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Starch digestion and absorption in nonruminants.
1Gastroenterology Division, Stanford University School of Medicine, CA 94305.
The Journal of Nutrition
|January 1, 1992
Summary
Physical processing and heating enhance starch digestion and absorption. This process involves pancreatic alpha-amylase and brush border enzymes, ultimately facilitating glucose transport for efficient assimilation in nonruminants.
Area of Science:
- Biochemistry
- Human Physiology
- Nutritional Science
Background:
- Starch is a primary digestible carbohydrate source.
- Its digestion involves complex enzymatic hydrolysis and transport mechanisms.
- Physical and thermal processing can alter starch bioavailability.
Purpose of the Study:
- To elucidate the sequential steps in starch digestion and absorption.
- To identify the key enzymes and transport proteins involved.
- To understand how physical and thermal processing affect starch assimilation.
Main Methods:
- Review of biochemical pathways for starch breakdown.
- Analysis of enzymatic activity at the brush border.
- Examination of glucose transport mechanisms in enterocytes.
Main Results:
- Pancreatic alpha-amylase initiates starch digestion in the duodenum.
- Brush border enzymes (glucoamylase, sucrase, alpha-dextrinase) complete hydrolysis to glucose.
- A specific 75-kDa protein facilitates Na+-dependent glucose cotransport, a rate-limiting step.
Conclusions:
- Starch assimilation is a highly efficient, multi-step process.
- Physical and thermal processing significantly enhance starch digestion and absorption.
- Understanding these mechanisms is crucial for nutritional science and food processing.