Surface wax composition of wild and cultivated Northern berries

L. Klavins*, J. Kviesis and M. Klavins

Laboratory of Natural Products Research, University of Latvia, Jelgavas street 1, LV-1004 Riga, Latvia
*Correspondence: linards.klavins@lu.lv

Abstract:

Surface wax of plants is the outer layer, which protects the plant from dehydration, extreme temperatures, UV radiation and changes in the environment, as well as attacks from moulds and bacteria. Studies of berry surface wax are of importance to understand metabolism character (factors affecting wax layer composition in different berry species) as well as to increase the shelf life of berries and increase the microbial resistance. The aim of this study was analysis of surface wax composition of commercially grown 8 blueberry (Vaccinium corymbosum) varieties, wild bilberry (Vaccinium myrtillus L.) and bog bilberry (Vaccinium uliginosum L.). More than 80 different compounds were identified and quantified belonging to 9 groups of compounds, namely, alkanes, phytosterols, alcohols, fatty acids, phenolic acids, ketones, aldehydes, esters and tocopherols. Significant differences were found between blueberry (Vaccinium corymbosum) and bog bilberry (Vaccinium uliginosum L.) surface wax composition. Amongst studied berries differences were found in concentrations of triterpenes (up to 62% in blueberries), and fatty acids (up to 26% in bilberries) identifying species related differences influencing associated functional properties of berry wax (antimicrobial activity, stress caused by environmental changes). Blueberry variety ‘Polaris’ had the highest amount of ursolic acid (9.30 g 100 g^-1), alpha-amyrin (11.07 g 100 g^-1) and lupeol (10.2 g 100 g^-1). Research on berry surface wax composition could help reduce loss of commercially produced berries due to environmental impacts or microbial attacks, prolonging shelf life and overall quality of fruits and vegetables post-harvest.

Key words:

bilberry, blueberry, bog bilberry, chemical composition, cuticle, cuticular, lipids, surface wax

Gas chromatography–mass spectrometry study of lipids in northern berries

L. Klavins, J. Kviesis, I. Steinberga, L. Klavina and M. Klavins*

University of Latvia, Raina blvd. 19, Riga, LV-1586, Latvia
*Correspondence: maris.klavins@lu.lv

Abstract:

Wild berries from forests and bogs of Northern Europe are an excellent source of natural antioxidants, vitamins and fatty acids, all of which are substances with high biological activity. This study investigates lipids extracted from fresh and powdered berries, using low-polarity solvents (chloroform, diethyl ether and others) and a mixture of chloroform and methanol. Berry lipids were analysed by gas chromatography–mass spectrometry. The following berries were analysed: blueberry (Vaccinium myrtillus L.), bilberry (Vaccinium uliginosum L.), two cultivars of highbush blueberry (Vaccinium corymbosum L.), lingonberry (Vaccinium vitis-idaea L.), cloudberry (Rubus chamaemorus L.), black crowberry (Empetrum nigrum L.), cranberry (Vaccinium oxycoccos L.) and rowanberry (Sorbus aucuparia L.). One hundred and elevencompounds were identified and quantified in the 9 species of analysed berries. The lipid fraction contained compound classes like fatty acids, sterols, triterpenoids, alkanes, phenolic and carboxylic acids and carotenoids. All fresh berries contained high amounts of C18 unsaturated fatty acids (for example, up to 102 μg g^-1 of blueberries) and phytosterols (86 μg of β-sitosterol g^-1 of blueberries), and high amounts of benzoic acid were found in lingonberries (164 μg g^-1). The analysed berry lipid profiles were compared using the principal component analysis and hierarchical cluster analysis. The two analyses showed that the lipid profiles of the studied berries reflect their taxonomy.

Key words: