In T 112/92 (OJ 1994, 192) document (1), as the closest prior art, referred to the use of glucomannan as a thickener for an ungelled processed food product, but did not mention its function as a stabiliser. The board applied the principles set out in T 59/87 date: 1990-08-14 (OJ 1991, 561) to the case in hand and stated that even if glucomannan did act as an emulsion stabiliser in preparing the product in accordance with document (1), this use would have been a hidden use. It came to the conclusion that the use of a substance as a stabiliser for emulsions, if not inextricably linked with its use as a thickening agent, was at least very closely related. The board held that it would have been obvious for the skilled person, knowing that glucomannan was effective as a thickening agent for emulsions, at least to try to find out if it was also effective as a stabiliser. Although T 59/87 date: 1990-08-14 had found that a claim to an inherent but hidden later use of a known substance could be novel, the subject-matter of such a claim would still lack inventive step if the prior art indicated a well-established link between the earlier and later uses (see also T 544/94).
Source: http://www.epo.org/law-practice/legal-texts/html/caselaw/2019/e/clr_i_d_9_13.htm
Date retrieved: 17 May 2021