Physico-chemical Characteristics of Nanovesicle−Carbohydrate Complexes in Grape Juice Concentrate

• Published in: Journal of agricultural and food chemistry Vol. 56; no. 4; pp. 1305 - 1315
• Main Authors: Jacob, Jissy K, Paliyath, Gopinadhan
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 27.02.2008
• Subjects: anthocyanin; antioxidant activity; beta-galactosidase; beta-Galactosidase - metabolism; Beverages; Biological and medical sciences; Biological Availability; carbohydrates; Cellulase - metabolism; cellulases; Chemical Composition of Foods/Feeds; chemical reactions; complex formation; dialysis; Dialysis Solutions - chemistry; enzymatic treatment; Flavonoids - analysis; Flavonoids - chemistry; Food industries; Fruit and vegetable industries; Fundamental and applied biological sciences. Psychology; glucosides; grape juice; juice concentrates; lipid nanovesicles; lipids; Magnetic Resonance Spectroscopy - methods; Octoxynol - chemistry; pectins; Pectins - analysis; Pectins - chemistry; Phenols - analysis; Phenols - chemistry; physicochemical properties; polygalacturonase; Polygalacturonase - metabolism; polymers; Polyphenols; structure-activity relationships; Vitis - chemistry; carbohydrates; Polyphenols; anthocyanin; grape juice; glucosides; Anthocyanin; Fruit; Glucoside; Flavonoid; Polyphenol; Grape; Pigments; Carbohydrate; Concentrate
• ISSN: 0021-8561; 1520-5118
• DOI: 10.1021/jf072928h

It is generally assumed that polyphenols, such as anthocyanins in fruit juice, exist in a free soluble state and are readily available for absorption in the gastro-intestinal tract. In the present study, we have investigated the interaction of polyphenols with soluble carbohydrate polymers, such as pectin and lipid nanovesicles, that are generated during homogenization of the fruit tissue during juice extraction. A commercially available grape juice concentrate contained nearly 25% of polyphenol fraction bound to macromolecules that were nondialyzable. Treatment of dialyzed juice with cellulase, pectinase, and β-galactosidase did not cause the release of bound polyphenols; however, treatment with triton X-100 caused an increased release of bound polyphenols. The dialyzate contained relatively more -3-O glucosides and -3-O-acetoyl glucosides in comparison to the bound fraction which was enriched in -3-O-coumaroyl glucosides, suggesting qualitative differences in the bound and the free anthocyanin composition. Electron microscopic analysis of the juice fractions revealed the presence of electron-dense nanovesicle−fiber complexes ranging from 10 to 200 nm in diameter. Such complexes were absent in the dialyzate fraction. Cellulase treatment did not change the morphology of the complexes; however, treatment with pectinase and β-galactosidase disrupted the complexes, releasing vesicular structures, suggestive of the pectin nature of the fibrous matrix. The dialyzed and the dialyzate fractions also showed differences in their 1H NMR and fluorescence spectral characteristics. The dialyzed fraction containing polyphenol−pectin complexes showed no superoxide scavenging capacity, reduced hydroxyl radical scavenging activity, and high 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity, indicating potential changes in functionality because of the complex formation.