Cuticle: The outermost layer, composed mainly of cutin, waxes, and other lipids, provides a protective barrier against environmental stressors and pathogens.

Epidermis: Beneath the cuticle, the epidermis contains cells that store anthocyanins, which are responsible for the red, blue, or purple pigmentation in grape skins. These pigments are crucial for grape-derived products' visual appeal and antioxidant properties.

Hypodermis and Mesocarp: These layers are rich in parenchyma cells and contain significant amounts of polysaccharides, particularly pectins, and cellulose, which contribute to the texture and structural integrity of the grape skin 11.

Polyphenols: Grape skins are a rich source of polyphenolic compounds, including flavonoids (anthocyanins, flavonols, flavan-3-ols) and non-flavonoids (phenolic acids, stilbenes). These compounds exhibit potent antioxidant, anti-inflammatory, and antimicrobial properties 12.

Tannins: Present in significant amounts, tannins contribute to the astringency and mouthfeel of wines. They interact with proteins and polysaccharides during the winemaking process, affecting the stability and aging potential of wine.

Aromatic Compounds: Grape skins contain various volatile compounds that contribute to the aroma and flavor profile of wines and juices. Terpenes, aldehydes, and esters are among the key aromatic compounds found in grape skins 13.

Dietary Fiber: High in insoluble dietary fiber, grape skins promote digestive health and can be utilized in functional food products to enhance their nutritional value 14.

Seed Coat (Testa): The outermost layer, providing a protective barrier for the seed. It is composed of lignified cells that contribute to the seed's hardness and resistance to environmental stress.

Endosperm: Located beneath the seed coat, the endosperm is a nutritive tissue that surrounds the embryo. It is rich in storage proteins and lipids, which provide essential nutrients for the developing plant.

Embryo: The innermost part of the seed, consisting of the embryonic plant. The embryo contains the cotyledons (seed leaves), radicle (future root), and plumule (future shoot).

Polyphenols: Grape seeds contain high concentrations of polyphenolic compounds, particularly proanthocyanidins, flavonoids, and phenolic acids. These compounds exhibit potent antioxidant, anti-inflammatory, and anticancer properties 15. Proanthocyanidins, also known as condensed tannins, are the most abundant polyphenols in grape seeds and are recognized for their cardiovascular benefits and ability to neutralize free radicals.

Lipids: Grape seed oil, extracted from the seeds, is rich in essential fatty acids, particularly linoleic acid (omega-6) and oleic acid (omega-9). These fatty acids are crucial for maintaining healthy cell membranes and supporting cardiovascular health 16.

Proteins: Grape seeds contain a significant number of proteins, including albumins, globulins, and glutelins. These proteins can be hydrolyzed to produce bioactive peptides with potential health benefits, such as antihypertensive and antioxidant activities 17.

Dietary Fiber: The high fiber content in grape seeds, primarily insoluble fiber, promotes digestive health by enhancing bowel movements and supporting gut microbiota 18.

Rachis: The main axis or central stem of the inflorescence. It supports the lateral branches and is crucial for the transport of nutrients and water to the developing flowers and berries.

Peduncle: The stalk that attaches the inflorescence to the grapevine. It provides structural support and serves as the conduit for nutrient and water flow from the vine to the inflorescence.

Pedicels: The small stalks that connect individual flowers to the rachis or lateral branches. Each flower or berry is attached to the pedicel.

Flowers: Grape flowers are small and typically green. They are arranged in clusters called cymes or panicles, depending on the grape variety. Each flower contains male and female reproductive organs, although some grapevine species may have unisexual flowers 19.

Floral Volatiles: These are aromatic compounds emitted by grape flowers, playing a vital role in attracting pollinators and facilitating fertilization. Common floral volatiles include terpenes, esters, and aldehydes 20.

Hormones: Plant hormones, such as auxins, gibberellins, cytokinins, and ethylene, regulate the growth and development of grape inflorescences. These hormones influence processes like flower initiation, differentiation, and fruit set 21.

Nutrients: Essential nutrients, including nitrogen, phosphorus, potassium, and micronutrients, are critical for the healthy development of inflorescences. These nutrients are transported through the rachis and pedicels to the flowers.

Polyphenols: Like other parts of the grapevine, inflorescences contain polyphenolic compounds that have antioxidant properties and contribute to the defense mechanisms against pathogens and environmental stressors 22.

Solvent Extraction:

Supercritical Fluid Extraction (SFE):

Ultrasound-Assisted Extraction (UAE):

Pressurized Liquid Extraction (PLE):

Microwave-Assisted Extraction (MAE):

Enzyme-Assisted Extraction (EAE):

Key compounds recovered from winemaking by-products 30:

Antioxidant Activity: Grape pomace polyphenols are potent antioxidants that neutralize free radicals and prevent oxidative stress, which is implicated in aging and various chronic diseases. The antioxidant capacity of these polyphenols is attributed to their ability to donate hydrogen atoms and their metal-chelating properties 40.

Anti-inflammatory Effects: Polyphenols in grape pomace have been shown to reduce inflammation by inhibiting the production of pro-inflammatory cytokines and enzymes such as cyclooxygenase (COX) and lipoxygenase (LOX). This anti-inflammatory activity is beneficial in preventing and managing inflammatory conditions such as arthritis and cardiovascular diseases 41.

Antimicrobial Properties: The antimicrobial activity of grape pomace polyphenols is effective against a range of pathogens, including bacteria, fungi, and viruses. These polyphenols disrupt microbial cell membranes, inhibit enzyme activity, and interfere with microbial DNA synthesis, making them useful in food preservation and the development of antimicrobial products 42.

Cardioprotective Effects: Regular consumption of grape pomace polyphenols has been linked to improved cardiovascular health. These polyphenols help reduce blood pressure and decrease LDL cholesterol levels while increasing HDL cholesterol. They also inhibit platelet aggregation, reducing the risk of thrombosis 43.

Anticancer Activity: Grape pomace polyphenols exhibit anticancer properties by inducing apoptosis, inhibiting cell proliferation, and preventing metastasis in various cancer cell lines. They modulate signaling pathways involved in cancer development, such as the PI3K/Akt and MAPK pathways, and enhance the efficacy of conventional chemotherapy 44.

Animal Feed: Grape pomace is often used as a feed supplement for livestock due to its high fiber and nutrient content. It can enhance the nutritional profile of animal diets and improve overall health 45.

Composting and Soil Amendment: When composted, grape pomace serves as an excellent organic fertilizer, enriching soil with essential nutrients and improving soil structure 46.

Extraction of Bioactive Compounds: The polyphenols and antioxidants extracted from grape pomace are used in the food, cosmetic, and pharmaceutical industries. These compounds are valued for their health-promoting properties, including anti-inflammatory, anti-cancer, and cardiovascular benefits 47.

Bioenergy Production: Grape pomace can be used to produce biofuels such as biogas and ethanol through fermentation processes, contributing to sustainable energy solutions 48.

Functional Foods and Beverages: Grape pomace polyphenols are added to functional foods and beverages to enhance their nutritional profile and provide health benefits. These polyphenols improve the antioxidant capacity of the products, contributing to overall health and wellness.

Nutraceuticals and Dietary Supplements: Due to their potent bioactive properties, grape pomace polyphenols are formulated into nutraceuticals and dietary supplements. These products are marketed for their antioxidant, anti-inflammatory, and cardioprotective effects, supporting various aspects of health 49.

Cosmetics and Personal Care Products: The antioxidant and anti-inflammatory properties of grape pomace polyphenols make them valuable ingredients in cosmetics and personal care products. They protect the skin from oxidative damage, reduce inflammation, and promote skin health, making them popular in anti-aging and skincare formulations 50.

Food Preservation: Grape pomace polyphenols are used as natural preservatives in the food industry due to their antimicrobial properties. They extend the shelf life of food products by inhibiting the growth of spoilage microorganisms and pathogens, ensuring food safety and quality 51.

Pharmaceutical Applications: The therapeutic potential of grape pomace polyphenols is explored in the development of pharmaceutical products. Their anticancer, cardioprotective, and anti-inflammatory properties are harnessed to create medications that can prevent and treat various diseases 52.

Waste Reduction: By repurposing grape pomace, the volume of waste generated by the wine industry is significantly reduced, alleviating disposal issues and environmental impact.

Economic Value: The transformation of grape pomace into valuable products can create additional revenue streams for wineries, promoting economic sustainability 53.