Explain factors influencing rs content of foods?
1) Presence of sugar and lipids: Studies so far show that presence or addition of lipids and sugar reduces RS content.
2) Calcium and potassium ions: Investigations have indicated that the yield of RS in starch gels decreases in the presence of calcium and potassium ions. These ions are adsorbed on starch and prevent the formation of hydrogen bonds between amylose and amylopectin chains.
3) Polyphenols and phytic acid Polyphenols (catechin, tannic acid) and phytic acid may affect starch digestibility through their interaction with amylose activity and contribute to RS formation.
4) Antinutritional factors: Presence of certain anti-nutrients, such as a-amylase inhibitors, greatly determines the extent of starch hydrolysis and hence the RS content.
5) Processing techniques: Freezing, storage, heating-cooling cycle, baking, flaking, popping increase the RS content while reheating of stored food, germination, fermentation results in reduction.
Thus, you have seen that a number of factors influence the RS content. It is important to note that at any given time, more than one factor may operate simultaneously thereby influencing the RS in a complex manner.