Wednesday, October 5, 2011


The crucial role of dietary fiber (DF) for maintaining good health is well known by now. In all dietary guidelines daily consumption of 25-30 gms of DF is recommended for good gut health and other health benefits. Cereals like Oats, Barley etc gained popularity because of high content of DF. Fruits and vegetables also provide DF but their daily consumption is limited because of availability and cost factor. Cereals such as wheat contain good levels of DF but modern processing technologies strip them of DF yielding only carbohydrate rich fractions. With pronounced shifting of dietary profiles from one rich in whole cereals, pulses, fruits and vegetables to animal products based foods, intake of DF has dramatically come down and this shift is more pronounced in wealthy countries where plenty of meat based foods are available at affordable cost. This has led to discovery and development of many DF rich materials for incorporation into processed foods. As DF is a multi billion dollar industry to day, pace of development is almost frenetic with many big players trying desperately to latch on to the band wagon. Here is a report on this interesting development.

"About 25 years ago, scientists studying cereal grains discovered a starch that didn't exactly act like a starch; it acted more liker a fiber. Specifically, it was resistant to digestion and didn't break down until it reached the lower intestinal tract. Starch … resistant to digestion. Ergo: resistant starch. Resistant starch occurs naturally in a number of agricultural products and in three forms. RS1 is prevalent in seeds, legumes and unprocessed or minimally processed whole grains. In RS1, the starch molecules are packed into dense granules and have more of the cell walls intact, creating a physical barrier that leaves few ends for the enzyme amylase to access.
RS2 contains much of the carbohydrate amylose. It, too, is packed into dense granules like RS1 but is not gelatinized – therefore, the starch does not break down and absorb water. RS2 therefore is digested very slowly. It's typically found in potatoes, corn, underripe bananas and flour.The third form of resistant starch, RS3, only becomes resistant when portions of the starch chain expand and then contract during food preparation or processing. It's another high-amylose starch, but the amylose forms during cooking, when the starch gelatinizes -- and at that point, it's digestible. However, cool the starch and the amylose condenses and becomes undigestible. Potatoes, breads and some cereals (such as corn flakes) are common food sources of RS3".

While consumers would be thrilled with the above development, how far these DF rich products will prove to be as effective as "true" fibers contained in fruits and vegetables as well as in whole grains remains to be seen. Even if these non-digestible food ingredients do not measure up to expectations of classical nutritionists, they still serve a useful purpose in evolving food products with lower calories and fat content. With obesity and life style health disorders spreading like wild fire all across the world, there is a widely felt need to evolve many products with lower calories and acceptable taste profile, to serve the needs of the neo-rich population with unlimited cash to spare for indulging in unhealthy foods and leading sedentary life style! Resistant starch and other forms of DF will help this cause at least.


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