In spite of the prevailing harsh economic situation in the country, with the resultant lowing purchasing power of the citizens, some families would still be engaged in the handling of large volumes of various food items during the end of year festivities. Several weddings, house warming and family gathering celebrations are likely to feature prominently at this period of the year.
One of the challenges home makers still face is that of preservation and storage of foods, such as turkey, chicken, fish, fruit juice, ice cream and sundry packaged drinks. Most of the frozen poultry consumed in Nigeria during this season are imported under unhygienic conditions. That is where freezing comes in.
Freezing of foods by keeping them at temperatures below zero (0) degrees Celsius has been one of the most effective methods of food preservation engaged in by farmers, fishermen and hunters since the early times. While thesetook place in unheated buildings during the cold season, by 1912 a man called Clarence Birdseye had started to offer quick-frozen foods to the public. The invention of refrigerators and subsequently deep freezers made freezing a household preservative choice from the 20th Century.And soon they became common items in home s of the super rich and supermarkets.
Additional preservatives are not required as micro-organisms, including the disease-causing ones (pathogens) hardly grow at temperatures below-9.5 degrees Celsius. A chemical called Carboxymethylcellulase (CMC) which is both odourless and tasteless is typically added as a stabilizer because it does not change the textural and organoleptic qualities of the frozen foods.
One of the advantages of freezing is that it slows down the decomposition of the food as residual moisture is converted into ice, thereby inhibiting the growth of most species of bacteria. The process is called Individually Quick Frozen (IQF),However, freezing should be conducted at lower temperatures if the food items are meant to be preserved for longer period of time.
Nutritional losses during Freezing.
Although there are claims that frozen foods retain their colours, taste and texture it is not unusual to find some frozen chicken looking paler than the fresh ones. The freezing of ice into small blocks do crush the tissues thereby making them tender. But of concern to nutritionists is the loss of some vital vitamins as scientific research has shown. These include:
· Vitamin A(Beta Carotene).Found in green, leafy vegetables, eggs, liver, cod liver oil, cheese, palm oil. The loss is little compared to some others during freezing and occurs most if the time for the process lasts long.
· Vitamin B1 (Thiamin). Present in enriched cereals and grains. The loss is put at 25 percent of its content.Thiamin dissolves easily in water and isdestroyed by heat.
· Vitamin B2 (Riboflavin).Found in milk, yoghurt and enriched cereals. Though research is not conclusive its los during freezing is put at between 4 and 18 per cent.Loss has been identified to be cause more by the method of preparing the food, especially vegetables for freezing than the freezing process itself.
Factors to be considered during freezing
Since quick freezing does not add to the physical quality of the food, care should be taken so that only good quality, matured and fresh foods are put forward for freezing. Tominimise physical and biochemical changes the food to be frozen should b passed through temperatures of between -1 and -5 degrees Celsius quickly.
Also, once it is removed form the freezer, the food should not be exposed to humid or warm environmental conditions.
Ideal packaging for frozen foods
To protect the health of consumers NAFDAC officials should inspect and monitor the cold storage facilities in use in the urban centres. This is also because of erratic electric power supply here in Nigeria. To prevent any form of contamination, materials used for packaging frozen foods should be of good quality to keep away dust, smoke, unclean water and sources of viruses and bacteria. Cover the frozen chicken or turkey with the recommended cellophane package after washing the exterior.
On the issue of mass production and preservation, each warehouse should be of adequate capacity to take the entire food items. It should be equipped with suitable mechanical refrigeration to provide for, under anticipated conditions of outside temperature and peak loading , maintaining a reasonably steady air temperature of 00F (-18oC) or colder in all cold storage areas in which frozen foods are stored.
Each Storage area should be equipped with two or more accurate and calibrated temperature measuring devices and at least one continuous recording device, installed to reflect the correct average air temperature. Temperature of each area should be recorded and dated each day. A file of such temperatures should be maintained for a period of at least two years. A member of management should review the continuous recording within one business day of its completion to ensure proper temperature have been maintained at all times.
It is recommended that refrigeration equipment installations include an audible or visual alarm system that will activate when refrigeration failure occurs. This alarm mechanism enhances rapid response to frozen foods exposure to adverse storage temperature. Telephone, email, text messaging or other appropriate communication systems should be used to immediately notify responsible parties if temperature deviations occur outside of normal business operating hours (e.g Nights, weekends, and holidays.)
Considering the high population of Nigerians, many of who will continue to depend more on frozen foods either for consumption or economic gains, there is still much more to do. We have higher temperatures here than in the temperate region. International standards must be set and met.Conditions under which the frozen foods are imported, stored and sold should be of concern to the relevant regulatory agency, NAFDAC. More researches should be conducted on the deleterious effects of the consumption of these unsafe frozen foods on the health of the unsuspecting consumers.
Nigeria should not be made a dumping ground for expired foreign frozen food. The smuggling of such should be curtailed. That is one of the many reasons NAFDAC should continue to stay at the ports.
Ayo OyozeBaje
