1. Introduction

Refrigeration slows down the chemical and biological processes in foods, such as the accompanying deterioration and the loss of quality, extending the shelf life of the products, with minimum changes to the sensory characteristics and nutritional properties.

Temperatures in the range of 0–5C slow down the development and growth of microorganisms, but some pathogenic agents can grow to large numbers at these temperatures or are still sufficiently virulent to cause poisoning. Because the activity of most of the pathogenic agents is only slowed down and not stopped, long-term storage of refrigerated products can finally

cause food poisoning [1]. In these cases, when a longer preservation period is needed, freezing must be used to minimize any physical, biochemical, and microbiological changes affecting quality during storage. The storage life of fresh perishable foods, such as meats, fish, fruits, and vegetables, can be extended by several days by cooling, and by several weeks or months by freezing [2, 3]. During freezing, most of the water content of the meat, about 80%, solidifies into pure ice crystals, accompanied by a separation of dissolved solids [2, 4].

Chilled foods are commonly grouped into three categories, according to the storage temperature range [1]:


In order to chill fresh foods, it is necessary to remove the sensible heat and also the heat generated by the respiratory activity of vegetables and fruits; in animal tissues, aerobic respiration rapidly declines when the supply of oxygenated blood is stopped at slaughter [1, 4].
