scholarly journals Enhancement of Black Tea Aroma by Adding the β-Glucosidase Enzyme during Fermentation on Black Tea Processing

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Supriyadi Supriyadi ◽  
Alfrista Ruri Nareswari ◽  
Aprilia Fitriani ◽  
Rachmad Gunadi
Keyword(s):  
Volatile Compound ◽  
Methyl Salicylate ◽  
Sodium Citrate ◽  
Black Tea ◽  
Tea Leaves ◽  
Citrate Buffer ◽  
Sodium Citrate Buffer

Black tea aroma is one of the essential attributes in determining the quality of black tea. β-Glucosidases were investigated for their ability to enhance the aroma of black tea by hydrolyzing the glycoside compound. The addition of β-glucosidase was done by dissolving the enzyme on a sodium citrate buffer (pH 5.0), which was then sprayed on tea leaves during black tea processing. The β-glucosidase treatment significantly increases the volatile compound from glycoside precursors such as linalool, geraniol, and methyl salicylate. Moreover, the volatile compound from carotenoid and lipid precursors (nerolidol and β-cyclocitral) was also increased with β-glucosidase treatment.

scholarly journals PENGARUH UMUR DAUN TEH DAN WAKTU OKSIDASI ENZIMATIS TERHADAP KANDUNGAN TOTAL FLAVONOID PADA TEH HITAM (Camellia sinesis)

2021 ◽  
Vol 10 (1) ◽  
pp. 41
Author(s):  
Jennifer Larisa Liem ◽  
Maria Marina Herawati
Keyword(s):  
Black Tea ◽  
Total Flavonoid ◽  
Enzymatic Oxidation ◽  
Average Level ◽  
Flavonoid Compound ◽  
Total Flavonoids ◽  
Tea Leaves ◽  
Time Treatment ◽  
Oxidation Stage

Flavonoid compound is an important compound of tea products. However, the flavonoid level content in black tea is lowest than other teas. This is due to the processing of black tea which has an enzymatic oxidation stage and  the tea age leaves when picking. Young tea leaves contain higher total flavonoids than old tea leaves. With an average level of total flavonoids, the young tea leaves is 27.76% qe w / w, while for the old tea leaves 18.61% qe w / w. However, the enzymatic oxidation time treatment did not affect the total flavonoids because the process only affected the quality of black tea steeping, on it’s colour, aroma, and taste. Keywords: age of tea leaves, black tea, enzymatic oxidation, total flavonoids

Sodium citrate buffer

2009 ◽  
Vol 2009 (12) ◽  
pp. pdb.rec12040-pdb.rec12040
Keyword(s):  
Sodium Citrate ◽  
Citrate Buffer ◽  
Sodium Citrate Buffer

scholarly journals Impact of the mosquito bug (Helopeltis theivora) infestation on the quality of tea (Camellia sinensis)

2017 ◽  
Vol 44 (2) ◽  
pp. 197-207 ◽  
Author(s):  
Razia Sultana Chowdhury ◽  
Irin Siddiqua Moly ◽  
Mainuddin Ahmed ◽  
Mohammad Shameem Al Mamun ◽  
Md Mozammel Hoque ◽  
...  
Keyword(s):  
Black Tea ◽  
Quality Parameters ◽  
Physiological Parameters ◽  
Lower Amount ◽  
Tea Leaves ◽  
Helopeltis Theivora ◽  
Tea Mosquito Bug ◽  
Chlorophyll A And B ◽  
Physiological And Biochemical

The influence of tea mosquito bug (Helopeltis theivora) infestation on the physiological and biochemical changes in tea leaves as well as quality parameters of the made tea was investigated. Results revealed that physiological parameters such as polyphenol, chlorophyll a and b, carotenoids, catechins, reducing sugar and antioxidant activity reduced when the shoots are infested by tea mosquito bug. Black tea prepared from Helopeltis infested shoots contained significantly lower amount of theaflavin and thearubigin ratio, highly polymerized substances, total liquor colour, colour index, caffeine and lipid than that of uninfested fresh tea leaves. The infestation of tea mosquito bug significantly reduced the physiological parameters of tea leaves and quality parameters of made tea that hamper the quality of drinking tea.Bangladesh J. Zool. 44(2): 197-207, 2016

Studies of the chemoenzymatic modification of cellulosic pulps by the laccase-TEMPO system

Holzforschung ◽  
2011 ◽  
Vol 65 (4) ◽  
Author(s):  
Ilabahen Patel ◽  
Roland Ludwig ◽  
Dietmar Haltrich ◽  
Thomas Rosenau ◽  
Antje Potthast
Keyword(s):  
Sodium Citrate ◽  
Similar Reaction ◽  
Carbonyl Groups ◽  
Citrate Buffer ◽  
Hydroxymethyl Group ◽  
Mediator System ◽  
Sodium Citrate Buffer ◽  
Reaction Proceeds ◽  
Aldehyde Groups ◽  
Aqueous Conditions

Abstract The chemoenzymatic modification of cellulosic pulps by the laccase-mediator system (LMS) consisting of laccase (EC 1.10.3.2) and the 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO) has been investigated. The reaction proceeds under mild aqueous conditions (sodium citrate buffer pH 6, 30°C) and introduces primarily aldehyde groups into cellulose so that carboxyl groups amount to one-third to one-fifth of the carbonyl groups only. LMS treatment caused uniform oxidation of the material, also in the high-molecular weight area, which is a non-typical behavior compared to other chemical oxidations of cellulose. Treatment of the pulp only with TEMPO or only with laccase caused no changes whatsoever, whereas treatment with the TEMPO-derived oxoammonium ion (in the absence of laccase) introduced carbonyl groups into the pulp, but no carboxyls. This chemoenzymatic approach was compared to the well-known chemical approach by means of TEMPO and hypohalite. Both approaches yielded comparable distributions of functional groups at the low oxidation degrees studied, indicating a similar reaction mechanism with the TEMPO-derived oxoammonium ion being the actual oxidant. The laccase is able to generate this oxoammonium ion, which in turn oxidized the 6-hydroxymethyl group into the corresponding aldehyde.

scholarly journals Wells–Dawson phosphotungstates as mushroom tyrosinase inhibitors: a speciation study

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Raphael Lampl ◽  
Joscha Breibeck ◽  
Nadiia I. Gumerova ◽  
Mathea Sophia Galanski ◽  
Annette Rompel
Keyword(s):  
Inhibitory Activity ◽  
Sodium Citrate ◽  
Structural Integrity ◽  
Inhibitory Effect ◽  
Moderate Activity ◽  
Citrate Buffer ◽  
Speciation Study ◽  
Protonated Forms ◽  
Sodium Citrate Buffer ◽  
Low Charge

AbstractIn order to elucidate the active polyoxotungstate (POT) species that inhibit fungal polyphenol oxidase (AbPPO4) in sodium citrate buffer at pH 6.8, four Wells–Dawson phosphotungstates [α/β-PV2WVI18O62]6− (intact form), [α2-PV2WVI17O61]10− (monolacunary), [PV2WVI15O56]12− (trilacunary) and [H2PV2WVI12O48]12− (hexalacunary) were investigated. The speciation of the POT solutions under the dopachrome assay (50 mM Na-citrate buffer, pH 6.8; L-3,4−dihydroxyphenylalanine as a substrate) conditions were determined by 183W-NMR, 31P-NMR spectroscopy and mass spectrometry. The intact Wells–Dawson POT [α/β-PV2WVI18O62]6− shows partial (~ 69%) disintegration into the monolacunary [α2-PV2WVI17O61]10− anion with moderate activity (Ki = 9.7 mM). The monolacunary [α2-PV2WVI17O61]10− retains its structural integrity and exhibits the strongest inhibition of AbPPO4 (Ki = 6.5 mM). The trilacunary POT [PV2WVI15O56]12− rearranges to the more stable monolacunary [α2-PV2WVI17O61]10− (~ 62%) accompanied by release of free phosphates and shows the weakest inhibition (Ki = 13.6 mM). The hexalacunary anion [H2PV2WVI12O48]12− undergoes time-dependent hydrolysis resulting in a mixture of [H2PV2WVI12O48]12−, [PV8WVI48O184]40−, [PV2WVI19O69(H2O)]14− and [α2-PV2WVI17O61]10− which together leads to comparable inhibitory activity (Ki = 7.5 mM) after 48 h. For the solutions of [α/β-PV2WVI18O62]6−, [α2-PV2WVI17O61]10− and [PV2WVI15O56]12− the inhibitory activity is correlated to the degree of their rearrangement to [α2-PV2WVI17O61]10−. The rearrangement of hexalacunary [H2PV2WVI12O48]12− into at least four POTs with a negligible amount of monolacunary anion interferes with the correlation of activity to the degree of their rearrangement to [α2-PV2WVI17O61]10−. The good inhibitory effect of the Wells–Dawson [α2-PV2WVI17O61]10− anion is explained by the low charge density of its protonated forms Hx[α2-PV2WVI17O61](10−x)− (x = 3 or 4) at pH 6.8.

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