Effect of thermal treatment on rutin content in selected buckwheat products using calcium as an internal tracer

Reversed-phase high-performance liquid chromatography (RP-HPLC) was used for rutin (quercetin-3-rutinoside) determination in selected buckwheat products (whole meal flour, broken seeds, seed hulls, herbs and baked cereal breads). The effect of various thermal procedures on content of rutin was evaluated using calcium as an internal tracker to correct changes in mass and composition of the buckwheat products. These factors are very seldom taken into account. The results show non-significant changes in rutin levels obtained in whole meal flour and broken seed samples after thermal treatment up to 150°C. Higher temperature already caused sudden fall in the observed rutin concentrations. The evaporation of some volatile compounds and degradation products can decrease the mass of the samples and formally increase the content of rutin (35.5 ±4.7 mg per 100 g for whole meal flour and 10.2 ±0.4 mg per100 g for broken seeds at 150°C). Serious decrease of rutin contents at elevated temperatures (>150°C) can be explained by its degradation (by breaking off the C-C bond in quercetin-3-rutinoside moiety) and/or evaporation (24.3 ±1.4 mg per 100 g for whole meal flour and 3.06 ±0.3 mg per100 g for broken seeds at 180°C). In case of baked cereal breads the level of rutin changed in dependence on the ratio between buckwheat and corn flour. Longer time leaching and higher temperature implicate higher rutin content in infusions prepared from buckwheat seed hulls and herbs

Effect of thermal treatment on rutin content in selected buckwheat products using calcium as an internal tracer

Reversed-phase high-performance liquid chromatography (RP-HPLC) was used for rutin (quercetin-3-rutinoside) determination in selected buckwheat products (whole meal flour, broken seeds, seed hulls, herbs and baked cereal breads). The effect of various thermal procedures on content of rutin was evaluated using calcium as an internal tracker to correct changes in mass and composition of the buckwheat products. These factors are very seldom taken into account. The results show non-significant changes in rutin levels obtained in whole meal flour and broken seed samples after thermal treatment up to 150°C. Higher temperature already caused sudden fall in the observed rutin concentrations. The evaporation of some volatile compounds and degradation products can decrease the mass of the samples and formally increase the content of rutin (35.5 ±4.7 mg per 100 g for whole meal flour and 10.2 ±0.4 mg per100 g for broken seeds at 150°C). Serious decrease of rutin contents at elevated temperatures ( > 150°C) can be explained by its degradation (by breaking off the C-C bond in quercetin-3-rutinoside moiety) and/or evaporation (24.3 ±1.4 mg per 100 g for whole meal flour and 3.06 ±0.3 mg per100 g for broken seeds at 180°C). In case of baked cereal breads the level of rutin changed in dependence on the ratio between buckwheat and corn flour. Longer time leaching and higher temperature implicate higher rutin content in infusions prepared from buckwheat seed hulls and herbs. © 2017 Potravinarstvo Slovak Journal of Food Sciences, License

Content of 4(5)-methylimidazole, caffeine and chlorogenic acid in commercial coffee brands

Content of 4(5)-methylimidazole (4-MeI), caffeine and chlorogenic acid in commercial coffee brands were determined using high-performance liquid chromatography (HPLC) with UV DAD and MS detectors. Positive ion ESI mass spectra of the 4-MeI standard yielded intense signals corresponding to [M+H]+ (83.0604) and [2M+H]+ ions (165.1115). Also, adducts of 4-MeI with acetonitrile from mobile were detected - [M+ACN]+ ions (124.0849). The LOD of 2.5 ng mL-1 and LOQ of 8.4 ng.mL-1 were calculated according to the following formulas: LOD = 3.SD/S, and LOQ = 10.SD/S, where S is the slope of the calibration curve and SD is the standard deviation of the noise. The caffeine content was compared to the results of the standard addition, 1st derivative and liquid-liquid extraction spectrophotometry. 4-MeI was in tens μg g-1 in the Vietnamese coffees while in units μg.g-1 in all Czech and Brazilian coffees (<2.4 μg.g-1 and <4.9 μg.g-1, respectively). The results for caffeine were within the documented range (0.31 - 2.20%) in all coffee samples. The lower content of caffeine and chlorogenic acid was observed in Vietnamese coffees. All the methods used for determination of caffeine in the Czech and Brazilian coffees gave acceptable precision and accuracy. However, there were significant differences in the results in Vietnamese coffees. The caffeine extractability (100 °C, 3 min brewing) almost reached 100% in Czech and Brazilian coffees, while it was less than 90% in Vietnamese coffees. The Czech and Brazilian coffees tend to produce more caffeine in brews than the Vietnamese coffee because of the different composition of blends and the particle size degree. © 2015 Potravinarstvo

Chemical composition of buckwheat plant parts and selected buckwheat products

Chemical composition plant parts (roots, stalks, leaves, blossoms) of common buckwheat (Fagopyrum esculentum Moench) and selected products made from its seeds (peels, whole seed, wholemeal flour, broken seeds, crunchy products Natural and Cocoa, flour, and pasta) was determined. Samples were dried and ground to a fine powder. All analyses were performed according to the Commission Regulation no. 152/2009, while rutin concentration was determined by the modified HPLC method. The lowest content of moisture was found in roots (4.3%) and in peels (almost 8%) and the highest moisture (nearly 11%) was discovered in seeds. The lowest amount of crude protein (3.5%) was found in peels, the highest crude protein amount (>13%) in both flours and leaves (23%). The starch content (>50% in dry matter) differs from one sample to another. Only in peels the content of starch was about 3.5%. From all examined samples, the lowest content of fat was found in crunchy products Cocoa, 1.7%. The lowest amount of histidine was determined in all studied samples, except peels, the highest content of glutamic acid was determined in almost all samples, except peels. Whole-meal flour is very rich source of Ca and Fe. The content of these elements was 1172 mg.kg-1 and 45.9 mg.kg-1, respectively. On the other hand, the highest content of Pb (>1 mg.kg-1) was found in broken seeds. The greatest concentration of rutin was determined in blossoms and leaves (83.6 and 69.9 mg.g-1), respectively. On the other hand, the lowest concentrations of rutin were found in buckwheat products (generally less then 1 mg.g-1, i.e. in wholemeal flour, 702 μg.kg-1, the lowest (almost 10 μg.kg-1) in pasta

Copper phosphinate complexes as molecular precursors for ethanol dehydrogenation catalysts

Nowadays, the production of acetaldehyde heavily relies on the petroleum industry. Developing new catalysts for the ethanol dehydrogenation process that could sustainably substitute current acetaldehyde production methods is highly desired. Among the ethanol dehydrogenation catalysts, copper-based materials have been intensively studied. Unfortunately, the Cu-based catalysts suffer from sintering and coking, which lead to rapid deactivation with time-on-stream. Phosphorus doping has been demonstrated to diminish coking in methanol dehydrogenation, fluid catalytic cracking, and ethanol-to-olefin reactions. This work reports a pioneering application of the well-characterized copper phosphinate complexes as molecular precursors for copper-based ethanol dehydrogenation catalysts enriched with phosphate groups (Cu-phosphate/SiO2). Three new catalysts (CuP-1, CuP-2, and CuP-3), prepared by the deposition of complexes {Cu(SAAP)}n (1), [Cu6(BSAAP)6] (2), and [Cu3(NAAP)3] (3) on the surface of commercial SiO2, calcination at 500 °C, and reduction in the stream of the forming gas 5% H2/N2 at 400 °C, exhibited unusual properties. First, the catalysts showed a rapid increase in catalytic activity. After reaching the maximum conversion, the catalyst started to deactivate. The unusual behavior could be explained by the presence of the phosphate phase, which made Cu2+ reduction more difficult. The phosphorus content gradually decreased during time-on-stream, copper was reduced, and the activity increased. The deactivation of the catalyst could be related to the copper diffusion processes. The most active CuP-1 catalyst reaches a maximum of 73% ethanol conversion and over 98% acetaldehyde selectivity at 325 °C and WHSV = 2.37 h-1CF BIC; European Regional Development Fund-Project “UP CIISB, (CZ.02.1.01/0.0/0.0/18_046/0015974, LM2018110); Grant Agency of Masaryk University, (CZ.02.01.01/00/22_008/0004572, MUNI/A/1298/2022, MUNI/J/0007/2021, QM4ST); Ministerstvo Školství, Mládeže a Tělovýchovy, MŠMT, (LM2018127, LM2023042, LM2023056, RP/CPS/2022/007); Grantová Agentura České Republiky, GA ČR, (GJ20-03636Y); Central European Institute of Technology, CEITECMEYS CR [LM2023042, LM2018127, CZ.02.1.01/0.0/0.0/18_046/0015974]; European Regional Development Fund-Project "UP CIISB" [LM2018110]; Czech Science Foundation [GJ20-03636Y]; Grant Agency of Masaryk University [MUNI/J/0007/2021, MUNI/A/1298/2022]; Quantum Materials for Applications in Sustainable Technologies (QM4ST) [CZ.02.01.01/00/22_008/0004572]; Ministry of Education, Youth and Sports of the Czech Republic [LM2023056]; Ministry of Education, Youth and Sports of the Czech Republic [RP/CPS/2022/007

Capillary electrophoresis fingerprinting and spectrophotometric determination of antioxidant potential for classification of Mentha products

In this work aqueous infusions from ten Mentha herbal samples (four different Mentha species and six hybrids of Mentha x piperita) and 20 different peppermint teas were screened by capillary electrophoresis with UV detection. The fingerprint separation was accomplished in a 25 mM borate background electrolyte with 10% methanol at pH 9.3. The total polyphenolic content in the extracts was determined spectrophotometrically at 765 nm by a Folin–Ciocalteu phenol assay. Total antioxidant activity was determined by scavenging of 2,2-diphenyl-1-picrylhydrazyl radical at 515 nm. The peak areas of 12 dominant peaks from CE analysis, present in all samples, and the value of total polyphenolic content and total antioxidant activity obtained by spectrophotometry was combined into a single data matrix and principal component analysis was applied. The obtained principal component analysis model resulted in distinct clusters of Mentha and peppermint tea samples distinguishing the samples according to their potential protective antioxidant effect. Principal component analysis, using a non-targeted approach with no need for compound identification, was found as a new promising tool for the screening of herbal tea products. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, WeinheimStudent project Grand at Masaryk University [MUNI/A/1500/2015

Comparison of Antioxidant Properties of Different Mentha Piperita Species and Commercial Teas by Capillary Zone Electrophoresis and Spectroscopy

A comparison of antioxidant properties of ten Mentha species and eleven commercially available peppermint teas was performed by electrophoretic fingerprinting of flavonoids and phenolic acids in aqueous infusions and by spectrophotometric determination of total polyphenolic content (TPC) and total antioxidant activity (TAA). Capillary zone electrophoresis with UV detection was used for measurement of fingerprints from the extracts. The antioxidant characteristics were determined by a spectrophotometric method using Folin-Ciocalteu, ABTS radical and DPPH methods. Significant differences were found among various Mentha species and also among different tea brands

Monitoring of HPLC profiles of selected polyphenolic compounds in sea buckthorn (Hippophaë rhamnoides L.) plant parts during annual growth cycle and estimation of their antioxidant potential

Presented work summarizes the data about polyphenolic profiles in various plant parts (leaves, shoots, berries) of sea buckthorn (Hippophaë rhamnoides L.) during the annual growth cycle. A reversed-phase high performance liquid chromatography method (RP-HPLC) coupled with diode-array detection (DAD) was optimized for determination of catechin, epicatechin, gallic acid, p-coumaric acid, caffeic acid, ferulic acid, rutin (quercetin 3-rutinoside) and quercitrin (quercetin 3-rhamnoside). The content of these polyphenolic compounds was monitored in extracts of sea buckthorn plant samples from April to October. The total antioxidant activity was determined using scavenging of 2,2-azino-bis(3-ethylbenzothiazoline-6-sulphonate) cation radical (ABTṠ+) and 1,1-diphenyl-2-picrylhydrazyl radical (DPPḢ). The total content of polyphenols was estimated by conventional spectrophotometric method using Folin-Ciocalteu reagent. The monitoring of temporal changes of selected polyphenolic compounds by RP-HPLC showed that catechin, epicatechin and gallic acid were the most abundant analytes in annual green shoots and leaves, and their content varied significantly during the studied period. © Versita Sp. z o.o

Analysis of organic acids, deacetyl asperulosidic acid and polyphenolic compounds as a potential tool for characterization of noni (Morinda citrifolia) products

Organic acids, deacetyl asperulosidic acid (DAA) and polyphenolic compounds in various noni (Morinda citrifolia L.) products (4 juices, 4 dry fruit powders and 2 capsules with dry fruit powder) were analyzed. Reversed-phase high-performance liquid chromatography (RP-HPLC) coupled with a variable wavelength detector (VWD) and electrospray ionization time-of-flight mass spectrometer (ESI-TOF MS) was applied for simultaneous analysis of organic acids (malic, lactic, citric and succinic acid) and DAA. An RP-HPLC method with diode-array detector (DAD) was developed for the analysis of polyphenolic compound content (rutin, catechin, quercitrin, kaempferol, gallic acid, caffeic acid and p-coumaric acid). The developed methods can contribute to better characterization of available noni products that is required from the consumers. In our study, we discovered significant dissimilarities in the content of DAA, citric acid and several phenolic compounds in some samples