Green tea extract assisted low-temperature pasteurization to inactivate enteric viruses in juices

Abstract

The current popularity of minimally processed foods is an opportunity for natural antimicrobial agents to be combined with mild heat treatments to act synergistically in reducing viral foodborne pathogens. Viral inactivation by heat-treatments (at 25, 40, 50 and 63 °C for 30 min) combined with aged green tea extract (aged-GTE) was initially evaluated in phosphate buffered saline (PBS) against murine norovirus (MNV-1) and hepatitis A virus (HAV) by cell culture, and against human norovirus by in situ capture RT-qPCR. The combination of aged-GTE and heat treatment at 50 °C for 30 min exerted strong antiviral activity, reducing by more than 5 log MNV-1 infectivity in PBS.Heating at 40 ºC for 30 min reduced the binding of norovirus to porcine gastric mucine (PGM) to 41.5% and the addition of aged-GTE further decreased the binding to 4.7%.Additionally, the reduction of MNV-1 and HAV infectivity was investigated in two different types of juices exposed to mild heat treatments alone, and combined with aged-GTE. The addition of aged-GTE increased to more than 4 log the inactivation of MNV-1 in juices exposed to 50 ºC for 30 min. However, this synergistic effect of aged-GTE combined with heat treatments was not observed for HAV in any of the juices. Aged-GTE, then, could be considered as an additional control measure to improve the food safety of mild heat pasteurized juices.

Antiviral Potential of Plants against Noroviruses

“…It was also found that the addition of aging GTE to mildly heat-treated juices increased the deactivation of MNV-1 by over 4 logs. The synergistic action of both antiviral agents reduced the infectivity of MNV-1, which confirms the hypothesis that GTE can be used as an additional control agent that improves food safety [ 99 ].…”

“…The antiviral activity of plant metabolites is the subject of many scientific studies [ 23 , 41 , 53 , 54 , 55 , 56 , 57 , 58 , 59 , 60 , 61 , 62 , 63 , 64 , 65 , 66 , 67 , 68 , 69 , 70 , 71 , 72 , 73 , 74 , 75 , 76 , 77 , 78 , 79 , 80 , 81 , 82 , 83 , 84 , 85 , 86 , 87 , 88 , 89 , 90 , 91 , 92 , 93 , 94 , 95 , 96 , 97 , 98 , 99 , 100 , 101 , 102 , 103 , 104 , 105 ,…”

“…MNVs were completely deactivated by GTE at 37 °C [ 46 ]. Based on subsequent research results, it was also found that the accumulation of catechin derivatives during the storage of the mature green tea extract (aged-GTE) (24 h at 25 °C) resulted in a significant increase in the antiviral activity of GTE against human GII.4 norovirus under laboratory conditions [ 98 , 99 ]. The results obtained by Falco et al [ 99 ] indicate a potential use of the synergistic antiviral effect of aged-GTE, and gentle heat treatment (50 °C, 30 min) to ensure food safety, mainly in fruit juices.…”

Impact of Theaflavins-Enriched Tea Leaf Extract TY-1 against Surrogate Viruses of Human Norovirus: In Vitro Virucidal Study

“…As there are no currently available disinfectants that can remove HuNoV inside the bivalve shellfish, it may be possible to consider investigating the application of TY-1 in this context. The results reported by Falco et al [ 52 ] suggested the possible synergistic virucidal activity of a gentle heat treatment with plant-derived components such as TY-1, which may contribute to controlling food-borne HuNoV transmission. Overall, further studies aiming to identify whether TY-1 can effectively inactivate HuNoV in bivalve shellfish foods, and on high-touch locations and food contact surfaces, are warranted.…”

Natural Products and Their Potential Anti-HAV Activity

“…In turn, the studies by Falcóa et al [ 100 ] used the HAV HM-175/18f strain (ATCC VR-1402) and FRhK-4 cells. GTE (Naturex SA, Avignon, France) was dissolved in PBS (pH 7.2) and incubated for 24 h (aged GTE) to increase antiviral activity.…”