Effect of storage conditions on content of pesticide residues in sweet cherries.

Dynamics of pesticides decomposition in sweet cherry fruits at different technologies of long-term storage, ultra-low oxygen and modified atmosphere packing, and after post-harvesting application of 1-methylcyclopropen and ozone has been studied. We assumed that type of pesticide and fruit storage conditions may have a profound effect on pesticide residues content. Therefore, levels of residues after applying combinations of active ingredients including acetamiprid, boscalid, cyprodinil, fenhexamid, fenpyrazamine, fludioxonil, fluopyram, pyraclostrobin, pirimicarb, tebuconazole, thiacloprid, and trifloxystrobin were monitored. We found these contents below tolerated maximum residue limits when applied at recommended times and depended on period prior to withdrawal. Low contents of acetamiprid, boscalid, fenpyrazamine, thiacloprid, pirimicarb, and fludioxonil were found when fruit were stored in modified atmosphere packages. Ozone affected degradation of tebuconazole, pyraclostrobin, and cyprodinil. However, differences between storage regimens were not statistically significant (p ≥ 0.05). Kinetic of degradation was studied with fruits stored after treatment with 1-methylcyclopropen and ozone.

Benefits and Pitfalls of HPLC Coupled to Diode-Array, Charged Aerosol, and Coulometric Detections: Effect of Detection on Screening of Bioactive Compounds in Apples.

The new screening method for rapid evaluation of major phenolic compounds in apples has been developed. Suitability of coupling HPLC/UHPLC separation with the diode-array detection and universal charged aerosol detection with respect to the presence of interfering substances was tested. Characteristics of both detection techniques were compared and method linearity, limits of detection and quantitation, and selectivity of them determined. Student t-test based on slopes of calibration plots was applied for the detailed comparison. The diode-array detection provided the best results regarding sensitivity and selectivity of the developed method in terms of evaluation of phenolics profiles. The response of the charged aerosol detector was negatively affected by co-eluting substances during rapid-screening analyses. Coulometric detection was used for advanced characterization of extracts in terms of antioxidant content and strength to obtain more complex information concerning sample composition. This detection also allowed evaluation of unidentified compounds with antioxidant activity. HPLC/UHPLC separation using a combination of diode-array and coulometric detectors thus represented the best approach enabling quick, yet complex characterization of bioactive compounds in apples.

Determination of major phenolic compounds in apples: Part I-Optimization of high-performance liquid chromatography separation with diode array detection.

The separation of seven phenolic compounds including gallic acid, chlorogenic acid, epicatechin, quercitrin, rutin, phloridzin, and phloretin present in apple peel and pulp and differing in elution properties has been optimized using high-performance liquid chromatography with diode array detection. Several stationary phases were tested to achieve the efficient separation of phenolic compounds in fruit extracts and C18 was found to be the most efficient. Core-shell and fully porous C18 packings were assessed with respect to the complex composition of the fruit extracts. The developed high-performance liquid chromatography method comprised gradient elution in which mobile phase A was water at pH 2.8 adjusted with acetic acid and B was acetonitrile. The gradient shape was the following: 0 min 95% A/5% B, 2.5 min 85% A/15% B, 12 min 50% A/50% B, 15 min 95% A/5% B. The flow rate was 1 mL/min, injection volume 10 µL, and UV detection at 255, 280, 320, and 365 nm was applied. Our method was validated for both C18 core-shell and fully porous packings. The resolution 6.2-14.8, symmetry 0.99-1.34, peak capacity 18-60, peak area repeatability 0.45-1.00% relative standard deviation, calibration range 0.125-5 mg/mL (0.25-10 mg/mL for chlorogenic acid and rutin), correlation coefficients of calibration curve 0.9976-0.9997, and accuracy evaluated as recovery 95.56-107.54% were determined for the core-shell column.