Analysis of Physical Properties of Dietary Fiber From Apple Waste

The purpose of the present study was to determine the suitability of apple fibers (dietary fiber) as a raw material for granulate pellets production, as an aspect of waste management in sustainable agriculture processes. Apple fibers are a waste produced during the agri-food processing of apples. It is obtained from apple peas and can be further used as a diet supplement or for animal feed purposes, reducing the breeding costs. The material was moisturized with water and a mixture of water and milk powder to a moisture content of 16%. During the tests, the maximum pressure of the process was determined for all trials carried out. Density, absorption and activity of water in the resulting agglomerate and in the raw material were examined. Increasing the temperature of the pressure process from 20 to 50°C results in an approx. 50% increase in the density of the test mixtures. Higher density of the resulting granules was obtained using lower agglomeration pressure. The increase in density of the granulate influences the reduction of its water absorption (decrease of its moisture content and water activity). Increasing the density of apple fiber (from loose fiber) decreases moisture and water activity.