Hydrocolloids modified natural

Natural thickeners can be defined as products obtained from natural sources such as plants, seeds, seaweeds and microorganisms. These products are high molecular weight polymers composed of polysaccharides and are often referred to as hydrocolloids. Production processes vary from simple collection of tree exudates and milling in the case of gum arabic to more complex production by fermentation as in the case of xanthan gum. A number of these natural thickeners are also derivatised in order to modify their properties. Table 2.1 provides a simple classification of these products by source. Tables 2.2-2.4 provide an overview of the main natural thickening agents and their applications. A brief description of each class of hydro colloids is given below but for more detailed information on each of the hydrocolloids there are a number of publications available [ 1—3]. 

Hydrocolloids (proteins and polysaccharides) are common materials for edible films and coatings, since they possess excellent gas barrier, creating a gentle modified atmosphere that helps maintaining quality of foods, such as fresh produces, dry fruits, and so on. However, they exhibit poor moisture barrier due to their hydrophihc nature (Kester and Fennema, 1986 Gennadios and Weller, 1990 Park and Chinnan, 1990 Gennadios et al., 1994). To overcome this problem, hpids are added to increase film hydrophobicity. 

This new category of naturally occurring hydrocolloid emulsifiers should be reconsidered by food technologists, because these gums can be used instead of some of the synthetic and restricted low molecular weight emulsifiers or chemically modified proteins. 

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