2.3. Fruit color measurement
Apple color was measured on red side of each of the thirty fruit using the Minolta CR-10 Chroma portable colorimeter (Minolta Co.,Osaka, Japan). Fruit chromaticity was recorded in CIE (Commission Internationale d’Eclairage) parameters L*, a*, b* and hue angle (h8)
color space coordinates.
2.4. Spectrophotometric determination of chlorophylls and
carotenoids in fruit skin
Two discs from the non-exposed side of each fruit (4 mm in diameter) were taken. For the extraction of chlorophyll and carotenoids, dimethyl sulfoxide (DMSO) was used. 0.5 ml DMSO was poured into microcentrifuge tubes, and one disc was added together with crystals of magnesium hydroxide carbonate to assure a sufficient concentration of Mg2+ ions in the solution. The disc was macerated for better extraction, and another 0.5 ml DMSO was added. Samples were left in a water bath (65 8C) in the dark for 2 h. After extraction, the samples were cooled to room temperature and decanted into cuvettes. Immediately afterwards, the absorptions were measured by spectrophotometer (Lambda Bio 20,PerkinElmer) at a wavelength of 480 nm (carotenoids), 649 nm(chlorophyll b) and 665 nm (chlorophyll a). Concentrations of chlorophylls a and b and carotenoids in the extract were counted up by using Wellburn (1994) equations.