Polysaccharides are carbohydrates containing many units of monosaccharides, hence the word ‘poly’ which means many.They provide us with dietary fiber. The number of connecting monosaccharides in polysaccharides can go up into the hundreds. A class of polysaccharides widely used as functional ingredients in the food industry are hydrocolloids. Hydrocolloids are defined as substances that form a gel in the presence of water. They are used mainly for their ability to thicken products and improve their overall texture. Examples are starch, pectin, cellulose derivatives, and gums.
Starch is the type that you may be mostly familiar with. Corn is the main source of starch supplied to the food industry, but other sources include wheat, pulses, potato, arrow root, and tapioca. Starch consist of two major components, amylose and amylopectin. Each of these components have a different structure and functional property. Therefore, depending on how much is in the starch, it will behave differently. For example, starches that are higher in amylose will gel more. This is ideal for gravies, soups and salad dressing that have a high viscosity. Starches high in amylopectin will thicken, but will not gel. They thicken at a lower temperature, which makes them more ideal for use in products like pie-fillings requiring low-temperature cooking.
Pectin is a substance found in the cell walls of plants, imparting rigidity and firmness. Food manufacturers add pectin to jams and jellies to give them their characteristics gel texture. Manufacturers will add more or less commercial pectin to jam and jelly formulas depending on how much is naturally present in the fruit. Fruits that are high in pectin include berries, peaches, apricots, grapes, cherries and apples. Fruits that are low in pectin include strawberries, raspberries, cherries, pineapple and apricots. In a future blog, I will discuss the chemistry of jam and jelly making and how pectin works.
Cellulose derivatives are vegetable cellulose that are chemically modified. They include hydroxypropylmethylcellulose (HPMC), hydroxyethylcellulose (HEC) and carboxymethylcellulose (CMC). They are used in products such as sauces, salad dressings and ice-cream as thickeners, emulsifiers and stabilizers.
Gums are also used as thickeners, emulsifiers and stabilizers. They are added to a wide variety of foods including sauces, salad dressings, ice-cream, bakery products, and sausages. The most popular ones are alginate, carrageenan, gum arabic, guar gum, locust bean gum, konjac gum and xanthan gum. Each of these gums have different functional properties, and so it will be important know your process and your product to determine if the type of gum is compatible.
Reference: Potter, N. N. & Hotchkiss J. H. (1998). Food Science, 5th edition. New York, NY: Springer Science+Business Media LLC.