Editing Dietary fiber (section)

===Physicochemical properties===
Dietary fiber has distinct [[physical chemistry|physicochemical]] properties. Most semi-solid foods, fiber and fat are a combination of gel matrices which are hydrated or collapsed with microstructural elements, globules, solutions or encapsulating walls. Fresh fruit and vegetables are cellular materials.<ref>Hermansson AM. Gel structure of food biopolymers In:  Food Structure, its creation and evaluation.JMV Blanshard and JR Mitchell, eds. 1988 pp. 25–40 Butterworths, London.</ref><ref>Rockland LB, Stewart GF. Water Activity: Influences on Food Quality. Academic Press, New York. 1991</ref><ref>{{cite journal | vauthors = Eastwood MA, Morris ER | title = Physical properties of dietary fiber that influence physiological function: a model for polymers along the gastrointestinal tract | journal = The American Journal of Clinical Nutrition | volume = 55 | issue = 2 | pages = 436–42 | date = February 1992 | pmid = 1310375 | doi = 10.1093/ajcn/55.2.436 | doi-access = free }}</ref>
* The cells of cooked potatoes and legumes are gels filled with gelatinized starch granules. The cellular structures of fruits and vegetables are foams with a closed cell geometry filled with a gel, surrounded by cell walls which are composites with an amorphous matrix strengthened by complex carbohydrate fibers.
* Particle size and interfacial interactions with adjacent matrices affect the mechanical properties of food composites.
* Food polymers may be soluble in and/or plasticized by water.
* The variables include chemical structure, polymer concentration, molecular weight, degree of chain branching, the extent of ionization (for electrolytes), solution pH, ionic strength and temperature.
* Cross-linking of different polymers, protein and polysaccharides, either through chemical covalent bonds or cross-links through molecular entanglement or hydrogen or ionic bond cross-linking.
* Cooking and chewing food alters these physicochemical properties and hence absorption and movement through the stomach and along the intestine<ref name=Eastwood92>{{cite journal |vauthors=Eastwood MA |title=The physiological effect of dietary fiber: an update |journal=Annu Rev Nutr |volume=12 |issue= |pages=19–35 |date=1992 |pmid=1323981 |doi=10.1146/annurev.nu.12.070192.000315 }}</ref>