Antecipação de safra, qualidade pós-colheita de caqui ‘Mikado’ (Diospyros kaki) e desenvolvimento/validação de nova metodologia para detecção e quantificação de cianamida hidrogenada em matriz de água

Abstract

'Mikado' Persimmon faces marketing problems because the harvest occurs in a short period of the year. It was performed an experiment with the use of hydrogen cyanamide (HC) and the influence of irrigation to evaluate if it is possible to anticipate the harvest in order to create alternatives for producers. The CH is currently the growth regulator that has the best performance to break the dormancy. However, in order to monitor the environment, it was developed one methodology for detection and quantification CH in water (from different sources), with low cost, high sensitivity, easy implement process and validated by international rules. The experiment of break dormancy of persimmon crop had the experimental randomized block design with lost parcels. There were evaluated six treatments in two blocks throughout the crop (harvested at each 15 days) in 2 successive years, the productivity of the trees (PT), and physical and chemical characteristics of the fruits. Data were analyzed individually in two different harvests and then the two harvests were compared. It was found that in the 2nd harvest the CH anticipated in 2 weeks the sprouting and the vegetative development of the flower closed from plants, regardless of the use of irrigation. However, the harvesting was in the same date for all treatments. In two seasons, the total soluble solids (TSS) and the size of the fruit increased over the crops, while condensed tannins (CT) decreased. From the first to the second harvesting, the PT and the CT of fruits increased, while the total titratable acidity and TSS of fruits decreased. The second part of this study aimed to develop a new CH quantification method using in situ derivatization with 2,6-dimethyl-4-quinolinecarboxylic acid N-hydroxysuccinimide ester, followed by dispersive liquid-liquid microextraction (DLLME) and HPLC analysis / fluorescence. Multivariate chemometric techniques were successfully used to obtain the optimum conditions for direct derivatization and DLLME extraction. Derivatization parameters and DLLME extraction conditions were optimized by a two steps design, 2k factorial design for screening and central composite design (CCD) design for optimization. Best derivatization conditions were addition of 600µL of derivatizing reagent, a temperature of 4ºC and pH 8.5, whereas for optimum extraction 800µL of solvent, 30% NaCl conc. w/v and pH 3.8 were chosen. The analytical performance of the method for routine analysis demonstrated excellent linearity from 10 to 200µg.L-1 with a correlation factor of 0.9996. Precision ranged from 3.5 to 5.5% and 8.5 to 8.6% for intraday and interday assays. The mean recoveries performed on water from different origins ranged from 90.2 to 110.2%.