Starch gelatinization

Last updated

Starch gelatinization is a process of breaking down of intermolecular bonds of starch molecules in the presence of water and heat, allowing the hydrogen bonding sites (the hydroxyl hydrogen and oxygen) to engage more water. This irreversibly dissolves the starch granule in water. Water acts as a plasticizer.

Contents

Gelatinization Process

Three main processes happen to the starch granule: granule swelling, crystallite and double-helical melting, and amylose leaching.

The gelatinization temperature of starch depends upon plant type and the amount of water present, pH, types and concentration of salt, sugar, fat and protein in the recipe, as well as starch derivatisation technology are used. Some types of unmodified native starches start swelling at 55 °C, other types at 85 °C. [3] The gelatinization temperature of modified starch depends on, for example, the degree of cross-linking, acid treatment, or acetylation.

Gel temperature can also be modified by genetic manipulation of starch synthase genes. [4] Gelatinization temperature also depends on the amount of damaged starch granules; these will swell faster. Damaged starch can be produced, for example, during the wheat milling process, or when drying the starch cake in a starch plant. [5] There is an inverse correlation between gelatinization temperature and glycemic index. [4] High amylose starches require more energy to break up bonds to gelatinize into starch molecules.

Gelatinization improves the availability of starch for amylase hydrolysis. So gelatinization of starch is used constantly in cooking to make the starch digestible or to thicken/bind water in roux, sauce, or soup.

Retrogradation

Gelatinized starch, when cooled for a long enough period (hours or days), will thicken (or gel) and rearrange itself again to a more crystalline structure; this process is called retrogradation. During cooling, starch molecules gradually aggregate to form a gel. The following molecular associations can occur: amylose-amylose, amylose-amylopectin, and amylopectin-amylopectin. A mild association amongst chains come together with water still embedded in the molecule network.

Due to strong associations of hydrogen bonding, longer amylose molecules (and starch which has a higher amylose content) will form a stiff gel. [6] Amylopectin molecules with longer branched structure (which makes them more similar to amylose), increases the tendency to form strong gels. High amylopectin starches will have a stable gel, but will be softer than high amylose gels.

Retrogradation restricts the availability for amylase hydrolysis to occur which reduces the digestibility of the starch.

Pregelatinized starch

Pregelatinized starch (Dextrin) is starch which has been cooked and then dried in the starch factory on a drum dryer or in an extruder making the starch cold-water-soluble. Spray dryers are used to obtain dry starch sugars and low viscous pregelatinized starch powder.

Determination

A simple technique to study starch gelation is by using a Brabender Viscoamylograph.[ citation needed ] It is a common technique used by food industries to determine the pasting temperature, swelling capacity, shear/thermal stability, and the extent of retrogradation. Under controlled conditions, starch and distilled water is heated at a constant heating rate in a rotating bowl and then cooled down. The viscosity of the mixture deflects a measuring sensor in the bowl. This deflection is measured as viscosity in torque over time vs. temperature and recorded on the computer. The viscoamylograph allows us to observe: the beginning of gelatinization, gelatinization maximum, gelatinization temperature, viscosity during holding, and viscosity at the end of cooling. [7]

Differential scanning calorimetry (DSC) is another method industries use to examine properties of gelatinized starch. As water is heated with starch granules, gelatinization occurs, involving an endothermic reaction. [8]

The initiation of gelatinization is called the T-onset. T-peak is the position where the endothermic reaction occurs at the maximum. T-conclusion is when all the starch granules are fully gelatinized and the curve remains stable.

See also

Related Research Articles

<span class="mw-page-title-main">Polysaccharide</span> Long carbohydrate polymers comprising starch, glycogen, cellulose, and chitin

Polysaccharides, or polycarbohydrates, are the most abundant carbohydrates found in food. They are long-chain polymeric carbohydrates composed of monosaccharide units bound together by glycosidic linkages. This carbohydrate can react with water (hydrolysis) using amylase enzymes as catalyst, which produces constituent sugars. They range in structure from linear to highly branched. Examples include storage polysaccharides such as starch, glycogen and galactogen and structural polysaccharides such as cellulose and chitin.

<span class="mw-page-title-main">Starch</span> Glucose polymer used as energy store in plants

Starch or amylum is a polymeric carbohydrate consisting of numerous glucose units joined by glycosidic bonds. This polysaccharide is produced by most green plants for energy storage. Worldwide, it is the most common carbohydrate in human diets, and is contained in large amounts in staple foods such as wheat, potatoes, maize (corn), rice, and cassava (manioc).

<span class="mw-page-title-main">Amylase</span> Class of enzymes

An amylase is an enzyme that catalyses the hydrolysis of starch into sugars. Amylase is present in the saliva of humans and some other mammals, where it begins the chemical process of digestion. Foods that contain large amounts of starch but little sugar, such as rice and potatoes, may acquire a slightly sweet taste as they are chewed because amylase degrades some of their starch into sugar. The pancreas and salivary gland make amylase to hydrolyse dietary starch into disaccharides and trisaccharides which are converted by other enzymes to glucose to supply the body with energy. Plants and some bacteria also produce amylase. Specific amylase proteins are designated by different Greek letters. All amylases are glycoside hydrolases and act on α-1,4-glycosidic bonds.

<span class="mw-page-title-main">Mochi</span> Japanese rice cake

Mochi, is a Japanese rice cake made of mochigome (もち米), a short-grain japonica glutinous rice, and sometimes other ingredients such as water, sugar, and cornstarch. The steamed rice is pounded into paste and molded into the desired shape. In Japan, it is traditionally made in a ceremony called mochitsuki. While eaten year-round, mochi is a traditional food for the Japanese New Year, and is commonly sold and eaten during that time.

<span class="mw-page-title-main">Croissant</span> Flaky, crescent-shaped pastry

A croissant is a buttery, flaky, viennoiserie pastry inspired by the shape of the Austrian kipferl but using the French yeast-leavened laminated dough. Croissants are named for their historical crescent shape. The dough is layered with butter, rolled and folded several times in succession, then rolled into a thin sheet, in a technique called laminating. The process results in a layered, flaky texture, similar to a puff pastry.

<span class="mw-page-title-main">Angel food cake</span> Type of sponge cake

Angel food cake, or angel cake, is a type of sponge cake made with egg whites, flour, and sugar. A whipping agent, such as cream of tartar, is commonly added. It differs from other cakes because it uses no butter. Its aerated texture comes from whipped egg white. Angel food cake originated in the United States and first became popular in the late 19th century. It gained its unique reputation along with its name due to its light and fluffy texture.

<span class="mw-page-title-main">Dextrin</span> Chemical compound

Dextrins are a group of low-molecular-weight carbohydrates produced by the hydrolysis of starch and glycogen. Dextrins are mixtures of polymers of D-glucose units linked by α-(1→4) or α-(1→6) glycosidic bonds.

<span class="mw-page-title-main">Amylose</span> Chemical compound

Amylose is a polysaccharide made of α-D-glucose units, bonded to each other through α(1→4) glycosidic bonds. It is one of the two components of starch, making up approximately 20–30%. Because of its tightly packed helical structure, amylose is more resistant to digestion than other starch molecules and is therefore an important form of resistant starch.

<span class="mw-page-title-main">Amylopectin</span> Chemical compound

Amylopectin is a water-insoluble polysaccharide and highly branched polymer of α-glucose units found in plants. It is one of the two components of starch, the other being amylose.

Desizing is the process of removing the size material from warp yarns after a textile fabric is woven.

<span class="mw-page-title-main">Parboiled rice</span> Partially cooked rice

Parboiled rice is rice that has been partially boiled in the husk. The three basic steps of parboiling are soaking, steaming and drying. These steps make the rice easier to process by hand, while also boosting its nutritional profile, changing its texture, and making it more resistant to weevils. The treatment is practiced in many parts of the world.

<span class="mw-page-title-main">Glucose syrup</span> Syrup made from the hydrolysis of starch

Glucose syrup, also known as confectioner's glucose, is a syrup made from the hydrolysis of starch. Glucose is a sugar. Maize (corn) is commonly used as the source of the starch in the US, in which case the syrup is called "corn syrup", but glucose syrup is also made from potatoes and wheat, and less often from barley, rice and cassava.p. 21

Carbohydrase is the name of a set of enzymes that catalyze 5 types of reactions, turning carbohydrates into simple sugars, from the large family of glycosidases.

<span class="mw-page-title-main">Resistant starch</span> Dietary fiber

Resistant starch (RS) is starch, including its degradation products, that escapes from digestion in the small intestine of healthy individuals. Resistant starch occurs naturally in foods, but it can also be added as part of dried raw foods, or used as an additive in manufactured foods.

<span class="mw-page-title-main">Waxy corn</span>

Waxy corn or glutinous corn is a type of field corn characterized by its sticky texture when cooked as a result of larger amounts of amylopectin. The corn was first described from a specimen from China in 1909. As this plant showed many peculiar traits, the American breeders long used it as a genetic marker to tag the existence of hidden genes in other maize breeding programs. In 1922 a researcher found that the endosperm of waxy maize contained only amylopectin and no amylose starch molecule in opposition to normal dent corn varieties that contain both. Until World War II, the main source of starch in the United States was tapioca, but when Japan severed the supply lines of the U.S., they forced processors to turn to waxy maize. Amylopectin or waxy starch is now used mainly in food products, but also in the textile, adhesive, corrugating and paper industry.

<span class="mw-page-title-main">Modified starch</span> Thickening agent

Modified starch, also called starch derivatives, are prepared by physically, enzymatically, or chemically treating native starch to change its properties. Modified starches are used in practically all starch applications, such as in food products as a thickening agent, stabilizer or emulsifier; in pharmaceuticals as a disintegrant; or as binder in coated paper. They are also used in many other applications.

Retrogradation is a reaction that takes place when the amylose and amylopectin chains in cooked, gelatinized starch realign themselves as the cooked starch cools.

<span class="mw-page-title-main">Potato starch</span> Thickening agent used for culinary purposes

Potato starch is starch extracted from potatoes. The cells of the root tubers of the potato plant contain leucoplasts. To extract the starch, the potatoes are crushed, and the starch grains are released from the destroyed cells. The starch is then left to settle out of solution or separated by hydrocyclones, then dried to powder.

<span class="mw-page-title-main">Instant noodles</span> Noodles sold in a precooked and dried block with flavoring

Instant noodles, or instant ramen, is a type of food consisting of noodles sold in a precooked and dried block with flavoring powder and/or seasoning oil. The dried noodle block was originally created by flash-frying cooked noodles, and this is still the main method used in Asian countries; air-dried noodle blocks are favored in Western countries. Dried noodle blocks are designed to be cooked or soaked in boiling water before eating. Ramen, a Japanese adaptation of Chinese noodle soup, is sometimes used as a descriptor for instant noodle flavors by some Japanese manufacturers. It has become synonymous in the United States with all instant noodle products.

<span class="mw-page-title-main">Floridean starch</span> Type of storage glucan

Floridean starch is a type of a storage glucan found in glaucophytes and in red algae, in which it is usually the primary sink for fixed carbon from photosynthesis. It is found in grains or granules in the cell's cytoplasm and is composed of an α-linked glucose polymer with a degree of branching intermediate between amylopectin and glycogen, though more similar to the former. The polymers that make up floridean starch are sometimes referred to as "semi-amylopectin".

References

  1. Jenkins, P J, and A M. Donald. "Gelatinisation of Starch: a Combined Saxs/waxs/dsc and Sans Study." Carbohydrate Research. 308 (1998): 133-147. Print.
  2. Zobel, H. F. (1988), Starch Crystal Transformations and Their Industrial Importance. Starch - Stärke, 40: 1–7. doi : 10.1002/star.19880400102
  3. Hans-Dieter Belitz, Werner Grosch, Peter Schieberle, Food chemistry, Edition 3, Springer, page: 318-323, year: 2004, ISBN   3-540-40818-5, ISBN   978-3-540-40818-5
  4. 1 2 USapplication 20080201807,Robert James Henry&Daniel Lex Ean Waters,"Gelatinization Temperature Manipulation", assigned to SOUTHERN CROSS UNIVERSITY, Rural Industries Research and Development Corporation
  5. Stanley P. Cauvain, Linda S. Young, Baking problems solved, Woodhead Publishing, page: 25-26, year: 2001, ISBN   1-85573-564-4, ISBN   978-1-85573-564-4
  6. Hegenbart. S.. Understanding starch functionality. Food product. Web. 1996 https://www.foodproductdesign.com/articles/1996/01/understanding-starch-functionality.aspx
  7. "Herausragende Analysetechnik: Brabender GmbH & Co KG". www.brabender.com.
  8. "siint.com" (PDF). www.siint.com.