxide gas, and to determine the survival rate of B. cinerea on stainless steel coupons. The D-value and z-value can be used to determine the appropriate combination of gas concentration and treatment time to achieve the desired log reductions of B. cinerea. Botrytis cinerea at initial levels of ~ 6 log spores/ml on SS coupons was treated with 36, 60, and 90 ppmv (0.1, 0.17, and 0.25 mg/l respectively), of ClO2 gas for 15, 30, 45, and 60 min; 6, 13, 20, and 26 min and 4, 8, 16, and 24 min, respectively. The first order linear model D-values for 36, 60, and 90 ppmv were 22.34 ± 2.53, 10.18 ± 0.75, and 10.65 ± 0.44 min respectively with a z-value of 175.43 ± 0.19 ppmv. The D-value decreased as the ClO2 gas concentration increased. The survival analysis determines the efficiency of B. cinerea to survive on the surface of the SS coupons without any added nutrients. It is important to determine the survival rate of B. cinerea during food processing or on food contact surfaces.In this study, the survival rate decreased from 60% on Day 3 to 17% on Day 4. Also, in this study, B. cinerea survived on the coupons without any nutrients for 7 days, which was the limit of testing.

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