Chopping/juicing vegetables and grinding miscellaneous grains/dried beans into powder will destroy dietary fiber and lose its nutritional value?

First of all, nutritional value is a very broad concept. After any food is processed, it is possible to lose or even strengthen some nutrients (for example, the absorption rate of fat-soluble vitamins is greatly increased when fat is used as the medium). However, whether the nutritional value is reduced depends on the angle of food/food use and some of its nutritional components.

For example, a few days ago, I mentioned in the article Diabetes: Eating coarse grains in this way can make blood sugar more stable and weight healthier. On the premise of equal food intake, grinding coarse grains is undoubtedly more beneficial to the elderly with bad dental diseases and get some corresponding nutrition. But for diabetic patients with oral health, it must be more conducive to the stability of blood sugar than whole grains.

Therefore, in today's popular science, we will not consider the nutritional value for the time being, but only talk about the "integrity" of dietary fiber.

The answer is: not at all! People worry too much!

First of all, let's understand the definition of dietary fiber:

definition

Refers to plant-derived food components that cannot be decomposed by human digestive tract enzymes. Dietary fiber is mainly a variety of non-starch polysaccharide plant substances, including cellulose, lignin, arabinoxylan, resistant starch, resistant dextrin, pectin, β-glucan, inulin, oligosaccharides and so on.

Whether it comes from natural foods, extracted from plants by physical, chemical and enzymatic methods, or synthetic carbohydrate polymers, all dietary fibers belong to carbohydrates.

It is also invisible to our naked eyes.

What is the "fiber" in vegetables?

This "fiber" is not another "fiber", but their true identity is: vascular tissue and vascular bundle of plants.

Taking celery stem as an example, after cutting the cross section, you can see strips of vascular bundles, which are composed of xylem and phloem. Its main function is to transport water, inorganic salts and organic nutrients to plants, and also to support plants.

Vascular bundles mostly exist in the stems and leaves of plants (vascular bundles in leaves are also called veins). That is, when we eat celery, it is easy to plug our teeth and be mistaken for "fiber" by us.

Therefore, when we process vegetables, we can see vascular bundles with the naked eye, not dietary fibers invisible to the naked eye.

In other words, the mechanism of dietary fiber is too small to be damaged by blades (whether kitchen knives or cooking machines).

Tip: Some vegetables that are not easy to plug teeth, such as day lily, green beans, peas, mustard greens, amaranth and celery leaves, have higher dietary fiber content than celery stems.

What about coarse grains and beans? Will grinding destroy dietary fiber?

The answer is still no.

Reason: Food crushing belongs to physical processing, which only makes the particles smaller, belonging to millimeter processing, and has little effect on micron-sized cells.

What's more, although coarse-grained beans have a rough taste, soluble dietary fiber is the main dietary fiber. Therefore, careful friends will find that oats are soft and glutinous after boiling/soaking, and beans are delicate and soft after boiling. These are the characteristics of soluble dietary fiber.

summary

Whether it's vegetables or coarse grain beans:

If you still feel a little confused, let me help you understand it from another angle:

The national standard for food safety defines dietary fiber in food as follows:

Next, please recall any prepackaged foods and drinks that you have come into contact with, and emphasize that you have added dietary fiber, which is considerable, does not need to be chewed, and is "not rough at all, or even lubricated"? Suggested thinking direction: beverages, dietary fiber supplements, milk powder, yogurt. ...

Well, speaking of which, I think you have completely dispelled your inner doubts, and this science popularization is over.

I am modest and thoughtful.

Seeing is not necessarily believing, but tasting is the same. ...