SCIENTIFIC PRINCIPLES OF CONTROLLED/MODIFIED ATMOSPHERE PACKAGING

Control of the spoilage of food has challenged the ingenuity of humans since the earliest of times. Concentrating and drying foods by natural (and artificial) means was the mainstay of food preservation. Fermentation also became a popular means of food preservation, relying on the anaerobic environment and the growth of microorganisms to produce inhibitory substances that ultimately preserve the food. In the developed world, refrigeration and freezing have become major factors in the extension of the storage life of foods. Under refrigeration the growth rate of microorganisms and the respiration rate of the food itself is markedly reduced. However, refrigeration has a selective effect on microorganisms. At all storage temperatures, down to the minimum at which water remains in the liquid state, there are microorganisms that will grow. Linear decreases in temperature result in geometric decreases in reaction or growth rate. Frozen storage eliminates microbial growth, reduces the rate of chemical oxidation, and has variable effects on texture depending on the food type, but it has the disadvantage of being energy expensive. To many, the advent of modified-atmosphere (MA) or controlled-atmosphere (CA) storage provides foods that are “fresh”, meaning “never frozen.” This is viewed as advantageous to food producers because it reduces costs compared with frozen storage, it avoids problems of texture change and it extends the storage life or protects foods from spoilage.