Foods are an essential requirement for sustenance of life. Primarily foods serve two main objectives. First and foremost is to provide us the energy to carry out our daily activities and secondly to satisfy our taste buds. However, all foods irrespective of their source – farm harvested or factory produced do not retain their attributes forever and have shelf lives which depend on their constitution and the environmental conditions under which they are stored prior to consumption.
Factors resulting in the degradation of food products covers some of the important factors that lead to deterioration of foods over time. It also explains the difference between best before date and use by date. To arrive at estimation of these dates stability studies play an important role. The present article highlights some of the food characteristic properties that lead to such decay and hope to preserve foods over their useful life.
The shelf life of pharmaceuticals is generally based on carefully planned stability studies through assay and microbiological tests at periodic intervals as it is often difficult to tell if a medicinal product has deteriorated or lost its potency through appearance alone. However, in contrast the degradation of food products becomes apparent through mould formation, colour changes, water separation, emanation of odour, etc. However, even then prediction of shelf life requires conducting stability studies under carefully controlled environmental conditions.
Date of expiry is mentioned on food labels and implies that consumption of such products after the mentioned date can have harmful health consequences. On the other hand, best before date becomes applicable when the product due to its deterioration can lose its texture, colour, taste or pleasant odour so that consumer acceptance becomes less but its consumption will not have any health implications. Foods having shelf life of two years or longer need not carry best before date on their labels.
Physical, chemical and microbiological studies on foods under controlled environmental conditions help in deciding the best before and expiry dates at the manufacturing stage before products are released in the market.
Nature of decay of food products
- Infestation of harvested crops by insects during storage due to lack of proper storage conditions
- Loss of nutrient levels below limits specified on labels
- Changes in texture – hardening or softening of product beyond its specified limits
- Gain or loss of moisture – such changes lead to undesirable changes in the appearance of a product
- Loss of flavour or product becoming rancid due to chemical changes accompanying degradation
- Microbiological decay which may become apparent through staining, mould formation or browning of the food specimen
Testing of stability of food products is carried out using general test conditions for long time studies and accelerated stability testing as in case of pharmaceutical products. However, accelerated testing is not applicable to frozen foods and other food items that form part of cold chain products.