Changes in starch granules due to dry heat is called the following:

Question

Accepted Answer

The correct option is 1:
Dextrinisation is the precise term for the chemical change that occurs when starch-containing foods are subjected to dry heat. This process involves the non-enzymatic breakdown of the large starch polysaccharide molecules—specifically, the amylose and amylopectin chains—into smaller fragments known as dextrins. Dextrins are shorter chains of glucose units and are also referred to as pyrodextrins in this context. A classic and easily observable example of dextrinisation is the browning of bread when it is toasted; the heat from the toaster causes the starch near the surface to break down. This chemical reaction leads to noticeable changes in the food's properties, including a characteristic golden-brown colour, a distinct toasted flavour (due to pyrodextrins), and a slightly sweeter taste compared to raw starch. Since the dextrins formed are shorter and simpler than the original starch, this process results in a product that is often more easily digestible, provided it is not overcooked.

The incorrect option is 2:
Retrogradation is a different process entirely; it is the recrystallisation or realignment of the amylose and amylopectin molecules in a cooled, gelatinised starch paste or gel, and it does not require dry heat. After a starch-thickened product, such as bread or a sauce, has been cooked and then cools, the starch molecules attempt to revert to their more crystalline, ordered structure. This "retrograde" movement expels water from the gel structure, a phenomenon known as syneresis. This change is the primary cause of staling in bread and the weeping of starch-thickened custards or gravies upon refrigeration. Therefore, retrogradation is a physical change linked to cooling and aging after gelatinisation, not the chemical decomposition by dry heat described in the question.

The incorrect option is 3:
Gelatinisation is the reaction of starch with moist heat, not dry heat, and is fundamentally a physical change, not a breakdown. When starch granules are heated in a liquid, they absorb water, causing them to swell and dramatically increase in size. This swelling ruptures the granule's structure, releasing amylose and thickening the liquid to form a viscous paste or gel, which is the mechanism used to thicken sauces, gravies, and custards. The presence of water is absolutely essential for gelatinisation to occur, as the granules need to hydrate and swell. Without liquid, this process cannot happen, so it cannot be the change that occurs due to dry heat.

The incorrect option is 4:
Fermentation is a completely different biochemical process performed by microorganisms, such as yeast or bacteria, to convert carbohydrates into alcohols, acids, or gases. For example, in bread-making, yeast ferments sugars to produce carbon dioxide gas, which causes the dough to rise. It is an anaerobic metabolic pathway used to generate energy in the absence of oxygen. This reaction is biological and involves enzymatic activity at moderate temperatures, bearing no relation to the direct, non-enzymatic chemical breakdown of starch granules into dextrins solely due to high dry heat.