Evaluation of selected parameters of mechanical and pneumatic press during grape pressing
2019
Zemanek, P., Mendel Univ. in Brno (Czech Republic) | Masan, V., Mendel Univ. in Brno (Czech Republic) | Burg, P., Mendel Univ. in Brno (Czech Republic) | Gladyszewska, B., University of Life Sciences in Lublin (Poland)
Modern wine technologies aim for selecting and optimizing the applied technological procedures, including the technical reinsurance of individual operations. One of the key operations, within the wine industry, with a direct impact on the quality of the produced wine is the process of grape pressing. The purpose of pressing is to separate the mold from the processed product by using pressure. The pressing efficiency, exerted by molding, is influenced by the particular type of the pressing device, the varietal properties affecting the consistency of the molded material, the pre-compaction process (crushing, maceration), the thickness of the mold and the number of the pressing cycles. This paper focuses on evaluation of the mechanical horizontal press WOTTLE RS 800 and the pneumatic press ŠKRLJ PST 80, with a volume of 800 litres pressing bins, that were evaluated during the period 2015−2017, while pressing the Sauvignon Blanc and Zweigeltrebe grape varieties. During the evaluation, the main focus was on monitoring the process of pressing, the change of the pressing pressure and its maximum achieved value, the average molding and the performance of the pressers. The results obtained show that, when pressing grapes by a mechanical press, the maximum pressure values are 0.51 MPa while the molding is in the range of 0.748−0.858 depending on the variety. For the pneumatic press, the maximum pressing pressure was 0.15 MPa and the mold variation was between 0.803−0.865. The mechanical press performance of the Sauvignon Blanc variety was 268 l•hE−1, 445 l•hE−1 for the pneumatic press. For the Zweigeltrebe variety, the performance of the mechanical press varied at 715 l•hE−1 and of the pneumatic press at 713 l•hE−1. The results of the evaluation illustrate the differences arising from the used press and have practical use in wine-making practice and in designing the technological equipment of the wine-growing operations. At the same time, they can serve as inputs when calculating wine production costs.
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