STORAGE QUALITY OF 'MD2' PINEAPPLE (ANANAS COMOSUS L.) FRUITS

Selected physical (texture, peel and flesh colour) and chemical (pH, titratable acidity (TA), soluble solids concentration (SSC) and ascorbic acid) characteristics of ‘MD2’ pineapple (Ananas comosus L.) fruits during storage were studied. The fruits were harvested at four different maturity stages according to the peel colour (stage 1 = mature green; stage 2 = colour break; stage 3 = 25% yellow peel; stage 4 = 50% yellow peel) and the fruits were stored at 10°C for 3 weeks. Peel and flesh color were measured by Minolta CR-300 Chroma Meter (Minolta Corp., Osaka, Japan). Flesh firmness was measured as penetration force using a texture analyzer Instron with Merlin Software. SSC were determined using juice extracted from flesh samples using a digital refractometer PAL-1 (Atago Co., Ltd., Tokyo, Japan) to obtain the %SSC. TA was measured using 5 ml juice that titrated with 0.1 mol/L NaOH and expressed as percentage of citric acid. The pH of the juice was measured using a glass electrode pH meter model Crison Micro pH 2000 (Barcelona, Spain). Ascorbic acid content determination was carried out using dye, 2,6-dichlorophenol-indophenol titration method and expressed as mg/100 g. The experimental design was a completely randomized design with three replications. The obtained data were analyzed by using ANOVA. When F values showing significance (P≤0.05), differences within each factor were determined by least significant differences using SAS. Significant differences (p<0.05) were found in peel and flesh colour, flesh firmness, SSC, TA, pH and ascorbic acid of ‘MD2’ pineapple fruit during storage. The results showed that postharvest storage at 10°C changed the ‘MD2’ pineapple fruit characteristics. The lightness of ‘MD2’ pineapple peel increased during storage showed that colour changed as ripening progressed. While the lightness of flesh decreased during storage indicated that colour changed from light yellow to deep yellow as ripening progressed. The flesh firmness of the fruits decreased during storage as the fruits ripened. Even though the soluble solids concentration of the ‘MD2’ pineapple fruits decreased during storage, fruits harvested at earlier stage showed higher soluble solids concentration than fruits harvested at later stage. The pH values declines slightly during storage at 10°C, while TA increased. Ascorbic acid content decreased significantly during storage.