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Title

EFFECT OF NOVEL SANITIZERS IN COMBINATION WITH HIGH-POWER-ULTRASOUND ON MNV-ION ROMAINE LETTUCE

Creator

Zeng, Jin

Date

2016, 2016-05

Description

Human norovirus is a leading cause of foodborne outbreaks around the world especially in fresh-cut products like romaine lettuce. Traditional...
Show moreHuman norovirus is a leading cause of foodborne outbreaks around the world especially in fresh-cut products like romaine lettuce. Traditional sanitizers such as sodium hypochlorite have been used in food industry to prevent contamination; however there are certain issues such as residuals and toxicity. Novel organic sanitizers have been developed and most of them have been proved not effective on human norovirus. High- Power-Ultrasound (HPU) has a potential to improve effectiveness of sanitizers for washing of fresh-cut produce. As a novel technology, HPU is a non-thermal processing that can enhance inactivating microorganisms in food. In the present study, we have systematically investigated the effect of sanitizers, Chico-wash, ProduceShield, Tsunami 100, EatCleaner and chlorine on human norovirus surrogate and the effect of HPU to enhance viral inactivation. For washing study, romaine lettuce leaves were cut into 5x5 cm2 pieces and spotinoculated with approximately 7 log PFU/ml of MNV-1. The leaves were washed for 60s, 90s, and 120s using various sanitizer concentrations. After washing, leaves were transferred into a stomach bag that contained 20ml of Dulbecco's modified eagle medium (DMEM) or phosphate buffer solution (PBS) containing 0.5M sodium thiosulfate to neutralize the sanitizers. Viruses were extracted by stomaching and recovered from the samples and quantified by viral plaque assay. Water wash without sanitizer was used as a negative control. For water wash, 1.1± 0.1 log PFU/g, 1.3 ± 0.1 log PFU/g and 1.3 ± 0.1 log PFU/g reduction were observed respectively under 60s, 90s and 120s washing.For 20% Chico-wash, under three different time intervals, MNV-1 reductions of 1.2 ± 0.1 log PFU/g, 1.1± 0.1 log PFU/g and 1.2 ± 0.2 log10 PFU/g were observed respectively. While for ProduceShield, at 20% concentration level, 1.5 log PFU/g, 1.6 log PFU/g and 1.6 log PFU/g reduction were observed respectively. For Tsunami 100, leaves were washed for 60s at different concentrations of 20, 40, 60, 80 and 100 ppm, the reduction of MNV-1 was 2.1 ± 0.2, 2.9 ± 0.3, 3.2 ± 0.3, 3.7 ± 0.2 and 3.7 ± 0.2 log PFU/g, respectively, on the surface of lettuce leaves. In HPU study, a high power ultrasound was introduced into washing step in combination with Tsunami 100 at concentrations of 20, 40, 60, 80, 100 ppm. The reduction of MNV-1 was 2.7 ± 0.3, 2.9 ± 0.5, 3.3 ± 0.7, 3.6 ± 0.7 and 3.8 ± 0.5 log10 PFU/g, respectively. For EatCleaner, lettuce leaves were washed for 60s and the reduction of MNV-1 was 1.9 ± 0.1 log10 PFU/g.The results suggest that Chico-wash and ProduceShield were not effective on removing MNV-1 from romaine lettuce while EatCleaner was effective. Tsunami 100 was effective on MNV-1. One-way ANOVA shows that introducing HPU could enhance MNV-1 inactivation at low Tsunami 100 concentration.
M.S. in Food Safety and Technology, May 2016
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