ICE CREAM STABILIZER

Ice cream is a complex food colloid that consists of air bubbles, fat globules, ice crystals and an unfrozen serum phase. Ice crystals and air bubbles are generally in the range of 20–50 μm. The air bubbles are usually to some extent coated with fat globules and the fat globules are coated with a protein/emulsifier layer. The serum phase consists of the sugars and high molecular weight polysaccharides in a freeze-concentrated solution. Various steps in the manufacturing process, including pasteurization, homogenization, ageing, freezing, and hardening, contribute to the development of this structure. Proteins and emulsifiers compete for inter facial space during the homogenization of the fat and the creation of the mix emulsion. Following homogenization, the emulsion is further affected by changes occurring during the ageing step, viz.,crystallization of the fat and rearrangement of the fat globule membrane to the lowest free energy state. This emulsion then undergoes both whipping and ice crystal formation during the dynamic freezing process, which contributes to the development of the four main structural components of the frozen product: discontinuous foam, a network of partially coalesced fat surrounding the air bubbles, ice crystals, and a continuous, freeze-concentrated, unfrozen aqueous solution

Stabilizers and emulsifiers have been conventionally used in ice cream as additives. Recently, there has been a tendency towards ‘all natural’ or ‘natural’ products which have given rise to the so called premium ice cream which is supposed to contain no additives. Yet because of the quality enhancing ability of stabilizers and emulsifiers, they remain as important ingredients for most ice creams and frozen desserts.

Stabilizers are substances which make it possible to maintain the physico-chemical state of a foodstuff; stabilizers include substances which enable the maintenance of a homogenous dispersion of two or more immiscible substances in a foodstuff and include also substances which stabilize, retain or intensify an existing colour of a foodstuff. Emulsifiers are surface active agents which improve the sensory quality of ice cream by aiding the whipping process, improve air cell distribution and enhance the products heat shock resistance. Despite their name, emulsifiers are actually used in ice cream to de-emulsify some of the fat.

Ice cream stabilizer is one of the important chemical or combination of chemicals formed by microbial origin, animal origin or vegetable origin. In case of vegetable origin the gum like arabic, acacia, guar gum, agar, carragheen etc. plays very important role. The gum is used as stabilizer the product for body and increases melting point, gelling property, texture, mouthfeel etc.

Over the years, the term gums was used to denote a wide range of compounds including polysaccharides, terpenes, proteins and synthetic polymers. Today, the term more specifically denotes a group of industrially useful polysaccharides or their derivatives that hydrate in hot or cold water to form viscous solutions or dispersions.

Gums are classified as natural and modified gums. Natural gums include seaweed extracts, plant exudates, gums from seed or root and gum obtained by microbial fermentation. Modified (semisynthetic) gums include cellulose and starch derivatives and certain synthetic gums such as low-methoxyl pectin, propylene glycol alginate, triethanolamine alginate, carboxymethyl locust bean gum and carboxymethyl guar gum.

The polysaccharides are classified on the basis of the dominant sugar constituent or constituents or the presence of a particular type of functional group, eg., sulfate ester.

Gums are used in industry because their aqueous solutions or dispersions posses suspending and stabilizing properties. In addition, gums may produce gels, act as emulsifiers, adhesives, flocculants, binders, film formers, lubricants or friction reducers, depending on the shape and chemical nature of the particular gum.