Starch Retrogradation

  1. Explain why starch retrogradation is not desirable in bread.
  2. Sometimes retrogradation of starch is desirable, and even promoted and accelerated. Discuss why this is so by giving appropriate examples.

37 Comments

  • Retrogradation is the realignment of amylose and amylopectin chains after gelatinisation occurs. It occurs at lower temperatures of onset of gelatinisation. Linear molecules of amylose and linear parts of amylopectin form hydrogen bonds which produces a crystalline structure. Retrogradation causes liquid to turn into a form of gel. In the retrogradation process, syneresis occurs where water is expelled from the liquid to form a gel.

    1. Retrogradation expels water from the bread structure. Water will then evaporate at suitable conditions to leave the bread structure causing the bread to lose moisture (staling). Hence, the bread will be more dry and may be undesirable in terms of taste. The presence of sugar, salt and eggs/emulsifiers help to retain the moisture of the bread when retrogradation of starch occurs.

    2. Some products can benefits from starch retrogradation. Cooked rice and potatoes undergo retrogradation when cooled. Resistant starches are formed. These starches are not digestible by humans in the intestines but bacteria living in the human gut can digest them. Thus, resistant starches provide food for these friendly bacteria. Digestion of resistant starches by friendly bacteria produces butyrate.

    Butyrate can be used as a source of energy for the cells lining the human colon. Utilisation of butyrate has shown positive health benefits such as preventing inflamation of the gut and other tissues as well as increasing resistance to metabolic and physical stresses.

    Resistant starch itself provide other health benefits such as improving satiety level, improving insulin sensitivity and lowering blood sugar levels.

    Some studies may have shown other possible benefits of retrogradation in other foods. Bread crumbs are made from dry (but not stale bread). Retrogradation can help to remove some moisture from the bread. Standard bread crumbs are usually a form of dry food product. In the making of rice stick noodles, controlled degree of retrogradation may aid the production of desirable physical properties such as transparent noodles and slightly tougher texture with the expulsion of water.

  • Starch retrogradation is a phenomenon by which leeched starch granule content such as amylose and amylopectin starts to realign and thus contributing to increased viscosity of the system. Starch retrogradation in bread is normally called as bread staling. Although the total moisture content in stale bread remains similar as in fresh bread, bread staling causes bread to be dry and hard, which is less appealing to consumers especially soft breads like filled buns, waffle and pancake. In this situation, starch retrogradation can be slowed by storing at <0 degree Celsius and adding lipids and proteins. Starch retrogradation in bread can be reversed, provided the extent of retrogradation is not too extreme, by adding a small amount of water and heat in an oven.

    However, starch retrogradation is sometimes desirable in certain products. In bread loaf, small degree of starch retrogradation (staling) improves the firmess and thus ease the slicing. This degree of starch retrogradation is achieve by amylose realigning themselves together, as amylose as linear chain molecules can start to align earlier than branched amylopectin. Starch retrogradation is also important for products like crouton. Crouton has a crispy texture can be found in salad. A certain degree of starch retrogradation (on the above average side) is desired, as this will make the middle layer slightly fluffy while the outer layer is hard and crunchy.

  • 1) When heated up in the presence of moisture or water molecules, for instance placing the bread dough in the oven, the starch molecules weaken and allow water molecules to enter, or get in between the chains of the sugar molecules and join with them. This swells the starch granule and begins to soften it up, making it so fluffy. Retrogradation occurs the moment bread is take out of the oven (cooling begins), the process begins to reverse itself. Retrogradation can expel water (syneresis) from the bread structure. Syneresis causes amylose molecules to pull back together into the starch granule, squeezing out the water molecules previously inside. Then, retrogradation allows the amylose molecules to realign in a linear-chain pattern. This structure is kept rigid because hydrogen bonding occurs between the chains of amylose. As a result, the bread feels hard and is now stale.

    2) Retrogradation is desirable until some extent like in bread crust, to get the crispy bread crust. Other example is parboiled rice (rice that has been partially boiled in the husk). It is boost in nutritional profile (carries 80% of the nutrients of brown rice). The starches in parboiled rice become gelatinized, then retrograded after cooling. Cooling brings retrogradation whereby amylase molecules re-associate with each other and form a tightly packed structure. This increases the formation of type 3-resistant starch which can act as a prebiotic and benefit gut health in humans.

  • 1. Starch retrogradation leads to bread staling where the amylose and amylopectin reallign themselves and gives bread firmer and less crispiness texture which are undesirable in bread.
    2. Retrogradation of starch is desirable in production of type III resistant starch and rice stick noodles. During production of resistant starch, retrogradation process is occur to allow the amylose and amylopectin bind with stronger bond, allow the starch able to resist digestion where digestion of starch into monomer (glucose) is at lower rate compared to normal starch thus low glycermic index (GI) and suitable for consumer with diabetes. During production of rice stick noodle, the aging process associated with retrogradation of rice starch, this process provide a harder and less sticky structure for noodle to be easily cut during extrusion process.

  • 1) Starch retrogradation is a phenomenon which the ruptured structure of starch from gelatinization process is restored. It is usually described as recrystallization during storage after starch pasting. The change in crystalline structure after pasting involves the formation of ordered double helical structure from amorphous glucans. This process will also expels water from the bread, which then stales the bread. This phenomenon will cause bread to have harder texture and less crispiness. However, starch retrogradation is reversible in bread by simply reheating the bread in the oven.

    2) Retrogradation can cause desirable effects in certain food by controlling it. First of all, we need to know the factors that causes retrogradation. It can be amylose-amylopectin ratio, temperature and size of linear starch molecules. By controlling the degree of retrogradation, we can produce food with wonderful properties to serve some needs such as resistant starch to diabetic patient and parboiled rice with high nutritional value.

  • 1) Starch retrogradation is a process that occurs when the molecules comprising gelatinized starch begin to reassociate in an ordered dstructure.In the initial phases of retrogradation,two or more molecules may form a simple juncture point,which then may develop into more extensively ordered regions.Retrogradation of gelatinized starch is a reorganization process that can involve either amylase or amylopectin,with amylase undergoing retrogradation at a more rapid rate than amyloprectin.The rate of retrogradaton depends on a number of variables,including the structure of amylase and amylopectin,ratio of amylase and amylopectin,temperature,starch concentration,botanical sources of the starch and the presence and concentration of other ingredients such as surfactants and salts. During baking,starch is gradually transitioned from an amorphous structure to a partially crystalline state,a result of inter or intramolecular interactions via hydrogen bonding of the amylase and amylopectin fractions.Upon recrystallization (retrogradation),starch will release water and the crumb becomes very firm and stale.The change in texture and flavor of starch-based products during storage is commonly called staling.
    2) Retrogradation, however, often exerts unacceptable influences on the texture of starchy foods, such as in staling of bread and hardening of rice cake. However, it has been reported that starch retrogradation could result in a reduction of GI value, due to the increased resistance to digestive enzymes .In some products, retrogradation can provide a desirable quality such as in the manufacture of rice stick noodles, resistant starch type 3 croutons, and bread crumb.For example in pasta products, gluten forms a viscoelastic network that surrounds the starch granules, which restricts swelling and leaching during boiling. Pasta extrusion is known to result in products where the starch is slowly digested and absorbed. Spaghetti is a comparatively rich source of resistant starch. The slow-release features of starch in pasta probably relates to the continuous glutenous phase. This not only restricts swelling, but possibly also results in a more gradual release of the starch substrate for enzymatic digestion. Pasta is now generally acknowledged as a low glycemic index food suitable in the diabetic diet.

  • 1)The retrogradation of starch is defined as recrystallization during storage after starch pasting. It is a process which takes place when the gelatinized starch molecules from an initially amorphous status begin to reassociate in a more ordered structure. Retrogradation occurs in amylose fraction and also amylopectin from gelatinized granules. The retrogradation of amylopectin is the primary component responsible for the staling of bread. The association and rearrangement of amylopectin in swelled starch particles proceed to gradually harden the particles. Bread that was initially soft and moist becomes progressively harder and drier. Retrogradation can lead to an obvious increase in the firmness of stored baked good and hence making it unattractive to consumers. Starch retrogradation is the major influencing factor of bread staling.

    2) Retrogradation can provide a desirable quality in the manufacture of starch based noodles, croutons, and bread crumb. Retrogradation is important to achieve the desired storage and culinary properties. The staled bread can be sliced into cubed and gives crunchy texture to the croutons as a result from retrogradation. Besides, the retrogradation behavior predicts the stability of the starch noodles and the capability to withstand boiling temperature. Without retrogradation, the noodles might simply dissolve in the soup.

  • Starch retrogradation isn’t desired in bread because it is part of the process of bread staling, where amylopectin crystallizes over time at cool temperature, causing the bread to be dry and hard, decreasing its appeal to consumers.

    Retrogradation is promoted in certain food products to modify its structural, mechanical or organoleptic properties. Examples are breakfast cereals and noodles. In breakfast cereals, the retrogradation of starch is desirable because it results in hardening and reduction of stickiness, making it easier to handle with its texture becoming crunchy. Noodles on the other hand are immersed in cold water after cooking to induce retrogradation to reduce stickiness and increase its chewiness.

  • 1. In bread starch retrogradation contributes to bread staling. As soon as the bread takes out from oven, starch retrogradation will occur immediately. Retrogradation of starch occur when the starch undergo temperature below gelatinized temperature (cooling). At this point, starch will reform and harden. The water that absorbed during baking will expel and evaporates. Staling makes the bread harder and dry thus, starch retrogradation is not desirable in bread.
    2. However, retrogradation also desirable for certain product such as croutons and bread crumb (usually used in making a crisp and crunchy coating for fried foods and to thicken the sauce). To make a fresh bread crumb, retrogradation of starch is needed to make it dry prior to cut the bread. Retrogradation give crunchy texture to bread crumb upon let it cool at low temperature.

  • 1. Starch retrogradation is a reversible process that may be reversed by heating. Bread, which is retrogradation is manifested by a stiffening of the structure or staling, making the product appear hard and dry. Starch retrogradation rate increases with decreasing moisture content and reduced temperature. Quick staling or increase in crumb firmness is one of the most unpleasant properties of gluten free bread. The mechanisms of staling are still being debated. It has been associated with starch retrogradation. Starch retrogradation alone is sufficient to cause bread firming. Within the starch phase, amylose retrogradation occurs very fast upon cooling and helps to stabilize the crumb. In contrast, amylopectin retrogradation is slower and seems to be the decisive factor for aspects of staling like crumb firming and loss of elasticity.
    2. Retrogradation of starch is desirable is some food. One of the example is rice stick noodles and it is contain high amylose rice. Sheet ageing is very important step for rice stick noodles because this is to harden and reduce stickiness of sheets, allowing them to be more easily cut into strips. During this step, retrogradation occurs.

  • 1) Starch retrogradation that happens in bread is known as bread stalling. During staling, the amylose and amylopectin in the bread rearrange themselves become semi crystalline state. The water that was absorbed during baking gets slowly expelled and eventually evaporates. Bread that was initially soft and moist becomes progressively harder and dry. Thus, staling in bread reduces their palatability and become undesirable. The rate of staling process can be slow down by adding in sugar, eggs, or dairy. The sugar helps to absorb and retain moisture while eggs and dairy both trap moisture and interfere with the retrogradation.
    2) In some products, retrogradation can provide a desirable quality such as in the manufacture of rice stick noodles, croutons, and bread crumb. The starch component of these products undergoes retrogradation, defined as partial crystallization of amylopectin within the gelatinized starch fraction, with an increase of firmness and a modification of taste. For example crouton give crispy texture, bread crumb give firmness and ease for slicing and the harder and less sticky rice stick noodles which can easily handle or cut during extrusion process.

  • 1. Starch retrogradation in bread is due to entrapment of water in the recrystallized amylopectin where moisture migrates from protein to the starch, results in modification of the gluten network, which is the so called bread staling. Bread staling is undesirable in bread as it results in loss of sensory parameters of bread such as flavor and texture. The flavor deterioration is caused by formation of complex compounds between the flavor compounds and the amylose while the texture causes changed in mouthfeel as the bread becomes firmer, dryer and shorter bite. Besides that, bread staling reduces the consumer acceptance of bakery products by the lost of crustiness, lost of crumb softness, loss of freshness due to equalization of moisture.

    2. Highly retrograded starch such as resistant starch that fraction formed upon food processing, is a useful starch derivative. It exhibits the beneficial physiological effects of therapeutic and nutritional values akin to dietary fiber. It is said that resistant starches are not digested by enzymes, but are fermented in the intestine, resulting in the production of short chain fatty acid that would decrease the risk of colon cancer. Besides that, resistant starches are also important as they can yield foods with greater nutritional quality, such as muesli bars, which contain only partially milled cereals. Meanwhile, for some other products such as rice stick noodles, retrogradation of rice starch causes reduced in stickiness and increase in hardness of the noodle to be easily cut during extrusion process.

  • 1. Starch retrogradation, the cause of ordinary texture staling of the bread crumb. Because firming of bread develops also over several days, most staling models view the changes in the amylopectin fraction as the primary cause for bread firming. The firming of bread crumb and the loss of crust crispness are essential factors in the loss of textural quality of bread on aging. Therefore, starch retrogradation is undesired in bread.

    2. Retrogradation can provide a desirable quality such as in the manufacture of rice stick noodles , resistant starch type 3 croutons, and bread crumb. Type 3 is formed when certain starchy foods, including potatoes and rice, are cooked and then cooled. In rice noodles processing, the cooling turns some of the digestible starches into resistant starches via retrogradation. During cooling or aging process, the swollen starch granules reorganize among themselves through the process of retrogradation. Too rapid retrogradation will give a very stiff strands while a much slower rate will give a very elastic structure that can bend or compress the noodles without breaking. The retrograded sheet at this moment has acquired a very good consistency and firmness.

  • Question 1:
    When starch is heated with water for gelatinization and then let stand, the association and rearrangement of amylopectin in swelled starch particles proceed to gradually harden the particles. This process is called the retrogradation of starch. Retrogradation is induced by low temperature, high amylose content and the presence of polar substances, such as salts.
    The term retrogradation is used to describe changes that occur as a result of the cooling and storage of starch products (E.g. bread). The most common negative effect of retrogradation in bread is decreased storage stability. The change in texture and flavor of bread during storage is commonly called staling. The product becomes dry and hard, often caused by starch retrogradation. Amylopectin starch or modified starch which attract small side chains that will act as a steric hindrance to recrystallization—is usually used to avoid retrogradation.

    Question2:
    The starch retrogradation and the resistant starch (RS) formation result in interesting sources of low GI and high content of RS foods. Foods such as corn meal and spaghetti are made out of grains that have their structures broken to elaborate the meal. This processing disrupts the cellular wall making the starch more available. It can explain, in part, the high GI produced by the corn meal when it is consumed immediately after it was cooked.

  • 1 & 2
    Retrogradation is the phenomenon in which the regular structure of starch molecules, lost during gelatinization, is restored during storage. Amylose molecules rearranging in an orderly fashion and is accompanied by gel hardening. When a hot starch is cooled, it generally forms a viscoelastic, firm and rigid gel or precipitate. The amylose realigning and forming double helixes that then will aggregate.
    Retrogradation is the cause behind firming of bread as it cools after baking and causes bread to become stale on storage. Bread changes in texture and flavour, making the bread ‘dry and hard’.
    During baking amylose leeches out and retrogrades almost fully on cooling, it affects texture by giving an elastic and tender crumb, thus the retrogradation of starch is desirable. On storage amylopectin branches slowly associates, causing the crumb and bread hardens (staling), the starch retrogradation is now not desirable in bread. Bread is observed to stale more rapidly at cool temperature and less rapidly at 60 ℃ or higher.

  • . Because it can cause bread firming.within starch phase, amylose retrogradation occurs very fast upon cooling and help to stabilize the crumb. in contrast, amylopectin retrogradation is slower and seems to be factor for aspects of staling like crumb firming and loss the elasticity. crumb firmness increase with over storage time when no drying occurs.

    2. Retrogradation is sometimes promoted to modify the structural, mechanical or organoleptic properties of certain starch-based products. For example, in the production of breakfast cereals and parboiled rice, since retrogradation results in hardening and reduced stickiness. For freezing/thawing methods, which accelerates retrogradation, is applied to cooked potato mash in the production of dehydrated mashed potatoes to decrease the amount of soluble starch and to improve the consistency of the reconstituted product. Similarly, Chinese rice vermicelli a type of rice noodle strands are conditioned after complete steam-gelatinization of starch in order to attain the desired textural characteristics. Other examples are rice stick noodles, croutons, and bread crumb. Water content and storage temperatures play key roles in the extent of retrogradation. The maximum extent of retrogradation of most starches is attained in starch gels containing 50%–60% solids.

  • 1. Starch retrogradation is a reaction that takes place in gelatinized starch when the amylose and amylopectin chains realign themselves. It is also normally described as recystallization (change in crystalline structure) after pasting involved the formation of ordered double helical structure. However, starch retrogradation is not desirable in bread because it largely responsible for bread staling. There are some changes which occur in bread as a result of staling such as increase of crumb firmness, lost of crust crispiness and even deterioration in flavor and aroma.

    2. Retrogradation of starch is desirable in the manufacture of products such as rice stick noodles, resistant starch type 3, croutons, bread crumb and others. Resistant starch type 3 formation is increased in a cooked starchy product such as potato and rice especially after cooling. It enhances insulin sensitivity, lowers blood sugar levels and improves metabolic health. Besides, retrogradation is applied to rice noodles to obtain characteristic chewiness and reduce stickiness. To make nice bread crumb and crouton, retrogradation also is needed to give crispy and firm texture.

  • 1. Starch retrogradation will caused the texture of bread harden. During baking a bread, starch in bread dough starts to gelatinise with presence of water and heat. The starch molecule absorbs water and swell and become semi-firm. When the bread is cools below gelatinisation temperature, the amylose and amylopectin chains starts to realign themselves to a more crystalline structure. Water that initially absorbed during baking will slowly expelled and eventually evaporated.
    2. Retrogradation of starch in desirable to get a crispy bread crumb. The harden crumb surface will protect the freshness of the crust. The crystalline structure of crumb will prevent the moisture evaporate in bread crust. Besides, in production of parboiled rice, the starches in parboiled rice become gelatinised and retrogate after cooling. Alpha amylose molecules will leach out from the starch granule network and diffuse into the surrounding aqueoes medium outside the granules Cooling of the rice will bring retrogradation whereby amylase molecules re-associate with each other and form a tightly struture.This increases the formation of type 3-resistant starch which can act as a prebiotic and benefit gut health in humans.

  • 1) Retrogradation is not desirable in bread because it cause the bread to become stale on storage. This happen because the regular structure of starch molecules (amylose) that lose during gelatinization is restored during storage cause the starch molecules to reform and harden. At the same time, syneresis occurs which the water that was absorbed during baking were squeezed out and gets slowly expelled and eventually evaporates. As a result, the bread became hard and dry.

    2. During retrogradation, resistant starch type 3 were form and it is usually found in cooked and cooled potatoes, grains and beans. When its cooled, this starch crystallize and become less digestible. Because of that, RS3 starch had more impact on satiety that other types of fibers. Besides, it also promotes intestinal or colonic health through their fermentation and action as prebiotic fibers.

  • 1. Starch retrogradation is a phenomenon in which the gelatinized starch has it amylose and amylopectin chain align themselves, causing the linking of hydrogen bond, thus the structure become compact and release out water. This is a process known as syneresis. Retrogradation is directly related to the staling or aging of bread. Syneresis cause by the retrogradation make the bread lose it water content, thus the bread harden. that’s why we do not favor retrogradation in bread making.
    2. Retrogradation is sometimes favorable. like in bread making, we let the bread retrograde for a while so we get the favorable crust. Retrograded rice also play a nice effect on weight control, gut function, and lipid concentrations. The resistant starch produced by the retrogradation help body metabolism.

  • 1. Retrogradation is changes that occur as a result of the cooling and storage of starch products. The change in texture and flavor of starch based products during storage is called staling. The product become dry and hard, cause by starch retrogradation. This is the reason why starch retrogradation is not desired in bread. The bread that is initially soft becomes harder and dry.

    2. Cooking normally cause starch gelatinization. But sometimes retrogradation can modify the structural, mechanical or organoleptic properties in certain starch based product. Since retrogradation results in hardening and reduce stickiness, product like breakfast cereals are most likely desired the retrogradation. Physical and chemical changes in dehydrated potatoes granules during cold storage and freeze-thaw cycles produce retrogradation. The rehydration rate of dehydrated potatoes granules decrease on storage, making these granules desirable for manufacture of extruded French fries because the granules remain cohesive during frying process

  • 1) Starch retrogradation is believed to be the main factor in the staling of bread. When the bread become staled, the texture of crumb become hard and looks dry, this is mainly because of retrogradation of amylopectin.

    2) Sometimes, retrogradation is desirable in food products, for example the Type 3 resistant starch. This is because some studies shown that the resistant starch gives so many health benefits, such as improved satiation, low glycemic index (GI), improve insulin sensitivity, very effective in lowering blood sugar level, and therefore very good for diabetic patients.

  • 1. Starch retrogradation is undesirable in bread because it can cause bread staling. Starch molecules in the raw bread dough begin to gelatinize during heating. They absorb moisture, swell and become semi-firm. starch retrogradation happen when the loaf comes out of the oven and cools to below gelatinization temperature, the starch molecules reform and harden. The water that was absorbed during baking gets slowly expelled and eventually evaporates. Bread that was initially soft and moist becomes harder and dry. Staling of the bread resulted some changes to the bread such as increase of crumb firmness, increase in crumliness of the crumb, deterioration in flavour and aroma and also lost of crispiness. The staling process happen more slowly in breads that enriched with sugar, eggs, or dairy. Sugar absorb and retain moisture while eggs and dairy trap moisture and interfere with retrogradation process. Besides, changes in starch play a major role in causing bread firmness. It occur when amylose and amylopectin chains realign themselves. When native starch is heated and dissolves in water, the crystalline structure of amylose and amylopectin molecules is lost and they hydrate to form viscous solution. Then, after viscous solution is cooled for long period, the linear molecules, amylose and linear parts of amylopectin molecules retrograde and rearrange again to a more crystalline structure.

    2. In some products, retrogradation can provide a desirable quality such as in the manufacture of rice stick noodles, resistant starch type 3 and bread crumb. RS3 formed when starch containing foods are cooked and cooled such as in legumes, bread, cornflakes and pasta. Water content and storage temperatures play key roles in the extent of retrogradation. Retrograded starch is linked to a reduction in colon cancer. retrograded starch is less digestible and recognized as a beneficial carbohydrate.

  • 1. Retrogradation refers to the occurance where the starch retrogrades to a more crystalline structure upon cooling. In other words, it is reaction that takes place in gelatinized starch when the amylose and amylopectin chains realign themselves, largely responsible for bread becoming hard (stale). Bread staling refers to all of the changes which occur in bread after baking results deterioration in flavour and aroma and loss of crispiness. As the changes occur above, thats why starch retrogradation is not desirable in bread.

    2. Precooked meals such as pasta and rice (parboiled) undergoes retrogradation following cooking with increase in firmness and a modification of taste. Other than that, Type 3 is one of the resistant starch (RS3) that is formed when starchy foods, including potatoes and rice are cooked and then cooled.The cooling turn some of the digestible starches into resistant starches via a process retrogradation. These type of starch can “resists” digestion in the small intestine. Besides that, it improve healths by feeds the friendly bacteria in the intestine and increase production of short chain fatty acids (butyrate).

  • 1. Retrogadation describe changes that occurs as a result of the cooling and the storage of starch products. Its refers to the association and crystallization of starch in water causing effects, such as precipitation, gelation, and changes in consistency and opacity. The most negative effect of retrogadation in food is decreased storage stability. Retrogradation is directly related to the staling or aging of bread. Starch retrogadation is sufficient to cause bread firming. Quick staling or increase in crumb firmness is one of the unpleasant properties of gluten-free bread. Amylose retrogadation occurs very fast upon cooling and helps to stabilize the crumb. in contrast, amylopectin retrogadation is slower and seems to be the decisive factor for aspects of staling like crumb firming and loss of elasticity. So, that is why retrogradation is undesirable in bread.

    2. Retrogradation is sometimes promoted to modify the structural, mechanical or organoleptic properties of certain starch-based products. For example, in the production of breakfast cereals and parboiled rice, since retrogradation results in hardening and reduced stickiness. Freezing or thawing which accelerates retrogradation, is applied to cooked potato mash in the production of dehydrated mashed potatoes to decrease the amount of soluble starch and to improve the consistency of the reconstituted product. the production of Japanese ‘harusame’ noodles also involves a freeze-thaw cycle to reduce stickiness and to obtain a characteristic chewiness. Chinese rice vermicelli (rice noodle) strands are conditioned after complete steam-gelatinization of starch in order to attain the desired textura; characteristics.

  • Starch retrogradation is one of the most unpleasant properties of gluten-free bread because it can cause quick staling or increase in crumb firmness. During baking, starch molecules in the raw bread dough begin to gelatinize at about 150 °C, whereby they absorb moisture, swell and then become semi-firm. This is the part which sets the structure or ‘crumb’ of the final loaf. When the loaf comes out of the oven and cools below the gelatinization temperature, the starch molecules reform and harden. The water which was absorbed during baking gets slowly expelled and eventually evaporates. The bread that was initially soft and moist becomes harder and dry.

    Retrogradation is a reaction that takes place in gelatinized starch when the amylose and amylopectin chains realign themselves causing the liquid to gel. Retrogradation is undesirable in stored baked goods and frozen cooked rice. However, in some products, retrogradation can provide a desirable quality such as in the manufacture of rice stick noodles, croutons and bread crumb. Resistant starch (RS) is one of the starch degradation products that escape from digestion in the small intestine of healthy individuals. Resistant starch is considered the third type of dietary fibre, as it can deliver some of the benefits of dietary fibre and some of the benefits of soluble fibre. Meanwhile, in some carbohydrates such as sugars and most starch are rapidly digested and absorbed as glucose into the body through the small intestine and subsequently used for short-term energy needs or stored.

  • 1. Retrogradation were defined as a process when amylose or amylopectine undergo slow recrystallization which leads to change in the visual appearance as well as flow properties of cooked starch. At the suitable concentration, starch develop viscosity rapidly upon gelatinization. When gelatinized starch cook is cooled, amylose and amylopectin segments start to slowly align to form hydrogen bond and then recrystallized. Retrogradation lead to an obvious increase in bread firmness or bread stalling. In regular wheat bread, starch will interact with gluten fibril and cross link them, thus leading to the stalling process.

    2. In certain condition, retrogradation is desirable to provide desired product’s quality, for example in manufacturing of stick noodles, resistance starch type 3, croutons and bread crump. Since most of people nowadays were concern about the healthier food, production of resistance starch(RS) from retrogradation is become more important. Special properties of RS which are less digestible give powerful benefits in improving insulin sensitivity, lower blood sugar levels and various benefit to digestion system. In human body, resistance starch cannot be digested, so it will go to the colon and undergo some fermentation process to form a good pro biotic bacteria.

  • 1 .The term retrogradation is used to describe the changes that occur on cooling and storage of starch product .Retrogradation occur after the gelatinization process involves the formation of a more organized structure by molecular amylose and amylopectin.Retrogradation can expel water from the polymer network. This is a process known as syneresis. A small amount of water can be seen on top of the gel. Retrogradation is directly related to the staling or aging of bread.Retrogradation is the main factor in staling of the bread.When water are expel from the bread,the bread will become stale. The main course is the retrogradation of amylopectin.Usually bread have a moist and soft texture,hard and dried texture are not desirable in bread .The most negative effect of retrogradation is it decrease the storage stability of food.
    2.Retrogradation not only give negative effect to food industry,it also give advantages and are desired in food industry.For example in the manufacture of rice stick noodles, resistant starch type croutons, and bread crumb .Hard texture is desired in bread crumb and the desired texture can be produced from retrogradation process.The bread crumb will become hard and and dry by undergoing retrogradation process.

  • 1. The retrogradation is the main factor responsible for the staling of the bread where the amylose and amylopectin molecules realign themselves in gelatinized starch. Retrogradation is not desirable in bread because it can increase the firmness of the bread during storage making them unattractive to consumer. Besides that, the breads will become hard, leathery, pleasant fresh flavor lost to the air and often unpleasant flavor is absorbed.
    2. The retrogradation of canned rice during storage is desirable as the hardness or the rice kernel increased with the duration of the storage time. This can prolong the shelf life of the canned rice as its’ moisture content become lower. Retrogradation of starch in the manufacture of rice stick noodles can be accelerated by low the temperature during aging process. The noodles sheets aged at lower produces optimal harder noodles and less sticky.

  • 1. Starch retrogradation is the changes that occur in gelatinized starch from initially an amorphous state to more ordered crystalline state. Crystallization of amylopectin is considered as one of the main changes occurring in starch retrogradation and it is one of the causes for staling of bread. This staling process begins during cooling even before starch has solidified sufficiently for the loaf to be cut. Bread staling is associated with firming of the crumb. During storage, the crumb generally becomes harder, dry and crumbly and the crust becomes soft and leathery.

    2. Starch retrogradation sometimes promoted to modify structure and mechanical organoleptic properties of certain starch-based product. In smooth mashed potatoes, retrogradations are desirable to prevent sticky mash. The retrogradation can decrease the amount of soluble starch and to improve the consistency of reconstituted product. The retrograde starch in mashed potatoes can be obtained by heating potatoes precisely to its gelatinization temperature, holding and chilling them.

  • Answer 1:
    Starch retrogradation has been defined as the process, which occurs when the molecular chains in gelatinized starches begin to reassociate in an ordered structure. During retrogradation, amylose forms double-helical associations whereas amylopectin crystallization occurs by reassociation of the outermost short branches. These gradual changes in starch component from amorphous to crystalline state results in Bread Staling. Freshly baked bread has crisp crust, soft crumb and appealing aroma. However, as a result of staling, the crumb firmness increases slightly, crispness of the bread crust decreases and the bread loaf loses it fragrances. Industrially, starch retrogradation in bread is countered by the addition of emulsifiers.

    Answer 2:
    Noodles: The cooking treatment after the cold extrusion of noodles permits the dispersion of the amylose, which forms a network during the cooling treatment as a result of retrogradation. Such network may avoid the dispersion of the starch components during the cooking of noodles, therefore, reducing the solid loss. This in turn decreases the stickiness and increases the noodle’s chewy property. Besides, the retrogradated starch also facilitates the process of cutting noodles into strips.
    Bread:Retrograded starch in bread results in firmness of the bread and thus the ease of slicing. In addition, retrogradation results in crunchy middle layer and fluffy inner part in breads
    Breakfast Cereals: They increase coating crispness of products and the bowl life of Breakfast cereals.
    Instant Mash Potato: Freeze/thawing accelerates retrogradation. This phenomena is applied to cooked potato in the production of mashed potatoes to decrease the amount of soluble starch and to improve the consistency of reconstituted products.
    Par-Boiled Rice:During par-boiling of rice, the kernels are subjected to a pre-treatment involving heating and drying. This process reduces the stickiness of the rice, possibly by allowing leached amylose to retrograde and/or form inclusion complexes with polar lipids on the kernel surface. Parboiling also affects the final cooking properties of the rice.
    Resistant Starch: When certain starch-rich foods are cooked and then cooled, the starch changes form, making it more resistant to digestion. Likewise, during storage, the dispersed polymers of gelatinized starch are said to undergo retrogradation to semicrystalline forms that resist digestion by pancreatic-amylase, which results in Type 3 resistant starch. It is found in: cooked/cooled foods like potatoes, bread, rice, cornflakes. The potential benefits of resistant starch includes better satiety, better insulin sensitivity, improved digestion, increased hydration and improved immunity.

  • 1) Retrogradation is used to describe changes that occur as a result of the cooling and storage of starch product. Most common of negative effect is deceased storage stability. Bread staling and loss of freshness are major economical hurdles from the baking industry. During baking, starch is transitioned from an amorphous structure to a partially crystalline state. During retrogradation, starch release water and the crumb becomes very firm and stale, crispiness of the bread crust decrease and the bread loaf loses its aroma make the bread unacceptable to the consumer. There are two main changes that are responsible for the loss of quality of bread which are due to the loss of moisture from the bread loaf and the migration of moisture from the crumb to the crust.
    2) Retrogradation can provide a desirable quality such as in the manufacture of rice stick noodles and resistant starch type 3. Slight retrogradation is desirable to improves cutting texture of the loaf especially in rye breads.

  • 1) When the loaf comes out of the oven and cools to below the gelatinization temperature, the starch molecules reform and harden which is lead to starch retrogradation. The water that was absorbed during baking gets slowly expelled and eventually evaporates. Bread that was initially soft and moist becomes progressively harder and dry.

    2) However, some food needs complete retrogradation to reach a better quality such as baking of crouton. The crumb is needed so that it can be reduced to the approximate size and shape of the individual crouton. So that the bread stick can then be sliced into disc or loaves sliced and cubed, or cut to whatever shape and sized are desired. Another example is production of rice stick noodles. The important step in producing rice stick noodle is sheet ageing where retrogradation are involves. The purpose of this is to harden and reduce the stickiness, allowing them to be more easily cut into strips.

  • 1) The retrogradation is not desirable in bread since it will affect the product during storage time. Rearrangement of amylose and amylopectin lead to the crystalline formation thus lead to the harden structure, which is known as stalling in bread and loafs. This gives undesirable texture and hardly can be acceptable by customers.
    2) Loaf and bread outer structure most likely to have the crispy and crunchy texture. Cookies and crackers also exhibit the same attribute, which are desirable. The food with crispy and harden structure mostly need retrogadation process to produce those desirable attribute.

  • 1- Starch retrogradation is not desirable in bread because it will give stale effect to the bread texture. Retrogradation occur when the bread is cooled or left at lower temperature for a long time after been baked where the amylose and amylopectin realign themselves to form crystalline structure. Recrystallize of amylopectin will increasing the rigidity of the swollen granules and reinforces the continuous amylose phase which cause the bread to firm.

    2-Sometimes retrogradation of starch is desirable, and even promoted and accelerated because retrogradation results in hardening and reduce stickiness which useful in the production of breakfast cereals and parboiled rice. Besides, in the production of dehydrated mashed potatoes, retrogradation is accelerated by freezing or thawing of cooked potato mashed to improve the consistency of the reconstituted product. Retrogradation also desirable in Japanese noodles production “harusame” that involve freeze-thaw cycle to reduce stickiness and to obtain a characteristic chewiness.

  • 1) During baking, starch molecules in the raw bread dough begin to gelatinize at about 150°, meaning they absorb moisture, swell, and then become semi-firm. This is partly what sets the structure of the final loaf. When the loaf comes out of the oven and cools to below the gelatinization temperature, the starch molecules reform and harden – starch retrogradation. The water that was absorbed during baking gets slowly expelled and eventually evaporates. Bread that was initially soft and moist becomes progressively harder and dry. Starch retrogradation can be temporarily reversed by reheating loaves of bread in the oven or individual slices in the toaster. Reheating brings the bread back up to the gelatinization temperature and causes the molecules to reabsorb some moisture. As long as the bread isn’t too old or had too much moisture evaporate, this reheating makes the bread palatable again. The staling process also happens more slowly in breads that are enriched with sugar, eggs, or dairy. The sugar helps to absorb and retain moisture while eggs and dairy both trap moisture and interfere with the retrogradation.

    2) Sometimes retrogradation is desired due to some reason. Retrogradation can reduce the stickiness and also alter the textural and physical properties of food products such as cookies biscuit and etc. For example in cookies, retrogradation is desired even promoted in order to get crunchy and crispiness of the cookies.

  • 1) The retrogradation of starch has been defined as a process which occurs when the molecules comprising gelatinized starch begin to reassociate in an ordered structure. Hence, an increase in rigidity was observed which was attributed both to starch retrogradation and to changes in the organization of the amorphous part of crumb. The most common negative effect of starch retrogradation is then decreased the storage stability of bread. Besides, the change in texture and flavor of bread during storage is commonly called staling. Starch retrogradation can lead to an obvious increase in the firmness of breads, causing them becomes dry, hard and made them unattractive to consumers. Thus, starch retrogradation is not desirable in bread.

    2) However, in some products, retrogradation can provide a desirable quality such as in the manufacture of rice stick noodles, resistant starch type 3, croutons, and bread crumb. There is a need to retrograde starch in processing starch-based noodle to achieve desired storage and culinary attributes because retrogradation can set the noodle structure. If retrogradation was not promoted, the noodles might simply dissolve in the soup which is not a desired outcome. The resistance of retrograded amylose crystallites to melting at temperature below 100 degree celcius is the basis of this persistent structure.

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