Determination of total dietary fiber

What is dietary fiber?

In the last few decades, scientists have been paying more and more attention to researching the beneficial effect of dietary fiber on the human body. Due to its complex nature, it is not easy to define dietary fiber.

Different world organizations and countries suggest different definitions, and one of the accepted definitions states that dietary fiber is all edible parts of plants or similar carbohydrates resistant to digestion by endogenous enzymes in the small intestine with complete or partial fermentation in the large intestine.

  The term dietary fiber includes various groups of compounds (from simple to complex) that we obtain from food consumption, such as: cellulose, hemicellulose, oligosaccharides, lignin, pectins, waxes and gums.

General distribution of dietary fiber

Fiber can be most simply classified into two categories: soluble and insoluble fiber.

Soluble fiber

are non-starch polymers that have the ability to bind water and form a gel, which prevents the absorption of glucose and fat from the small intestine and generally slows down the passage time of the contents through the small intestine.

This group of fibers is not digestible, and their complete breakdown occurs only as a result of bacterial fermentation, which produces short-chain fatty acids that serve as fuel for the body.

Insoluble fiber

belong to the group of compounds that pass through the digestive system almost unchanged. The most important characteristic of these fibers is the binding of a large amount of water, thus stimulating digestion, increasing the volume of faecal mass. They are of great importance in maintaining the health of the digestive system.

Total dietary fiber is the sum of soluble and insoluble fiber.

Classification of dietary fiber

Sources of dietary fiber and their role in the body

Dietary fiber can be found in a wide range of foods that we eat every day.

The most important sources are: cereals, fruits, vegetables, nuts, seeds and legumes, while on the other hand, eggs and meat do not contain dietary fiber.

Various health organizations recommend dietary fiber intake in the amount of 25g/day, which also depends on the age and gender of the individual.

It is common knowledge that dietary fibers are attributed a beneficial physiological effect on the body, and their metabolism begins in the mouth, where they are torn by chewing and moistened by mixing with saliva.

They enter the stomach through the esophagus, where they stay and delay the emptying of the stomach contents and create a feeling of satiety.

Certain fibers in the small intestine slow the digestion and absorption of nutrients including digestible carbohydrates, fats and proteins.

Reduced absorption of carbohydrates also means reduced absorption of glucose, which is why fiber is important for the glycemic index.

Some of the significant functional roles of fibers in our body:

-          They contribute to the good functioning of the digestive tract

-          They maintain a constant level of energy after the main meals

-          They maintain a normal level of cholesterol and glucose in the blood

-          They create a feeling of satiety

-          They help in achieving or maintaining body weight

Regular intake of dietary fiber ensures health and protection of the body from various diseases such as cardiovascular diseases, obesity, increased cholesterol, colon cancer, diabetes and other related diseases.

   Also, excessive consumption of dietary fiber can have a negative impact on health such as flatulence, diarrhea, cramps, reduced absorption of vitamins and minerals (zinc, potassium, magnesium, iron).

sources of dietary fiber

Determination of total dietary fiber

Due to the growing interest of scientists in dietary fiber, various analytical methods have been developed over the years to determine the proportion of dietary fiber in a particular food.

The greatest contribution to the development of the dietary fiber analysis method was made by Leon Prosky, after whom the method was named the "Prosky method", which was later accepted by the AOAC (English Association of Official Analytical Chemists).

This method is also called AOAC method 985.29 - the "gold standard" method

The Sample Control laboratory has an accredited modified method AOAC 985.29 for the determination of total dietary fiber in food.

Using "state of the art" Ankom TDF Fiber Analyzer equipment, we are able to quickly and accurately determine the proportion of total dietary fiber in food.

Modern equipment simulates the digestion of the sample as in the human stomach, treating the sample with enzymes (alpha amylase, protease and amyloglucosidase) in an acidic environment, after which the sample is decomposed, leaving behind total dietary fibers.

  This procedure enables automatic digestion, precipitation and filtration of the sample, which significantly speeds up the determination process itself, as well as the number of analyzed samples in one day.

Ankom TDF Fiber Analyzer