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Classification of Food Stuff
In discussing food safety and quality, food stuff may be broadly grouped according to their susceptibility to microbial contamination (presence of nutrients and water) and/or shelf life. These are:
*Very high moisture and high acid foods*
Most fruits and vegetables belong to this category. These include fruits such as mango, pineapple, coconut, papaya, apple, tomato, cashew, pear, avocado, lime, etc. Although these contain large amount of water, are high acid foods and hardly supports the growth of spoilage bacteria. They are usually spoiled by moulds and can remain on the shelf for 2 to 3 days at temperature of about 30 oC before deterioration starts. Cucumber and lettuce comprisedabout 96% water. Ninety-four percent of tomato's weight is water, and green cabbage is 93%. Cauliflower, eggplant, red cabbage, peppers and spinach contain 92% water, whereas broccoli is 91%. Most of the above are less prone to spoilage because of their low nutrient density, especially in terms of proteins.
- **High water and protein foods. **
This class comprises foods such as lean meats and poultry, fish, eggs, milk, yoghurt, cheese. They support the growth and proliferation of both spoilage and pathogenic bacteria because of the high proteins and moisture content. Such foods must be processed immediately to remove much of the water or chilled otherwise spoilage will start within 1 to 2 hrs. Fish and especially offal (intestines) must be processed or chilled immediately because of the high microbial loads associated with them. **Medium water foods**
This includes foods such as potatoes, yam, cocoyam and cassava. They are chiefly starchy foods with low levels of other nutrients. Their water content can enable them stay in the appropriate storage for about 2-3 months without need for facilities such as chiller to prevent microbial proliferation.
**Low water and low acidfoods**
These comprised cereal grains (e.g. rice, maize) and grain legumes (cowpea, beans, bambaranut) foods. These foods have both low water content and low acidity to supports the growth and proliferation of microbes. However the nutrient content especially proteins and fats can decompose during improper storage into substances that may constitute health hazards if consumed.
**Oilseeds crops**
This group includes crops such as soybean, peanut, sunflower, cotton-seed, palm oil, etc. They generally contain large amount of fats/oils between 22-40% and provide the necessary fatty acid to support proper human growth and development. Because of the lipids content, food crops in this group are susceptible to fat breakdown especially soybean due to its content of polyunsaturated fatty acids that easily go rancid.
Generally, any food (plant or animal origin)fit for consumption is considered sound and free from all forms of contaminants unless infected from the outside. Thus the aim in food safety programme is to:
a. Prevent non-food and harmful substances from coming into contact with the food.
b. Destroy or remove those that are already in the food
c. Prevent them from re-contaminating after sterilizing the food.
Thanks for reading, see you in my next post.