4.3.1. Sources of contamination

Assuming the bacteria are not internalized in the plant tissue, surface sanitisation is normally an effective way to remove pathogenic bacteria from products. Many reports show that contaminated surfaces are most likely the source of product contamination, and that the risk of contamination is highest between the primary trimming and chopping and the packaging stages. Sources of contamination that should be considered are: hands, gloves, and personal protective equipment; slicers; conveyors; washing tanks and wash water; holding containers and racks for packaging, and packaging equipment.

Cross-contamination is one of the main risks to food safety during processing. Cross-contamination can occur in three main ways:

• Food to food. Food can become contaminated by bacteria from other foods. This type of cross-contamination is especially dangerous if raw foods come into contact with cooked foods.
• People to food. People can be a source of cross-contamination to foods, when good hygienic practices are not performed by food handlers, such as handling foods after using the toilet without first properly washing hands, touching raw meats and then preparing foods without washing hands between tasks, using an apron to wipe hands between handling different foods, or wiping a counter with a towel and then using it to dry hands.
• Equipment to food. Contamination can be passed from kitchen equipment and utensils to food. This type of contamination occurs because the equipment or utensils are not properly cleaned and sanitized between each use.

Temperature during storage and distributioncan also be a source of contamination. Disease-causing pathogens can grow well in food when it is kept at temperature between 5°C and 57°C, which is known as the temperature danger zone. If food is kept at these temperatures for more than 4 hours, pathogens can grow to levels high enough to cause serious food-borne illnesses. Therefore, it is very important to keep hot food at 60 C or higher and cold food at 5°C or lower, and check the food’s temperature at least every 4 hours during storage and distribution.

To prevent or reduce the amount of pathogens, different methods of sanitation are implemented. Sanitation is a multistep process that involves cleaning and sanitizing as two very important and separate steps. Effective cleaning and sanitation procedures, which include debris removal, use of detergent solutions, rinsing with water, disinfection where necessary and dry cleaning, are required to achieve the correct level of hygiene in food-handling or production facilities. If these are not adhered to, there is a greater risk of food becoming contaminated by pathogenic or spoilage microorganisms. There is also a risk of biofilms forming on factory and food preparation surfaces if these programs are inadequate. It is important to avoid the use of phenolic and metal-ion based products as they may cause product tainting and consumer safety issues.

Cleaning and sanitation programs include four steps:

• Routine procedures performed throughout and at the completion of food processing or preparation on a daily basis;
• Periodic procedures required less frequently;
• Monitoring to ensure the procedures are performed correctly;
• Verification to check the effectiveness of the program.