The Actinidia genus includes a number of commercial fruit species with a wide range of countries of origin. Some species such as A. arguta or A. kolomikta are characterized by a high level of resistance to frost. The aim of this study was to compare the fruit of selected cultivars of kiwiberry. In the kiwiberry fruit, sucrose was the predominant type of sugar. Citric acid was dominant in all samples; it was most represented in the pulp of kiwiberry seedlings and in the skin of kiwiberry ‘Issai’. Kiwiberry fruits feature a higher ascorbic acid content in the skin in comparison with the commercial A. chinensis cultivars. Antioxidant activity of kiwiberry fruit skin was up to 18 times higher than that of the pulp. In view of the kiwiberry fruit having no hair, it is possible to eat the whole fruit, including the skin containing substances beneficial to health.

This study evaluated the physiochemical changes of one commercial European pear variety ‘Conference’ and one Asian pear variety ‘Yali’ during 60 days of storage at 1 °C. Content of organic acids, ethylene and formation of CO₂ were determined using HPLC/UV-VIS and GC/FID and TCD detectors, respectively. This study presents an evaluation of the influence of the above-mentioned factors and long-term storage on quality parameters, including the antioxidant capacity of an important European and Asian pear cultivar. There was a significant effect of temperature on respiration rate in both varieties. Development of the respiration intensity had a similar course in European and Asian pears. The high values of CO₂ production at the beginning of storage for the variety ‘Conference’ (14.08 mg·kg⁻¹·h⁻¹) and ‘Yali’ (23.37 mg·kg⁻¹·h⁻¹) were followed by a sharp decline of 80% and 83% at later stages of storage at 1 °C, respectively. Ethylene formation in fruit increased with storage time and was the highest after 60 days in cold storage, especially in ‘Yali’ (7.14 µL·kg⁻¹·h⁻¹). The results show the relation between ethylene formation and ripening-related fruit parameters. The ‘Yali’ variety showed negligible changes in soluble solids content and flesh firmness during storage ranging from 0.35 to 0.60 MPa. The most represented sugar determined enzymatically was fructose and malic acid was the dominant organic acid in pear fruit. Antioxidant activity determined using the FRAP and DPPH methods did not change significantly during 60 days of storage.

This study focuses on analyzing the impact of various fining agents on apple cider and evaluating their effects on its physical–chemical and sensory properties. Despite its common cloudy state, some consumers prefer clear apple cider. Within this study, two variations of apple cider were analyzed: original cider and cider with added barrique extract. Eight different fining agents were applied to these samples, specifically bentonite, gelatin, polyvinylpolypyrrolidone, egg white protein, activated carbon, pea protein, isinglass, and silica gel. The results revealed that the use of fining agents significantly impacted the antioxidant content in apple cider. The most substantial reduction in antioxidants was observed in samples with added activated carbon, resulting in a 75% decrease to values of 0.11–0.26 mmol TE/L. This decrease in antioxidants correlated with a decline in total polyphenols. Sensory analysis demonstrated statistically significant differences among the various apple cider samples. Bentonite and egg white protein had minimal adverse effects on sensory properties, while activated carbon had the most pronounced negative impact on the aroma and taste of the cider. This study provides valuable insights into the use of fining agents in winemaking technology and their effects on the quality of apple cider, considering consumer preferences.

Acta Universitatis Agriculturae et Silviculturae Mendelianae Brunensis, the scientific journal of the Mendel University in Brno, Czech Republic

The concentrations of sugars and acids are very important for the quality and the stability of wines. In addition, the proportion of the two main acids, i.e., tartaric acid and malic acid, is a significant factor for wine taste and stability. Over a period of three seasons in an organic vineyard, the influence of leaf area on the concentration of total soluble solids (TSS), pH, titratable acidity (TA), the concentration of tartaric acid and malic acid, and their mutual proportions were monitored. Vines of three varieties (‘Rhine Riesling’, ‘Pinot Gris’, ‘Sauvignon Blanc’) were treated using three different treatments (proportion of leaves removed 0%, 40%, and 70%). All varieties exhibited positive correlations between leaf area and TSS. In terms of relationships between TA and leaf area, ‘Sauvignon Blanc’ was the most sensitive variety. The highest differences between the individual variants were found for this variety. The tartaric to malic acid ratio displayed a significant seasonal effect, which was mostly more important than leaf area reduction. The size of the leaf area mainly affected the accumulation of sugars in the grapes, while content and ratio of acids was not affected so significantly. Therefore, leaf area regulation is one of the ways to optimize the composition of grapes in organic vineyards.