South Korean Study Validates That SARS-CoV-2 Can Remain Viable On Foods For A Long Time Depending On Storage Temperatures
A new study by researchers from the Department of Food and Nutrition, College of Biotechnology and Natural Resources, Chung-Ang University-South Korea has found that the SARS-CoV-2 coronavirus can remain viable on many food products for a long time depending on the storage temperatures.
The study findings showed that at freezing temperatures, SARS-CoV-2 remained viable for up to four weeks on the tested food items.
Thailand Medical News
had previously already covered various studies that SARS-CoV-2 could also be food borne!
This new study aimed to evaluate the viability of SARS-CoV-2 on food matrices, depending on storage temperature, and inactivate the virus contaminating food using disinfectants.
In the study, two different SARS-CoV-2 strains (L and S types) were used to contaminate lettuce, chicken, and salmon, which were then stored at 20,4 and −40 °C.
The study findings showed that the half-life of SARS-CoV-2 at 20 °C was 3–7 h but increased to 24–46 h at 4 °C and exceeded 100 h at −40 °C. SARS-CoV-2 persisted longer on chicken or salmon than on lettuce.
The study also showed that treatment with 70% ethanol for 1 min inactivated 3.25 log reduction of SARS-CoV-2 inoculated on lettuce but not on chicken and salmon. ClO2 inactivated up to 2 log reduction of SARS-CoV-2 on foods. Peracetic acid was able to eliminate SARS-CoV-2 from all foods.
The virucidal effect of all disinfectants used in this study did not differ between the two SARS-CoV-2 strains; therefore, they could also be effective against other SARS-CoV-2 variants.
The study findings demonstrated that the viability of SARS-CoV-2 can be extended at 4 and −40 °C and peracetic acid can inactivate SARS-CoV-2 on food matrices.
The study findings were published in the peer reviewed journal: Food Microbiology.
The key highlights of the study findings were:
-The viability of SARS-CoV-2 at −40 °C was increases 30 times rather than at 20 °C.
-Peracetic acid at twice the recommended concentration inactivated SARS-CoV-2 on food matrices.
-Ethanol and chlorine dioxide were not effective to inactivate SARS-CoV-2 on food matrices.
The SARS-CoV-2 coronavirus, the causative pathogen of the COVID-19 pandemic, is a betacoronavirus that primarily spreads through respiratory droplets and aerosols.
It is believed that the seafood market in Wuhan, China, is the initial source of SARS-CoV-2. About 55% of China's COVID-19 cases detected in December 2019 were associated with this market.
Numerous studies have linked other COVID-19 outbreaks with virus-contaminated frozen foods and food packaging materials. These observations have raised global concern over food safety during the pandemic.
The study team assessed the viability of SARS-CoV-2 on three food items stored at different temperatures. They also determine the potency of three disinfectants in inactivating the virus on food items.
For the study, three food items were selected for the viral viability test: lettuce, chicken, and salmon.
These food items were then contaminated with SARS-CoV-2 and stored at 20 °C (room temperature), 4 °C (refrigerated), and -40 °C (frozen).
The study team selected food-grade ethanol, chlorine dioxide, and peracetic acid as disinfectants for the virus inactivation test.
Except for ethanol, which was used at 30%, 50%, and 70% concentrations, the other two disinfectants were used at three different concentrations, including the recommended concentration and half and twice the recommended concentration.
Interestingly, the lowest viability of SARS-CoV-2 on food items was observed at room temperature. No detectable viral titers were obtained on any food items after 48 hours of contamination. Among various food items, the highest half-life of SARS-CoV-2 was observed on salmon, followed by chicken and lettuce.
However, a significant induction in viability was observed at 4 °C. The highest viability at 4 °C was observed on salmon, where SARS-CoV-2 remained infectious for up to 14 days following contamination. On lettuce and chicken, SARS-CoV-2 remained detectable for up to 10 days.
The highest half-life was observed on salmon, followed by chicken and lettuce. A five- to nine-fold induction in the virus half-life was observed at 4 °C compared to that observed at room temperature.
Alarmingly, at freezing temperatures, SARS-CoV-2 remained viable for up to four weeks on the tested food items. Significant induction of more than 30-fold in the viral half-life was also observed on each food item.
The study findings also showed that short-term exposure of one minute to 70% ethanol effectively inactivated SARS-CoV-2 on lettuce but failed to do the same on chicken and salmon. The inactivation of the virus on chicken and salmon was observed after a five-minute exposure to 70% ethanol.
Also, no significant virus-inactivating effect was observed for chlorine dioxide at all tested concentrations and exposure periods. At the highest concentration and exposure time, chlorine dioxide was found to reduce viral infectivity to a certain level only on lettuce.
However, in contrast to chlorine dioxide, peracetic acid showed significantly higher potency in inactivating SARS-CoV-2 on food items. Specifically, peracetic acid completely inactivated the virus at twice the recommended concentration on each tested food item.
Peracetic acid (PAA) is produced by combining acetic acid (vinegar) and hydrogen peroxide. The result is a peroxide version of acetic acid (vinegar) that has a very distinctive and a pungent vinegary smell.
The United States Environmental Protection Agency first registered peracetic acid as an antimicrobial in 1985 for indoor use on hard surfaces. Use sites include agricultural premises, food establishments, medical facilities, and home bathrooms. Peracetic acid is also registered for use in dairy and cheese processing plants, on food processing equipment, and in pasteurizers in breweries, wineries, and beverage plants. It is also applied for the disinfection of medical supplies, to prevent biofilm formation in pulp industries, and as a water purifier and disinfectant. Peracetic acid can be used as a cooling tower water disinfectant, where it prevents biofilm formation and effectively controls Legionella bacteria. A trade name for peracetic acid as an antimicrobial is Nu-Cidex.
Corresponding author, Changsun Choi from Department of Food and Nutrition, School of Food Science and Technology-Chung-Ang University told Thailand Medical News, “The study findings indicate that the viability of SARS-CoV-2 on food items increases more than 30 times at freezing temperatures compared to room temperature. In addition to storage temperature, viral viability also depends on the type of food.”
The two viral variants studied here, included SARS-CoV-2 S and SARS-CoV-2 L. SARS-CoV-2 L shows higher viability on food items than SARS-CoV-2 S. However, peracetic acid was identified as a highly effective disinfectant that can completely inactivate both viral variants on food items.
It was also noted that the highest potency of peracetic acid was observed at two times higher than the recommended concentration. However, no antiviral efficacy of chlorine-based disinfectants was observed in the study.
Health authorities should also focus on possible contamination of imported frozen and seafood products and also how such products are retailed with proper guidelines for the public as to how to manage and consume foodstuffs to prevent getting infected with the SARS-CoV-2 virus.
For the latest on Food Borne SARS-CoV-2
, keep on logging to Thailand Medical News