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Forchlorfenuron (CPPU) is a plant growth regulator widely used in kiwifruit production. Although research on the toxicological and environmental effects of CPPU is well-established, the nature and toxicological properties of its metabolites are much less well-known. Using high resolution mass spectrometry and nuclear magnetic resonance, the CPPU previously unidentified metabolites in Xuxiang and Jinyan kiwifruit were identified as N-(2-chloro-4-pyridinyl)-N′-(2-hydroxy-4-methoxyphenyl)-urea (metabolite 1) and N-phenyl-N′-4-pyridinylurea (metabolite 2, CAS: 1932-35-0). Their structures were confirmed by synthesis (metabolite 1) and by comparison with a commercial standard (metabolite 2). Quantitative studies demonstrate that CPPU and its metabolites are mainly retained in the kiwifruit peel, while the content is dependent on the nature of the peel surface, with the smoother peel of Jinyan kiwifruit retaining smaller amounts of the compound. Cell viability experiments in Caco2 and Lo2 cells show that the metabolites may have a lower cytotoxicity compared to the parent compound CPPU.

This work was undertaken to evaluate the microbiological characteristics and antioxidant and physiological activities in kiwifruits (Actinida deliciosa var. Qinmei) with/without cinnamaldehyde (C1) and citral (C2) fumigation treatments (5 μL/L) during 0, 3, 6, 9, and 12 d of storage at 4 °C. Essential oils (EOs) treatment lowered the total viable counts, yeast, and mold to 1.54, 2.36, and 2.05 log CFU/g, respectively. Moreover, EOs improved the antioxidant activities of kiwifruit. They enhanced phenolics and flavonoids content in fruit tissue by 49.48% at day 3 and 56.93% at day 6, respectively. In addition, ascorbic acid in treated groups had the lower losing rate. Similarly, MDA (malondialdehyde), H O (hydrogen peroxide), and O (superoxide anion) production were effectively decreased in the range of 27.27% to 54.38%. Physicochemical characteristics showed that kiwifruits from treated group maintained higher levels of flesh luminosity and firmness. EOs also decreased the levels of reducing sugar by 45.97% at day 3, and increased the content of soluble protein and hydrolyzed amino acid. Therefore, postharvest EOs treatment has positive effects on delaying senescence and enhancing antioxidant capacities in kiwifruit.

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Pesticides are widely used in the process of kiwifruit growth to promote fruit expansion. This study was aimed to assess the effects of pesticides on the quality of kiwifruit by applying high and normal concentrations of forchlorfenuron (CPPU) and thidiazuron (TDZ) to “Xuxiang” (XX) green kiwifruit and “Jinyan” (JY) gold kiwifruit. Sixty kiwifruit trees were used to comprehensively evaluate the effects on the pulp and whole kiwifruit. In addition to the weight gain effect and basic physical‐chemical properties (vitamin C, total protein, glucose and fructose, organic acids), the main nutritional qualities (in vitro and cellular antioxidant activity (CAA), and dietary minerals) were also evaluated. The vitamin C content of XX was not affected by pesticides, but the use of CPPU reduced vitamin C of JY pulp by 23% (p < 0.05). Pesticides did not reduce the antioxidant values of XX pulp in vitro but significantly reduced CAA values (32%–47%). In JY pulp, pesticides treatments had no significant effect on antioxidant values in vitro except that CPPU treatments significantly reduced the ferric reducing antioxidant power (FRAP) value by 21% (p < 0.05). Reasonable use of pesticides can effectively improve taste of kiwifruit, increasing kiwifruit weight and the content of certain nutrients. Practical Application Based on observed changes in nutritional components, CPPU may be more suitable for XX while TDZ may be more suitable for JY. The significance of this study may affect kiwifruit farmers and ultimately help improve the sensory quality of kiwifruit.