Now the winemaker has his white juice, he may well decide to clarify it, to clear it of all the little grapey fragments still in suspension in it, particularly for protectively made wines. Centrifuges were once used for this but they can easily spin out too many solids. More usual today is to let solids settle to the bottom of a holding tank and then run off the clear juice into the fermentation vat to increase the tannin level, and some particularly traditional winemakers, especially in Burgundy, like to ferment whole bunches. This works only in climates with growing seasons long enough to ripen the stems fully as well as the fruit, otherwise the stems would make the wine taste horribly tough (most Australian red grapes, for example, would have unacceptably low acid levels if not picked until the stems were ripe). (A very particular exception to the destemming rule for reds is a fermentation technique called carbonic maceration,characteristic of Beaujolais,someCôtes du Rhône, and naturally tough Carignan in the Languedoc-Roussillon, where the aim is to produce fruity wines without much tannin. Here whole bunches are put into a saeled fermentation vat, the bottom layer of grapes is crushed by the weight of grapes above and starts fermenting naturally, giving off carbon dioxide . The whole vat becomes saturated in carbon dioxide under whose influence the whole grapes in the upper part of the vat undergo a special sort of internal fermentation whosw products have a characteristic soft,almostrubbery smell.)