Abstract: The subject matter of the invention is a process for preparing a liquid food product enriched with oligosaccharides and with polysaccharides starting from berries, in the absence of alcoholic fermentation in the presence of the berries, which comprises (a) heating the berries at a temperature ranging from 40° C. to 100° C., (b) placing the berries under vacuum at a pressure ranging from 103 to 3×104 Pa, and (c) a step of maceration of the berries by inoculation of one or more pectolytic enzymes, and extraction of the juice before any fermentative process.

Abstract: Enzyme degrading rhamnogalacturonane II (RG-II) having an endo-.beta.-L-rhamnopyranosyl-(I.fwdarw.3')-D-apiofuranosyl hydrolase activity and/or an endo-.alpha.-L-fucopyranosyl-(I.fwdarw.4)-L-rhamnopyranosyl hydrolase activity. This enzyme can be produced by a microorganism, especially of the penicillium species, such as the branches 1-1577 and 1-1578 lodged with the CNCM. The RG-II can obtained from plant extracts by means of a method comprising a chromatography stage.