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Author

Linards Klavins

Bio: Linards Klavins is an academic researcher from University of Latvia. The author has contributed to research in topics: Vaccinium & Vaccinium myrtillus. The author has an hindex of 4, co-authored 17 publications receiving 88 citations.
Topics: Vaccinium, Vaccinium myrtillus, Wax, Bilberry, Berry

Papers
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Journal ArticleDOI
TL;DR: In this paper, the composition and morphology of cuticular waxes of northern wild berry species bilberry (Vaccinium myrtillus L.), lingonberry and crowberry (Empetrum nigrum L.) were investigated.

38 citations

Journal ArticleDOI
TL;DR: In this article, the authors used the response surface method to optimise the method of extraction of polyphenols (anthocyanins specifically) from berry press residues of American cranberry.
Abstract: Vaccinium genus berries (bilberries, blueberries, lingonberries, cranberries) are gathered in the wild as well as cultivated on an industrial scale for use in the food industry. Extraction of juices from these berries produces press residues (pomace) as a waste product. Berry press residues are an excellent source of phenolic compounds and have a potential of use as a polyphenol-rich material. The aim of the present study was to optimise the method of extraction of polyphenols (anthocyanins specifically) from berry press residues of American cranberry using the response surface method and to validate the optimal polyphenol/anthocyanin extraction conditions also for other Vaccinium berries and their press residues. Comparison of whole berry and berry press residue extracts helps to determine the potential berry source materials for further processing and production of products with high antioxidant levels. The composition of anthocyanins was determined in five different berry species of the Vaccinium genus (whole berries and press residues), the results were obtained using the optimised extraction conditions, and the analysis was done by UPLC and LC-TOF/MS.

37 citations

Journal ArticleDOI
05 May 2020-Foods
TL;DR: The analyzed blueberries had the highest amount of wax present on their surface, triterpenoids were the main wax constituent in these berries, with up to 62% wax composition, however, other berries showed differences based on concentration and composition of cuticular wax.
Abstract: The outer-most layer of plant surface, the cuticle, consists of epi- and intra-cuticular wax. It protects the plant from dehydration, extreme temperatures and UV radiation, as well as attacks from pests such as molds and bacteria. Berry cuticular waxes are studied to understand the metabolism character (factors affecting wax layer composition in different berry species) and increase the microbial resistance and shelf life of berries. The aim of this study was analysis of the surface wax composition of nine species of wild and cultivated berries from Northern Europe. Cuticular wax analysis were done using gas chromatography-mass spectrometry. A total of 59 different compounds were identified belonging to nine groups of compounds, namely, alkanes, phytosterols, alcohols, fatty acids, phenolic acids, ketones, aldehydes, esters and tocopherols. The analyzed blueberries had the highest amount of wax present on their surface (0.9 mg berry−1), triterpenoids were the main wax constituent in these berries, with up to 62% wax composition. Berry species and varieties were compared based on their surface wax composition—similarities were found between different blueberry varieties; however, other berries showed differences based on concentration and composition of cuticular wax.

18 citations

Journal ArticleDOI
TL;DR: An overview of the development and application of analytical chemistry methods, such as isotope ratio analysis, liquid and gas chromatography, spectroscopy, as well as DNA-based methods and electronic sensors, for the authentication of berries and berry-based food products is provided in this paper.
Abstract: Berries represent one of the most important and high-valued group of modern-day health-beneficial "superfoods" whose dietary consumption has been recognized to be beneficial for human health for a long time. In addition to being delicious, berries are rich in nutrients, vitamins, and several bioactive compounds, including carotenoids, flavonoids, phenolic acids, and hydrolysable tannins. However, due to their high value, berries and berry-based products are often subject to fraudulent adulteration, commonly for economical gain, but also unintentionally due to misidentification of species. Deliberate adulteration often comprises the substitution of high-value berries with lower value counterparts and mislabeling of product contents. As adulteration is deceptive toward customers and presents a risk for public health, food authentication through different methods is applied as a countermeasure. Although many authentication methods have been developed in terms of fast, sensitive, reliable, and low-cost analysis and have been applied in the authentication of a myriad of food products and species, their application on berries and berry-based products is still limited. The present review provides an overview of the development and application of analytical chemistry methods, such as isotope ratio analysis, liquid and gas chromatography, spectroscopy, as well as DNA-based methods and electronic sensors, for the authentication of berries and berry-based food products. We provide an overview of the earlier use and recent advances of these methods, as well as discuss the advances and drawbacks related to their application.

17 citations

Journal ArticleDOI
TL;DR: In this paper , the authors evaluated the variability in the biologically active compounds, antioxidant capacity and physico-chemical properties, as well as the development of tools for the authenticity and quality control of wild bilberries in different geographical locations.
Abstract: The aim of this study was to characterize the variation in biologically active compounds, antioxidant activity and physico-chemical properties in naturally grown bilberries gathered from different sites in Northern Europe. The variability in the biologically active compounds, antioxidant capacity and physico-chemical properties, as well as the development of tools for the authenticity and quality control of wild bilberries (V. myrtillus L.) in different geographical locations was evaluated. The berries of bilberries were handpicked during the summers of 2019 and 2020 during the time periods when they are typically harvested for commercial purposes in Northern Europe (Norway (NOR), Finland (FIN), Latvia (LVA) and Lithuania (LTU)). Berries from locations in NOR were distinguished by their higher mean TPC (791 mg/100 g FW, average), whereas the mean TPC of samples from the most southern country, LTU, was the lowest (587 mg/100 g FW). The TPC of bilberries ranged from 452 to 902 mg/100 g FW. The TAC values of investigated bilberry samples varied from 233 to 476 mg/100 g FW. A high positive correlation was found between TPC and antioxidant activity of the bilberry samples (R = 0.88 and 0.91 (FRAP and ABTS assays, respectively)), whereas the correlation between TAC and antioxidant activity was lower (R = 0.65 and 0.60). There were variations in the TPC and TAC values of investigated berries, suggesting that genotype also affects the TPC and TAC in berries. In 2020, the pH values and TSS contents of berries were significantly lower than in 2019. To the best of our knowledge, this is the first comprehensive reported evaluation of the biologically active compounds in wild bilberries from different Northern European countries using one laboratory-validated method.

16 citations


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Journal ArticleDOI
TL;DR: The major focus of this review is to provide comprehensive information on valorisation of agri-food wastes and by-products with focus laid on bioactive compounds and bioactivity.
Abstract: Sustainable utilization of agri-food wastes and by-products for producing value-added products (for cosmetic, pharmaceutical or food industrial applications) provides an opportunity for earning additional income for the dependent industrial sector. Besides, effective valorisation of wastes/by-products can efficiently help in reducing environmental stress by decreasing unwarranted pollution. The major focus of this review is to provide comprehensive information on valorisation of agri-food wastes and by-products with focus laid on bioactive compounds and bioactivity. The review covers the bioactives identified from wastes and by-products of plants (fruits, exotic fruits, vegetables and seeds), animals (dairy and meat) and marine (fish, shellfish seaweeds) resources. Further, insights on the present status and future challenges of sustainably utilizing agri-food wastes/by-products for value addition will be highlighted.

200 citations

Journal Article
TL;DR: In this article, the authors investigated the composition and the antioxidative activities of oils from the seeds and the soft parts of a range of northern berries extracted by supercritical CO 2.
Abstract: The present study investigated the composition and the antioxidative activities of oils from the seeds and the soft parts of a range of northern berries extracted by supercritical CO 2 . The seed oils of the species of Rubus , Vaccinium , Empetrum , Fragaria and Hippophae were rich in linoleic (18:2n-6, 34–55% of total fatty acids) and α-linolenic (18:3n-3, 29–45% of total) acids with n-6:n-3 ratios of 1:1–1:2. The seed oils of the species Ribes contained, in addition to linoleic and α-linolenic acids, γ-linolenic (18:3n-6) and stearidonic (18:3n-4) acids. In seed oils from European rowanberry ( Sorbus aucuparia L.) and snowball berry ( Viburnum opulus L.), linoleic and oleic (18:1n-9) acids together exceeded 90% of the total fatty acids. The sea buckthorn (SB) pulp oil had palmitoleic (16:1n-7), palmitic (16:0) and oleic acids as the major fatty acids. The SB pulp oil and snowball berry seed oil were rich in α-tocopherol (120 and 110 mg/100 g oil, respectively), whereas raspberry seed oil contained a high level of γ-tocopherol (320 mg/100 g oil). Seed oils of cranberry (180 mg/100 g oil), Arctic cranberry (190 mg/100 g oil) and lingonberry (120 mg/100 g oil) are rich sources of γ-tocotrienol. The berry seed oils and the SB pulp oil showed varying peroxyl radical scavenging efficacies (300–2300 μmol α-tocopherol equivalent per 100 g oil) and inhibitory effects on perioxidation of microsomal lipids (250–1200 μmol trolox equivalent per 100 g oil) in vitro. The peroxyl radical scavenging activity positively correlated with the total content of tocopherols and tocotrienols of the oils ( r = 0.875, P = 0.001). The SB seed oil and pulp oil were active in scavenging superoxide anions produced by xanthine–xanthine oxidase system and inhibited Cu 2+ -induced LDL oxidation in vitro. The SB oils also protected purified DNA and rat liver homogenate from UV-induced DNA oxidation in vitro. The current research suggests potential of supercritical CO 2 -extracted oils from northern berries as nutraceuticals and ingredients of functional foods.

104 citations

Journal ArticleDOI
TL;DR: European cranberry, Vaccinium oxycoccos fruit, is a valuable source of antioxidants and other biologically active substances, similar to American cranberry (V. macrocarpon) which is well known and studied.
Abstract: Lesser known fruits or underutilized fruit species are recently of great research interest due to the presence of phytochemicals that manifest many biological effects. European cranberry, Vaccinium oxycoccos fruit, as an important representative of this group, is a valuable source of antioxidants and other biologically active substances, similar to American cranberry (V. macrocarpon) which is well known and studied. European cranberry fruit is rich especially in polyphenolic compounds anthocyanins (12.4–207.3 mg/100 g fw), proanthocyanins (1.5–5.3 mg/100 g fw), and flavonols, especially quercetin (0.52–15.4 mg/100 g fw), which mostly contribute to the antioxidant activity of the fruit. Small cranberry is also important due to its various biological effects such as urinary tract protection (proanthocyanidins), antibacterial and antifungal properties (quercetin, proanthocyanidins, anthocyanins), cardioprotective (proanthocyanidins) and anticancer activities (proanthocyanidins), and utilization in food (juice drinks, jams, jellies, sauces, additive to meat products) and pharmacological industries, and in folk medicine.

92 citations

Journal ArticleDOI
TL;DR: Findings indicate that USAE is a method of choice for extracting high-value bioactive phenolics from blueberry pomace and selective enrichment of different phenolic fractions is possible under select extraction conditions.
Abstract: The increase in diet-related chronic diseases has prompted the search for health-promoting compounds and methods to ensure their quality. Blueberry pomace is a rich yet underutilized source of bioactive polyphenols. For these high-value bioactive molecules, ultrasound-assisted extraction (USAE) is an attractive and green alternative to conventional extraction techniques for improving purity and yields. This study aimed to assess the impact of USAE parameters (sonication time, solvent composition, solid/liquid ratio, pH and temperature) on the recovery of phenolic compounds from blueberry pomace and antioxidant activity of the extracts. Total phenolic, flavonoid and anthocyanin contents (TPC, TFC and TAC) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging activity were analysed. USAE in 50% ethanol/water was the most efficient, yielding the highest TPC (22.33 mg/g dry matter (DM)), TFC (19.41 mg/g DM), TAC (31.32 mg/g DM) and DPPH radical scavenging activity (41.79 mg Trolox/g DM). USAE in water showed the lowest values even at low (1/40) solid/liquid ratio (7.85 mg/g DM, 3.49 mg/g DM, and 18.96 mg/g DM for TPC, TFC and TAC, respectively). Decreasing the solid/liquid ratio in water or 50% ethanol significantly increased TPC, TFC, TAC and DPPH radical scavenging. With ethanol, increasing the temperature in the range 20–40 °C decreased TPC but increased TFC and DPPH radical scavenging activity. Anthocyanin profiles of water and ethanolic extracts were qualitatively similar, consisting of malvidin, delphinidin, petunidin and cyanidin. These findings indicate that USAE is a method of choice for extracting high-value bioactive phenolics from blueberry pomace. Selective enrichment of different phenolic fractions is possible under select extraction conditions.

62 citations

Journal ArticleDOI
TL;DR: Fruits are good resources of anti-di diabetic nutrients and a balanced diet rich in different fruits is recommended for diabetic patients and the pre-diabetic population.
Abstract: Background Diabetes mellitus (DM), a chronic disease characterized by hyperglycemia, is an increasing global health problem which is associated with various chronic diseases such as hypertension, hyperlipidemia and cardiovascular diseases. Despite traditional insulin therapy, nutrients and nutritional factors are also known to play a significant role in the control and treatment of DM. Scope and approach This comprehensive review focuses on recent advances in knowledge and understanding of the anti-diabetic effects of fruit consumption. Particular attention will be paid to natural antioxidants found in different fruits that may have anti-diabetic effects in human. Key findings and conclusions Oxidative stress is an important cause and therapeutic target of DM. Plant-based food such as fruits are rich sources of natural antioxidants. Various epidemiological studies, clinical studies, in vivo and in vitro studies showed that fruits with different phytochemical profiles have the ability to lower blood glucose to normal levels. Bioactive compounds identified to have anti-diabetic activities include phenolic compounds, polysaccharides, vitamin C, and most of them have antioxidant activity or can induce antioxidant systems in different experimental models. Therefore, fruits are good resources of anti-diabetic nutrients and a balanced diet rich in different fruits is recommended for diabetic patients and the pre-diabetic population.

51 citations