Changes in nutritional properties of minimally processed apples during storage Emiliano Cocci, Pietro Rocculi ∗ , Santina Romani, Marco Dalla Rosa Alma Mater Studiorum, Universit` a degli Studi di Bologna, Campus Scienze degli Alimenti, Piazza Goidanich 60, 47023 Cesena, Italy Abstract The effects of an antioxidant dipping treatment (in an aqueous solution of 1% ascorbic acid (AA) and 1% citric acid for 3 min) and of modified atmosphere (90% N 2 O, 5% O 2 and 5% CO 2 ) packaging (MAP) on some functional properties of minimally processed apples have been investigated. In particular, AA and total polyphenol (TP) contents and the overall antioxidant power of the product were monitored during 8 days of low temperature storage. Colour, texture and some chemical indices associated with the ripening stage of the product (titrable acidity and soluble solids content) were also evaluated. As a consequence of the anti-browning treatment, the AA content of dipped samples was about 20-fold higher than not treated samples at the beginning of storage and remained higher until the sixth day of refrigeration. Moreover, the dipping treatment resulted in an increase in the apple slice antioxidant activity, while MA had a negative effect on AA levels. As shown by the positive correlation between the AA and TP results, TP levels were higher for treated samples compared to those not treated over the whole storage period, because of the reducing action of AA that prevented a high level of TP degradation. Results of the other physico-chemical parameters investigated confirmed the synergistic preservative effect on the colour of MA, together with the dipping treatment, while structural decay of fruit tissue was evident due to the anti-browning chemical agents used. Keywords: Golden Delicious; Fresh-cut; Dipping; Modified atmosphere packaging; Ascorbic acid; Total polyphenols; Antioxidant activity 1. Introduction Despite growing interest and increased consumer selec- tion of fresh, processed products (or minimally processed), little information is available on nutrient stability or on the effectiveness of postharvest treatments (e.g. modified atmo- sphere packaging and dipping) on their nutritive value reten- tion during storage (Klein, 1987; Ahvenainen, 1996). This is because in this stage of minimally processed product devel- opment, the maintenance of nutritional value has not been the primary concern of shippers and producers, who have paid particular attention to safety and organoleptic aspects. Klein (1987) reviewed the nutritional consequences of minimal processing on fruit and vegetables and concluded that conditions able to maintain desirable sensory character- istics will also preserve nutrients. Ahvenainen (1996) showed that washing does not decrease the vitamin content (vitamin C and carotenes) of grated carrot, shredded Chinese cabbage or peeled potatoes significantly. The main negative factor was the storage time. Minimal processing of red lettuce stored at 5 ◦ C for 7–14 days caused a decrease in total polyphe- nol (TP) content of both green and red vegetable tissues, but wounding did not induce significant changes in the caffeic acid derivatives and flavonoids of these tissues (Ferreres et al., 1997). As far as fresh-cut strawberries and persimmons were concerned, the two products responded differently to the wounding stress in regard to the oxidation of ascorbic acid (AA), but in both cases, the post-cutting life based on visual quality ended before significant losses of total AA occurred (Wright and Kader, 1997). Research on minimally processed Swiss chard (Gil et al., 1998a) showed that its antioxidant content was lower under storage in modified atmosphere (7% O 2 and 10% CO 2 ) packaging (MAP), than in intact or minimally processed product stored in air, after 8 days of refrigeration. The effect of cutting and storage in air and