Biology Reference
In-Depth Information
CHAPTER FOUR
Food Microstructure and
Starch Digestion
Riddet Institute, Massey University, Palmerston North, New Zealand
1
Corresponding author: e-mail address: j.x.singh@massey.ac.nz
Contents
1.
Introduction
138
2.
Starch Digestion
139
3. Microstructure of Natural Foods and Starch Digestion
140
3.1
Case I: Microstructural characteristics of potato and starch digestion
142
3.2
Case II: Microstructural characteristics of navy beans and starch digestion
153
4.
Rheology of Food Matrix and Starch Digestion
157
4.1
Rheology (flow behavior) of digesta
161
5.
Formulated Foods and Starch Digestion
163
5.1
Influence of food matrix composition on starch digestion
163
5.2
Influence of food processing on starch digestion
168
6.
Conclusions
172
Acknowledgment
173
References
173
Abstract
Microstructural characteristics of starch-based natural foods such as parenchyma or cot-
yledon cell shape, cell size and composition, and cell wall composition play a key role in
influencing the starch digestibility during gastrointestinal digestion. The stability of cell
wall components and the arrangement of starch granules in the cells may affect the free
access of amylolytic enzymes during digestion. Commonly used food processing tech-
niques such as thermal processing, extrusion cooking, and post-cooking refrigerated
storage alter the physical state of starch (gelatinization, retrogradation, etc.) and its
digestibility. Rheological characteristics (viscosity) of food affect the water availability
during starch hydrolysis and, consequently, the absorption of digested carbohydrates
in the gastrointestinal tract. The nonstarch ingredients and other constituents present in
food matrix, such as proteins and lipids interact with starch during processing, which
leads to an alteration in the overall starch digestibility and physicochemical character-
istics of digesta. Starch digestibility can be controlled by critically manipulating the food
microstructure, processing techniques, and food composition.
