As the grapes approach ripeness winemakers typically spend morning after morning walking through the vineyards, passing up and down the rows of vines, tasting grapes; plucking berry after berry from different vines gives an over-all picture of how the the flavours are developing in any particular block.
When the grapes get very close to ripeness, nearly ready for harvest, often a sample of 100+ berries will be collected randomly from across a vineyard block, or part of a block. Those grapes will be squeezed, and the juice then gives a clearer impression of the whole block. These two glasses have samples from the west side of a block (W) and the middle-west part (M-W) part of a block. the juice is tasting fantastic, very sweet, very delicious, and packed with flavour: probably ready to be picked next week.
Winemakers also often like to inspect the seeds; when the grapes are ripe the seeds change; the seeds of unripe grapes are green and slightly softer; as the ripen they go browner and harder.
