Food Structure


S. H. Yiu


Factors that determine the digestibility of carbohydrates and minerals in cereals are examined . Most carbohydrates and minerals in cereals are structurally bound, either surrounded by or associated with cell wall components not easily digested by non-ruminant animals and humans. Treatments such as mechanical grinding and heat improve the digestibility of nutrient s . Further processing and cooking result in structural and physeochemical changes of cereal starch, phytate, and dietary fiber. Such changes greatly Influence the physiological and metabolic effects in animals and humans. The digestive breakdown of most nutrient components is also dependent on the activities of enzymes in cereals and in the mammalian digestive system. However, starch, phytate, and dietary fiber are not entirely and readily degraded by enzymes. Undegraded components reduce both the caloric value of the food and the availabilities of other nutrients by interacting with them in the gastrointestinal tract. Studies on avallabil Hies of carbohydrates and minerals in cereal foods are conducted in humans and rats or under in vitro conditions, using various analytical methods Including microscopy. The advantage of applying light microscopy and scanning electron microscopy coupled with energy dispersive X-ray microanalysis to study the digestive breakdown of structural components in cereal foods is highlighted by demonstrating the capabilities of the techniques to reveal both structural and microchemical information.

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