Following pressing, we added a small dose of Sulphite to prevent spoilage organisms turning the precious juice into perry vinegar or worse. For the first time this season, we plan to ferment all our ciders and perrys without the addition of a single strain cultured yeast. Instead we're relying on the natural yeasts present in the fruit, and those which have built up through successive seasons on our cidermaking equipment. Although this can be slightly more risky, there are definite advantages to natural yeast fermentations.
The early part of a natural fermentation is with a range of low alcohol-tolerant yeasts which can give an added complexity to the finished cider/perry. When these yeasts have done their job, the fermentation is taken over by the more robust Saccharomyces strains of yeast which tend to build up in the ciderhouse and cidermaking equipment over successive years of milling and pressing.
In previous years, the fermentation resulting from the addition of a cultured yeast has been rather too quick for our liking, and usually continues until all the sugars have been converted to alcohol resulting in quite a dry cider/perry. Natural yeasts tend to ferment the juice more slowly over the course of several months, giving ciders and perrys with a better, often sweeter flavour, and with less tendency to produce 'off' flavours such as Hydrogen Sulphide. For us it's all about fine tuning and aiming to improve our ciders and perrys, something all small-scale producers should aim to do in our opinion.