Jerneja Jakopic

Black fruits, especially blackberries and black currants, are highly appreciated by consumers due to their nutraceutical properties, which have reported health benefits. This study aimed to assess the fruit quality of the blackberry (cv. ‘Čačanska Bestrna’) and black currant (cv. ‘Čačanska Crna’) created at the Fruit Research Institute, Čačak (Republic of Serbia) by evaluating basic quality parameters (fruit weight, soluble solids), and content of primary (sugars and organic acids) and secondary (phenolic compounds) metabolites. Additionally, the study examined the quality of frozen and long-term frozen storage (6, 9, and 12 months). The results showed that ‘Čačanska Crna’ contained a high level of total soluble solids (15.23°Bx), sugars (93.06 mg g−1), and a high index of sweetness (159.48) as well as a high content of acids (34.35 mg g−1) in the fruit. Both species were found to contain forty-seven phenolic compounds, including phenolic acids, flavanols, and anthocyanins, analyzed using high performance liquid chromatography-mass spectrometry (HPLC-MS). ‘Čačanska Bestrna’ had the highest amounts of phenolic acids (66.85 mg 100 g−1) and flavanols (53.99 mg 100 g−1), whereas ‘Čačanska Crna’ showed the highest levels of flavonols (8.57 mg 100 g−1) and anthocyanins (139.11 mg 100 g−1). Furthermore, the study revealed that anthocyanins were the most abundant phenolic group in both blackberries and black currants, and their levels remained constant during frozen storage. The sugar content in both species remained unchanged, while the acid concentration increased over time in blackberries but remained consistent in black currants. Overall, the findings highlight the superior phenolic content, particularly anthocyanins, of the cultivars with black fruits selected in Serbia. These cultivars have great commercial potential for the fresh market and processing. Moreover, the study suggests that frozen storage is an effective method for preserving their quality and beneficial properties.

The aim of this research was to evaluate the effect of a combination of several mycorrhizal and bacterial biostimulants, applied before and after planting, on the ‘Clery’ strawberry’s performance. Vegetative and reproductive parameters (the number of crowns per plant, root/canopy weight and dimensions, the number of fruits per plant, individual fruit weight, and fruit yield per plant) were monitored on nine harvest dates. Additionally, external and internal fruit quality (firmness, color, soluble solids content, and primary and secondary metabolites) was determined. The application of product combinations resulted in significantly improved vegetative growth, fruit dimensions, and fruit weight. Consequently, more than 30% higher yields were determined for the treated plants. A minor decrease in vitamin C (approx. 6%), total individual sugars (approx. 10%), organic acids (approx. 9%), and total phenolics (approx. 7%) was detected in the treated plants, but the differences were not uniform during the harvest. The accumulation of anthocyanins was least affected by product application, and the fruit exhibited comparable color characteristics, which is important for the consumers. The use of biostimulants in intense strawberry production is justified as the products improve the vegetative development of strawberry plants, which produce significantly more marketable fruit.