The analysis of reports on GP and its components (peel, seeds, stalks) as a natural source of antimicrobial bioactive compounds was conducted using the bibliometric review method as a search strategy and data selection criteria (12). The review was conducted using the Scopus and Web of Science (WoS) databases. These databases were queried on January 27, 2025, and results published between 2021 and 2025 were considered. To ensure a thorough assessment of the literature, not only GP, but also its individual components were included in this bibliometric analysis to identify specific research trends and application patterns.

The data used for this study were extracted with the following descriptors: (i) Scopus: TITLE-ABS-KEY and subject area (Agricultural and Biological Sciences OR Immunology and Microbiology OR Materials Science): (grape AND (peel OR seed OR resid* OR waste OR agroindustrial OR by-product OR pomace)) AND (antimicrobial OR fungici* OR antibacteri* OR antifungi*) AND (polyphenol* OR phenol* OR flavon* OR anthocyanin* OR phenolic*); (ii) WoS: TOPIC and web of science categories (Food Science technology OR Microbiology OR Polymer Science OR Materials Science OR Biothecnology applied microbiology OR Nutrition Dietetics): (grape AND (peel OR seed OR resid* OR waste OR agroindustrial OR by-product OR pomace)) AND (antimicrobial OR fungici* OR antibacteri* OR antifungi*) AND (polyphenol* OR phenol* OR flavon* OR anthocyanin* OR phenolic*).

Then, a review of the title, abstract and keywords was conducted to determine the relevance of the articles to be selected for further analysis. The inclusion criteria were as follows: (i) research articles; (ii) full text in English, either subscription or open access; (iii) scientific articles targeting grape pomace or other grape residues as a natural source of antimicrobials for food preservation; and (iv) studies with data on antimicrobial activity. The exclusion criteria were: (i) review articles, book chapters, theses, dissertations, abstracts, and papers presented in seminars or symposia; (ii) studies on grape pomace or its components that did not include antimicrobial activity data; and (iii) articles on grapes and not on grape pomace or its components. The selected articles that met the inclusion criteria were organized in a spreadsheet program for better data management. A literature review was created considering the previously selected articles (Figure 1).

The keyword search yielded 127 and 99 documents in WoS and Scopus, respectively. After the exclusion of duplicate citations and the outcome of the screening phase, 65 studies were selected to be included in the final analysis and discussion of the results. From 2021 to 2023, the number of articles published on GP and its components as a natural source of antimicrobial bioactive compounds increased (Figure 2A). Most of the selected articles were published in 2023 (n = 21), with a decrease in publications observed in 2024 (n = 13). The years selected for this search resulted in the following number of published articles: 10 articles in 2021, 18 articles in 2022 and 3 articles in 2025.

Several scientific journals have published research articles on GP and its components as a natural source of antimicrobial bioactive compounds (Figure 2B). The scientific journals in which articles were published as part of this review were identified. Antioxidants (n = 6), Microorganisms (n = 3), Food Chemistry (n = 3), Polymers (n = 2), LWT-Food Science and Technology (n = 2), International Journal of Biological Macromolecules (n = 2), Antibiotics (n = 2), Journal of Food Processing and Preservation (n = 2) and Foods (n = 2) are the main journals with more than one publication on this topic in the above mentioned period.

Figure 3 shows the GP and its components used as well as the respective countries in which the studies were carried out. Thirty seven countries have published on them as a natural source of antimicrobial compounds. The concept of single-country publications (SCP) refers to articles authored by researchers from the same country, while multi-country publications (MCP) indicate international collaboration between authors from different countries. This study identified 48 SCP and 17 MCP and showed that Italy (5 SCP and 5 MCP) and Spain (5 SCPs and 5 MCP) have the most publications on this topic. Egypt (4 SCP and 3 MCP), Romania (5 SCP and 1 MCP), Brazil (4 SCP and 1 MCP) and Portugal (2 SCP and 2 MCP) are the other countries that published the most articles on this topic between 2021 and 2025.

The most important grape by-products used in the selected articles are GP (n = 33) and grape seeds (n = 27). The use of GP as a potential antimicrobial agent is expected to improve the utilization of this waste at the local level. This is particularly important considering that the major wine-producing countries such as Italy (5.4 million tons in 2022), Spain (3.6 million tons in 2022) and Portugal (666 thousand tons in 2022) (3) account for 53% (n = 16) of the selected articles with GP between 2021 and 2025. In addition, it is important to utilize the waste in countries such as Brazil, the 14th largest grape producer, with an estimated loss rate of 8.3% and Egypt, the 13th largest producer, with a loss rate of approximately 9% (3).

To accurately evaluate the antimicrobial potential highlighted by this research, standardized methodologies are essential. In this context, the most frequently used methods for determining microbial inhibitory effects in the selected articles are the agar/disk diffusion test (n = 29) and the activity minimum inhibitory concentration (MIC) determination by microdilution technique (n = 23). These tests are useful to confirm microbial inhibitory activity over a short period of time. However, they have the limitation that they cannot capture the exact quantitative inactivation dynamics of the microorganism under investigation. Therefore, it is not possible to use only such results for the robust design of an industrial or clinical application (13). The analysis of the selected articles revealed a preponderance of studies on antibacterial activity (n = 44), followed by the evaluation of antimicrobial activity against both fungi and bacteria (n = 18), while only a few studies exclusively investigated antifungal activity (n = 3). Most studies analyzed a combination of Gram-positive and Gram-negative bacteria (n = 53). The most important Gram-positive bacteria analyzed were Staphylococcus aureus (n = 42), while among the Gram-negative bacteria Escherichia coli was analyzed most frequently (n = 52). Among the fungi, Candida albicans was the predominant microorganism (n = 11). These cases are developed in Section 4.

This bibliometric overview not only highlights the increasing scientific interest in GP but also underscores the crucial role of its bioactive compounds in driving this research focus. The following section will delve into the specific antimicrobial compounds found in GP.

Beyond polyphenols, grape pomace contains a range of other antimicrobial constituents that act through complementary mechanisms, broadening its antimicrobial spectrum.

Organic acids, such as tartaric and malic acids, are abundant in grape skins and seeds and contribute significantly to microbial inhibition by lowering environmental pH. This acidification denatures bacterial enzymes, impairs nutrient uptake, and interferes with membrane potential. De Andrade et al. (5) demonstrated that Syrah grape skin residues, rich in these acids, effectively suppressed spoilage bacteria in food matrices.

Vitamin C (ascorbic acid), while present in smaller quantities, acts as a pro-oxidant under stress conditions, enhancing polyphenol-mediated antimicrobial activity. Gómez-Mejía et al. (2) showed that vitamin C combined with GP polyphenols potentiated DNA fragmentation and protein oxidation, indicating synergistic bacterial inactivation.

Dietary fibers, including cellulose, hemicellulose, and lignin, also contribute indirectly to antimicrobial defense. These fibers serve as physical barriers that limit microbial adhesion and biofilm development on surfaces. Additionally, during fermentation in the gut, fiber fractions selectively modulate microbiota, suppressing pathogens and supporting beneficial taxa (15, 35). Lignin-derived phenolics released during microbial degradation may also exert bacteriostatic effects.

GP-derived compounds exert antimicrobial effects through multiple, interrelated mechanisms. The antimicrobial potential of these polyphenols is strongly influenced by their structural features, such as the number and position of hydroxyl and methoxy groups, the presence of prenyl substituents and their ability to delocalize π-electrons. These features determine their amphipathic nature and their ability to interact with microbial membranes and intracellular targets (38, 39). A primary mechanism of action is the disruption of microbial membranes. Polyphenols interact with phospholipid bilayers and membrane-associated proteins, impairing membrane integrity, increasing permeability and leading to leakage of intracellular contents. An example of this are anthocyanin-rich extracts that cause membrane damage in Escherichia coli and Staphylococcus aureus (7) and catechins that alter membrane fluidity (40, 41).

In parallel, these bioactive compounds also disrupt enzymes and metabolic processes. Polyphenols can inhibit key enzymes such as ATP synthase and thus disrupt energy metabolism and stop ATP production (11). In addition, studies have shown that they can block the replication and transcription of nucleic acids by inhibiting bacterial DNA gyrase and topoisomerase (31, 40).

Another important antimicrobial mechanism is the inhibition of quorum sensing (QS) and biofilm formation. Polyphenols act as QS inhibitors by interfering with autoinducer signaling pathways and preventing the expression of virulence factors and biofilm-related genes. For example, GP extracts have been shown to inhibit biofilm formation by Listeria monocytogenes and Salmonella spp. (35).

In addition, specific compounds such as stilbenes and ellagic acid can interfere with bacterial cell division. These polyphenolic components can target FtsZ proteins or DNA polymerases and thus stop proliferation (14, 42). Beyond direct cellular interference, polyphenols also exert chelation of metal ions, especially essential metals such as iron and zinc, depriving microbes of important cofactors for metabolic enzymes (2, 43).

A final important mechanism is the generation of oxidative stress. Certain polyphenols, including resveratrol and ellagic acid, can promote the intracellular accumulation of reactive oxygen species (ROS), leading to oxidative damage to lipids, proteins and DNA. This pro-oxidant activity has been observed in several microbial systems and contributes to cell death pathways (11, 14, 42).

Taken together, these multifaceted effects, membrane disruption, enzyme inhibition, suppression of quorum sensing, impairment of cell division, metal chelation and ROS generation explain the strong and broad antimicrobial efficacy of GP bioactives. These multifunctional mechanisms are closely related to the structural diversity of polyphenolic compounds, which enables them to act simultaneously on multiple microbial targets. Their multifunctionality and synergy with other components make them promising tools for natural food preservation strategies (38, 39, 44).

Comprehensive reviews by Rossi (38), Lobiuc (39), Ecevit (44), and Takó (45) provide detailed discussions on the mechanisms of action and microbial responses related to the antimicrobial potential of polyphenols, further supporting the importance of these compounds for food safety and preservation.

Numerous methods have been developed for the extraction of bioactive compounds from complex plant matrices. These range from conventional techniques such as solvent maceration (65, 66) or acid hydrolysis to more advanced methodologies that require specialized equipment, including ultrasound-assisted extraction (UAE) (53, 67), microwave-assisted extraction (MAE) (11), and supercritical fluid extraction (SFE) (1, 29). The quantification of extracted compounds typically involves the Folin–Ciocalteu assay for total phenolic content (TPC) (4, 5, 48) and the colorimetric determination of flavonoids via aluminum chloride complexation (4, 65). Results are commonly expressed in milligrams of gallic acid equivalents (GAE) or rutin/quercetin equivalents per milliliter of extract or gram of dry plant material. In some studies, total anthocyanin content was also evaluated by the pH differential method (4, 65). High-performance liquid chromatography (HPLC) is widely used (33, 68, 69) as well as ultra-high-performance liquid chromatography (UPLC) (4, 17, 70). Some studies further include mass spectrometry for the identification of individual polyphenols (1, 23, 33, 71).

Several authors have employed experimental design approaches to optimize extraction conditions (7, 33). Table 1 provides an overview of the extraction methods reported in the literature for isolating bioactive compounds from GP or its derived fractions. It also details the specific bioactive compounds identified in the resulting extracts, where such identification was conducted by the authors.

According to the literature reviewed, as detailed in Section 2, the most extensively studied bacterial genera are Escherichia, Staphylococcus, and Bacillus, followed, in decreasing order of frequency, by Salmonella, Pseudomonas, and Listeria. Within these genera, the most commonly analyzed species are E. coli, S. aureus, B. subtilis, S. enterica, P. aeruginosa, and L. monocytogenes, respectively (Table 1). The most commonly employed methodologies for evaluating the antimicrobial activity of GP extracts include the micro- or macrodilution methods, agar well and disk diffusion assays, and a variety of colorimetric and spectrophotometric techniques. These methods often provide complementary information and are used in combination in several studies (4, 24, 80). Based on the reviewed literature, these methodologies can be broadly classified into two categories: those that yield quantitative data and those that are qualitative in nature. Table 1 summarizes the methodologies employed by each author to assess the antimicrobial activity of grape pomace extracts or their derivatives, as well as the microbial strains used for these determinations.

Various encapsulation strategies have been explored to enhance the antimicrobial efficacy and stability of GP extracts, particularly through nanoparticle-based systems and protein–polysaccharide matrices.

Vorobyova et al. (25) synthesized silver nanoparticles (AgNPs) using deep eutectic solvent (DES)-derived GP extracts, achieving antimicrobial activity against Bacillus subtilis and Escherichia coli, as confirmed via the agar well diffusion method, with inhibition zones of 9 mm and 16 mm, respectively. Similarly, Anitha et al. (20) reported the synergistic antibacterial and antioxidant potential of bioconjugated silver nanoparticles synthesized from a grape seed extract mixture and chemically reduced silver. The polyphenol–AgNP complexes exhibited potent bactericidal activity, highlighting their relevance in addressing antibiotic-resistant bacterial strains.

In the study from Selim et al. (67) developed green nanoparticles by combining grape seed extract with metallic selenium and zinc oxide. These hybrid nanoparticles aim to capitalize on the bioactivity of plant-derived polyphenols and the antimicrobial properties of metal oxides, presenting a sustainable alternative for food preservation or biomedical use.

The use of chitosan (CH) coatings enriched with water-soluble polyphenol extracts from grape seed was investigated by Zhao et al. (59). Their findings demonstrated that such coatings effectively inhibited the growth of spoilage bacteria, particularly Pseudomonas spp., and mitigated the deterioration of physical attributes including color, texture, and water-holding capacity in meat fillets. Fillets treated with composite coatings (CH + grape seed polyphenols) showed improved quality during storage compared to those coated with chitosan alone, indicating a synergistic antibacterial effect.

Mihalcea et al. (29) investigated the encapsulation of GP extracts using a coacervation technique involving two different formulations: one based on bovine β-lactoglobulin and lactose, and another with Maillard reaction-induced glycosylation. The resulting powders demonstrated high retention of polyphenols and flavonoids, with enhanced protective capacity observed in the Maillard-induced formulation. This study not only provided a detailed phytochemical characterization of a local grape variety but also highlighted the relevance of glycosylation in improving the stabilization and delivery of bioactive compounds for diverse applications.

Over the years, food preservation has become a major concern due to spoilage, which has led to continuous efforts to extend shelf life, reduce wastage and ensure food safety (83). Strategies employed include the replacement of synthetic food preservatives and the extensive use of antibiotics with natural antimicrobials (13). Grape waste, which is rich in bioactive compounds such as polyphenols, flavonoids and tannins, has shown great potential for extending the shelf life of food (42). Their antimicrobial and antioxidant properties make these extracts promising candidates for application in food preservation strategies (32, 49).

Investigating the antibacterial and antifungal activity of grape waste is important to discover new, effective, naturally occurring food preservatives. In addition, its use as a food additive can help improve human health by preventing lipid oxidation and the formation of potentially harmful compounds such as acrylamide and improving sensory properties such as color and texture (7, 36). Studies have shown that the addition of grape seed extract to cheese increases its shelf life and improves its antioxidant potential. It also inhibits the growth of psychrotrophic bacteria, molds and yeasts (84). Similar results were observed in yogurt samples supplemented with grape seed extract, which showed a significant effect on the inhibition of pathogens. In that case, correlations were found between the added concentration of the extract and antibacterial activity against Escherichia coli (Pearson’s r = 0.914; p < 0.05) and Staphylococcus aureus (Pearson’s r = 0.952; p < 0.05) (60).

In addition, the addition of red grape pomace to sheep cheese showed the potential to inhibit the growth of Pseudomonas (MIC = 25 mg/mL), a microorganism often associated with spoilage of food of animal origin. The cheese also showed an inhibitory effect (MIC = 50 mg/mL) against several foodborne pathogens, including Escherichia coli, Listeria monocytogenes, Salmonella Typhimurium and Stenotrophomonas maltophilia (19). In this context, the use of grape residues as antimicrobial agents for the development of innovative foods or the fortification of existing products has been studied in detail. Table 2 shows the use of these residues as antimicrobial agents in various foods.

In connection with innovative food preservation technologies, scientific interest in smart packaging has increased in recent years. The incorporation of bioactive compounds into packaging has been explored as an effective strategy to extend the shelf life of products and ensure their quality during production, storage and marketing (83, 85). Smart packaging increases food safety by enabling real-time monitoring of food quality throughout the supply chain. They control factors such as temperature fluctuations, microbial spoilage, packaging integrity and freshness, helping to reduce food waste and curb foodborne diseases (83). Among these technologies, freshness indicators stand out as a smart packaging system that monitors and communicates food quality through color changes that indicate microbial growth and chemical changes during storage and/or transportation (83). Active packaging technology, on the other hand, integrates substances with antioxidant and/or antimicrobial properties directly into the packaging material. The bioactive effect of active packaging contributes to the preservation of food by reducing accelerated deterioration processes and improving its nutritional, microbiological and physicochemical quality, thus extending its shelf life (85).

Originally, synthetic compounds were often used for this purpose. However, concerns about the potential health risks associated with these substances have encouraged the search for natural alternatives (85). In this context, grape waste is considered as a potential resource for natural pigments with halochromic properties, antioxidant and antimicrobial compounds in the development of smart food packaging (Figure 5). The overview focuses on the addition of grape pomace and its components to various films to improve their antimicrobial properties.

In a study by Moselhy et al. (80), coating with grape by-products had a significant effect on the microbiological preservation of chicken meat. During 21 days of storage at 4°C, the coated chickens showed a significant reduction in counts in the four microbial groups studied (total bacterial count, spore-forming bacteria, molds and yeasts and total coliforms). In contrast, in the chicken from the control treatment, the total bacterial count at the end of storage exceeded the safety index (80). Qiu et al. (75) investigated the antifungal activity of polyvinyl alcohol (PVA) films containing 15% grape skins (UGS15-PVA) and PVA films. Both films were immersed in milk to allow the polyphenols to transfer from the film into the liquid. It was observed that the milk that came into contact with the PVA film was completely covered with fungi. In contrast, the milk stored with the UGS15 PVA film showed significantly less fungal growth. This result suggests that grape polyphenols have an antifungal effect.

Compared to the control samples, the film-forming solutions with aqueous grape seed extract led to a 2.8-log₁₀ and 5.5-log₁₀ reduction in the viable count of E. coli (gram-negative) and S. aureus (gram-positive) (54). The antibacterial activity tests show that the addition of grape pomace extract gives the polypropylene films a bactericidal activity of over 30% against Escherichia coli. In the case of Bacillus subtilis (Gram-positive bacteria), this activity is over 50% for all films produced with different proportions of the extract. This bactericidal effect is due to the presence of polyphenols in the film with grape residues, which irreparably damage structural proteins and other important biomolecules such as DNA and RNA. Despite undergoing thermal treatment during processing, the films retain antimicrobial functionality due to the partial stability of polyphenols present in the incorporated grape pomace; a significant fraction of these compounds resists degradation and remains active within the film matrix (50).

Compounds extracted from grape pomace and incorporated into films also show antimicrobial activity. Bilayer films rich in grape tannins showed bacteriostatic activity against Listeria innocua and Escherichia coli (37). These results underline the potential of grape tannin films as a good alternative for active coatings or packaging material to control bacterial growth.

To better understand the technological development and emerging trends in the industrial use of grape pomace for food purposes, patent data was retrieved from the Derwent World Patents Index (accessed March 13, 2025). The patents listed in Table 3 emphasize the use of grape pomace and its components, either as an antimicrobial agent, as a food additive or as an active component in food packaging. These innovations focus on the development of new functional food products, antimicrobial ingredients and active or edible packaging materials. In particular, the concentration of patents in countries such as China and South Korea indicates a strategic investment in the valorization of winery by-products through biotechnological and packaging innovations. In contrast, countries such as Brazil, despite being a major grape producer, still show limited technological patent activity in this area, highlighting a gap and a potential opportunity for innovation and industrial scaling in the Latin American context.

A crucial prerequisite for the use GP in food preservation is, as with any other food additive, compliance with legal and toxicological requirements. The European Union has one of the most advanced legal frameworks for food by-products. According to Regulations (EC) No 178/2002 and No 2015/2283, the use of food by-products as natural additives requires prior authorization as a novel food. In addition, the EU has a strict waste management policy that includes fines for the improper disposal of solid residues. Nevertheless, there is increasing innovation in the valorization of by-products for higher value applications such as food packaging and functional ingredients (86).

To utilize phenolic-rich extracts in food, food supplements or packaging, EU regulations require compliance with food quality standards. These include validated hygiene protocols, microbiological testing and screening for allergens, mycotoxins, pesticides and heavy metals using advanced analytical techniques such as LC–MS/MS, real-time PCR and ELISA (87).

A comprehensive literature review shows no toxicology studies or established ADI values for GP as a whole. Most of the available toxicological data focus on grape seed extract (GSE), a specific fraction of GP obtained by targeted extraction procedures. Thus, studies on GSE have demonstrated safety and bioactivity in both in vivo and in vitro models (13, 69). However, these results cannot be directly extrapolated to the whole pomace matrix, which contains peels, pulp and stems and has a more complex chemical composition.

Furthermore, there are no official recommendations for the ideal phenolic intake levels associated with health benefits or defined safety thresholds for food applications. Nevertheless, Rubín-García reported that in adults, improvements in health markers, including reductions in body weight, blood pressure and fasting plasma glucose levels, were associated with a total polyphenol intake of approximately 259 mg/day per 1,000 kcal, consisting mainly of flavonoids (166 mg/day/1000 kcal) and phenolic acids (72 mg/day/1000 kcal) (88). Similar trends were observed in adolescents, but with a higher polyphenol intake (~683 mg/day), mainly flavonoids (~530 mg/day) and phenolic acids (~97 mg/day) (89).