Developing strategies to stimulate local consumption, export and ...

and browning of the tissue (due to various enzymatic and non-enzymatic reactions) which is amajor problem that occurs especially during the freezing process. While the enzymepolyphenol oxidase is considered the major one responsible for tissue browning in artichoke,there are indications that other enzyme systems such as peroxidase could also be contributingto the total discolouration in some fruits and vegetables (Vamos-Vigyaso, 1981). It isgenerally accepted that during artichoke processing the cell damage that occurs leads to darkcolouration of the tissue which is due to the reaction of phenolic compounds such ascaffeolyquinic acid with ferric iron (Hughes et al., 1962; Mathew and Parpia, 1971).One of the main purposes of this study was to experiment with various anti-browningcompounds to find the most effective in controlling browning of artichoke during the freezingprocess. It is known that anti-browning compounds can be used singularly or in combinationfor their synergistic effect (Son et al., 2001). A large number of approved food additives haveshown various degrees of inhibitory effects such as citric and ascorbic acids on carrambola(Weller et al., 1997), L-cysteine and citric acid in potatoes (Gunes et al., 1997), acetic acid inLettuce (Tomas-Barberan et al., 1997) and citric acid and ascorbic acid in artichoke (Lattanzioet al., 1989). Another technique used to inhibit enzymatic browning is blanching in plainwater heated to various temperatures or water mixed with organic chemicals to enhance theblanching effects. Toivonen (1992), working on enzymatic browning in various parsnipscultivars, concluded that the effectiveness of anti-browning agents is limited by the extent ofthe injury sustained by the particular cultivar.