Texture characteristics of the grape berry skin and seed (Vitis viniferaL. cv. Kékfrankos) under postveraison water deficit

Water deficit has a great impact on grape and wine composition. One aspect of phenolic maturity in redgrapevine cultivars is skin phenolic concentration (i.e. anthocyanins). However, extractability of thesecomponents is also an important factor during wine making; therefore skin and seed texture proper-ties have a role in this process. Six-year-old Kékfrankos grapevine (Vitis vinifera L.) was submitted todifferent water regimes (severe, moderate and nil stress) from veraison under greenhouse conditions.Berry quality parameters (sugar and skin phenolic concentration), skin and seed texture properties weremeasured by a texture analyser at two harvest dates. Water deficit resulted in decreased photosyntheticactivity; therefore non-stressed plants produced higher sugar concentration in their berries comparedto the stressed vines. Also, water deficit induced increased phenolic concentration in the skin. However,moderate stress treatment showed higher anthocyanin, catechin and total polyphenol concentrationthan in the severely stressed berries. A significant increase of skin thickness of the stressed berries wasobserved during ripening; however, no clear relationship was found between skin thickness and its phe-nolic concentration. Skin break force as well as skin break energy and skin rigidity presented a significantincrease as a result of water shortage. No relationship was found between skin thickness and skin hard-ness. This result suggests that grape skin mechanical properties are dependent on skin structure ratherthan its thickness. Similarly, there were significant differences among the treatments in seed mechanicalproperties; however the effect of water stress disappeared by the second harvest