By Harsha Pore*
The word starch came from German for root which means strong, stiff and strengthen. Starch is also known as amylum. Starch is a carbohydrate consisting of numerous glucose units joined by a glycosidic bond. Starch is the most common form of carbohydrate and is available in large number of food ingredients mainly in tubers and cereals, such as rice, wheat, potatoes, maize etc. We often think of potatoes as a “starchy” food, yet other plants contain a much greater percentage of starch (Potatoes 15%, Wheat 55%, Corn 65%, and Rice 75%).
Starch is a white or off-white, odorless, tasteless powder. It is granular organic chemical compound produced by plants. It is a polysaccharide comprising glucose monomers. The formula for starch is (C6H10O5)n.(H2O)
The simplest form of starch is amylose and amylopectin, which is a mixture of these two molecules. Natural starches consist of 10 – 30 % of amylase and 70 – 90 % of amylopectin. Amylose is a linear polysaccharide composed entirely of D-glucose units joined by the α-1,4-glycosidic linkages. Amylopectin is a branched-chain polysaccharide composed of glucose units linked primarily by α-1,4-glycosidic bonds but with occasional α-1,6-glycosidic bonds, which are responsible for the branching.
Starch is the storage of energy. In humans and other animals, starch from plants is broken down into its constituent sugar molecules, which supply energy to the tissues. The human digestive process breaks down the starches into glucose units with the aid of enzymes, and those glucose molecules can circulate in the blood stream as an energy source. Tillery, et al. point out an interesting example of this enzyme-catalyzed breakdown process. If you chew a piece of bread for a while, it will begin to taste sweet because of the enzymes in saliva are already beginning to break down the starch into glucose, a sugar.
The starch industry extracts and refines starches from seeds, roots and tubers, by wet grinding, washing, sieving and drying. The main commercial refined starches are cornstarch, tapioca, arrowroot, wheat, rice, and potato starches. These are natural starches, the chemically modified starch is also available in the market.
A modified starch is a starch that has been chemically modified to allow the starch for proper functioning under conditions frequently encountered during processing or storage, such as high heat, high shear, low pH, freeze/thaw and cooling.
Application of starch in Food Industry
Starch used as an additive in food industry, food starches can be used as a thickening and stabilising agent in foods such as puddings, Ice creams, Soups, Sauces, Gravies, Salad dressings. They function as thickeners, extenders, emulsion stabilizers and are exceptional binders in processed meats. Potato starch, corn starch and modified starch are highly used starches in food industry.
Resistant starch is also highly used starch in healthy food applications as it helps in digestion.
High amylose starch from corn has a higher gelatinization temperature than other types of starch and retains its resistant starch content through baking, mild extrusion and other food processing techniques. It is used as an insoluble dietary fiber in processed foods such as bread, pasta, cookies, crackers, pretzels and other low moisture foods. It is also utilized as a dietary supplement for its health benefits. Below are the examples.
1] Baked products (bread, pies, samosas, wafers, biscuits and sausages)
Baked products like biscuits, pies, bread, cakes wafers and sausages are high density products requiring heat resistant starches. Hence cross linked starches are used since they are more resistant to oven baking temperatures of 120 ≥ 230°C. Gelatinized starches are also used in ready-to-eat cereal meals such as corn-flakes, etc. The temperature, humidity and degree of stirring determine the texture and quality of the product.
2] Confectionery (candy, sweets and sweetmeat)
Oxidized starches have high clarity or transmittance, low viscosity and low temperature stability. It is frequently used in confectioneries for coating candies and sweets since they easily melt.
3] Gravies, soups and sauces (soups, sauces, tomato paste or ketchup)
Crosslinked starched have higher stability for granules-swelling, high temperature resistant, high
shear stability and acidic conditions stability. They are used as viscosifiers and texturizers in soups, sauces, gravies, bakery and dairy products. Etherified starches have improved clarity of starch paste, greater viscosity, reduced syneresis and freeze-thaw stability. Crosslinked starches
4] Mayonnaises, salad dressing, ice cream, spreads and beverages
Hydrolyzed and esterified starches are mostly used in salad dressing and beverages. Hydrolyzed starc3h (acid-modified starches) has lower paste viscosity under cold and hot conditions. Hence they are used in mayonnaises and salad dressing. Esterified starches have lower gelatinization temperature and retrogradation, lower tendency to form gels and higher paste clarity, and are used in refrigerated and frozen foods, as emulsion stabilizers and for encapsulation of beverage clouds.
5] Pasta (spaghettis, macaroni, others)
Pregelatinized and crosslinked starches are mostly used in pastas. Gelatinized starch affects pastas elasticity and softness, delectableness and digestibility. Crosslinking gives the needed structural firmness to the pasta.
6] Puddings (custard, pap, others)
Pregelatinized starches are used in puddings, instant lactic mixtures and breakfast foods to achieve thickening or water retention without employing heat. They are also used in ready-to-use bread mixtures. They are used where little or no heat is required and the increased absorption and retention of water improves the quality of the product; as an agglutinant in the meat industry; and as a filling for fruit pies. (Source: https://www.intechopen.com/books/chemical-properties-of-starch/chemical-properties-of-starch-and-its-application-in-the-food-industry)
The application of starch is wide. The industries manufacturing starches in large quantities and are readily available. In India and in abroad, starch application is very common. For every alternate use in cooking, manufacturing, baking starch has been used. The only issue with the starch is it gets retrograde after cooking, to avoid such retrogradation, we need to add gums in the products. The easy way to achieve desired softness and consistency in starch rich products. The industries like Cargill, Baneo, Ingredion are biggest players in starch manufacturing. Starch like resistant starches are healthy in nature and helps in digestion, also, main source of carbohydrates leads energy. Starches are very friendly in nature and can be used in cooking, just add a little and make your favourite dish.
* The Author is R & D Manager at Maverix Platforms Pvt Ltd