Intermediate moisture content foods IMFs

Intermediate moisture content foods (IMFs) such as pet food and continental sausages rely on fats and water-binding humectants such as glycerol to lower water activity. Fat, which is essentially hydrophobic, does not bind water, but acts as a filler for IMFs to increase the volume of the product. 

Intermediate Moisture Foods (IMF s) are characterised by a moisture content of about 15 to 50% and by an aw between 0.60 and 0.85. Traditional IMF s, such as jams, fruit cakes and some ripened cheese are stable at ambient temperatures for various shelf periods (Table 3.59). Water content of IMF s may be lowered to a level which prevents microbial spoilage by the addition of humectants, pH adjustments and antimicrobial agents. Newer IMF s, such as designed for space rations, clinical nutrition and pet foods, can be prepared by adjusting the formulation of the product so that its aw is below 0.86 by use of the following techniques [11 ] ... 

The water content of foods is very variable. It may be as low as 0% in vegetable oils and as high as 99% in some vegetables and fruit. Water by itself is free of calories and plain water does not contain nutritive substances, but it may be an ingredient itself in foods. Foods are described as dry or low-moisture foods if they have very low water content. These are most often solid food systems. Liquid food systems and tissue foods where water is the dominating constituent of the solution are high-moisture foods. Foods that contain moderate levels of water are intermediate-moisture foods (IMFs). 

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