Wine juice is sterilized at high temperatures for a short contact time (meaning seconds – for this reason it is referred to as “flash”). Sterilization kills any micro-organisms present (including cells and spores) – and the product, once sterile will be sterile forever up to the point of the opening of the juice package.

Flash sterilization preserves the flavour, taste and aroma of grape juice.
Furthermore sterilization brings to zero any risk of fermentations in the bag, and allows a better and safer fermentation, when needed, because any eventual wild yeast has been killed. This means it improves indefinitely the shelf life.

Pasteurisation is a process where the temperatures are usually lower but the product is under heating for a long time (not seconds like the flash sterilization). Pasteurisation REDUCES THE MICRO-ORGANISM BUT DOESN’T KILL ALL OF THEM. So a product that is pasteurised in not sterile at all and can have micro-organisms that can develop a second time.

Further to this, the long contact time burns the aromas and gives the taste of a typical “cooked aftertaste”. In the case of a wine kit another negative effect is on the colour – the colour will change very quickly with age giving to the white the typical gold/brownish tone and in the red the flat/brownish tone that has nothing to do with a real wine.
This means in short terms that whatever raw material you use – juice or concentrate or both – the pasteurisation process would have a heavy and negative impact on it. This would also become worse and worse with the passing of time.

Higher temperature
Shorter contact time + aseptic filling
Low impact on the product
Longer shelf life
Sterilization kills ALL micro-organisms

Lower temperature
Longer contact time
Deterioration of the product
Shorter shelf life

Posted in: Wine