3.1.1.a Berry sampling

Overview

A harvest order is established prior to the harvests to plan their progression. The order takes into account the evolution of the ripening process and the estimated yields per plot.
Monitoring grape ripeness helps define a precise harvest sequence for each plot or plot section in order to obtain the ideal aromatic potential in accordance with the desired wine style.
Volume projections enable the selection of the most suitable vinification vessel.
The harvest order is a tool that has to remain "flexible", since it is likely to be modified on a daily basis due to a variety of factors, in particular the weather and logistical issues.

The importance of berry sampling when establishing the harvest order

To monitor a plot's degree of ripeness, it is necessary to collect regular grape samples and to measure key parameters. It is rare that all the berries reach full maturity simultaneously, this is referred to as asynchronism or heterogeneity, and can be due to several factors:

• Heterogeneous flowering progression and fertilization of the ovules. A fertilized ovule which produces a viable seed is sufficient for berry development. The quantity of normal, viable seeds per berry will positively influence its volume. Flowering can be spread over a fortnight, sometimes longer when the weather is not optimal, and thus not all the grapes start developing at the same time.

• Existing heterogeneity within the plot: soil type, topography, plot orientation, proximity of a water source, etc. The hydration and nitrogenous state of the vine must also be taken into account, which influences fruit quantity and contributes to heterogeneous development within the bunches.

• The bunches' location and the amount of sunlight they receive. One side may be directly exposed to the sun while the other side of the bunch is always in the shade. This can lead to differences in ripening.

• When fruit shatter and/or millerandange phenomena are observed within the plot, berry sizes and their degree of maturity can vary.

Sampling protocol

Depending on intra-plot heterogeneity, sample collection should reflect the entire plot as much as possible to obtain the most accurate results. Row ends and shorter rows may also behave differently from the rest of the plot. When the plot displays two different degrees of vigour and/or two geographically different profiles, it is possible to set up two sampling zones representative of these intra-plot identities. Mapping, especially with regard to vigour and soil type, is a useful method to identify variation and set up a precise collection protocol. Berry sampling should preferably be carried out on healthy vines. Sampling should also be undertaken on the same rows of vines throughout ripeness monitoring in order to obtain the most accurate monitoring possible. This can be achieved by choosing rows representative of the plot and tagging them.

These samples should ideally be taken in the morning to preserve berry freshness. The harvested berries can then be placed in appropriate containers during sampling and transport. At Chateau Latour, for example, sample collection boxes are provided for this purpose to reduce the risk of crushing the berries and oxidation of the juice. Reusable plastic labels are placed in each box to enable optimal organization during analysis. All the berries are kept in polystyrene boxes with ice packs.

200 to 300 berries may be collected per plot depending on the type of analysis required in the laboratory. After crushing and lightly pressing the berries, 30 to 50 ml of juice is necessary to perform all the tests. It is preferable to take berries from the whole bunch, so 5 berries per bunch should be carefully removed, both from the side exposed to the sun and the non-exposed side, and from all the bunch's extremities (top, middle and base).