Masters Theses

Date of Award

5-2011

Degree Type

Thesis

Degree Name

Master of Science

Major

Food Science and Technology

Major Professor

Doris H. D'Souza

Committee Members

Federico M. Harte, Gina M. Pighetti

Abstract

Human noroviruses (HNoV) have been implicated in gastrointestinal outbreaks associated with fruits and juices. Virus survival studies and non-thermal inactivation technologies that maintain nutritional and sensory attributes of juices are needed. In the absence of culturable HNoV, cultivable murine norovirus (MNV-1) and feline calicivirus (FCV-F9) surrogates are used. This study aimed to (1) determine HNoV surrogate survival in juices (orange juice (OJ) and pomegranate juice (PJ)), juice blends (OJ-PJ), and milk over 21 days at refrigeration; (2) determine high pressure homogenization (HPH) effects alone on HNoV surrogates in milk, OJ, OJ-PJ blend or with an emulsifier (lecithin) for FCV-F9 and MNV-1 in milk and OJ; (3) determine HNoV surrogate survival in blueberry juice (BJ) after 21 days at refrigeration and HPH inactivation. Our results showed no reduction of MNV-1 after 21 days in OJ and milk, but 1.4 log reduction in PJ and complete reduction after 7 days in OJ-PJ. FCV-F9 was completely reduced after 14 days in OJ and PJ; by ~3 logs after 21 days in milk, and completely reduced after 1 day in OJ-PJ. MS2 was reduced by ~1.28 log in OJ and <1 log in>milk, PJ, or OJ-PJ after 21 days. At 300 MPa HPH, FCV-F9 in milk and OJ was reduced by ≥4 log10PFU/ml and MNV-1 in milk by ~1.3 log and negligibly in OJ. In PJ-OJ, FCV-F9 was completely reduced at 250 MPa. At 300 MPa in PJ-OJ, MNV-1 and MS2 showed 1.78 and 4.1 log10PFU/ml reduction. FCV-F9 showed complete reduction in OJ or milk combined with lecithin at 300 MPa. Thus, juice-blends and lecithin aid in viral reduction by HPH. In BJ, FCV-F9 was undetectable after 1 day while MNV-1showed minimal reduction after 21 days and MS2 was undetectable after 7 days. FCV-F9, MNV-1, and MS2 survived after 21 days in PBS. FCV-F9 and MS2 showed complete reduction after minimal homogenization pressures in BJ. Overall, milk was the most protective media for HPH and virus survival. These viral survival patterns that aid in foodborne viral transmission can be used in quantitative viral risk assessment studies along with HPH to prevent/control virus outbreaks.

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