White versus blue: Does the wild 'albino' bilberry (Vaccinium myrtillus L.) differ in fruit quality compared to the blue one?

Increasing the Content of Bioactive Compounds in Apple Juice Through Direct Ultrasound-Assisted Extraction from Bilberry Pomace

The increasing trend of diet-related chronic diseases has stimulated research into developing new food products and beverages with health-promoting potential. At the same time, new resources, including plant by-products, are currently being investigated as a sustainable source of bioactive compounds. In this context, the present study focused on the enrichment of apple juice with anthocyanins and other phenolic compounds by direct ultrasound-assisted extraction (UAE) from bilberry pomace. Response surface methodology combined with a Box-Behnken design was used to find the optimal extraction conditions for maximizing the total anthocyanin content (TAC), total phenolic content (TPC) and DPPH radical scavenging activity (RSA) in the enriched apple juices and to characterize their phenolic profile as influenced by the extraction temperature. UAE from 15% bilberry pomace during 15 min in apple juice at 80 °C resulted in the highest TAC (262.73 mg CGE/L), TPC (1700.91 mg GAE/L) and RSA (8.93 mmol Trolox/L) of the enriched apple juice. The chromatographic polyphenolic profile of the control and enriched juices showed that, besides anthocyanins, phenolic acids (chlorogenic, gallic, caffeic, 3-hydroxybenzoic, p-coumaric, ellagic and protocatechuic acids) and flavonoids (epigallocatechin and catechin) were extracted from the bilberry pomace directly in the apple juice, while the extraction temperature differently impacted the content of individual phenolic compounds.

HPLC-Mass spectrometry analysis of phenolics comparing traditional bilberry and blueberry liqueurs

The purpose of this study was to investigate the differences between the phenolics compositions of bilberry and blueberry liqueurs, to determine whether these are comparable. Both bilberry and blueberry liqueurs have the same name on the market, however they differ in phenolic composition and content. A total of 43 compounds were identified, 36 in the bilberry liqueur, and 21 in the blueberry liqueur. High performance liquid chromatography coupled with mass spectrometry (HPLC-MS) was used to identify and quantify these compounds, where they were fragmented to the MS4 fragments. Anthocyanins were the major phenolics group detected in the bilberry liqueurs, but only the second most abundant phenolics group in the blueberry liqueurs. The most abundant phenolics group in the blueberry liqueurs was hydroxycinnamic acids. The lowest content of individual phenolic compounds was for blueberry liqueur made from whole fruit. This study will provide valuable data to consumers in their choice of a more expensive bilberry liqueur or a cheaper blueberry liqueur.

The telomere-to-telomere gap-free reference genome of wild blueberry (Vaccinium duclouxii) provides its high soluble sugar and anthocyanin accumulation

Vaccinium duclouxii, endemic to southwestern China, is a berry-producing shrub or small tree belonging to the Ericaceae family, with high nutritive, medicinal, and ornamental value, abundant germplasm resources, and good edible properties. In addition, V. duclouxii exhibits strong tolerance to adverse environmental conditions, making it a promising candidate for research and offering wide-ranging possibilities for utilization. However, the lack of V. duclouxii genome sequence has hampered its development and utilization. Here, a high-quality telomere-to-telomere genome sequence of V. duclouxii was de novo assembled and annotated. All of 12 chromosomes were assembled into gap-free single contigs, providing the highest integrity and quality assembly reported so far for blueberry. The V. duclouxii genome is 573.67 Mb, which encodes 41 953 protein-coding genes. Combining transcriptomics and metabolomics analyses, we have uncovered the molecular mechanisms involved in sugar and acid accumulation and anthocyanin biosynthesis in V. duclouxii. This provides essential molecular information for further research on the quality of V. duclouxii. Moreover, the high-quality telomere-to-telomere assembly of the V. duclouxii genome will provide insights into the genomic evolution of Vaccinium and support advancements in blueberry genetics and molecular breeding.

Src Tyrosine Kinase Inhibitory and Antioxidant Activity of Black Chokeberry and Bilberry Fruit Extracts Rich in Chlorogenic Acid

Edible berries such as the fruits of black chokeberry (Aronia melanocarpa (Michx.) Elliott) and bilberry (Vaccinium myrtillus L.) are considered to be rich in phenolic compounds, which are nowadays attracting great interest due to their promising health benefits. The main objective of our study was to investigate, for the first time, their inhibitory properties on Src tyrosine kinase activity, as this enzyme plays an important role in multiple cellular processes and is activated in both cancer and inflammatory cells. In hydroethanolic fruit extracts, 5.0-5.9% of total polyphenols were determined spectrophotometrically, including high amounts of hydroxycinnamic acid derivatives. HPLC analysis revealed that the black chokeberry and bilberry extracts contained 2.05 mg/g and 2.54 mg/g of chlorogenic acid, respectively. Using a time-resolved fluorescence resonance energy transfer (TR-FRET) assay, the extracts studied were found to have comparable inhibitory effects on Src tyrosine kinase, with IC50 values of 366 µg/mL and 369 µg/mL, respectively. The results also indicated that chlorogenic acid contributes significantly to the observed effect. In addition, both fruit extracts exhibited antioxidant activity by scavenging DPPH and NO radicals with SC50 values of 153-352 µg/mL. Our study suggested that black chokeberry and bilberry fruits may be beneficial in cancer and other inflammation-related diseases.

In Vitro Hypoglycemic Potential, Antioxidant and Prebiotic Activity after Simulated Digestion of Combined Blueberry Pomace and Chia Seed Extracts

This study aimed to evaluate the hypoglycemic potential, antioxidant activity and prebiotic activity of a hydroalcoholic extract of blueberry pomace (BP), an aqueous extract of chia seeds (CS) and a novel combination of BP–CS extracts (BCM) for further use as ingredient of functional food. Spectrometric and HPLC analyses were used to characterize the total phenolic and flavonoid content and composition of BP, while CS was analyzed for total carbohydrate content. Data showed that the BCM mixture exerted an inhibition of α-amylase activity, which was 1.36 times higher than that of BP and 1.25 higher than CS extract. The mixture also showed better scavenging activity of free DPPH radicals than individual extracts, and had an IC50 value of 603.12 µg/mL. In vitro testing indicated that both serum- and colon-reaching products of simulated intestinal digestion of BCM presented the capacity to protect Caco-2 intestinal cells against oxidative stress by inhibition of reactive oxygen species production. In addition, the colon-reaching product of BCM digestion had the capacity to significantly (p < 0.05) stimulate the growth of Lactobacillus rhamnosus and Lactobacillus acidophilus, revealing a prebiotic potential. All these results indicated that improved biological activity of the novel combination of BP and CS extracts could be due to the synergistic action of constituents. The combination is recommended for further testing and the development of novel functional food for controlling type 2 diabetes and gastrointestinal conditions.

Bilberries: Curative and Miraculous - A Review on Bioactive Constituents and Clinical Research

Bilberry (Vaccinium myrtillus L.) fruits are an important part of local diets in many countries and are used as a medicinal herb to treat various disorders. Extracts from fruits are often a part of eye health-promoting supplements, whereas extracts from leaves are advertised for type 2 diabetes mellitus and glycemic control. This review provides an overview of the current knowledge of the phytochemical contents of bilberry fruits and leaves and their bioactivities, critically summarizes origins of the health claims and the outcome of clinical trials, with special attention towards those published in the past 10 years. Overall, the three most referenced indications, which are type 2 diabetes mellitus, vision disorders and circulatory diseases, all include contradictory results with no clear conclusion as to the benefits and recommended dosages. Moreover, the indications for vision disorders and diabetes originate from unproven or false claims that have been repeated in research since the 20th century without consistent fact-checking. Beneficial clinical results have been attested for the treatment of dyslipidemia and chronic inflammatory disorders when applied as dietary supplementation of fresh bilberries or as anthocyanin-rich bilberry fruit extracts. However, there is a general lack of double-blinded controlled research with larger sample sizes.

Fruit Quality and Yield of Three Highbush Blueberry (Vaccinium corymbosum L.) Cultivars Grown in Two Planting Systems under Different Protected Environments

Due to the increasing interest in highbush blueberry (Vaccinium corymbosum L.) among consumers, together with the problems of climate change and specific substrate requirements, a novel approach to intensive blueberry production is required. Here, ‘Duke’, ‘Aurora’, and ‘Brigitta’ blueberry cultivars were planted under the protective environments of a high tunnel and black hail net, each using ridge and pot planting systems. The high tunnel increased the maximal air temperature on average by 7.2 °C compared to the hail net. For all three cultivars, harvest began 6 to 18 days earlier under the high tunnel than under the hail net; however, lower yields and individual phenolics contents were obtained for the fruit. In ‘Aurora’ and ‘Brigitta’, environmental conditions under the high tunnel also reduced plant volume and fruit sugar/organic acid ratio. Growing blueberry plants in 60 L pots had no negative effects on plant volume and fruit ripening time, yield, firmness, color, and chemical composition. This study represents the first to compare highbush blueberry grown under the high tunnel and hail net protective environments using ridge and pot planting systems across three different cultivars. Here, we can conclude that optimal highbush blueberry production of ‘Duke’, ‘Aurora’, and ‘Brigitta’ under the climate conditions of the study provides earlier ripening times under the high tunnel. However, according to fruit yield and quality, all three cultivars benefit from the hail net over the high tunnel, while ‘Duke’ and ‘Brigitta’ also benefit in particular from the hail net combined with growth in pots.

Phenolic profiles and their responses to pre- and post-harvest factors in small fruits: a review

The consumption of small fruits has increased in recent years. Besides their appealing flavor, the commercial success of small fruits has been partially attributed to their high contents of phenolic compounds with multiple health benefits. The phenolic profiles and contents in small fruits vary based on the genetic background, climate, growing conditions, and post-harvest handling techniques. In this review, we critically compare the profiles and contents of phenolics such as anthocyanins, flavonols, flavan-3-ols, and phenolic acids that have been reported in bilberries, blackberries, blueberries, cranberries, black and red currants, raspberries, and strawberries during fruit development and post-harvest storage. This review offers researchers and breeders a general guideline for the improvement of phenolic composition in small fruits while considering the critical factors that affect berry phenolics from cultivation to harvest and to final consumption.

Characterization and Quantification of Nonanthocyanin Phenolic Compounds in White and Blue Bilberry (Vaccinium myrtillus) Juices and Wines Using UHPLC-DAD-ESI-QTOF-MS and UHPLC-DAD

The nonanthocyanin phenolic compounds in juice and wine produced from fruits of white bilberry, a nonpigmented mutant of Vaccinium myrtillus, and blue bilberry (pigmented variety) were analyzed using liquid chromatography with a diode array detector (LC-DAD) and LC-DAD-electrospray ionization-quadrapole/time of flight hybrid mass spectrometry (ESI-QTOF-MS). On the basis of elution order, UV-vis spectra, accurate mass data, and fragmentation pattern and standards, 42 compounds including 22 phenolic acids, 15 flavonols, and 5 flavan-3-ols, were identified in juices and wines prepared from the two bilberry varieties. The levels of most individual nonanthocyanin phenolic compounds in white bilberry products were significantly lower than those in pigmented ones. In bilberry juices, phenolic acids were the most predominant, accounting for approximately 80% of total phenolic content, with p-coumaroyl monotropeins and caffeic acid hexoside being the major phenolic acids. After fermentation, the total contents of phenolic acids, flavonols, and nonanthocyanin phenolic compounds significantly increased, while the content of total flavan-3-ols decreased significantly. p-Coumaroyl monotropeins still dominated in the wine products, while caffeic acid content showed dramatic elevation with the significant drop of caffeic acid hexoside.

Development of new bilberry (Vaccinium myrtillus L.) based snacks: Nutritional, chemical and bioactive features

The sustainable exploitation of fruit and cereal processing is being conducted to produce novel food products with promising nutritional properties and high content in added value compounds. Herein, three bilberry fruit-based snacks supplemented with edible petals and fruits were characterized for their nutritional properties and chemical composition. The phenolic profile, antioxidant, antibacterial and hepatotoxic properties were analyzed. Protein (3-4 g/100 g dw) and carbohydrates (94.3-94.8 g/100 g dw) represented the major macronutrients. The combination of bilberry fruits with edible petals, calendula and rose, improved the nutritional and phytochemical input in organic acids and tocopherols content, respectively. Also, the supplementation with apple and goji fruits provided higher content in phenolic acids and anthocyanins (up to a 9-fold higher concentration, 199.7 µg/g of extract), also resulting in a higher antioxidant and antibacterial activities. The results obtained can contribute for the development of novel sustainable and healthier snacks for the food industry.

Polyphenols as Possible Agents for Pancreatic Diseases

Pancreatic cancer (PC) is very aggressive and it is estimated that it kills nearly 50% of patients within the first six months. The lack of symptoms specific to this disease prevents early diagnosis and treatment. Today, gemcitabine alone or in combination with other cytostatic agents such as cisplatin (Cis), 5-fluorouracil (5-FU), irinotecan, capecitabine, or oxaliplatin (Oxa) is used in conventional therapy. Outgoing literature provides data on the use of polyphenols, biologically active compounds, in the treatment of pancreatic cancer and the prevention of acute pancreatitis. Therefore, the first part of this review gives a brief overview of the state of pancreatic disease as well as the procedures for its treatment. The second part provides a detailed overview of the research regarding the anticancer effects of both pure polyphenols and their plant extracts. The results regarding the antiproliferative, antimetastatic, as well as inhibitory effects of polyphenols against PC cell lines as well as the prevention of acute pancreatitis are presented in detail. Finally, particular emphasis is given to the polyphenolic profiles of apples, berries, cherries, sour cherries, and grapes, given the fact that these fruits are rich in polyphenols and anthocyanins. Polyphenolic profiles, the content of individual polyphenols, and their relationships are discussed. Based on this, significant data can be obtained regarding the amount of fruit that should be consumed daily to achieve a therapeutic effect.

The Influence of Local Habitat and Microclimate on the Levels of Secondary Metabolites in Slovak Bilberry (Vaccinium myrtillus L.) Fruits

The berries of Vaccinium myrtillus L. are usually collected in the wild for the purpose of being a food source. They are naturally high in phenolic compounds, which possess antioxidative properties, so the berries are therefore often labeled as “functional foods”. This study evaluated seven samples of bilberry fruits from different locations in Slovakia for the content of the main phenolic compounds (anthocyanins, flavonoids and tannins) using European Pharmacopoeia 9 spectrophotometric methods. A thorough analysis of environmental factors showed that several phenolic constituents are closely corresponding with their respective environments, as well as with each other. The environmental factors with statistically significant correlations in this study are altitude, habitat type, sunlight exposure, and soil carbon content. Our findings suggest that the berries collected at sunny sites with no topsoil damage contain more phenolic compounds. The lowest amounts of phenolic compounds were found in samples from dense forests or with visible soil erosion and windthrow damage. The negative effect of windthrow damage on the levels of secondary metabolites in bilberry fruits has been described for the first time. This study observed no relationship between the amount of phenolic compounds and soil pH, soil nitrogen levels, or slope exposition.

Vaccinium myrtillus L. Fruits as a Novel Source of Phenolic Compounds with Health Benefits and Industrial Applications - A Review

Consumers' demand for healthier foods with functional properties has had a clear influence on the food industry and in this sense, they have been attaching natural sources of bioactive ingredients into food products. Vaccinium myrtillus L. (bilberry) is known to be a functional food, presenting its fruits in the form of a small dark blueberry. This coloration is due to its high content in anthocyanin, being also associated with bilberries' beneficial health effects. In the bilberry industry, there is a very high annual loss of this fruit due to the less aesthetic shape or appearance, in which they cannot be considered suitable for sale and are therefore disposed of as biological waste. Therefore, it is of great importance to valorize this fruit and this review aimed to completely characterize the fruits of V. myrtillus in order to comprehend the relationship between their consumption and the beneficial effects regarding consumer's health. Thus, this review provides a description of the nutritional and bioactive compounds present in bilberry fruits, followed by their beneficial health effects. An overview of the natural pigments present in these fruits was also explored, focusing particularly in the anthocyanins composition, which represents the most widely studied class of bioactive compounds of V. myrtillus fruits. Finally, industrial applications of these fruits and by-products, as an efficient approach to the production of value-added products with economical and environmental impact, were also discussed. In general, V. myrtillus is a rich source of micronutrients and phytochemical compounds, such as organic acids, sugars, vitamins, fibers and phenolic compounds (anthocyanin and non-anthocyanin compounds), with nutritional and functional properties, that justify the growing interest in these berries, not only for food applications, but also in the pharmaceutical industry.

Are Processed Bilberry Products a Good Source of Phenolics?

Bilberries are processed into different food products and beverages. Therefore, we studied how various bilberry items (puree, infusion, liqueur, and fresh and pasteurized juices) differ in secondary metabolites as compared to the fresh fruit. For this purpose, we identified phenolics with a liquid chromatography-mass spectrophotometry (LC-MS) system and compared phenolic profiles and phenolic contents in various bilberry products prepared from the same raw material. Our results show that processing significantly affected the biochemical pattern and levels of phenolics. Total analyzed phenolics decreased with processing, mostly due to anthocyanins, which had the highest share in phenolic profile of all bilberry-based products. The highest differences among products in flavanol (63.7-fold), followed by flavonol contents (26.3-fold). Fresh fruits had the highest content of total anthocyanins (5,190 mg/100 g dry weight [DW]), followed by puree (2,719 mg/100 g DW), infusion (2,469 mg/100 g DW), and liqueur (1,830 mg/100 g DW), whereas fresh and pasteurized juices had the lowest content of total anthocyanins (921 and 1,099 mg/100 g DW).

PRACTICAL APPLICATION

Although we confirmed the common belief among consumers that the consumption of fresh berries is more beneficial than consuming processed products, this study showed that various bilberry-derived products can also be valuable source of phenolic compounds all year round.

A wild 'albino' bilberry (Vaccinium myrtillus L.) from Slovenia shows three bottlenecks in the anthocyanin pathway and significant differences in the expression of several regulatory genes compared to the common blue berry type

Relative expressions of structural genes and a number of transcription factors of the anthocyanin pathway relevant in Vaccinium species, and related key enzyme activities were compared with the composition and content of metabolites in skins of ripe fruits of wild albino and blue bilberry (Vaccinium myrtillus) found in Slovenia. Compared to the common blue type, the albino variant had a 151-fold lower total anthocyanin and a 7-fold lower total phenolic content in their berry skin, which correlated with lower gene expression of flavonoid 3-O-glycosyltransferase (FGT; 33-fold), flavanone 3-hydroxylase (FHT; 18-fold), anthocyanidin synthase (ANS; 11-fold), chalcone synthase (CHS, 7.6-fold) and MYBPA1 transcription factor (22-fold). The expression of chalcone isomerase (CHI), dihydroflavonol 4-reductase (DFR), leucoanthocyanidin reductase (LAR), anthocyanidin reductase (ANR) and MYBC2 transcription factor was reduced only by a factor of 1.5-2 in the albino berry skins, while MYBR3 and flavonoid 3',5'-hydroxylase (F3'5'H) were increased to a similar extent. Expression of the SQUAMOSA class transcription factor TDR4, in contrast, was independent of the color type and does therefore not seem to be correlated with anthocyanin formation in this variant. At the level of enzymes, significantly lower FHT and DFR activities, but not of phenylalanine ammonia-lyase (PAL) and CHS/CHI, were observed in the fruit skins of albino bilberries. A strong increase in relative hydroxycinnamic acid derivative concentrations indicates the presence of an additional bottleneck in the general phenylpropanoid pathway at a so far unknown step between PAL and CHS.

Polyphenol metabolism in differently colored cultivars of red currant (Ribes rubrum L.) through fruit ripening

Rare red currants colors caused by low anthocyanin content in the pink and a lack of anthocyanins in the white cultivar correlated with low ANS gene expression, enzyme activity, and increased sugar/acid ratios. Changes in the contents of polyphenols, sugars, and organic acids in berries of the three differently colored Ribes rubrum L. cultivars ('Jonkheer van Tets', 'Pink Champagne', and 'Zitavia') were determined by LC-MS and HPLC at 4 sampling times during the last month of fruit ripening. The activities of the main flavonoid enzymes, chalcone synthase/chalcone isomerase (CHS/CHI), flavanone 3-hydroxylase (FHT), and dihydroflavonol 4-reductase (DFR), and the expression of anthocyanidin synthase (ANS) were additionally measured. Despite many attempts, activities of flavonol synthase and glycosyltransferase did not show reliable results, the reason of which they could not be demonstrated in this study. The pink fruited cultivar 'Pink Champagne' showed generally lower enzyme activity than the red cultivar 'Jonkheer van Tets'. The white cultivar 'Zitavia' showed very low CHS/CHI activity and ANS expression and no FHT and DFR activities were detected. The DFR of R. rubrum L. clearly preferred dihydromyricetin as substrate although no 3',4',5'-hydroxylated anthocyanins were present. The anthocyanin content of the red cultivar slightly increased during the last three weeks of ripening and reached a maximum of 890 mg kg^-1 FW. Contrary to this, the pink cultivar showed low accumulation of anthocyanins; however, in the last three weeks of ripening, their content increased from 14 to 105 mg kg^-1 FW. Simultaneously, the content of polyphenols slightly decreased in all 3 cultivars, while the sugar/acid ratio increased. The white cultivar had no anthocyanins, but the sugar/acid ratios were the highest. In the white and pink cultivars, reduction/lack of anthocyanins was mainly compensated by increased relative concentrations of hydroxycinnamic acids and flavonols.

Proanthocyanidins and hydrolysable tannins: occurrence, dietary intake and pharmacological effects

Tannins are a heterogeneous group of high MW, water-soluble, polyphenolic compounds, naturally present in cereals, leguminous seeds and, predominantly, in many fruits and vegetables, where they provide protection against a wide range of biotic and abiotic stressors. Tannins exert several pharmacological effects, including antioxidant and free radical scavenging activity as well as antimicrobial, anti-cancer, anti-nutritional and cardio-protective properties. They also seem to exert beneficial effects on metabolic disorders and prevent the onset of several oxidative stress-related diseases. Although the bioavailability and pharmacokinetic data for these phytochemicals are still sparse, gut absorption of these compounds seems to be inversely correlated with the degree of polymerization. Further studies are mandatory to better clarify how these molecules and their metabolites are able to cross the intestinal barrier in order to exert their biological properties. This review summarizes the current literature on tannins, focusing on the main, recently proposed mechanisms of action that underlie their pharmacological and disease-prevention properties, as well as their bioavailability, safety and toxicology.

LINKED ARTICLES

This article is part of a themed section on Principles of Pharmacological Research of Nutraceuticals. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.11/issuetoc.