Received November 21st 2011 // Accepted July 27th 2012// Published online October 23rd 2012
DENOYA, G. I.1; ARDANAZ, M.2; SANCHO, A. M.1; BENÍTEZ, C. E.1; GONZÁLEZ, C.1,3; GUIDI, S.1
Enzymatic browning, which is mainly catalyzed by the enzyme poliphenol oxidase (PPO), is one of the major problems affecting quality and limiting shelf life of fresh cut fruits and vegetables. Traditionally, sulfites are used to inhibit the enzyme. However, its presence in the food has induced allergenic reactions, particularly in asthmatic persons. Consequently, it has been evaluated the effect of other PPO inhibitors in order to obtain fresh and natural products. In the present work, the evolution of PPO activity and the chromatic characteristics of the pulp were evaluated in cv. Granny Smith apple slices. The slices were submitted to three treatments: I. 2% ascorbic acid + 1% citric acid + 0.5% EDTA; II. 1% ascorbic acid + 0.5% citric acid + 0.25% EDTA; and III. water, used as control. During the storage, parameters of the CIE L*a*b* color space of the slices were evaluated, indicating that both treatments containing additives were effective in preventing browning. The specific activity of PPO was determined spectrophotometrically in apple extracts obtained from each treatment. The results indicated that the stronger treatment (I) had induced the most effective inhibition of the enzyme. On view of the present results, It is proposed to evaluate the “in vitro” effectiveness of the inhibitors in order to compare these results with the ones obtained with apple slices.
Keywords: poliphenol oxidase, fresh cut fruit, ascorbic acid, citric acid, EDTA, apples.