Effect of grape ( Vitis vinifera L.) varieties and harvest periods on bioactive compounds, antioxidant activity, phenolic composition, mineral contents, and fatty acid compositions of Vitis leave and oils

Evolution of Leaf Chlorophylls, Carotenoids and Phenolic Compounds during Vegetation of Some Croatian Indigenous Red and White Grape Cultivars

During the ripening process of grapes, the grapevine leaves are the most active green organs that are important for photosynthesis, which is closely linked to the development and metabolism of the plant. The detection of plant pigments and phenolic compounds in grapevine leaves can be a good indicator of the ageing process, vine vigor and the plant's ability to respond to fungal attack. In a one-year study, the development of leaf chlorophylls, carotenoids and phenolic compounds during the ripening of six indigenous Croatian grape cultivars and the international cultivars Merlot and Chardonnay was investigated. The chlorophyll a/b ratio and total chlorophyll and total carotenoid concentrations were also investigated. PCA was used to highlight relevant information from the data with the aim of distinguishing individual compounds based on the cultivar and phenological stage. The leaf total hydroxycinnamic acid and flavan-3-ol concentrations decreased slowly during grape development, with the highest concentration immediately after flowering and the lowest during grape ripening. The concentrations of β-carotene, lutein and xanthophylls tended to decrease during bunch closure or veraison, while the concentration of chlorophylls a and b peaked during veraison and then decreased during grape ripening. This research will provide an opportunity to select cultivars with the physiological adaptation to synthesize secondary metabolites that are important for managing stress conditions.

Valorization of grape (Vitis vinifera) leaves for bioactive compounds: novel green extraction technologies and food-pharma applications

Grape leaves, scientifically known as Vitis vinifera, the primary by-product obtained after the processing of grapes, are gathered in enormous amounts and disposed of as agricultural waste. For more sustainable agriculture and better food systems, it is crucial to investigate these byproducts' nutritional values. The primary bioactive compounds present in grape leaves are quercetin, resveratrol, caffeic acid, kaempferol, and gallic acid, which favour pharmacological effects on human health such as antioxidant, anti-inflammatory, anti-obesity, anti-diabetic, and hepatoprotective. Furthermore, grape leaves extract has been used as a functional ingredient for creating both food and non-food products. The aim of the current review is to review the nutritional and phytochemical composition of various varieties of grape leaves, their health-promoting characteristics and their applications. The study also highlights the various extraction techniques including conventional and non-conventional methods for extracting the various bioactive compounds present in grape leaves. Grape leaves bioactives can be extracted using environmentally safe and sustainable processes, which are in line with the rising demand for eco-friendly and healthful products worldwide. These methods are perfectly suited to the changing needs of both customers and industries since they lessen environmental effect, enhance product quality, and offer financial advantages.

Hydroponic Cultivation of Vine Leaves with Reduced Carbon Footprint in a Mediterranean Greenhouse

Vine leaves are considered a delicacy food however they are only produced as a byproduct for a short harvest period due to grape cultivation practices and numerous chemical applications. In this work, vine plants were cultivated hydroponically in a greenhouse, to extend the cultivation period and along with high plant density, maximize fresh leaves yield. Four different substrates were tested—Perlite, Perlite-Attapulgite, Perlite-Zeolite, 1.7Perlite-higher density planting—with soil treatment as a control, and the experimental cultivation lasted a total of about seven months in the year 2021. Quantitative and qualitative characteristics such as leaves number and weight, color of leaves, nitrates, photosynthetic parameters, total phenols, and plant nutrient concentrations were assessed, while the product’s environmental impact was calculated. The 1.7Perlite treatment produced a 1.6–2.0 times higher number of leaves per hectare than the other hydroponic treatments and 8.7 times higher than the soil treatment, while no statistically significant differences were found regarding qualitative characteristics. Consequently, the 1.7P treatment resulted in a 1.4 to 7.6 times lower product carbon footprint compared to the other treatments. In future research, substrates water and nutrient retention will be further studied along with year-round production in a heated greenhouse with full climate control so that plants are kept evergreen.

Bacterial Endophytes from Vitis vinifera L. - Metabolomics Characterization of Plant-Endophyte Crosstalk

Bacterial endophytes are known to protect Vitis vinifera L. against various harmful effects of the environment and support its growth. However, for the most part, biochemical responses of such co-existence have not yet been fully elucidated. In this work, we aimed to characterize the activities of endophytic consortia in a plant-endophyte extract by measuring five indicators of colonization (overall endophyte metabolic activity, microbial ACC deaminase activity, ability to solubilize phosphorus, ability to convert atmospheric nitrogen to ammonia ions, and ability to produce growth promoting indole acetic acid), and find relationships between these activities and metabolome. The V. vinifera canes for the metabolomics fingerprinting were extracted successively with water and methanol, and analysed by ultra-high performance liquid chromatography coupled with high resolution mass spectrometry. For data processing, the MS-DIAL - MS-CleanR - MS-FINDER software platform was used, and the data matrix was processed by PCA and PLS-DA multivariate statistical methods. The metabolites that were upregulated with the heavy endophyte colonization were mainly chlorins, phenolics, flavonoid and terpenoid glycosides, tannins, dihydropyranones, sesquiterpene lactones, and long-chain unsaturated fatty acids.

Metabolomic fingerprinting as a tool for authentication of grapevine (Vitis vinifera L.) biomass used in food production

Use of 'green biomass' of the grapevine is gradually extending into the food industry. The aim of our study was to demonstrate the potential of metabolomic fingerprinting for characterization of grapevine leaves and canes. Our method comprises successive aqueous-methanolic extractions, followed by U-HPLC-HRMS/MS. For data processing, PCA and (O)PLS-DA methods were utilized, and mathematical models were validated. We showed that from all factors investigated, harvesting season explained most of the variability between samples, followed by locality combined with farming system. The identified statistically significant metabolites for harvesting season models mostly represented the groups of fatty acids, fatty phenols, (lyso)phospholipids, flavonoids and organic acids. For models of localities with different farming systems, majority of identified metabolites significant for organic farming belonged to groups of fatty acids and their derivatives, terpenoids, sterols, and fat soluble vitamins, whereas for conventional farming, the only identified significant metabolites were the pesticide residues.