The present research aimed at evaluating the vitamin C, total phenolic content (TPC), phenolic compounds, carotenoids, and chlorophyll contents, as well as antioxidant activity (AAC) of six Actinidia species fruit. Vitamin C, phenolic compounds, carotenoids and chlorophylls were measured using high-performance liquid chromatography. TPC was determined using the Folin–Ciocalteau reagent, and AAC using 2,2-diphenyl-1-picryl hydrazyl (DPPH) assay. The highest concentrations of vitamin C and TPC were found for Actinidia kolomikta fruit (1008.3 and 634.1 mg/100 g fresh weight [FW], respectively). Among phenolic compounds, seven phenolic acids and three flavonoids were identified. The 2,5-dihydroxybenzoic acid prevailed in A. kolomikta (425.54 mg/100 g FW), while tannic acid dominated in other species (4.63–100.43 mg/100 g FW). The largest amounts of chlorophylls and carotenoids were identified as Actinidia macrosperma (4.02 and 2.09 mg/100 g FW, respectively). The AAC of fruit extracts decreased in the order of A. kolomikta > Actinidia purpurea > Actinidia melanandra > A. macrosperma > Actinidia arguta > Actinidia deliciosa according to the DPPH assay.

The rapid increase in the production of hardy kiwi fruit (A. arguta) since the beginning of the 21st century has required the development of new cultivation technologies and postharvest handling procedures in order to extend the supply and transport of the fruit to distant markets. Fruit storage focuses on the inhibition of ripening processes regulated by ethylene activity or respiration. Both of these are effectively regulated by appropriate concentrations of O₂ and CO₂ in the atmosphere surrounding the fruit. In this study, the effect of the concentration of both gases in the cold room on the physico-chemical indices of fruit quality, i.e., mass loss, firmness, soluble solids and monosaccharides content, titratable acidity and acid content, and color of the peel was evaluated. Studies have shown that high CO₂ concentrations inhibit ripening processes more effectively than low O₂ concentrations. Softening of berries as well as an increase in soluble solid contents was recorded during the first 4 weeks of storage in the fruit. However, the increase in monosaccharides was fairly stable throughout the study period. The increase in soluble solids content as well as the loss of acidity were more strongly determined by CO₂ than O₂, although the acid content in a 10% CO₂ atmosphere did not change. Additionally, the fruits were greener after storage in 10% CO₂, but the weakness was skin dulling and darkening. The results indicate that the use of high CO₂ concentrations (5–10%) effectively inhibits ripening processes in fruit. After 12 weeks of storage, the fruit was still not suitable for direct consumption, which suggests that the storage period can be extended further.

Dynamic changes have taken place in the production of sweet cherry (Prunus avium L.) in Poland over the last 20 years. New cultivars with both early- and late-ripening dates have appeared, and modern high-intensity cultivation techniques are being implemented. The main attribute of the fruit, in addition to its unique taste, is its health-promoting properties. In this research, which was conducted at the Warsaw University of Life Sciences in 2021, our main objectives were to evaluate seven selected Czech cherry cultivars (‘Jacinta’; ‘Horka’; ‘Tamara’; ‘Helga’; ‘Fabiola’; ‘Kasandra’; ‘Kordia’) with regard to their dessert quality and contents of biologically active compounds, and to indicate the most valuable cultivar under the conditions of central Poland. The cultivars tested differed in both the fruit quality and health-promoting properties. ‘Jacinta’, ‘Horka’, Tamara’ and ‘Fabiola’ had the largest fruits. The ‘Fabiola’ and ‘Kordia’ fruits had the highest firmness, while the ‘Jacinta’ and ‘Horka’ fruits had the highest soluble solid contents (SSCs) and titratable acidities (TAs). We found the highest SSC-to-TA ratio in the ‘Fabiola’ cultivar. ‘Jacinta’ proved to be the most valuable cultivar in terms of bioactive compounds, and it had the highest antioxidant activity (DPPH). Some of the traits were closely correlated with each other, mainly in relation to the biologically active compounds. Darker fruits contained more bioactive compounds and had a higher antioxidant activity. It was also proved that size of fruits as well as SSC and TA are also correlated with fruit color. Intensively colored fruit are larger and have higher SSC and TA. In sweet cherry fruit, the contents of polyphenols and flavonoids, as well as the high DPPH, are strongly determined by the high content of cyanidin-3-galactoside.