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    Topic review

    Pectins and Olive Pectins

    Subjects: Biology
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    Definition

    Pectins are a component of the complex heteropolysaccharide mixture present in the cell wall of higher plants. Structurally, the pectin backbone includes galacturonic acid to which neutral sugars are attached, resulting in functional regions in which the esterification of residues is crucial. Pectins influence many physiological processes in plants and are used industrially for both food and non-food applications. Pectin-based compounds are also a promising natural source of health-beneficial bioactive molecules. Olives, the fruit of the olive tree, are consumed as part of the healthy Mediterranean diet or processed into olive oil. Pectins from olives have recently emerged as promising compounds with health-beneficial effects. 

    1. Introduction

    Pectins are present in the primary cell walls and middle lamellae in higher plants within a complex heteropolysaccharide matrix, which contains up to 30% pectins together with cellulose and hemicellulose [1][2] resulting in networks due to linkages among them. Carbohydrates are the major components of the cell wall, which contain only 5–10% of proteins, including extensins and arabinogalactan proteins [3][4]; all are modified during fruit ripening. Despite the diversity of their chemical composition across species and tissues, pectins are known to play a key role in plant tissue firmness and plant development, modulating the properties of the cell wall and cell functions. In plant tissues, pectins in the middle lamella also contribute to cell-to-cell adhesion and act as a barrier against pathogens [3][5][6]. Many studies have also highlighted the interaction between pectin chains and the cellulose-hemicellulose network [1][4][7][8][9][10][11][12][13].
    Pectin polysaccharides have been extensively used as a functional ingredient in the food industry and also in non-food industries during the production of cosmetics, packaging materials or pharmaceuticals. Over the last few years, several studies point to an increasing interest in pectins as health-promoting molecules for biomedical applications. Nevertheless, it is well established that pectin extraction methods strongly influence the structure and properties of these polysaccharides [1][14]. This review summarizes current knowledge concerning pectin sources and extraction protocols. Additionally, we provide evidence that olive fruits may be a promising natural source of bioactive pectic polysaccharides obtained during olive oil production, which also valorize traditional industrial by-products or wastes.

    2. Structure, Quantification, and Qualification

    2.1. Pectins

    Pectins are complex heteropolysaccharides, which include at least 17 kinds of monosaccharides and over 20 types of linkages, with a backbone of α-1,4-D-galacturonic acid (70%) in which homogalacturonan (HG), rhamnogalacturonan (RG-I and RG-II), and xylogalacturonan (XG) domains, linked by covalent or ionic interactions, can be distinguished [14][15]. Homogalacturonan linear domain monosaccharides are partially C-6 methyl-esterified and may be C-2/3 O-acetylated in some plant sources, and the degree of esterification is a parameter that affects pectin functionality [16]. This “smooth region” of HG is the most abundant pectin domain (comprising 60–65%) in plant cell pectins [15] and has been recently related to epidermal morphogenesis in plants [17]. The “hairy” regions of pectin molecules include both RG-I and RG-II, to which nonionic side chains containing many neutral sugars are attached [18]. RG-I domains include rhamnose residues in the galacturonic acid backbone with many side chains containing other neutral sugars, such as galactose or arabinose [8]. It is well established that the monosaccharide composition and architecture of both HG and RG-I domains vary significatively during plant development [19]. Only little structure variations in pectin RG-I domains have been reported in different plants [20]. RG-II is a much more complex domain, in which up to 12 types of sugar may be present, including the rarely observed apiose, xylose, or fucose [20].

    2.2. Olive Pectins

    The industrial production of olive oil generates huge quantities of a wet organic matter commonly known as olive pomace, composed of 60–70% water and containing 98% of the total phenols in the olive fruit, known for their beneficial properties for health [21]. Pectic polysaccharides comprise approximately 39% of this wet olive pomace. The degree of methyl esterification is approximately 48% and the degree of acetylation is approximately 11%. Compared to citrus commercially available low-methoxyl-pectins, olive pomace pectin extracts show a higher degree of methyl-esterification, acetylation, and total neutral sugar content, but a lower galacturonic acid percentage or molecular weight [21]. The presence of arabinan-rich pectic polysaccharides in olive pomace is notable, and its quantification is a parameter to evaluate the ripeness of the olive fruits [21]. These agricultural wastes therefore appear to be an interesting source of health-beneficial biomolecules that can be recovered to yield environmental and economic benefits [22].

    3. Extraction

    3.1. Pectins

    From the raw biomass, the industrial process of extraction requires pre-extraction protocols, followed by hydrolysis and isolation of pectins and post-extraction solubilization.

    Both single digestions and combined methods have been used extensively for pectin extraction [1][14][20][23]. Single extraction methods use acid or alkali solutions in addition to enzyme treatments to release pectins from the cell wall, where it forms complex networks with cellulose and hemicellulose.

    Pulsed electric field extraction or the use of hot water or chelating agents, such as oxalate or sodium hexametaphosphate, are also single extraction methods [1][24]. A pulsed electric field applies a high voltage during a short time to a food product, increasing cell membrane permeability and facilitating bioactive molecules release [24]. Nevertheless, these protocols are time- and energy-consuming, with low extraction yields and inadequate pectin quality or functionality, as well as environmental disadvantages due to contaminants generated [14][25]. However, the structure and properties of pectins are influenced by the extraction method; thus, there is a need to find novel extraction techniques that achieve the optimal yield and quality of the by-products generated and the isolated pectic polysaccharide products [23]. Accordingly, combined techniques using subcritical water-, ultrasound-, microwave-, or ultrasonic/microwave-assisted protocols are promising approaches for pectin extraction [1].

    3.2. Olive Pectins

    At present, two-phase extraction is preferred in the olive oil industry as it reduces the consumption of water and the generation of liquid pollution. The resulting solid phase includes water and vegetable mass and is commonly known as “wet olive pomace” [26][21]. Pectins are minor compounds in the olive fruit but comprise up to 35% of the olive pomace during processing [22][21], depending on the ripening stage and other factors related to cultivar conditions and olive variety [27][28][29].

    Pectins can be extracted from olive pomace as an “alcohol-insoluble residue” (AIR), which also includes additional cell wall materials such as cellulose, hemicellulose or proteins [27]. Conventional methods already described, such as high temperature or acid solvents, have been used extensively in extraction protocols [28][30][31]. Some data point to low molecular weight pectins as bioactive compounds and, accordingly, hydrothermal treatment has appeared as a promising technology for the production and solubilization of pectins from olive pomace, as temperature is a critical parameter for maintaining the bioactivity of pectin [32][33]. Regarding the million tons of olive pomace produced every year by the olive oil industry, this by-product appears to be a noteworthy source of bioactive molecules, including pectic polysaccharides.

    4. Industrial Applications

    4.1. Pectins

    Pectins have been used historically as additives in the food industry, including gelling, emulsifying, and stabilizing agents, as well as texture or thickness modulators, and fat-replacing components [18][34]. They have good biocompatibility and biodegradability, lack toxicity, and contribute to our dietary soluble fibers as no enzymatic digestion pectins occur in the human upper gut [18]. Nevertheless, some properties of pectins are strongly influenced by the number and localization of the esterified residues in the homogalacturonan region of the molecule [8]. Consequently, high-methylesterified (HM, 60–80%) and low-methylesterified (LM, 30–40%) pectins are suitable gelling agents for various products. Vegetable jellies include LM pectins, whereas other jellies, marmalade, mayonnaise, juices, or canned fish include HM pectins, which are more suitable for gelation [18][35].
    The properties of pectins are also used in non-food industries, such as the pharmaceutical or cosmetics industry. As an emulsifier or thickening agent, pectins are present in cosmetic products and they are also useful as delivery vehicles for genes [31] or drugs [18][36][37][38]. Other industrial applications suggest that pectin-containing polymers are suitable for the preparation of biomaterials for various purposes [18].

    4.2. Olive Pectins

    Olive pomace polysaccharides have an 11% (acetyl)–48% (methyl) low degree of esterification, which points to the gelling potential as a food ingredient of this by-product in oil production [22]. What is more, in the presence of calcium, olive pomace pectins are able to form elastic gels more resistant to high temperatures than those commercial low-methoxyl-pectin/calcium gels [21]. The emulsifying activity of olive pomace polysaccharides has been proven compared with traditional sources of pectins [33].

    5. Bioactivity

    5.1. Pectins

    New ventures to find natural sources of pectins in plants have the potential to expand what is known about vegetal polysaccharides as bioactive compounds that are available in large quantities but are still considered as waste. Many biomaterials are based on the pectin molecule, and many studies have assessed the efficiency of pectins as wound-healing agents [39] or in tissue engineering [18][40][41]. Pectins are a common dietary source of oligosaccharides from fruits and vegetables that are fermented in the colon by the gut microbiota. Promising activities include bactericidal, immunomodulatory, anti-inflammatory [42][43], antioxidant, cardioprotective, probiotic [44], cholesterol [45], serum glucose-reducing [46], and intestinal and obesity regulator [22][39][47] functions for pectin oligosaccharides. Moreover, low molecular weight fragments from pectins exhibit antitumoral activities [22][48][49][50][51][52]. Recent studies have also pointed to the importance of fruit and vegetables as an important source of pectin molecules containing the RG-I domain [19][53].

    5.2. Olive Pectins

    The chemical composition of olive fruits varies depending on the cultivar, environmental conditions, and the maturation from green to black fruits. Many studies have provided data concerning olive phenols [54], but despite the importance of pectin transformation in the cell wall, there is little published research on this topic [6][26][22][27].
    As already stated, the olive pomace resulting from olive oil production has been described as a valuable source of olive pectins [21]. Given the economic and environmental relevance of olive cultivars and the increasing popularity of natural, bioactive, and healthy phytochemicals, olive pectin extracts are a potential new complement for both nutrition and health improvement that support research into the composition and distribution of olives [26].
    Polysaccharide-enriched extracts from olive pomace have shown health-promoting activities in in vitro experiments, including those related to antioxidant behavior and the regulation of glucose or lipid metabolism compared with commercial pectins [33]. There are promising results demonstrating the antitumoral activity of pectin extracts from olive oil by-products [52].

    The entry is from 10.3390/biology10090860

    References

    1. Cui, J.; Zhao, C.; Feng, L.; Han, Y.; Du, H.; Xiao, H.; Zheng, J. Pectins from fruits: Relationships between extraction methods, structural characteristics, and functional properties. Trends Food Sci. Technol. 2021, 110, 39–54.
    2. Zdunek, A.; Pieczywek, P.M.; Cybulska, J. The primary, secondary, and structures of higher levels of pectin polysaccharides. Compr. Rev. Food Sci. Food Saf. 2021, 20, 1101–1117.
    3. Uluisik, S.; Seymour, G.B. Pectate lyases: Their role in plants and importance in fruit ripening. Food Chem. 2020, 309, 125559.
    4. Voiniciuc, C.; Pauly, M.; Usadel, B. Monitoring polysaccharide dynamics in the plant cell wall. Plant Physiol. 2018, 176, 2590–2600.
    5. Saffer, A.M. Expanding roles for pectins in plant development. J. Integr. Plant Biol. 2018, 60, 910–923.
    6. Parra, R.; Paredes, M.A.; Labrador, J.; Nunes, C.; Coimbra, M.A.; Fernandez-Garcia, N.; Olmos, E.; Gallardo, M.; Gomez-Jimenez, M.C. Cellwall composition andultrastructural immunolocalization of pectin and arabinogalactan protein during olea europaea l. fruit abscission. Plant Cell Physiol. 2020, 61, 814–825.
    7. Cosgrove, D.J. Diffuse growth of plant cell walls. Plant Physiol. 2018, 176, 16–27.
    8. Liu, J.; Bi, J.; McClements, D.J.; Liu, X.; Yi, J.; Lyu, J.; Zhou, M.; Verkerk, R.; Dekker, M.; Wu, X.; et al. Impacts of thermal and non-thermal processing on structure and functionality of pectin in fruit- and vegetable- based products: A review. Carbohydr. Polym. 2020, 250, 116890.
    9. Fu, J.; Mort, A. Progress towards identifying a covalent cross-link between xyloglucan and rhamnogalacturonan in cotton cell walls. Plant Physiol. 1997, 114S, 83.
    10. Vidal, S.; Williams, P.; Doco, T.; Moutounet, M.; Pellerin, P. The polysaccharides of red wine: Total fractionation and characterization. Carbohydr. Polym. 2003, 54, 439–447.
    11. Abdel-Massih, R.M.; Baydoun, E.A.-H.; Brett, C.T. In vitro biosynthesis of 1,4-b-galactan attached to a pectin–xyloglucan complex in pea. Planta 2003, 216, 502–511.
    12. Popper, Z.A.; Fry, S.C. Xyloglucan–pectin linkages are formed intra-protoplasmically, contribute to wall-assembly, and remain stable in the cell wall. Planta 2008, 227, 781–794.
    13. Femenia, A.; Rigby, N.M.; Selvendran, R.R.; Waldron, K.W. Investigation of the occurrence of pectic-xylan–xyloglucan complexes in cell walls of cauliflower stem tissues. Carbohydr. Res. 1999, 39, 151–164.
    14. Marić, M.; Grassino, A.N.; Zhu, Z.; Barba, F.J.; Brnčić, M.; Rimac Brnčić, S. An overview of the traditional and innovative approaches for pectin extraction from plant food wastes and by-products: Ultrasound-, microwaves-, and enzyme-assisted extraction. Trends Food Sci. Technol. 2018, 76, 28–37.
    15. Christiaens, S.; Van Buggenhout, S.; Houben, K.; Jamsazzadeh Kermani, Z.; Moelants, K.R.N.; Ngouémazong, E.D.; Van Loey, A.; Hendrickx, M.E.G. Process–Structure–Function Relations of Pectin in Food. Crit. Rev. Food Sci. Nutr. 2016, 56, 1021–1042.
    16. Levesque-Tremblay, G.; Pelloux, J.; Braybrook, S.A.; Müller, K. Tuning of pectin methylesterification: Consequences for cell wall biomechanics and development. Planta 2015, 242, 791–811.
    17. Haas, K.T.; Wightman, R.; Meyerowitz, E.M.; Peaucelle, A. Pectin homogalacturonan nanofilament expansion drives morphogenesis in plant epidermal cells. Science 2020, 367, 1003–1007.
    18. Noreen, A.; Nazli, Z.I.H.; Akram, J.; Rasul, I.; Mansha, A.; Yaqoob, N.; Iqbal, R.; Tabasum, S.; Zuber, M.; Zia, K.M. Pectins functionalized biomaterials; a new viable approach for biomedical applications: A review. Int. J. Biol. Macromol. 2017, 101, 254–272.
    19. Wu, D.; Zheng, J.; Mao, G.; Hu, W.; Ye, X.; Linhardt, R.J.; Chen, S. Rethinking the impact of RG-I mainly from fruits and vegetables on dietary health. Crit. Rev. Food Sci. Nutr. 2020, 60, 2938–2960.
    20. Dranca, F.; Oroian, M. Extraction, purification and characterization of pectin from alternative sources with potential technological applications. Food Res. Int. 2018, 113, 327–350.
    21. Coimbra, M.A.; Cardoso, S.M.; Lopes-Da-Silva, J.A. Olive pomace, a source for valuable Arabinan-rich pectic polysaccharides. In Carbohydrates in Sustainable Development I. Topics in Current Chemistry; Rauter, A., Vogel, P., Queneau, Y., Eds.; Springer: Berlin/Heidelberg, Germany, 2010; Volume 294, pp. 129–141.
    22. Babbar, N.; Dejonghe, W.; Gatti, M.; Sforza, S.; Elst, K. Pectic oligosaccharides from agricultural by-products: Production, characterization and health benefits. Crit. Rev. Biotechnol. 2016, 36, 594–606.
    23. Adetunji, L.R.; Adekunle, A.; Orsat, V.; Raghavan, V. Advances in the pectin production process using novel extraction techniques: A review. Food Hydrocoll. 2017, 62, 239–250.
    24. Nowacka, M.; Tappi, S.; Wiktor, A.; Rybak, K.; Miszczykowska, A.; Czyzewski, J.; Drozdzal, K.; Witrowa-Rajchert, D.; Tylewicz, U. The Impact of Pulsed Electric Field on the Extraction of Bioactive Compounds from Beetroot. Foods 2019, 7, 244.
    25. Khedmat, L.; Izadi, A.; Mofid, V.; Mojtahedi, S.Y. Recent advances in extracting pectin by single and combined ultrasound techniques: A review of techno-functional and bioactive health-promoting aspects. Carbohydr. Polym. 2020, 229, 115474.
    26. Ghanbari, R.; Anwar, F.; Alkharfy, K.M.; Gilani, A.H.; Saari, N. Valuable nutrients and functional bioactives in different parts of olive (Olea europaea L.)—A review. Int. J. Mol. Sci. 2012, 13, 3291–3340.
    27. Diarte, C.; Iglesias, A.; Romero, A.; Casero, T.; Ninot, A.; Gatius, F.; Graell, J.; Lara, I. Ripening-related cell wall modifications in olive (Olea europaea L.) fruit: A survey of nine genotypes. Food Chem. 2021, 338, 127754.
    28. Jiménez, A.; Rodríguez, R.; Ferriáhdez-Caro, I.; Guillén, R.; Fernández-Bolaños, J.; Heredia, A. Olive fruit cell wall: Degradation of peptic polysaccharides during ripening. J. Agric. Food Chem. 2001, 49, 409–415.
    29. Moustakime, Y.; Hazzoumi, Z.; Joutei, K.A. Effect of proteolytic activities in combination with the pectolytic activities on extractability of the fat and phenolic compounds from olives. SpringerPlus 2016, 5, 739.
    30. Sánchez-Romero, C.; Guillén, R.; Heredia, A.; Jiménez, A.; Fernández-Bolaños, J. Degradation of pectic polysaccharides in pickled green olives. J. Food Prot. 1998, 61, 78–86.
    31. Vierhuis, E.; Korver, M.; Schols, H.A.; Voragen, A.G.J. Structural characteristics of pectic polysaccharides from olive fruit (Olea europaea cv moraiolo) in relation to processing for oil extraction. Carbohydr. Polym. 2003, 51, 135–148.
    32. Lama-Muñoz, A.; Rodríguez-Gutiérrez, G.; Rubio-Senent, F.; Fernández-Bolaños, J. Production, characterization and isolation of neutral and pectic oligosaccharides with low molecular weights from olive by-products thermally treated. Food Hydrocoll. 2012, 28, 92–104.
    33. Rubio-Senent, F.; Rodríguez-Gutiérrez, G.; Lama-Muñoz, A.; Fernández-Bolaños, J. Pectin extracted from thermally treated olive oil by-products: Characterization, physico-chemical properties, invitro bile acid andglucose binding. Food Hydrocoll. 2015, 43, 311–321.
    34. Naqash, F.; Masoodi, F.A.; Rather, S.A.; Wani, S.M.; Gani, A. Emerging concepts in the nutraceutical and functional properties of pectin—A Review. Carbohydr. Polym. 2017, 168, 227–239.
    35. Shakhmatov, E.G.; Toukach, P.V.; Makarova, E.N. Structural studies of the pectic polysaccharide from fruits of Punica granatum. Carbohydr. Polym. 2020, 235, 115978.
    36. Katav, T.; Liu, L.S.; Traitel, T.; Goldbart, R.; Wolfson, M.; Kost, J. Modified pectin-based carrier for gene delivery: Cellular barriers in gene delivery course. J. Control. Release 2008, 130, 183–191.
    37. Smistad, G.; Bøyum, S.; Alund, S.J.; Samuelsen, A.B.C.; Hiorth, M. The potential of pectin as a stabilizer for liposomal drug delivery systems. Carbohydr. Polym. 2012, 90, 1337–1344.
    38. Rehman, A.; Ahmad, T.; Aadil, R.M.; Spotti, M.J.; Bakry, A.M.; Khan, I.M.; Zhao, L.; Riaz, T.; Tong, Q. Pectin polymers as wall materials for the nano-encapsulation of bioactive compounds. Trends Food Sci. Technol. 2019, 90, 35–46.
    39. Munarin, F.; Tanzi, M.C.; Petrini, P. Advances in biomedical applications of pectin gels. Int. J. Biol. Macromol. 2012, 51, 681–689.
    40. Coimbra, P.; Ferreira, P.; de Sousa, H.C.; Batista, P.; Rodrigues, M.A.; Correia, I.J.; Gil, M.H. Preparation and chemical and biological characterization of a pectin/chitosan polyelectrolyte complex scaffold for possible bone tissue engineering applications. Int. J. Biol. Macromol. 2011, 48, 112–118.
    41. Munarin, F.; Guerreiro, S.G.; Grellier, M.A.; Tanzi, M.C.; Barbosa, M.A.; Petrini, P.; Granja, P.L. Pectin-based injectable biomaterials for bone tissue engineering. Biomacromolecules 2011, 12, 568–577.
    42. Markov, P.A.; Popov, S.V.; Nikitina, I.R.; Ovodova, R.G.; Ovodov, Y.S. Anti-inflammatory activity of pectins and their galacturonan backbone. Russ. J. Bioorganic Chem. 2011, 37, 817–821.
    43. Singh, V.; Yeoh, B.S.; Walker, R.E.; Xiao, X.; Saha, P.; Golonka, R.M.; Cai, J.; Bretin, A.C.A.; Cheng, X.; Liu, Q.; et al. Microbiota fermentation-NLRP3 axis shapes the impact of dietary fibres on intestinal inflammation. Gut 2019, 68, 1801–1812.
    44. Licht, T.R.; Hansen, M.; Bergström, A.; Poulsen, M.; Krath, B.N.; Markowski, J.; Dragsted, L.O.; Wilcks, A. Effects of apples and specific apple components on the cecal environment of conventional rats: Role of apple pectin. BMC Microbiol. 2010, 10, 13.
    45. Chen, Y.; Xu, C.; Huang, R.; Song, J.; Li, D.; Xia, M. Butyrate from pectin fermentation inhibits intestinal cholesterol absorption and attenuates atherosclerosis in apolipoprotein E-deficient mice. J. Nutr. Biochem. 2018, 56, 175–182.
    46. Viebke, C.; Al-Assaf, S.; Phillips, G.O. Food hydrocolloids and health claims. Bioact. Carbohydr. Diet. Fibre 2014, 4, 101–114.
    47. Jiang, T.; Gao, X.; Wu, C.; Tian, F.; Lei, Q.; Bi, J.; Xie, B.; Wang, H.; Chen, S.; Wang, X. Apple-Derived Pectin Modulates Gut Microbiota, Improves Gut Barrier Function, and Attenuates Metabolic Endotoxemia in Rats with Diet-Induced Obesity. Nutrients 2016, 8, 126.
    48. Nangia-Makker, P.; Hogan, V.; Honjo, Y.; Baccarini, S.; Tait, L.; Bresalier, R.; Raz, A. Inhibition of human cancer cell growth and metastasis in nude mice by oral intake of modified citrus pectin. J. Natl. Cancer Inst. 2002, 94, 1854–1862.
    49. Dutta, R.K.; Sahu, S. Development of oxaliplatin encapsulated in magnetic nanocarriers of pectin as a potential targeted drug delivery for cancer therapy. Results Pharma Sci. 2012, 2, 38–45.
    50. Leclere, L.; Van Cutsem, P.; Michiels, C. Anti-cancer activities of pH- or heat-modified pectin. Front. Pharmacol. 2013, 4, 128.
    51. Delphi, L.; Sepehri, H.; Khorramizadeh, M.R.; Mansoori, F. Pectic-oligoshaccharides from apples induce apoptosis and cell cycle arrest in MDA-MB-231 cells, a model of human breast cancer. Asian Pac. J. Cancer Prev. 2015, 16, 5265–5271.
    52. Bermúdez-Oria, A.; Rodríguez-Gutiérrez, G.; Alaiz, M.; Vioque, J.; Girón-Calle, J.; Fernández-Bolaños, J. Pectin-rich extracts from olives inhibit proliferation of Caco-2 and THP-1 cells. Food Funct. 2019, 10, 4844.
    53. Mao, G.; Wu, D.; Wei, C.; Tao, W.; Ye, X.; Linhardt, R.J.; Orfila, C.; Chen, S. Reconsidering conventional and innovative methods for pectin extraction from fruit and vegetable waste: Targeting rhamnogalacturonan I. Trends Food Sci. Technol. 2019, 94, 65–78.
    54. Rubio-Senent, F.; Rodríguez-Gutiérrez, G.; Lama-Muñoz, A.; Fernández-Bolaños, J. Chemical characterization and properties of a polymeric phenolic fraction obtained from olive oil waste. Food Res. Int. 2013, 54, 2122–2129.
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