Effect of Cyclodextrins on the Thermal Epimerization of Tea Catechins

Okumura, Hiroki; Ichitani, Masaki; Takihara, Takanobu; Kunimoto, Ko‐Ki

doi:10.3136/fstr.14.83

Cited by 13 publications

(10 citation statements)

References 23 publications

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“…The predominant reactions of catechins during exposure to heat appear to be isomerization and autooxidation (Komatsu et al 1993. Isomerization of epicatechins to their nonepi isomers is thermodynamically favorable (Okumura et al 2008). The heats of formation ( H f ) of the nonepi isomers are 1-2 kcal mol −1 lower than those of epi forms, and this difference is sufficient to drive epimerization during typical thermal processes (Okumura et al 2008).…”

Section: Thermal Stabilitymentioning

confidence: 99%

“…Isomerization of epicatechins to their nonepi isomers is thermodynamically favorable (Okumura et al 2008). The heats of formation ( H f ) of the nonepi isomers are 1-2 kcal mol −1 lower than those of epi forms, and this difference is sufficient to drive epimerization during typical thermal processes (Okumura et al 2008). The significance of thermally induced isomerization is reflected in studies demonstrating that retorted green tea beverages contain (−)-GCG as their predominant catechin species, whereas (−)-EGCG is the predominant species present in unprocessed green tea (Chen et al 2001, Zhu et al 2003.…”

Section: Thermal Stabilitymentioning

confidence: 99%

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Influence of Formulation and Processing on Absorption and Metabolism of Flavan-3-Ols from Tea and Cocoa

Neilson

Ferruzzi

2011

Annu. Rev. Food Sci. Technol.

101

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Flavan-3-ols are a major subclass of the class of plant phytochemicals known as flavonoids. Flavan-3-ols are commonly found in fruit, vegetable, and botanical products, including tea, cocoa, grapes, and apples. Both monomeric catechins and polymeric procyanidins are common in the diet, along with several derivatives produced by degradation of these species during processing. Both epidemiological and biological evidence suggests a health-protective role for dietary flavan-3-ols, leading to increased interest in the bioavailability of these compounds from foods. Flavan-3-ol bioavailability depends on numerous factors, including digestive release, absorption, metabolism, and elimination. In addition to these in vivo factors, the complexity of whole-food systems (physical form, flavan-3-ol form and dose, macronutrient and micronutrient profile, processing, etc.) influences the absorption efficiency and circulating profile of flavan-3-ols. An understanding of how food matrices may influence flavan-3-ol absorption will provide a framework to design and develop functional products that positively affect flavan-3-ol absorption and, by extension, potential bioactivity.

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Section: Thermal Stabilitymentioning

confidence: 99%

Section: Thermal Stabilitymentioning

confidence: 99%

Influence of Formulation and Processing on Absorption and Metabolism of Flavan-3-Ols from Tea and Cocoa

Neilson

Ferruzzi

2011

Annu. Rev. Food Sci. Technol.

101

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“…Previously, we reported on the UV absorption spectra of green tea catechins and showed that gallated and nongallated catechins exhibited quite different pH dependence (Okumura et al, 2007). As shown in Fig.…”

Section: Resultsmentioning

confidence: 81%

“…This peak corresponds to ultra high MWs that exceed the GPC column size exclusion limit of approximately 600,000. Thus, the sample contains very high molecular weight gel components.Previously, we reported on the UV absorption spectra of green tea catechins and showed that gallated and nongallated catechins exhibited quite different pH dependence (Okumura et al, 2007). As shown in Fig.…”

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confidence: 81%

Persimmon Tannin Gel: Formation by Autoxidation and Caffeine Adsorption Properties

Ahmad

Linh

Akimoto

et al. 2013

FSTR

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Water-insoluble gel was prepared from persimmon tannin (PT) solution by the autoxidation process. The gelation reaction proceeded by applying oxygen gas and natural light to the aqueous PT solution, without using harmful reagents or catalysts. Adsorption behavior of the PT gel was assessed using caffeine. Batch adsorption studies were conducted to evaluate the influence of experimental parameters such as contact time, initial concentration of adsorbates, adsorbent dose and temperature. The equilibrium data were analyzed using Freundlich and Langmuir isotherm models. Thermodynamic parameters such as Gibbs free energy, enthalpy, and entropy changes were also calculated, showing that caffeine adsorption on the PT gel is an exothermic process and feasible at lower temperatures. The present results suggest that the PT gel can be used as an effective adsorbent for removing caffeine from solutions.Keywords: adsorption, autoxidation, caffeine, gel, isotherm, persimmon tannin *To whom correspondence should be addressed. E-mail: loahmad@stu.kanazawa-u.ac.jp (L.O. Ahmad) kunimoto@se.kanazawa-u.ac.jp (K. Kimoto) IntroductionTannins are a group of polyphenol compounds that are distributed widely in many plant species, where they serve as defense mechanisms against predators. Persimmon fruits (Diospyros kaki L.) are rich in soluble and non-soluble condensed tannins (proanthocyanidins). Low molecular weight soluble tannins are believed to be responsible for the astringency of the persimmon fruit (Matsuo and Ito, 1978). Tannins are also known to form complexes and precipitates with macromolecules, such as proteins and polysaccharides, alkaloids, and heavy metals (Haslam, 1989).Chemical characterization of persimmon tannin (PT) has long been hampered because of its heterogeneous character and high molecular weight. Matsuo and Ito (1978) first reported on the composition and structure of persimmon condensed tannin. Their proposed structure consists of coupled flavan-3-ols, catechin, catechin-3-O-gallate, gallocatechin, and gallocatechin-3-O-gallate residues as the repeating units, with a molar ratio of 1:1:2:2, respectively. They also showed that the PTs are large molecular weight (ca. 13.8 kDa) polymers belonging to the proanthocyanidin B group, with carbon-carbon interflavan linkages between C-4 of one unit and C-8 (or C-6) of another. According to Xu et al. (2012), the stereochemistry of the flavan-3-ol unit of the PT is mainly 2,3-cis, which corresponds to epi-type catechins as shown in Fig. 1.Kaki-shibu, a fermented product made from the juice of immature astringent persimmons, is an important source of condensed tannins traditionally used in tanning paper (fiber hardening) and fishing nets (corrosion prevention), and for removing protein during the brewing of rice wine "sake" and soy sauce in Japan (Sugiura and Subhadrabandhu, 1996). PT gel was used in all adsorption experiments.A stock solution of caffeine (1,000 mg/L) was prepared by dissolving the required amount of caffeine in ultrapure water. The stock solution was ...

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“…However, as green tea catechins are characterized by strong bitterness and astringency, the development of products that can be consumed regularly is necessary for their efficient, routine intake. To date, research papers and patents concerning processing techniques, such as the masking of bitterness and astringency using cyclodextrin (Okumura et al, 2008(Okumura et al, , 2009Hayashi et al, 2010) and the suppression of bitterness and astringency with the addition of chitosan complex and soy milk protein, have been reported. However, the intrinsic taste and flavor of green tea may be impaired and the cost of manufacturing may be increased due to additives such as protein and chitosan.…”

Section: Introductionmentioning

confidence: 99%

Improvement of the Bitterness and Astringency of Green Tea by Sub-Critical Water Extraction

Miyashita

Etoh

2013

FSTR

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Green tea is known for its high content of functional catechins and is commonly consumed for its health-promoting effects. However, green tea catechins are highly bitter and astringent, and thus the development of products that can be consumed regularly is necessary for their efficient, routine intake. The aim of this study was to use sub-critical water extraction (SWE) to produce a green tea extract both less bitter and less astringent than typical green tea. Results from chemical evaluation using a taste sensor analyzer indicated that SWE reduced bitterness, astringency and unpleasant taste while it retained the original fragrance in the green tea extract. Furthermore, the SWE-produced extract had higher amounts of arginine and water-soluble pectin, which are thought to mask the bitterness and astringency of green tea.

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Effect of Cyclodextrins on the Thermal Epimerization of Tea Catechins

Cited by 13 publications

References 23 publications

Influence of Formulation and Processing on Absorption and Metabolism of Flavan-3-Ols from Tea and Cocoa

Influence of Formulation and Processing on Absorption and Metabolism of Flavan-3-Ols from Tea and Cocoa

Persimmon Tannin Gel: Formation by Autoxidation and Caffeine Adsorption Properties

Improvement of the Bitterness and Astringency of Green Tea by Sub-Critical Water Extraction

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