Stability of SARS-CoV-2 as consequence of heating and microwave processing in meat products and bread

The new severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that was first found in 2019 in Wuhan, China, caused coronavirus disease 2019 (COVID-19). It then spread worldwide rapidly, causing the 2019-2020 coronavirus pandemic. To date, it has been indicated that various transmission ways might be participated in outbreaks of COVID-19. Among these, food products, whether raw or processed, might be carriers for SARS-CoV-2. Therefore, this study was aimed to evaluate the effect of cooking and microwave process of meat products and bread on the stability of SARS-CoV-2. In this regard, sausages and hamburger as meat products and toast bread were inoculated with a viral load of 5.70 log fifty percent tissue culture infective dose (TCID50)/mL in order to create a simulated cross-contamination condition. The results showed that frying of hamburger at 225ºC for about either 6 or 10 min resulted in complete inactivation of SARS-CoV-2. Furthermore, a 5-log decrease in SARS-CoV-2 load was observed in sausages as a consequence of cooking process at 78ºC for either 20 or 30 min. Additionally, the effect of microwave oven at power of 630 watt on stability of SARS-CoV-2 showed that exposing toast bread for either 30 s or 1 min in this power led to a 5-log decrease in SARS-CoV-2 load in the toast bread.

Stability of severe acute respiratory syndrome coronavirus 2 in dairy products

The present investigation was performed to determine the stability of severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) under several industrial processing situations in dairies, including pasteurization, freezing, and storage in acidic conditions. Ten treatments were selected, including high‐temperature short‐time (HTST)‐pasteurized low‐fat milk, low‐temperature long‐time‐pasteurized low‐fat milk, extended shelf life (ESL)‐pasteurized low‐fat milk, HTST‐pasteurized full‐fat milk, LTLT‐pasteurized full‐fat milk, ESL‐pasteurized full‐fat milk, pasteurized cream, ice cream frozen and stored at −20 or −80°C, and Doogh (as a fermented milk drink with initial pH < 3.5) refrigerated for 28 days. The viral particles were quantified by RT‐PCR methodology. Besides, the virus infectivity was assessed through fifty‐percent tissue culture infective dose (TCID₅₀) assay. These products were seeded with a viral load of 5.65 log TCID₅₀/mL as a simulated cross‐contamination condition. Pasteurization techniques were sufficient for complete inactivation of the SARS‐CoV‐2 in the most dairy products, and 1.85 log TCID₅₀/mL virus reduction in full‐fat milk (fat content = 3.22%). Freezing (either −20°C or −80°C) did not result in a virally safe product within 60 days of storage. Storage at high acidic conditions (initial pH < 3.5) completely hampered the viral load at the end of 28 days of refrigerated storage. This research represents an important practical achievement that the routine HTST pasteurization in dairies was inadequate to completely inactivate the viral load in full‐fat milk, probably due to the protective effect of fat content. Furthermore, freezing retain the virus infectivity in food products, and therefore, relevant contaminated foods may act as carriers for SARS‐CoV‐2.

Development and characterization of a novel edible film based on Althaea rosea flower gum: Investigating the reinforcing effects of bacterial nanocrystalline cellulose

Althaea rosea flowers were used to procure the gum (ARG) needed for film preparation. Pretest studies suggested 1.5% ARG + 50% glycerol as optimum for film preparation. The reinforcement impact of 3, 5, and 8 wt% bacterial nanocrystalline cellulose (BNC) incorporation (based on the dry weight of ARG) was investigated on the structural, mechanical, physical, thermal, optical, morphological, and barrier properties of films. The Results suggested that increasing the BNC concentration until a certain level (5 wt% BNC) could improve the latter properties. However, at higher concentration (8 wt% BNC), cellulose nanoparticles tended to agglomerate, which led to the impairment of some of those properties, especially barrier properties. According to AFM and SEM results, BNC addition increased surface roughness and coarseness. All BNC-loaded films showed better functions compared to control sample (0 wt% BNC) and the film containing 5 wt% BNC was suggested as the optimum film.