Amylopectin in Starch Structures

Amylopectin, being among the largest molecules in nature, functions as the principal constituent in the majority of starches. The varying proportions of amylose and amylopectin in starches add to their intriguing nature, as they possess the ability to influence and modify the texture, quality, and stability of starch-based food products.

Typically, starch consists of around 20–30% amylose and 70–80% amylopectin. In contrast to amylose, amylopectin is characterized by numerous shorter chains. The amylopectin molecule, marked by branching, features regions with differing degrees of branches, making up about 5% of the entire molecule. This branching contributes to the formation of a highly complex molecular structure.

Within amylopectin, short chains come together to form double-helices that undergo crystallization, playing a role in the semi-crystalline nature of starch granules. In regions with extensive branching, side-chains of amylopectin cluster, creating crystalline zones. These side chains are classified as A, B, and C chains, each displaying distinctive characteristics. A chains are the shortest, while C chains serve as the main structural elements of the amylopectin molecules. B chains, linked to the C chains, carry one or more branches and are further categorized into B1, B2, B3, and B4 based on their length and the number of clusters they encompass.
Amylopectin in Starch Structures

Starches: Major polysaccharide in plants

Chemically is composed of two glucan polymers, amylose, and amylopectin. These polymers are deposited in granules of different sizes, large A-, medium B- and small C-type, and shapes, as disk-like and spherical.

It provides humans with energy (4 cal per gram) and is hydrolyzed to glucose, supplying the glucose that is necessary for brain and central nervous system functioning.

Nutritionists agree that carbohydrates should be an important part of human diet. The European Food Safety Authority (EFSA) recommends that the intake of total carbohydrates, including carbohydrates from starchy foods (generally in the form of tubers or root vegetables) should range from 45-60% of the total energy intake for both adults and children.

Amylose influences the packing of amylopectin into crystallites and the organization of the crystalline lamella within starch granules. This is important for properties related to water uptake as swelling and gelatinization.

Starch is used in the food industry either as food products or additives for thickening, preservation and quality enhancer in baked foods, confectioneries, pastas, soups and sauces, and mayonnaises.

Starch can be used as a food additive to control the uniformity, stability and texture of soups and sauces, to resist the gel breakdown during processing and to raise the shelf life of products.

Starch sources are numerous, with common ones derived from cereal grains such as wheat, corn, or rice. Wheat yields a cloudy, thick mixture, while cornstarch produces more clear mixtures such as gravies or sauces. Vegetables, roots and tubers, including the root of cassava, and potatoes.
Starches: Major polysaccharide in plants

Cross-linked starches

Cross-linked starches are those that undergo a molecular reaction at selected hydroxyl (-OH) groups of two adjoining intact starch molecule.

The purpose of cross-linked is to enable the starch to withstand such conditions as low pH, high shear or high temperatures.  Cross-linked as well as cross-linked and stabilized starches are extensively used throughout the food industry to thicken, stabilize and texturize food systems.

Cross-linked starches are used when a stable, high-viscosity starch paste is needed particularly when dispersion is to be subjected to high temperature, shear or low pH. They play an important role in suspending other food ingredients to provide nutritionally uniform foods. The cross-linked starches become less fragile and more resistant to rupture than the original unmodified starch. Although it is more tolerant of high temperatures, it is not more tolerant of cold temperatures.

These starches are used in many foods, especially acid food products such as pizza sauce or barbecue sauce because the modified starch is more acid resistant than an unmodified starch. They are used in the preparation of pie filling, bread, puddings, baby foods, soups, gravies, salad dressing etc and for retort foods and aseptic processing.

As a result of cross-linking, a starch swells less and is less thick. In retort sterilization of canned foods, cross-linked starches with a slow gelatinization of swelling rate are used to provide low initial viscosity, high heat transfer and rapid temperature increase for quick sterilization.
Cross-linked starches

Tempering the eggs

Once milk/cream mixture have been flavored, it’s time to add the eggs. Tempering is the process of slowly adding a hot liquid to eggs in a recipe, in order to gradually raise the temperature thus slowly exposing eggs to heat without the danger of coagulation.

In this manner, the eggs do not curdle and produce an unacceptable consistency. If the eggs are not properly tempered the hot liquid will cook them, making final product uncomfortably reminiscent of scrambled eggs.

Overheating eggs in sauces, puddings and soft custards can be avoided by tempering the eggs. For sauces and puddings, cook the starch first - it needs extra time to thicken and lose its raw taste – then add the eggs.

Egg also can be tempered with hot liquid milk, is carefully streamed into them, bringing the eggs up to a very high temperature without cooking them.
Tempering the eggs

Cold water swelling starches

Since insoluble ingredients like cook-up starches tend to sediment without agitation, viscosity-increasing ingredients like xanthan gum or cold-water swelling starches are used.

Cold water-swelling starch (CWS) is an instant starch that remains as an intact granule. It offers convenience stability clarity and texture. CWS starches have smooth texture similar to cook-up starch and more processing tolerance than conventional pre-gelatinized starches.

By increasing the viscosity of the brine system, a network is built up that prevents the cook-up from settling.

CWS scratches may be gelling or non-gelling, They may be used in no-cook or cold-process salad dressings providing the thick, creamy mouthfeel in no fat salad dressing.

CWS is dispersible in sugar solutions or corn syrups by rapid stirring; the resulting dispersion can be poured into molds, where it sets to a rigid gel that can be sliced easily. The result is a gum candy.

Cold water swelling starch is also useful in making desserts and in muffin batters.
Cold water swelling starches 

What is retrogradation?

Retrogradation is another important property of starch. Retrogradation refers to the occurrence where starch reverts or retrogrades to a more crystalline structure upon cooling.

In most products, retrogradation causes deterioration of quality and therefore retrogradation has to be avoided.

Both amylose and amylopectin may participate in a textural change that makes them somewhat more ‘gritty’ with time.

In particular it appears that retrogradation is the recrystallization of the amylopectin where the amylose molecules clump together and separate from the sol or gel, thus destroying the semi-elastic network on which its properties depend.

Retrogradation is more likely to occur in a high amylose starch. Starches with a very high amylose content undergo retrogradation less readily than those with a lower amylose content and such starches are commercially available to food manufacturers,.

This occurrence is noted in baked products that become ‘stale’ no longer ‘fresh’ tasting or ‘fresh’ handling.  It is also observed in leftover, long-grain rice.

Moreover, the term retrogradation can also be used to describe changes occurring during cooling from gelatinization temperatures as well as changes occurring during long-term storage.
What is retrogradation?

Starch gelatinization

Starch is the most common carbohydrates polymer in foods. It is known to go through transformation and gives diverse physical structures and properties.

When starch granules are heated in the presence of water, the granules eventually lose the double-helical crystalline structure and the Maltese cross. This process is known as gelatinization.

Starches of different botanical sources and genetic backgrounds display different gelatinization properties, including gelatinization temperature, enthalpy change and melting of amylose-lipid complex.

The gelatinization of starch is an irreversible process, and each starch has its own characteristic gelatinization temperature.

Water acts as a plasticizer during starch gelatinization, lowering the melting temperature of starch. This decreases the glass transition temperature of the non-crystalline regions of native starch and leads to melting of the crystalline parts as temperature is increased.

Starch gels are composites of swollen gelatinized granules embedded in a continuous amylose network.

When the gelatinized starch is continuously heated in excess water, the starch granules swell, develop viscosity and become a paste. This is known as pasting.
Starch gelatinization

Usage of waxy starch in food

Waxy starch essentially does not contain amylose and virtually all amylopectin, while nonwaxy starch consists of two kinds of glucose polymers, i.e. amylopectin and amylose.

Waxy starches are derived from some natural strains of barley, corn, rice and sorghum. Waxy starch begins to thicken at lower temperature, become less thick, and undergo less retrogradation than nonwaxy varieties. 

Waxy maize starch has an amylopectin content of approximately 99%. It is valued for use in products where a gel is not desirable. It is preferred in the manufacture of canned and frozen food products.

The freeze thaw characteristics of waxy rice starch are similar to those of waxy maize and waxy sorghum starches. All three can advantageously be used in frozen pie fillings and other frozen products.

Unmodified waxy starch and blend with normal starch and flours normally is used in salad dressing, sterilized canned and frozen food, soups, broth, puffed cereals and snack food.
Usage of waxy starch in food

Starch in corn

The complex carbohydrates found in foods are starches and fiber. There are a number of varieties of corn usually classified as starchy or waxy, depending on the characteristics of the carbohydrate present.

Starch the major component of corn, is located in the starchy endosperm in simple spherical granules that vary in diameter from 2 to > 20 um. Starches in general are long chain of glucose and corn starch is no exception.

Corn starch granules are insoluble in cold water but undergo irreversible loss of granular structure (gelatinization) when the slurry is heated to 62 to 72 °C. The starch in corn kernel is roughly 75% amylopectin and about 25% amylase.

The gelatinized slurry form gels air thick pastes that are opaque with a short texture, depending on water availability and processing time.

The corn industry makes widespread use of enzymes for carbohydrate conversion. The advent of enzyme technology in the corn industry in the 1960s dramatically changed the starch industry and allowed the development of new products.

Starch granules are used as an ingredient, modified or further processed into glucose and fructose or other industrial chemicals.

New varieties of corn yield waxy cornstarches that are used to stabilize frozen sauces and fillings.
Starch in corn

Rye starch

Rye is another member of the wild grass family whose cultivation stretches back into antiquity.

Rye starch is contained in the grain of the rye, Secale cereal, Linn. It consist practically of large and small grains, with but few of intermediate size; the larger ones being, on the whole, somewhat larger than the corresponding ones of wheat.

Among the grains of medium and small size, hat-shaped and bell shaped ones are to be found; these are very seldom seen in wheat starch.

Industrial production of rye starch was carried out during World War II, but as soon as the supply of wheat, maize and potato starches returned to normal production ceased.

Rye starch has been tried as a gelling and thickening agent in the food industry and also in non-food applications.

Most of the structure provided by rye flour in bread comes from the interaction of its protein with pentosans and the gelatinization of its starch. Wheat flour in added in varying amounts to compensate for the gluten deficiency on rye.

Rye starch can be substituted for potato starch. A combination of rye starch and lipids has been used in desert mixes.
Rye starch

Starch

Starch is by far the most important source of carbohydrates in the human diet amounting to approximately 50% of total carbohydrate in the United States, but often as much as 75% total carbohydrates in some of the developing countries.

Starch is a polysaccharide made up of many glucose units bonded together – 3000 or so in each molecule of starch. Shorter carbohydrate chains composed of 3 to 1o glucose molecules are called oligosaccharides.

Starch is partly digested in the mouth and changed in the small intestine to glucose.

All the major economic sources of starch are plants. Starch and starch like molecules can also be found in other kingdoms, of life, including bacteria, algae and animals.

Starchy foods such as potatoes, bread and pasta provide other nutrients as well as starch. For example, bread is a good source of protein, B-group vitamins and minerals such as calcium and iron.

Other major sources of starch include cereal grains, such as wheat, rice, rye, millet, sorghum and corn. These grains contain 76 percent starch. Tubers, such as potatoes and cassavas and root vegetables such as parsnips, also supply starch.

Starch

Food starch

Starch is a plant polysaccharide stored in roots and seeds of plants and is in the endosperm of grain kernel.

The word of starch comes from Middle English word, strechen meaning ‘to stiffen’. Starch can exist in two forms, amylose and amylopectin, both of which are polymers of D-glucose.

The amylase molecule is a linear, unbranched structure in which the glucose residues are attached solely through a-1,4 glycosidic bonds. Amylopectin, on the a other hand, is a branched-chain polymer, the branch points occurring through a-1,6 glycosidic bonds.

Starch provides humans with energy 4 kcal per gram and is hydrolyzed to glucose, supplying the glucoses that is necessary for brain and central nervous system functioning.

To digest starches, humans have specialized digestive enzymes called amylases.

These enzymes breakdown starches into glucose, which is either used immediately as an energy source or stored in the liver and to be released when needed.

Food starch

Starch gelatinization process

Gelatinization process is characterized by the gelatinization temperature, above which the gelatinization of the starch suspension starts due to heat and moisture transfer phenomena.

It is the process that starch molecules undergo to thicken a liquid. It was defined by the expert as phase transition of granules from an ordered state to a disordered one.

When moist heat is applied to starch, the granules gelatinize, forming a mixture of thick, soft and creamy consistency.

This behavior makes starch useful for many purposes in food as an adhesive and thickening agent and industrial applications such as making paper paint and cosmetics.

There are three stages of gelatinization using starch:
*Heating the starch
*Absorbing the liquid
*Thickening the liquid

The process is essential for many industrial processes as it alters the rheology and viscosity properties of the system that the starch is in and it also makes the starch more accessible to enzymatic action.
Starch gelatinization process

Starch in food

Humans and their ancestors have always eaten starchy foods derived from seeds, roots and tubers. The practical use of starch products and perhaps of starch itself, developed when Egyptians, in the pre-dynastic period, cemented strips of papyrus together with starch adhesive made from wheat.

Starch is second only to water as the most abundant component of food.

Starches are carbohydrates that are storage materials in the seed and roots of many plants. Starches are commonly derived from corn, wheat, rice and other grains, as wee as potatoes and other root-like vegetables.

Starch has a negligible osmotic pressure, which allows plants to store large reserves of carbohydrate without disturbing the cell’s water relations.

Starch molecules are polymers of anhydroglucose and occurs in both linear and branched form. The degree of polymerization and accordingly, the molecular weight of the naturally occurring starch molecules vary radically.

Starch is, made up of many units of glucose linked together in different forms. In the intestine, starch is broken down to glucose and utilized of energy.

Moist heat causes starch grains to swell and rupture, thus converting starch to a form that is readily digested.

In the body, much of the glucose may be utilized directly as a source of energy, but some of it is converted into fat, the muscles utilizing fatty acids indirectly as fuel for energy. Excess carbohydrates not required for energy, when ingested (eaten) will be stored in the body as fat.

Food starches are commercially manufactured and available for use in products such as baked food, beverages canned, frozen and glassed foods, confections, dairy products, dry goods, meat products and canned
Starch in food

Starch in General

Humans and their ancestors have always eaten starchy foods derived from seeds, roots and tubers. The practical use of starch products and perhaps of starch itself, developed when Egyptians, in the pre-dynastic period, cemented strips of papyrus together with starch adhesive made from wheat.

Starches are carbohydrates that are storage materials in the seed and roots of many plants. Corn, wheat, rice and other grains, as wee as potatoes and other rootlike vegetables, contain significant amount of starch.

Starch has a negligible osmotic pressure, which allows plants to store large reserves of carbohydrate without disturbing the cell’s water relations.

Starch is, made up of many units of glucose linked together in different forms. In the intestine, starch is broken down to glucose and utilized of energy.

Cooling (moist heat) causes starch grains to swell and rupture, thus converting starch to a form that is readily digested.

In the body, much of the glucose may be utilized directly as a source of energy, but some of it is converted into fat, the muscles utilizing fatty acids indirectly as fuel for energy. Excess carbohydrates not required for energy, when ingested (eaten) will be stored in the body as fat.

The starches important in foods are primarily of plant origin and exhibit the following properties:
1 They are not sweet
2 They are no readily soluble in cold water
3 They form pastes and gels in hot water
4 They provide a reserve source in plants and supply energy in nutrition
5 They occur in seeds and tubers as characteristics starch granules

When a suspension of starch granules in water is heated, the granules swell due to water uptake and gelatinize: this increase the viscosity of the suspension and finally, a paste of formed which, on cooling can form a gel.

Gelatinization process is characterized by the gelatinization temperature, above which the gelatinization of the starch suspension starts due to heat and moisture transfer phenomena.

Many starches particularly the cereal starches such as corn, sorghum and wheat and also some of the flours such as wheat and potato flours, have a characteristics flavour which is caused by material other than carbohydrate. The flavours appear to be due to the oxidation of lipids present catalyzed by traces of copper and iron.

Because of their viscosity, starch pastes are used to thicken foods, and starch gels, which can be modified by sugar or acid are used in puddings.

Both pastes and gels can revert changes in food textural properties. Partial breakdown of starches yields dextrin, which are intermediate in chain length between starches and sugars and exhibit other properties intermediate between these two classes of compounds.

Many cooks use starch for such diverse properties as thickening gravies and soups, making a sweet pudding or dusting pastry before cooking.

For such purposes powdered starch in packet form in soften in direct competition with the wheat flour found in nearly every British and American and many Continental household, whilst in the latter potato starch or, quite often potato flour is in customary use.
Starch in General

Starch

Starch is a polysaccharide made up of glucose until linked together to form long chains. It is one of the most abundant storage polysaccharides in plants and at the same time the most important energy source in human and animal nutrition.

After cooking starch is highly digestible by human beings, raw starch often resists digestion.

The number of glucose molecules joined in a single starch molecule varies from five hundreds to several hundred thousand, depending on the type of starch.

Starch is the storage form of energy for plants. However to use it for humans, either as structuring compound in foods or for technical application, as it does not provide all the desired properties.

Two types of starch molecules exist-amylose and amylopectin. Amylose averages 20 to 30 percent of the total amount of starch in most native starches.

Amylopectin is a branched chain polymers. Amylose consists of linear chain polymers.

Different plants have different relative amounts of amylose and amylopectin. These different proportions of the two types of starch within the starch grains of the pant five each starch its characteristics properties in cooking and gel formation.

The crystalline structure of the granule is attributed to the presence of the amylopectin molecules, which arrange themselves in concentric rings. The rings consist of soft amorphous and hard semi crystalline shells.

In food starches are used to increase viscosity or to form gels. Because starch is insoluble in water, a mixture of starch with forms a suspension.

Thermal processing can change the physiochemical properties of starch, therefore it can affect s the texture of food products, characterization of aqueous starch suspension behavior and its interaction with other food additives.
Starch

Starches

Starches
Starches are carbohydrates that are storage materials in the seed and roots of many plants. Corn, wheat, rice and other grains, as potatoes and other rootlike vegetables, contain significant amount of starch.

Starch is, made up of many units of glucose linked together in different forms. In the intestine, starch is broken down top glucose and utilized of energy.

Cooling (moist heat) causes starch grains to swell and rupture, thus converting starch to a form that is readily digested.

In the body, much of the glucose may be utilized directly as a source of energy, but some of it is converted into fat, the muscles utilizing fatty acids indirectly as fuel for energy.

Excess carbohydrates, not required for energy, when ingested (eaten) will be stored in the body as fat.
Starches