Yoghurt type, production

The frequency of use of each of the terms of the CATA question to describe the six yoghurt samples, as well as the ideal yoghurt, is shown in Table 11.3. The ideal yoghurt was described by the terms smooth, homogeneous, creamy, consistency and sweet, which indicates that these were the main drivers of liking for this type of product, as expected (Bayarri et al., 2011 Pohjanheimo and SandeU, 2009). 

For fermented milks, for example yoghurt, acidophilus milk and bifido products, stabilisers are widely used in many countries to improve viscosity and prevent wheying-off. Several types of stabilisers (e.g. gelatins, starch, pectins, carrageenans and cellulose derivatives) are used. The choice depends on the characteristics wanted and the technology used. The main parameters to be considered in the choice of stabiliser for fermented milks are heat stability and sensitivity towards low pH and salts. The effect of stabilisers on the activity of starter cultures must also be taken into consideration (Kalab et al., 1983). 

The acidity of food is related to the amount of undissociated and dissociated forms of carboxyKc acids and oxonium ions, respectively, that are present. The major substances that give a sour taste in foods are undissociated hydroxycarboxylic acids, citric and malic acids. Often, however, other carboxylic acids occur, such as ascorbic acid in most types of fruits, tartaric acid in grapes, isocitric acid in blackberries, oxalic acid in rhubarb, lactic acid in some dairy products (such as yoghurt), fermented cucumbers, cabbage, oKves, vinegar and propionic acid in Emmental type cheeses (see Section 8.2.6). The acidity of cola drinks is provided by phosphoric acid, sometimes accompanied by citric or other acids. Carboxylic acids also act as bacteriostatic agents and affect a number of biochemical and chemical reactions. 

Carthamin was used as a wool dye in ancient times and is now the only chalcone type pigment recommended in some countries for food colouring. As a food additive, carthamin is known as Natural Red 26. Its properties are not yet well known, but it may become a promising food colouring, for example for yoghurt and other dairy products. 

The main sources of contamination of the food chain with mono-cycHc aromatic hydrocarbons are oil spills, but also include a variety of coatings and plastics. MonocycHc aromatic hydrocarbons may also arise as products of the combustion of various materials. Food contamination occurs primarily by absorption from the air and water, and in animals from the surrounding environment. Another type of food contamination is migration from packaging materials. In recent years, much attention has been paid to contamination of yoghurt and biscuits by styrene (vinylbenzene) released from the polystyrene used to manufacture various packagings. 

Other food types enriched by plant sterols include meat products enriched with plant stanol ester (Atria Ltd, Finland). As sterol esters are lipids, they can be incorporated into practically any food form that contains at least some fat in it. However, the level of fat can be very low, as has been shown in low-fat yoghurts and in milk or milk-juice drinks, where the plant stanol or sterol ester provides virtually the only fat in the product. 

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