Rapid Spectrophotometric Determination of Caffeine

Ishler, N. H.; Finucane, T. P.; Borker, Emanuel

doi:10.1021/ac60024a010

Cited by 43 publications

(21 citation statements)

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“…Soluble solids were estimated by the method of Lockhart (5), using 15 ml. aliquots of the filtered brew Total soluble solids were estimated in the coffee grounds by the method of Lockhart Caffeine was estimated by the spectrophotometric method of Isliler, Iiiiiucanc, and Borker (2). For analysis of the coffee brew, 20 ml.…”

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confidence: 99%

EXTRACTION RATES FOR SELECTED COMPONENTS IN COFFEE BREW^a

Merritt

Proctor

1959

Journal of Food Science

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Knowledge of extraction rates for the major components of coffee in contact with water and the effect of time and temperature thereon is important to the coffee industry inasmuch as it would provide a more objective measure of cup quality which in turn would aid in the improvement of coffee as a beverage.Little basic information on extraction rates exists in the literature. Prescott (12) found that the best temperature range for a high quality coffce beverage lay between 185 -203" F. (85 -95" C.) and that the contact time between grounds and water should be relatively short. Under these conditions the caffeine was almost completely extracted and bitterness induced by temperatures at or near boiling and prolonged extraction was absent.Lockhart (5) noted that the rate at which each chemical component in coffee in contact with water is dissolved "is not only different but is directly dependent upon the temperature of the extraction." Natarajan, Nair, Rao, and Bhatia (11) found that extraction of chlorogenic acid varied with temperature; the higher the temperature the greater was the extraction of chlorogenic acid into the brew. Their observations were for a contact time of five minutes at temperatures of 209" F. (98" C.), 185" F. (85" C), and 167" F. (75" C).This report describes an investiagtion of extraction rates for selected components in coffee brew ; namely, soluble solids, color, caffeine, trigonelline, chlorogenic acid, and tannin for time intervals of 0.5, 1,2, 5, and 10 minutes, and for temperatures of EXPERIMENTAL Material. The coffee for this study was a "fine grind" ( 6 ) comniercial blend received from The Coffee Brewing Institute, Inc., vacuum-packed in one-pound cans. It was stored at a temperature of -20" F. (-29" C.). Samples were removed from the storage room and equilibrated for 24 hours at 36-40" F. (2-4" C.) before use.Preparation of brew. Brews were prepared with redistilled water in accordance with the formula recommendations of The Coffee Brewing Institute, Inc. (13). The water was heated to boiling in a 1500 ml. Pyrex beaker covered with aluminum foil, and then cooled to a temperature slightly higher than that desired for a given brew, in order to correct for the cooling effect of the coffee itself.The following chart gives the necessary information, found by experimentation, for obtaining a given brew temperature : Contribution No. 363 from the Department of Food Technology. Deceascd September 24, 1959. 735

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confidence: 99%

EXTRACTION RATES FOR SELECTED COMPONENTS IN COFFEE BREW^a

Merritt

Proctor

1959

Journal of Food Science

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“…Among the advantages proposed for fructose in this use are greater retention and utilization. Weichselbaum, Elman and Lund (1) reported lower total blood sugar levels and less urinary excretion in man with intravenous infusions of fructose as compared to glucose. However, Beal, et al ( 2 ) , found little difference in blood sugar levels in man after intravenous infusion of similar quantities of the two hexoses, and in contrast to the results of Weichselbaum's group, found greater quantities of reducing substances in the urine after fructose than after glucose.…”

Section: Blood Sugar Levels and Urinary Excretion Ofmentioning

confidence: 94%

“…An ultraviolet spectrophotometric method has been proposed by Ishler, Finucane, and Borker (1) for the determination of caffeine in coffee and Jones and Thatcher (2) have made a similar application to medicinals. No methods have appeared for the spectrophotometric determination of theobromine alone or in mixtures with caffeine.…”

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Analysis of Mixtures of Theobromine and Caffeine by Spectrophotometric Method

Miles

Englis²

1954

Journal of the American Pharmaceutical Association (Scientific

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“…Posteriormente, Holiday 18 descreveu que a cafeína apresentou um limite máximo de absorção no UV entre os comprimentos de onda de 271 e 275 nm. Ishler et al 19 desenvolveram um método espectrofotométrico de baixo custo para análise de cafeína em produtos do café. O extrato aquoso da matriz foi tratado com óxido de magnésio e ferrocianeto de zinco para remoção de trigonelina e outros compostos interferentes.…”

Section: Espectrofotometriaunclassified

Cafeína: revisão sobre métodos de análise

María¹,

Moreira²

2007

Quím. Nova

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Recebido em 19/8/05; aceito em 24/3/06; publicado na web em 30/8/06 ANALYTICAL METHODS FOR CAFFEINE. Gravimetric and Bailey-Andrew methods are tedious and provide inflated results. Spectrofotometry is adequate for caffeine analysis but is lengthy. Gas chromatography also is applied to the caffeine analysis but derivatization is needed. High performance liquid chromatography with ultraviolet detection (HPLC-UV) and reversed phase is simple and rapid for xanthine multianalysis. In HPLC-UV-gel permeation, organic solvents are not used. HPLC-mass spectrometry provides an unequivocal structural identification of xanthines. Capillary electrophoresis is fast and the solvent consumption is smaller than in HPLC. Chemometric methods offer an effective means for chemical data handling in multivariate analysis. Infrared spectroscopy alone or associated with chemometries could predict the caffeine content in a very accurate form. Electroanalytical methods are considered of low cost and easy application in caffeine analysis.Keywords: caffeine; methylxanthines; analytical methods. INTRODUÇÃOA cafeína é um alcalóide, identificado como 1,3,7-trimetilxantina, cuja estrutura contém um esqueleto de purina (Figura 1). Este alcalóide é encontrado em grande quantidade nas sementes de café (Coffee sp.) 1 e nas folhas de chá verde (Camilla sinensis) 2 . Também pode ser achado em outros produtos vegetais, particularmente no cacau (Theobroma cocoa) 3 , no guaraná (Paullinia cupana) e na erva-mate (Ilex paraguayensis) 2 . Embora uma parcela pequena da população consuma cafeína na forma de fármacos, como por ex. antigripais, grande parte deste alcalóide é ingerida na forma de bebidas. Uma xícara de café pode conter em média cerca de 80 mg de cafeína, enquanto uma lata de coca-cola em torno de 34-41 mg 4 .A cafeína é um dos alcalóides com atividade biológica mais ingeridos no planeta. Apresenta ação farmacológica variada provocando, dentre outros efeitos, alterações no sistema nervoso central, sistema cardiovascular e homeostase de cálcio. Os efeitos da cafeí-na sobre o comportamento humano têm sido objeto de estudos a algumas décadas. Esses efeitos podem ser descritos como 5-7 aumento da capacidade de alerta e redução da fadiga, com concomitante melhora no desempenho de atividades que requeiram maior vigilância. Em contrapartida, o consumo de cafeína pode afetar negativamente o controle motor e a qualidade do sono, bem como causar irritabilidade em indivíduos com quadro de ansiedade 6 . O efeito da ingestão de cafeína sobre o sistema cardiovascular ainda é motivo de grande controvérsia 8,9 . Seu consumo regular parece elevar a pressão arterial de forma persistente e, desta forma, indivíduos com hipertensão, doença coronariana e arritmia cardíaca deveriam ser encorajados a reduzir seus níveis de ingestão de cafeína [10][11][12] . Com relação à homeostase de cálcio, dados compilados em uma revisão indicam que a cafeína não é prejudicial ao metabolismo ósseo de indivíduos cujo consumo de cálcio é adequado as suas necessidades metabólicas 13 . ...

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Rapid Spectrophotometric Determination of Caffeine

Cited by 43 publications

References 9 publications

EXTRACTION RATES FOR SELECTED COMPONENTS IN COFFEE BREW^a

EXTRACTION RATES FOR SELECTED COMPONENTS IN COFFEE BREW^a

Analysis of Mixtures of Theobromine and Caffeine by Spectrophotometric Method

Cafeína: revisão sobre métodos de análise

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Rapid Spectrophotometric Determination of Caffeine

Cited by 43 publications

References 9 publications

EXTRACTION RATES FOR SELECTED COMPONENTS IN COFFEE BREWa

EXTRACTION RATES FOR SELECTED COMPONENTS IN COFFEE BREWa

Analysis of Mixtures of Theobromine and Caffeine by Spectrophotometric Method

Cafeína: revisão sobre métodos de análise

Contact Info

Product

Resources

About

EXTRACTION RATES FOR SELECTED COMPONENTS IN COFFEE BREW^a

EXTRACTION RATES FOR SELECTED COMPONENTS IN COFFEE BREW^a