acidulate

verb

1. (transitive)To make slightly or moderately acid; to acidify.
2. (transitive)To make sour in a moderate degree; to sour somewhat.

   “Twenty leeches were ordered to be applied round the nose every two days; frequent emollient fomentations; the local vapour bath; general bathing; stimulating pedilavia; a strict regimen; vegetables, milk, white meats; demulcent or acidulated drinks; avoidance of exposure to the sun or to cold air; flannel waistcoat and trousers. This treatment, being strictly observed for two months, caused all the inflammatory symptoms to disappear, […]”

   “The kernel of San Domingo cocoa was more acidulated than that of Venezuela and was not inferior in other respects, experience proving that the chocolate made of the two cocoas in combination had a more delicate flavour than that made from the cocoa of Venezuela alone.”

3. (transitive)To use an acidic catalyst, with the chemical change being emphasised over the importance of the change in pH. Used in the processing of biodiesel co-products.