Meat and poultry are important components of human food. Human being consumes meat & poultry for thousands of years. Preservation of these highly perishable products is of major concern. Freezing is an excellent way to preserve animal products such as meat, fish, chicken, etc. Freezing inhibits the growth of microorganisms and helps to maintain the quality of meat. Meat and poultry are first processed before freezing in order to increase their shelf life. Frozen poultry products include chicken breasts, chicken legs, chicken wings, whole chicken, etc. Other types of frozen products include frozen salmon, frozen bacon, frozen ground turkey, frozen beef, frozen fish & shellfish, etc.
Processing of Poultry: Before freezing poultry, it undergoes various processing steps like receiving, stunning, slaughtering & bleeding, defeathering, washing, cutting & deboning, packaging, etc. All these steps are important and need to be carried out before freezing.
Meat and poultry are highly perishable products. At ambient temperature bacteria and pathogens grow in large numbers thereby causing spoilage of the meat. The temperature between 5 – 60°C is considered as a ‘DANGER ZONE’ in which bacteria grows rapidly. If meat and poultry are kept at this temperature for a long time then the pathogens will grow and cause spoilage. Consumption of this spoiled meat will lead to food poisoning & food-borne illness. To stop the growth of pathogens it is important to lower the temperature of the product. Freezing does not kill spoilage organisms however it simply stops their multiplication (1).
In the market, freshly slaughtered meat is available but it should be consumed quickly within a specific time frame. However, frozen meat can be stored for several months without disrupting its quality. All pathogens cause harm to human health. Some microbes do not cause harm, however, the ones which cause harm are called pathogens. Some of the pathogens that grow in meat and poultry include Salmonella, E. coli, Campylobacter, etc.
There are different types of freezing techniques that are used to freeze meat and poultry. Different types of freezing methods include blast freezing, plate freezing, cryogenic freezing, etc. Small meat pieces require less time to freeze whereas, large meat pieces and whole chicken require more time. Lower air temperature increases the speed of freezing. Moving air rather than still air also increases the speed of cooling.
Problems while freezing poultry:
- Freezer Burn: Freezer burn is a term for moisture loss from frozen food products. It happens when the meat is left in the freezer for a long time or if it is not packed properly. It loses the moisture from the meat and hence the quality gets deteriorated. When meat gets freezer burned, the colour of the meat changes to brown or grey making it unacceptable to consumers. The surface of the meat becomes tough, hard & looks dry. This is because the oxygen in the nearby air has pulled flavours and colours from the meat’s tissue. This affects the quality of food but it is still safe to eat unless it is spoiled or has a bad odour. Freezer burn can be avoided with the use of proper packaging that will minimize oxygen exposure.
- Loss in nutritional quality: Meat is a highly nutritious product. It contains proteins, fats, vitamins & minerals. It also contains saturated and unsaturated fatty acids (2). In meat and poultry products, there is little change in nutrient value during freezer storage. Even in case of fresh poultry, there can be changes in the nutrient value if left at ambient temperature for a long time. If meat and poultry are not packed properly, it can lead to the oxidation of fat in the meat resulting in bad odour and thus corrupting the quality of meat.
- Loss of colour: Colour changes can occur in frozen poultry & meat. The bright red colour of meat usually turns brown. This can happen if the meat is exposed to oxygen, freezer burn, or long storage. Freezing usually does not cause colour changes in poultry. When meat is fresh and protected from the air, it has a very dark, bright, and cherry red colour. In addition to the colour change, if the meat or poultry has an off odour, is sticky or slimy, it should not be consumed. Chicken meat is pinkish white in the breast and wings and in other parts pink to light red.
Storage of Poultry: Packaging is a physical barrier to cross-contamination. The act of covering food keeps microorganisms from contacting the food. Covered perishable foods can be stored longer and at better quality than uncovered foods. Some studies have shown that Modified Atmosphere Packaging (MAP) and Vacuum Packaging help prolong the storage of meat and poultry products (3). To help preserve foods longer, it is important to eliminate oxygen from the packaging. Vacuum packaging removes air from packages and produces a vacuum inside. The best temperature for storing frozen poultry and meat products is -18°C or below. Proper packaging, storage, and correct temperature is the only key to maintaining the quality and freshness of meat.
Frozen meat and poultry products have become an important part of our daily life. Nowadays due to busy schedules, cooking meat and poultry can be time-consuming. Thus, frozen ready-to-cook poultry products are easily available in the market such as frozen chicken spring rolls, chicken nuggets, chicken salami, chicken sausages, etc. This helps in reducing time and provides a wide variety of tasty and healthy products. A wide variety of frozen meat and fish products are also available like frozen kebabs, frozen fish tikkas, frozen fish cutlets, etc.
- Willenberg & Mills-Gray, 2019, Freezing Meat, Poultry, Fish, Eggs & Dairy Products, Univ of Missouri Extension (https://mospace.umsystem.edu/xmlui/bitstream/handle/10355/86302/gh1504.pdf?sequence=1&isAllowed=y)
- Hussein & others, March 2022, Effect of freezing on chemical composition and nutritional value in meat. https://www.researchgate.net/publication/339602967_Effect_of_freezing_on_chemicalcomposition_and_nutritional_value_in_meat
- Narasimha Rao & Sachindra, February 2007, Modified atmosphere and vacuum packaging of meat and poultry products https://www.researchgate.net/publication/233466595_Modified_atmosphere_and_vacuum_packaging_of_meat_and_poultry_products
- https://extension.uga.edu/content/dam/extension-county-offices/forsyth- county/facs/2020_Article_Freezing%20Meat%20and%20Poultry.pdf