Effect of Buckwheat Groats Processing on the Content and Bioaccessibility of Selected Minerals

Abstract

Adequate supply of minerals in the diet is necessary for the proper functioning of the human body. In recent years gluten-free diet, which rigorous forms may lead to deficiencies of mineral components (especially Mg, Mn, Zn and Cu), is becoming more and more popular. Buckwheat grains do not contain gluten, and their nutritional value is very high. They are often consumed in the form of groats, which are obtained from roasted and dehulled seeds. The purpose of the work was to determine how conducting the buckwheat groats production in industrial conditions affects the content and availability of magnesium, manganese, zinc and copper. The results indicated that husk removal had a particularly adverse effect on the total manganese content and its amount released by enzymatic digestion, whereas it had a positive effect on the post-digestion zinc level by increasing it by nearly half. Hydrothermal processes especially affected the release of analysed elements simulated by the in vitro method, and the extent of changes depended on the processing parameters. It was shown that bioaccessibility of minerals may be increased by treating buckwheat at a lower temperature for a short time, which has a particularly beneficial effect on the manganese and magnesium. Treating grains at a higher temperature reduces the bioaccessibility of all analysed elements, which was particularly noted for zinc and copper. Based on the obtained results, it should be stated that buckwheat groats should be a regular part of human diet, because they are a good source of easily digestible mineral compounds. Their consumption should be especially considered by people on a rigorous gluten-free diet, as they can prevent mineral deficiencies associated with its use.

Keywords: bioaccessibility; buckwheat; dehulling; food processing; minerals; roasting.

Figure 1

The scheme of buckwheat groats processing.

Figure 2

The content of minerals in dehulled buckwheat grains and groats. a, b, c—values referring to individual minerals and denoted by the same letters are not statistically different at p < 0.05.

Figure 3

The bioaccessibility [%] of analysed minerals from different types of buckwheat products.

Figure 4

Principal component analysis in assessment of total content of analysed minerals and their amount released by in vitro digestion of buckwheat grains. Explanatory notes: Mg I, Mn I, Zn I, Cu I—total content of minerals in buckwheat grains; Mg II, Mn II, Zn II, Cu II—content of minerals released by in vitro digestion of buckwheat grains; GWH—grains with hull; DG—dehulled grains.

Figure 5

Principal component analysis in assessment of total content of analysed minerals and their amount released by in vitro digestion of buckwheat groats. Explanatory notes: Mg I, Mn I, Zn I, Cu I—total content of minerals in buckwheat groats; Mg II, Mn II, Zn II, Cu II—content of minerals released by in vitro digestion of buckwheat groats; RG—roasted groats; UG—unroasted groats.