Dietary recommendations for Nordic Countries urge the use of plant foods as a basis for healthy nutrition. Currently, the intake of dietary fibre (DF) is not at adequate level. Berries are an elementary part of the recommended healthy Nordic diet, and could be utilized at higher amounts to promote DF intake among other nutritional benefits. Aura et al (2015) studied the DF content, carbohydrate composition and non-carbohydrate fibre content of Finnish bilberries and a bilberry press cake from juice processing. In addition, microstructure of all samples was studied using light microscopy.
The results showed that the total DF contents of fresh and freeze-dried bilberries and the press cake were 3.0%, 24.1% and 58.9%, respectively. Most of the DF was insoluble. Only about half of it consisted of carbohydrates, the rest being mostly sulphuric acid insoluble material, waxy cutin from skins and resilient seeds. Bilberry seeds represented over half of the press cake fraction, and in addition to skin, seeds were the major DF sources. Microscopy imaging revealed that skins in the press cake were intact and the surface of the seeds had thick-walled cells.
In conclusion, the insoluble and non-carbohydrate nature of DF of bilberries is quite different from that in f.ex. grains and vegetables, which are the major sources of DF in the Finnish diet. Consumption of 100-133 g bilberries or 5-7 g dry bilberry press cake would be adequate to increase the daily intake of DF to the recommended minimum level of 25 g/day. Bilberry press cake thus is a good source of insoluble non-carbohydrate DF, and could be used to provide DF-rich foods to contribute to versatile intake of DF. This would increase the amount of very recalcitrant insoluble DF and bring anthocyanins as co-passengers, thus diversifying DF intake. Non-carbohydrate DF may have distinct physiological effects, the health relevance of which calls for further studies.
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Aura et al 2015_ Bilberry and bilberry press cake as sources of dietary fibre