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Effect of Processing on the Content of Condensed Tannins in Rapeseed Meals

1989; Wiley; Volume: 54; Issue: 4 Linguagem: Inglês

10.1111/j.1365-2621.1989.tb07951.x

1750-3841

Fereidoon Shahidi, M. Naczk,

Food Quality and Safety Studies

ABSTRACT The condensed tannins of rapeseed meals produced by a two‐phase solvent extraction system were determined and compared with those of hexane‐extracted meals. Ground seeds were extracted with absolute methanol, 95% methanol, 10% (w/w) ammonia in methanol or 10% (w/w) ammonia in 95% methanol and hexane as a second phase. Tannins were extracted with 70% (v/v) aqueous acetone and assayed by the 0.5% vanillin methodology. Methanol alone extracted only 16% of the tannins; addition of 5% (v/v) water to methanol increased the efficiency of tannin extraction to 36%. The methanol‐ammonia‐water/hexane, however, was the most effective solvent system for the removal of tannins. The resultant meals contained from 4% to 33% of the condensed tannins which were originally present in rapeseed meals.