Fruit Quality Characteristics and Biochemical Composition of Fully Ripe Blackberries Harvested at Different Times

Blackberries and Mulberries: Berries with Significant Health-Promoting Properties

Blackberries and mulberries are small and perishable fruits that provide significant health benefits when consumed. In reality, both are rich in phytochemicals, such as phenolics and volatile compounds, and micronutrients, such as vitamins. All the compounds are well-known thanks to their medicinal and pharmacological properties, namely antioxidant, anti-inflammatory, anti-cancer, antiviral, and cardiovascular properties. Nevertheless, variables such as genotype, production conditions, fruit ripening stage, harvesting time, post-harvest storage, and climate conditions influence their nutritional composition and economic value. Given these facts, the current review focuses on the nutritional and chemical composition, as well as the health benefits, of two blackberry species (Rubus fruticosus L., and Rubus ulmifolius Schott) and one mulberry species (Morus nigra L.).

Black Queens of Fruits: Chemical Composition of Blackberry (Rubus subg. rubus Watson) and Black Currant (Ribes nigrum L.) Cultivars Selected in Serbia

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.

Effects of Different Nitrogen Forms on Blackberry Fruit Quality

To study the optimal form of nitrogen (N) application and to determine the best harvest date for blackberries, different N fertilizers were applied during the critical growth period of blackberry plants. The results showed that NH₄⁺-N significantly improved the appearance of blackberry fruits, including their size, firmness, and color, and promoted the accumulation of soluble solids, sugars, anthocyanin, ellagic acid, and vitamin C (VC), while fruit treated with NO₃^--N accumulated more flavonoids and organic acids and had improved antioxidant capacity. In addition, the fruit size, firmness, and color brightness decreased with the harvest period. While the contents of sugars, anthocyanin, ellagic acid, flavonoids, and VC were higher in the early harvests and then decreased as the season progressed, the total antioxidant capacity and DPPH radical scavenging capacity increased. In all, application of NH₄⁺-N is recommended, as it is more beneficial to fruit appearance, taste, and nutritional quality. Harvests in the early stage help to obtain a good fruit appearance, while harvests in the middle and later stages are more beneficial to fruit taste and quality. This study may help growers to determine the best fertilization scheme for blackberries and choose the appropriate harvest time according to their needs.

Ultrasound-Assisted Extraction of Blackberry Seed Oil: Optimization and Oil Characterization

Ultrasound-assisted extraction (UAE) was applied to extract oil from blackberry (BB) seeds. The effect of UAE conditions on oil recovery and quality was investigated. Favorable experimental conditions (ultrasound intensity (UI), extraction temperature, and time) were investigated using response surface methodology (RSM). A Box–Behnken design was used to predict optimized conditions for BB seed oil extraction. These conditions were as follows: 13.77 W/cm2 UI, 45 °C extraction temperature, and 15 min extraction time. The experimental value obtained for extraction efficiency under optimal conditions was 87 ± 0.34%, in good agreement with the optimized predicted value. UAE does not affect the oil composition and confers higher antioxidant values in BB seed oil in comparison with Soxhlet extraction.

Antioxidant Guided Fractionation of Blackberry Polyphenols Show Synergistic Role of Catechins and Ellagitannins

In the present study, blackberry extract was prepared using a previously optimized solid-liquid extraction method in 70% aqueous acetone aimed at the recovery of its principal phenolics. Subsequently, 0.5 g of freeze-dried extract was subjected to flash chromatography fractionation, which was conducted on a C18 column using a binary solvent system of water and methanol at 10 mL/min. The total phenolic content (TPC), 2,2-diphenyl-1-picrylhydrazyl (DPPH), and ferric reducing antioxidant power (FRAP) activities of the obtained 42 flash fractions were determined, and a strong positive correlation (r ≥ 0.986) was exhibited among them. Furthermore, the graph of the antioxidant indices of the flash fractions resembled the flash chromatogram, suggesting a good correlation among the compounds within the chromatographic peaks and the antioxidant indices. LC-MS/MS identified as many 28 phenolics, including cinnamtannin A2 reported for the first time in blackberries. This study further established the role of dominant anthocyanins (cyanidin-3-O-glucoside and cyanidin-3-O-rutinoside), but uniquely those of ellagitannins and catechins on the antioxidant capacity of blackberries.

Polymeric Compounds of Lingonberry Waste: Characterization of Antioxidant and Hypolipidemic Polysaccharides and Polyphenol-Polysaccharide Conjugates from Vaccinium vitis-idaea Press Cake

Lingonberry (Vaccinium vitis-idaea L.) fruits are important Ericaceous berries to include in a healthy diet of the Northern Hemisphere as a source of bioactive phenolics. The waste generated by the V. vitis-idaea processing industry is hard-skinned press cake that can be a potential source of dietary fiber and has not been studied thus far. In this study, water-soluble polysaccharides of V. vitis-idaea press cake were isolated, separated, and purified by ion-exchange and size-exclusion chromatography. The results of elemental composition, monosaccharide analysis, ultraviolet–visible and Fourier-transform infrared spectroscopy, molecular weight determination, linkage analysis, and alkaline destruction allowed us to characterize two polyphenol–polysaccharide conjugates (PPC) as neutral arabinogalactans cross-linked with monomeric and dimeric hydroxycinnamate residues with molecular weights of 108 and 157 kDa and two non-esterified galacturonans with molecular weights of 258 and 318 kDa. A combination of in vitro and in vivo assays confirmed that expressed antioxidant activity of PPC was due to phenolic-scavenged free radicals, nitrogen oxide, hydrogen peroxide, and chelate ferrous ions. Additionally, marked hypolipidemic potential of both PPC and acidic polymers bind bile acids, cholesterol, and fat, inhibit pancreatic lipase in the in vitro study, reduce body weight, serum level of cholesterol, triglycerides, low/high-density lipoprotein–cholesterol, and malondialdehyde, and increase the enzymatic activity of superoxide dismutase, glutathione peroxidase, and catalase in the livers of hamsters with a 1% cholesterol diet. Polysaccharides and PPC of V. vitis-idaea fruit press cake can be regarded as new antioxidants and hypolipidemic agents that can be potentially used to cure hyperlipidemic metabolic disorders.

Variation in Bioactive Compounds and Antioxidant Activity of Rubus Fruits at Different Developmental Stages

Blackberry and raspberry have high nutritional, health value, and are popular with consumers for their unique flavors. To explore the relationships between nutrient accumulation, antioxidant substance contents in blackberry and raspberry fruits, and fruit growth and development, seven Rubus cultivars were selected, and contents of the main active substance were determined. "Clode Summit" had the highest soluble sugar and fructose contents, "Chester"-the highest total phenol content, and "Bristol'-the highest anthocyanin content. Generally, the contents of flavonoids and total phenols showed a downward trend with the development of fruit in seven Rubus cultivars, and the content of anthocyanins increased rapidly in the later stage of development. Pearson correlation analysis showed extremely significant correlation between antioxidant activity and the contents of vitamin E, total phenols, and flavonoids. Flavonoids were extremely significantly positively correlated with the content of total phenols, and the contents of flavonoids and anthocyanins in various cultivars were highly negatively correlated. Considering the different nutritional ingredients and active antioxidant substance contents, "Clode Summit", "Bristol", and "Chester" are recommended for raw consumption, processing, and medicinal purposes, respectively. These results provide a reference for comparing the main active substance contents in different Rubus cultivars and their changes across fruit development stages.