Starch plays an important role in the textures of many kinds of food products and serves as a major source of energy for humans. In some cases, native starch does not have the functional properties for food processing requirements such as thickening and stabilization. Therefore, starches used in the food industry are often modified to overcome undesirable changes in product texture and appearance caused by retrogradation or starch breakdown during processing and storage. Starch contains abundant hydroxyl groups. Each anhydroglucose unit contains two hydroxyls (at C2 and C3), and some anhydroglucose units contain other hydroxyls (at C6). These hydroxyls are potentially able to react with any chemicals having reactivity with alcoholic hydroxyls. This includes a wide range of compounds, such as acid anhydrides, organic chloro compounds, aldehydes, epoxy, and ethylenic compounds. Thus, starch can be modified in various ways to improve its functionality depending on the purpose of its application. Commercially modified starches include hydroxypropylated and/or cross-linked and acetylated and/or cross-linked starches, which are widely used in the food, textile, and paper industries: l Cross-linking: Cross-linked starches are widely used as thickeners in foods, particularly when a high and stable viscosity is required. Cross-linking minimizes granule rupture, loss of viscosity, and formation of a stringy paste during cooking. l Hydroxypropylation: Hydroxypropylated starch derivative formed by reaction of starch with propylene oxide is primarily used in the food industry. This modification improves the shelf life, freezeethaw stability, cold-storage stability, clarity, and texture properties of starch paste. Cross-linking of hydroxypropylated starch imparts viscosity stability and a desired short-textured property of the paste. Swollen but intact starch granules are usually desired in most food starch applications to maintain rheological properties. However, for each application, there is an optimum level and balance between hydroxypropyl substitution and cross-linking. Acetylation: Acetylated starch derives from a low-degree substitution of three free hydroxyl groups at C2, C3, and C6 of native starch in the presence of an alkaline catalyst and by esterification with acetic anhydride (acetylation) in aqueous medium.
Effect of starch addition to fluid dough during the bread making process
GUERZONI, MARIA ELISABETTA;GIANOTTI, ANDREA;VERNOCCHI, PAMELA
2011
Abstract
Starch plays an important role in the textures of many kinds of food products and serves as a major source of energy for humans. In some cases, native starch does not have the functional properties for food processing requirements such as thickening and stabilization. Therefore, starches used in the food industry are often modified to overcome undesirable changes in product texture and appearance caused by retrogradation or starch breakdown during processing and storage. Starch contains abundant hydroxyl groups. Each anhydroglucose unit contains two hydroxyls (at C2 and C3), and some anhydroglucose units contain other hydroxyls (at C6). These hydroxyls are potentially able to react with any chemicals having reactivity with alcoholic hydroxyls. This includes a wide range of compounds, such as acid anhydrides, organic chloro compounds, aldehydes, epoxy, and ethylenic compounds. Thus, starch can be modified in various ways to improve its functionality depending on the purpose of its application. Commercially modified starches include hydroxypropylated and/or cross-linked and acetylated and/or cross-linked starches, which are widely used in the food, textile, and paper industries: l Cross-linking: Cross-linked starches are widely used as thickeners in foods, particularly when a high and stable viscosity is required. Cross-linking minimizes granule rupture, loss of viscosity, and formation of a stringy paste during cooking. l Hydroxypropylation: Hydroxypropylated starch derivative formed by reaction of starch with propylene oxide is primarily used in the food industry. This modification improves the shelf life, freezeethaw stability, cold-storage stability, clarity, and texture properties of starch paste. Cross-linking of hydroxypropylated starch imparts viscosity stability and a desired short-textured property of the paste. Swollen but intact starch granules are usually desired in most food starch applications to maintain rheological properties. However, for each application, there is an optimum level and balance between hydroxypropyl substitution and cross-linking. Acetylation: Acetylated starch derives from a low-degree substitution of three free hydroxyl groups at C2, C3, and C6 of native starch in the presence of an alkaline catalyst and by esterification with acetic anhydride (acetylation) in aqueous medium.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
