Citric acid will give a sharper taste than malic acid for the equivalent amount of acid present. Pear juice also contains minor acids such as quinic and shikimic acids. The tannin content of apple juices gives the resulting cider an overall flavour of bitterness with some astringency. The tannin content of pear juices is quite different. The juice also contains complex leucoanthocyanins which are colloidal in nature and which are responsible for the heavy hazes and precipitates characteristic of perries.
Pear juices are lower in soluble pectin than apple juices.
The soluble nitrogen content of pear juices is even lower than that of apple juices. The levels of asparagine and aspartic acid are lower. The final result of all this is that pear juice does not support yeast growth as well as does apple juice and fermentation is therefore often sluggish. Commerical operations routinely add ammonium sulphate to the juice to ensure rapid fermentations. The compounds contributing to flavour, namely the higher alcohols and esters, are similar in perries compared with ciders.