Fruit and Vegetable Processing Waste as Potential Raw Material for Food Enrichment With Dietary Fiber

For many years, dietary fiber (DF) has been an underestimated component of plant foods. Currently, there is a growing appreciation of its health-promoting properties, especially in relation to its effect on the digestive tract. For this reason, both raw materials and products with the highest possible DF content are sought. Fruit and vegetable pomace seems to be both a raw material and a waste product with these characteristics. The aim of this study was to compare the content of neutral detergent fiber (NDF) and acid detergent fiber (ADF) in pomace from the processing of apples, chokeberries, blackcurrants, raspberries, red cabbage, two strawberry varieties, and two carrot varieties. In the study, the content of NDF, ADF, and cellulose was determined using the van Soest method, and the content of soluble dietary fiber fraction SDF, hemicellulose, and lignin was calculated. The highest content of both DF fractions was shown in chokeberry pomace (NDF-90.32 g/100 g DM, ADF-54.44 g/100 g DM), and the lowest-in Flakkese carrot pomace. High content of the soluble fraction was characteristic for apple pomace and both carrot varieties. Based on the PCA analysis, the similarity of individual raw materials was found in terms of the analyzed discriminants. The features of two raw materials, i.e., blackcurrant and chokeberry, were significantly different from the others, which may have practical significance when selecting specific raw materials for processing. The PCA analysis also showed the mutual dependencies between the analyzed discriminants. Chokeberry pomace, blackcurrants, and two strawberry varieties proved to be the most suitable for the production of functional food rich in fiber due to the content of all DF fractions.