QUALITY EVALUATION OF HARDY KIWIFRUIT (ACTINIDIA KOLOMIKTA) USING NON-DESTRUCTIVE AND HOLISTIC RESEARCH METHODS
Keywords:ascorbic acid, biocrystallization, elektrochemical parameters
Fresh hardy kiwifruit (Actinidia kolomikta (Maxim. & Rupr.) Maxim.) possible to store for only two weeks at 0–5°C, therefore in order to maintain longer, the fruit have to be processed. The purpose of the study was to determine the quality of the Actinidia kolomikta fruit using research methods that are faster and easier, i.e. bioelectric Vincent method and biocrystallization. Four cultivars of Actinidia kolomikta fruits – ‘Landė’, ‘Paukštės Šakarva’, ‘Laiba’ and ‘Lankė’ – were investigated. Fresh, frozen and freeze-dried fruit were analysed. The amount of dry matter was determined by drying the samples to constant mass at 105 ºC, ascorbic acid was determined by titration with 2,6-dichlorphenol-indophenol sodium salt dehydrate. The pH and redox potential were measured by 781 pH/Ion Meter, electrical conductivity was measured by conductometer. P value as combined parameter was calculated according to the formula. Biocrystallization studies were carried out with fresh, frozen and freeze-dried fruits of all cultivars. The images derived from the encoded by sort samples were characterised with respect to the visual strength of form expression and were described by 10 criteria, criteria were evaluated using a 5-point scale. Research results showed that the dry matter and ascorbic acid content of A. kolomikta fruit significantly depended on the cultivar. Dry matter content of frozen fruit decreased from 4 to 7%, but increased during freeze-drying process by 6 to 7 times compare to the fresh fruit. Fruit processing methods increased pH, redox potential and P values. The lowest redox potential and P values were determined for fresh fruit, medium for freeze-dried and the highest for frozen fruit samples.