Influence of harvest day on changes in mechanical properties of grape berries

Abstract

Changes in the composition, physical and mechanical properties occur in grape berries during the ripening process, but the heterogeneity of the grapes harvested at different ripening stages affects the reliability of the results obtained. The characterization of the mechanical properties of grape berries seems to be an important parameter for understanding grape ripening. In this work, these changes were studied in seven grapevine varieties (Riesling, Blaufränkisch, Pinot Noir, Cerason, Malverina, Laurot, and Hibernal) harvested during six consecutive weeks. Mechanical behaviour was measured using compression and puncture tests using of TIRATEST 27025 testing machine. Skin mechanical properties were evaluated using a puncture test carried out on the equatorial side. The dependence of these properties on the chemical composition has been evaluated. These parameters of force/time curves were studied by puncture test: the berry skin break force, the needle displacement at the skin break and the berry skin break energy. The crushing force, the plate displacement at the crushing strength and the berry crushing energy were studied from force/time curves by compression test. Results of the puncture test shows that there the skin break strength and the acidity content are monotonic functions of the time. A comparison of different varieties from the point of the value of the crushing force was obtained by vertical and transversal loading. The crushing force is monotonically decreasing function of the harvesting time like the break force evaluated at the puncture test. The correlation between the skin break strength and the sugar content is significant namely for the varieties: Hibernal, Riesling, Malverina, and Cerason.

Mechanical properties of sugar beet root during storage

“…Our work indicates that all the described parameters increase with the duration of the storage (Miraei Ashtiani et al, 2016;Nedomová et al, 2016Nedomová et al, , 2017. Explanations as in Table 1.…”

High stability of genotypic differences in puncture resistance of sugar beet (Beta vulgaris) roots under various growing conditions

“…First studies revealed that sugar beet roots with a high puncture resistance of the periderm have a high tissue firmness (Kleuker & Hoffmann, 2020; Nause et al, 2020) confirming findings for potatoes (Anzaldúa‐Morales et al, 1992) and grapes (Nedomová et al, 2016). The close relationship between puncture resistance and tissue firmness is already established in very young sugar beet roots grown in the glasshouse.…”

Detection of Microbiota during the Fermentation Process of Wine in Relation to the Biogenic Amine Content

“…These natural factors have a significant impact on the occurrence of microorganisms in the ecosystem. Of all the microorganisms present on the surface of grapes, yeast is the most important [2]. Yeast populations on immature berries are low.…”