PL
Celem pracy było przeanalizowanie wpływu stopnia rozdrobnienia warzyw na przebieg konwekcyjnego suszenia oraz na proces rozdrabniania suszu. Materiał badawczy stanowiły bulwy ziemniaka i korzeń marchwi. Próby przed pomiarami pocięto w plastry o średnicy 2,5 cm i grubości 3,0 mm oraz w paski o kształcie prostopadłościanów (0,30 × 0,35 × 2,5 cm). Proces suszenia prowadzono w pojedynczej warstwie, stosując temperaturę powietrza 60°C i prędkość przepływu 0,5 m⋅s⁻¹. Do redukcji wymiarów suszu wykorzystano rozdrabniacz nożowy. Stwierdzono, że w przypadku marchwi i ziemniaka zwiększenie powierzchni prób przed suszeniem średnio o 50% powodowało kilkukrotne skrócenie czasu tego procesu. Susz ziemniaczany i marchwiowy charakteryzowały się podobną podatnością na rozdrabnianie, aczkolwiek nieco niższe nakłady energii na ten proces uzyskano dla surowca w postaci pasków. Wskaźnik rozdrabniania Sokołowskiego zawierał się od 81 kJ·kg⁻¹mm⁰∙⁵ (paski marchwi) do 90 kJ·kg⁻¹mm⁰∙⁵ (plastry ziemniaka). Przeprowadzone badania wykazały, że stopień rozdrobnienia warzyw istotnie wpływa zarówno na proces suszenia, jak i na energochłonność rozdrabniania suszu.
EN
Drying and grinding are two basic processes in food processing, where the final result is determined by either the properties of the raw material and processing parameters. The aim of the study was to analyze the influence of vegetables size reduction on the kinetics of convection drying and grinding process of dried materials. The potato tubers and carrot roots were used for investigations. Before measurements the moisture content of raw materials was evaluated and the samples were cut into slices (2.5 cm diameter and 3.0 mm thick) and strips with the shape of parallelepipeds (0.30 × 0.35 × 2.5 cm). The drying was carried out in a single layer, using an air temperature of 60°C and flow rate 0.5 m⋅s⁻¹. The Henderson and Pabis model was used for describing the drying kinetics. The dried samples were comminuted by using the laboratory knife mill. The sieving test was used to determine the size distribution of the pulverized material and the average particle size was calculated. Besides, the grinding energy indices were determined. The experiment was performed in triplicate. The obtained data was further subjected to a statistical analysis and the consequent evaluations were analyzed for a variance analysis. It was found that both in the case of carrots and potatoes increasing the area of samples before drying (approximately about 50%) decreased several times the drying period. The drying time of potatoes was shorter then drying period of carrot. Dried potatoes and carrots were characterized by similar susceptibility to fragmentation, although a slightly lower grinding energy requirements were obtained for the raw material in the form of strips. The average particle size of ground material changed from 0.340 to 0.404 mm in the case of potato and carrots strips, respectively and from 0.475 mm to 0.514 mm in the case of potato and carrot slices, respectively. Sokołowski`s grinding index ranged from 81 kJ·kg⁻¹mm⁰∙⁵ (carrot strips) to 90 kJ·kg⁻¹mm⁰∙⁵ (potato slices). The study showed that the size reduction of vegetables before drying had especially significant effect on the drying process and to a much lesser extent influenced on the grinding process of dried material.