Table 4.
Food processes, virus inactivation factors, and resulting risk of the product if viruses are present before processinga
| Process | Example of food product | Virus inactivation (log10) | Risk of infection of consumer if viruses are present before processingb | Likelihood of presence before processingb | Remarks |
|---|---|---|---|---|---|
| Thermal treatments | |||||
| Boiling at 100 °C | Any liquid food (e.g. milk) or solid food boiled in water | HAV and PV>4 (Hollinger and Ticehurst, 1996) | Negligible | Unlikely | Likelihood of presence depending on food; kinetic data lacking |
| 60 °C, 30 min (liquids or solid foods) | HAV<2 (Hollinger and Ticehurst, 1996) or HAV>4 Croci et al., 1999, Millard et al., 1987 PV<2 (Nissen et al., 1996) NoV: incomplete inactivation (Dolin et al., 1972) | Medium | Inactivation in solid foods lower than in liquids; dependent on fat and protein content | ||
| Pasteurisation of solid foods (70 °C or equivalent, 2 min) | Paté and other cooked meats | HAV<2 (Millard et al., 1987) FeCV>3 (Doultree et al., 1999) | Medium | Unlikely | Inactivation dependent on fat and protein content |
| Pasteurisation of liquids and immediate packing (e.g. HTST 71.7 °C for 15 sec) | Milk, ice cream | HAV<2 (Bidawid et al., 2000a) | Medium | Unlikely | Inactivation dependent on fat and protein content |
| UHT and aseptic filling (>120 °C) | Long-life milk, other dairy products | Negligible | Unlikely | ||
| Other physical/chemical/biological processes | |||||
| Drying (spray and freeze drying) | Dried milk, instant dried soups, dessert mixes, chocolate | HAV, FeCV<1 Doultree et al., 1999, Mbithi et al., 1991 | High | Unlikelyc | No information on commercial drying |
| Freezing | Ice-cream, frozen desserts (containing fruit) | HAV, PV, FeCV<1 (Hollinger and Ticehurst, 1996) | High | Possible | |
| Fermentation | Cheese, Yoghurt | No information | Unlikely | Microbial inactivation of viruses is found for sludge (Ward, 1982) | |
| Acidification | Fruit juices, still fruit drinks | NoV: pH 2.7, 3h incomplete (Dolin et al., 1972) HAV: pH 1, 5h incomplete (Hollinger and Ticehurst, 1996) | Medium | Possible | No quantitative data on inactivation |
| Homogenisation | Incomplete | High | Likelihood of presence depending on type of product | ||
| Depuration of oysters and mussels | NoV incomplete (Grohmann et al., 1981) | High | Likely | ||
| High hydrostatic pressure (600 MPa, 1h) | PV<1 (Wilkinson et al., 2001) | High | Likelihood of presence depending on type of product | ||
| Virus inactivation in water | Possible (drinking water); likely (surface water) | ||||
| Chlorination (0.5 mg free chlorine/l, 1 min) | HAV>3, HAV<2, HRV<2, PV>3 Abad et al., 1994, Sobsey, 1989 | Variable | Risk is low for PV but medium for HRV and HAV | ||
| UV radiation (20 mJ/cm2) | PV 3 or less (Sommer et al., 1989) HRV<3 (Sobsey, 1989) | Low | |||
| Ozone treatment (0.2 mg/l, 10 min) | HAV>3, PV 2 or less, HRV<1 Kim et al., 1999, Sobsey, 1989 | Variable | Risk is low for HAV but medium/high for PV and HRV | ||
| Cleaning of equipment and surfaces | |||||
| Rinsing with (lots of) water | HAV<2 (Bidawid et al., 2000b) | Medium/low | |||
| Ethanol (70%, 10 min) | HAV<2, HRV<3 (Abad et al., 1997) | Medium | |||
| Chlorhexidine digluconate (0.05%, 10 min) | HAV<1, HRV<1 Abad et al., 1997, Kawana et al., 1997 | High | |||
| Sodium hypochlorite (0.125%, 10 min) | HAV<3, HRV<3 Abad et al., 1997, Kawana et al., 1997 | Low | |||
| Sodium chlorite (30%, 10 min) | HAV>3, HRV>5 (Abad et al., 1997) | Negligible | |||
| Catering | |||||
| Washing, rinsing (where water >1% of food) and the food is eaten without additional cooking | Washed salads, Fruits (strawberries) | No substantial removal or inactivation | High | Possible | Any removal of viruses will be by mechanical action only; very difficult to remove any microorganisms from foods by washing alone (Mariam and Cliver, 2000b) |
| Freezing of drinking water to prepare ice | Ice for drinks or for cold foods | No inactivation | High | Possible | Freezing is an excellent way to preserve viruses; therefore best to assume there will be no inactivation after one freeze/thaw cycle |
| Chilling of drinking water or use of water from tap without any treatment | No inactivation | High | Possible | Chilling will slow down the inactivation rate of viruses | |
Viruses for which data were used to assemble this table are the (common) foodborne hepatitis A virus (HAV), Noroviruses (NoV) [and the animal model viruses feline calicivirus (FeCV) and canine calicivirus (CaCV)], human rotavirus (HRV), rhesus rotavirus (RV), and poliovirus (PV). Note: estimates included in this table are based on extrapolation of data from scientific studies and should be regarded as indicative only. Data in this table cannot be used to calculate risks. For precise process calculations or predictions on food manufacturing processes, additional experimental information is needed.
Unlikely=no reports are known in which NoV, HAV, RV, or PV were found on these food items. Possible=sporadic contamination with NoV, HAV, RV, or PV has been reported on these food items. Likely=contamination with NoV, HAV, RV, or PV is reported frequently on these food items. Negligible risk=product highly unlikely to contain infectious viruses; treatment results in at least 4 log10 inactivation of common foodborne viruses. Low risk=product unlikely to contain infectious viruses in numbers likely to cause disease in healthy individuals; treatment results in approximately 3 log10 inactivation of common foodborne viruses. Medium risk=product may contain infectious viruses in numbers that may cause disease; treatment results in approximately 2 log10 inactivation of common foodborne viruses. High risk=products in which the level of viruses is likely to be high enough to cause disease in healthy individuals; treatment results in less than 1 log10 inactivation of common foodborne viruses. Variable risk=treatment results in significant differences in inactivation of several common foodborne viruses.
Before spray drying in dried milk processes, a substantial heat step destroys viruses.