Note: Quantification of Ascorbic Acid and Dehydroascorbic Acid in Fresh Olives and in Commercial Presentations of Table Olives
Ascorbic acid (AA) and dehydroascorbic acid (DHAA) were determined by high performance liquid chromatography (HPLC) in fresh green olives as well as a diversity of commercial presentations of table olives (based on both Spanish-style green olives and directly brined olives). Fresh green olives (Manzanilla cv.) immediately after harvest contained about 9mg total ascorbic acid/100g f.w., with DHAA representing more than 90% of this amount. During the post-harvest period (till 2 weeks) the total vitamin C remained stable when olives were stored at 6°C, but significant degradation occurred at ambient temperature (~35% loss after 7 days). In commercial presentations of table olives, in general, the main contribution to the total vitamin C level appeared to come from AA added as an antioxidant, the maximum level being found in Manzanilla olives stuffed with anchovy streams (36.1mg/100g f.w.). However, in some samples (e.g. plain olives) that did declare any added AA, very low levels (0.1-0.6mg total AA/100g f.w.) were found. Our hypothesis is that, in those samples, AA would be degraded by lactic acid bacteria and/or yeast from olive fermentation, whereas pasteurisation in other presentations (e.g. stuffed olives) would stabilise added AA.