3.2.5.d Managing the unexpected

If expected yields are not obtained, what can be done?

When volumes are reduced, it is possible to blend several plots to obtain sufficient final volumes. Choosing the plots to blend can be complex and depends on a number of parameters including the grape variety, the quality potential of the plots in question and the type of terroir (Criteria for choosing a blend of plots or plot-based vinification depending on the vatting facilities).

If the plots do not have the same characteristics or if the winemaker simply does not wish to blend so as to bring out each plot's identity, vinification in larger volume containers is an option. However, leaving a vat partially empty can be risky and requires several precautions. Excessive contact with oxygen can lead to undesirable oxidation. It is therefore necessary to protect the vat by filling the empty part with an inert gas before and after fermentation (Adapting to real volumes: managing partially-filled vats).

What if the yields are higher?

If volumes are more substantial than earlier estimations, it is possible to adapt the choice of vats beforehand, and prioritize the use of larger vats. Otherwise, the batch may need to be split between two or more vats. A proportion can also be vinified in barrels (Wood).

If the volumes are much higher than expected, it is possible to draw off ("bleed") some of the must to further concentrate a red wine and reduce volumes. The ideal bleeding percentage can be calculated in relation to the weight and volume of 100 berries. The marc/juice ratio can then be determined by pressing these 100 berries, the weight of the dry matter divided by the weight of the juice gives a ratio between 0.15 and 0.35, which represents the percentage of skin and seeds in relation to the juice and enables the calculation of the optimal volume of juice to bleed.

For example, if the weight of 100 berries is very high, this weight can be brought down to a more standard theoretical weight to calculate the ideal theoretical volume of a vat. Merlot berries that reach a 100 berry weight of over 200 g can be candidates for bleeding. This choice should also be based on berry tastings and analyses. Bleeding should be carried out with good quality, ripe grapes, otherwise the effect of concentration may not improve the must's quality.