An open-top wine fermenters are an

An open-top wine fermenters are an important piece of winemaking equipment. Made in stainless steel, oak, concrete or plastic of variable sizes without a fixed lid, for the fermentation of red grapes. When making red wines, they are fermented by using the entire grape, skins and all parts of the berry - (whereas white wines are fermented using only the juice). So when making red wines, measures need to be taken into account for an ideal result. Winemaking 101 - during fermentation, yeast creates both alcohol and carbon dioxide (CO2 gas). As the CO2 bubbles up through the wine, a portion gets trapped inside the skins and causes them to float on the surface in a layer called ‘the cap’. The cap causes the volume of ‘must’ to expand inside the tank - which can protect the wine from outside elements. So when you are filling red wine fermenters, one must keep in mind that you will not be able to fill the tank right to the top with ‘must’, you will need to leave enough space for the cap to expand due to the build-up of CO2 gas. Therefore, if you are wanting to be able to ferment a set volume of red wine, you will need to choose a fermenter slightly larger in size than the desired finished volume of wine.The grape skins in the ‘cap’ tend to dry out quite quickly, plus they contain colour and so much of the wines character, flavour and aroma compounds. The skins need to be pumped-over with the wine several times a day during fermentation. For large volumes this is done with a large pump in a process called ‘pumping-over’ (because you are pumping wine over the top and through the cap). For smaller volumes this wetting of the cap is usually done manually using a specific punching down tool-paddle designed for the job. Using the plunger, you simply break-up the cap and gently stirring, submerging it back into the wine. This process is called ‘punching the cap’. In order to use the punching down tool, however, you will need to have access to the surface of the wine. Therefore an open-top wine fermenter (not sealed or closed) is ideal for fermenting small to medium parcels of red wine.