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Biogenic amines were determined by using high-pressure liquid chromatography during spoilage of raw Engraulis encrasicholus (anchovies), during ripening and shelf life. Histamine, cadaverine, tyramine, and putrescine were extensively formed at the beginning of spoilage, while β-phenylethylamine and tryptamine were formed only at advanced stages of spoiling. Serotonin, spermine, and spermidine levels were constant throughout spoilage. Seventeen lots of anchovies were evaluated through the typical ripening process. Each ripening process lasted 18 to 22 weeks, Only a slight formation of biogenic amines was observed during the first period of ripening (2 to 4 weeks). According to our results, ripening had little influence on the formation of amines, and therefore the amount of amines in the final products depends primarily on the levels of these substances in the raw material. During shelf-life studies, anchovies packed in brine were more stable, from the point of view of biogenic amine formation, than anchovies packed in oil. High formation of tryptamine and histamine was observed in both products when they were stored at room temperature. Refrigerated storage prevents amine formation.

Biogenic amine contents and microbial contamination (wild yeasts and lactic acid bacteria) were followed during beer fermentation in both industrial and pilot plants. No significant change in the amine contents was observed, except for tryptamine and tyramine. Tyramine formation showed a great variability (from 8 to almost 30 mg/l), while tryptamine formation was always much lower than tyramine (

Data de consum preferent; Data de caducitat; Aprofitament segur Fecha de consumo preferente; Fecha de caducidad; Aprovechamiento seguro Best-before date; Use-by date; Safe use El document revisa les causes, intrínseques i extrínseques, i els mecanismes de degradació dels aliments i el sistema de marcatge de dates als envasos. Segons aquesta revisió, estableix uns criteris i uns períodes per al consum i l’aprofitament segur i satisfactori dels aliments, un cop ha transcorregut la data que hi ha marcada. El documento revisa las causas, intrínsecas y extrínsecas, y los mecanismos de degradación de los alimentos y el sistema de marcaje de fechas en los envases. Según esta revisión, establece unos criterios y unos periodos para el consumo y el aprovechamiento seguro y satisfactorio de los alimentos, una vez ha transcurrido la fecha que hay marcada en el envase. The present document reviews intrinsic and extrinsic causes as well as food spoilage mechanisms and the date mark system on packaging. Based on this review, it establishes a few criteria and periods for safe and satisfactory use and consumption of food, after the date marked on the package has expired.

Here, we report on the optimisation and validation of a liquid chromatographic method for the determination of 12 biologically active amines from vegetal food products in a single 40-min run. The suitability of the method was checked in five vegetal products of distinct matrix: spinach (leaves), hazelnut (high protein and fat content), banana, potato (high starch content), and milk chocolate (processed). Sample preparation consisted of a 0.6 M perchloric acid extraction from a minced homogeneous aliquot. For samples with high starch content, a previous mild hydrolytic treatment was required to prevent gel formation. The range of linearity was from 0.1 to 10 mg/l, except for serotonin and spermine (from 0.5 to 10 mg/l), and the correlation coefficient was higher than 0.997 (P < 0.001) for all standard curves. The detection limits and the determination limit were below 0.07 and 0.2 mg/l, respectively, except for spermine, which was 0.14 and 0.4 mg/l. The precision of the method was satisfactory; the relative standard deviation obtained for each amine in each product was acceptable according to Horwitz. Recovery was between 77 and 110% for all amines, irrespective of the product.

The distribution of biogenic aromatic amines, and also those of aliphatic diamines and polyamines, in red and white Spanish wines, was examined. Moreover, a study was carried out to determine whether the degree of irrigation affects the endogenous amine contents in grape as well as its evolution during the winemaking process. Amine levels were variable, ranging from not detected to 100 mg/l. Putrescine, which constituted the major amine, tyramine and histamine contents were significantly higher in red than in white wine. The aromatic phenylethylamine, and the aliphatic cadaverine, agmatine, spermine and spermidine, were detected in very low amounts in a few samples. Both, diamines and polyamines, were the only amines observed in grape samples, showing similar levels, irrespective of the water-stress degree, and their levels decreased significantly during winemaking. Most probably, the low levels of di- and polyamines in wine arise from those endogenously found in grape berries and the water-stress does not seem to be a factor influencing the contents.

Amounts of volatile and biogenic amines, pH and microbial counts were monitored in Mediterranean anchovy (Engraulis encrasicholus) over 23 days of ice storage with the aim of examining their suitability as indicators of freshness. Counts of Enterobacteriaceae reached the maximum limits stipulated by Spanish regulations after 5 days of storage in ice, while those of mesophilic bacteria took 7 days. Levels of volatile amines hardly increased during ice storage. Amounts of biogenic amines did increase, though there were differences from one amine to the other. Cadaverine, the most abundant biogenic amine, showing the earliest increase, coinciding with the shelf-life time as determined through Enterobacteriaceae counts. Amounts of histamine remained below the maximum levels established by both European Union and Food and Drug Administration regulations. Other biogenic amines were found at much higher levels than histamine. Results demonstrated the suitability of the biogenic amine index (as the sum of histamine + tyramine + putrescine + cadaverine) as a freshness indicator for anchovies stored in ice, with a limit of acceptability set at 15 mg kg−1. Copyright © 2005 Society of Chemical Industry

Volatile and biogenic amines from three batches of anchovies, marinated in vinegar, were studied. The anchovies had been vacuum-packed and kept in refrigerated storage for 3 months. Trimethylamine and total volatile basic nitrogen levels were very low and constant throughout marinating and storage process: less than 1 and 10 mg/100 g, respectively. Certain amine levels, mainly those of tyramine and serotonin, increased slightly, particularly during storage. However, even the highest recorded levels were much lower than those considered to be hazardous for human consumption. To study the influence of raw material freshness in the amine profile, two laboratory trials using fresh and spoiled anchovies and simulating the industry standard marinating process were carried out. Levels for both volatile and biogenic amines were dependent on raw material quality, proving consistently higher in those deriving from nonfresh fish. Vinegar marinating leads to a decrease in the accumulation of amines in anchovy while their concentration in the vinegar solution increases due to the vinegar effect as solvent extractor.

Biogenic amine formation in tuna inoculated with two micro-organisms reported as powerful in vitro histamine producers, Morganella morganii and Klebsiella oxytoca, was investigated. Inoculated and non-inoculated tuna samples were stored in ice, under refrigeration at 8–10 °C and at 20±1 °C. Ten biogenic amines were studied and changes were found only in cadaverine and histamine in inoculated samples. Therefore, the in vitro ability of K. oxytoca to form cadaverine and that of both microorganisms to form histamine was confirmed in inoculated samples. Storage temperature had a crucial effect on the amount and intensity of amine production. On the other hand, the potential ability of M. morganii to form putrescine was not shown in the inoculated samples, regardless of the storage temperature.

An optimised ion-pair reversed-phase high-performance liquid chromatographic method with automatic o-phthalaldehyde post-column derivatization and spectrofluorometric detection for the same-run separation and quantification of 12 biogenic amines and polyamines in alcoholic beverages has been validated. The reliability of the method was satisfactory in terms of linearity (from 0.5 to 15 mg/l), precision (relative standard deviation below 5%), recovery (from 98.7 to 101.1%), and sensitivity (detection limit between 0.03 and 0.06 mg/l). The automatic accomplishment of the derivatization step reduces time and effort of analysis, especially thanks to the easy preparation of the sample.

Se comenta la posible necesidad, conveniencia y/u oportunidad de la suplementacion de alimentos con nutrientes u otros productos con actividad biologica y las repercusiones de su consumo en el organismo. Se exponen algunos ejemplos de suplementaciones de alimentos, destacando las razones que pueden justificarla y los efectos beneficiosos que se pretende alcanzar; pero tambien, si los hubiera, los aspectos mas controvertidos que de tal suplementacion podrian derivarse. No se ha pretendido exhaustividad sino que se han escogido algunos ejemplos suficientemente significativos.

Two infant milks claimed to have the same final composition in liquid and powdered form respectively were stored for 12 mo at 20, 30, and 37 °C. Vitamin E, thiamin, riboflavin, pyridoxine, folic acid, and nictoinamide remained constant at the three temperatures. However, there were statistically significant losses of vitamin A (approximately 35%) in samples stored at 37 °C. No differences were observed in vitamin stability between the two infant milks studied. Final levels of vitamin A were always higher than the minimum set by Spanish legislation. Vitamin A overfortification (approximately 200%) was more than that needed to compensate for losses during storage.

Changes in tyramine, in its precursor amino acid tyrosine, and in Pediococcus spp. were followed during 54 beer fermentations. No statistical relationship between tyramine production and wort tyrosine levels was found, either between the amount of tyramine formed or the decrease in tyrosine through beer fermentation. However, tyramine formation significantly correlated with Pediococcus spp. contamination (r=0.876; P

Two methods for the extraction of fat from powdered infant milk were compared. The methods were: (i) a cold method which involves an extraction with pentane and (ii) a modification of the Pont method, which involves the heating of the sample. Peroxide values were used in order to compare the oxidation effect of the two methods. The modified Pont method provided statistically higher values of peroxides (P

Changes in furfural compounds and reactive lysine were monitorized in three commercial liquid infant milks during 9 months of storage at 20, 30, and 37 degrees C. Samples consisted of two ultrahigh temperature (UHT)-treated milks and one conventionally sterilized milk. Reactive lysine remained constant throughout storage at the three temperatures, whereas, in general an increase in furfural compounds was observed. The heat treatment used in the manufacture of milk is an important factor that influences the levels of furfural compounds although the composition of the milk is also a critical factor. Finally, a study was conducted to find the kinetic equations describing furfural compounds changes and allowing for the prediction of the influence of time and temperature of storage on those changes.

The progress of the Maillard reaction in two infant milks (liquid and powdered forms of the same commercial brand) was monitored for 9 months of storage at 20, 30, and 37 °C. An increase in furfura...

The concentrations of 10 biogenic amines were determined in fresh tuna (n = 20) and canned tuna (n = 38) purchased in Spain and also in samples taken at 5 stages of 12 canning processes (n = 60). Spermine and spermidine were the only amines found in all samples but were lower in canned than in fresh tuna samples (p < 0.05). The Food and Drug Administration legal limit for histamine (50 μg/g) was not exceeded in any samples, and the levels of the other biogenic amines commonly related with fish spoilage were, in general, low in all samples studied; no significant difference was found between fresh and canned tuna. Results showed that both the inosine monophosphate ratio and certain biogenic amines could be useful as quality indicators for the raw fish used in canned tuna, since no change was observed throughout the canning process, except for spermine and spermidine. Decreases in both spermine and spermidine were significant only after the sterilization step, which is in agreement with the significant diff...

Objectives: Study was conducted in order to investigate the association of vitamin E intake and other factors with plasma α-tocopherol concentration in a non-smoking Mediterranean population. Design: A cross-sectional study was conducted in a subsample of a representative sample of the Catalan population. Subjects: Sample size was 143 men and women, aged between 18 and 75 y, and final response rate reached 61.9% of the initial sample. Interventions: Serum alpha-tocopherol concentration standardized by serum total lipids was used as a proxy of the nutritional status of vitamin E. Vitamin E intake and alcohol consumption were estimated by a replicated 24 h recall method. Dietary data were collected in two different periods, winter and summer, in order to account for seasonal variation in nutrient intake, and were corrected for random within-person variability in order to account for day-to-day variation in nutrient intake. Multivariate linear regression models were fitted in order to estimate the determinants of serum α-tocopherol concentration. Results: In this population study, for each one mg increase in vitamin E intake, serum α-tocopherol concentration increased, on average, 0.66 micromol/L, after adjusting for age, gender, Body Mass Index (BMI), alcohol consumption and energy intake. BMI also influenced significantly serum α-tocopherol concentration, whereas alcohol intake, age and gender did not show significant associations with serum α-tocopherol. Conclusions: The study showed that vitamin E nutritional status was associated to vitamin E intake and BMI in non-smokers. Sponsorship: This study was supported by a research agreement between the Department of Health of the Autonomous Government of Catalonia and the Bosch Gimpera Foundation of the University of Barcelona (Contract 2415/95).

Biogenic amines and polyamines in meat and meat products were determined by HPLC. Spermine and spermidine were the only amines always detected in meat and meat products, ranging from 6.4 to 62.1 mg/kg for spermine and from 0.7 to 13.8 mg/kg for spermidine. Tyramine, histamine, putrescine, and cadaverine contents varied greatly, especially in ripened products and even among samples from the same commercial brand. Biogenic amines in cooked products were, in general, lower than 10 mg/kg, whereas 40% of ripened products reached levels above 300 mg/kg. Amine content in dry-cured ham was similar to those found in cooked products. High amounts of biogenic amines in some cooked products could be related to the use of low hygienic quality meat. Besides the contribution of the raw materials, amine formation can occur during the fermentative-ripening process. Adverse reactions due to interaction between monoamine oxidase inhibitors drugs and tyramine are expected in ripened products. Keywords: Biogenic amines; meat;...

Anchovies are a semipreserved fish product obtained without heating, and for this reason contents of biogenic amines could be modified during its storage. Changes of 10 biogenic amines during the s...

Ten biogenic amines in Spanish beers were studied using HPLC, Agmatine, tyramine and putrescine were the prevailing amines, while histamine, beta-phenylethylamine, tryptamine, cadaverine, spermine and spermidine were detected at relatively low levels (in general2 mg/l). On the basis of the wide range of levels observed for tyramine (from 1.90 to 31.55 mg/l), the consumption of beer requires restriction in patients receiving monoamine oxidase inhibitor drugs. Biogenic amine levels in beers of the same type from the same company and from different companies were monitored every month over 1 year. Agmatine and putrescine levels showed minimal fluctuations in beers from the same company as well as from different breweries. Raw materials and brewing conditions would not affect the levels of those amines. However, tyramine levels were subject to wide fluctuations in beers produced by particular breweries irrespective of whether they were produced by the same company. Relatively high levels of tyramine were specific to some breweries.

Biogenic amines (histamine, tyramine, β-phenylethylamine, serotonin, tryptamine, putrescine, cadaverine, agmatine, spermine and spermidine) in raw materials, worts and beers, and their evolution during brewing were studied using HPLC. Hop and especially malt contributed to amine contents in wort and beer. Amines were not detected in rice, used as adjunct cereal. High amine production was found during malting. Spermine and spermidine levels decreased sharply during mashing, while the other amines increased, except for putrescine that did not vary. No significant changes in formation of amines occurred during fermentation, except for tryptamine and tyramine. Tyramine formed ranged from 9.70 to 27.30 mg/L.

A liquid chromatographic method is described for the determination in one run of the following 10 biogenic amines in beers: histamine, tyramine, serotonin, (β-phenylethylamine, tryptamine, cadaverine, putrescine, agmatine, spermine, and spermidine. The method is based on ion-pair chromatographic partition on a reversed-phase column and involves a postcolumn reaction with o-phthalaldehyde (OPT) to form fluorescent derivatives with amines. Treatment of beer samples before injection requires only a filtration through a 0.45 μm filter. It is necessary to obtain a perchloric extract for analysis of raw materials (malt and hops). The method was tested for lack of interference from amino acids and other amines. Linearity, precision, recovery, and sensitivity were satisfactory. Detection limits ranged from 0.30 to 0.40 mg/L, and determination limits ranged from 0.40 to 0.50 mg/L, except for serotonin and spermine, which were slightly higher. The simple preparation of sample and the automatic accomplishment of derivatization steps considerably reduce analysis time and effort.

Chemical and microbiological parameters were studied during the industrial production of salt-ripened anchovies (Engraulis encrasicholus). Gradual acidification and increases in the proteolysis index and in total volatile basic nitrogen were observed. At the end of the maturing process, the values reached pH 5.55 +/- 0.03, 21.33 +/- 5.82%, and 44.06 +/- 12.47 mg/ 100 g, respectively. In the three studied anchovy batches, the biogenic amines tyramine, histamine, putrescine, cadaverine, and agmatine increased during ripening. The highest values were found in the batch where initial microbial load was highest (batch 1), especially for enterobacteria and enterococci. Tyramine was the most abundant amine, reaching values from nondetectable to 90 mg/kg, whereas histamine did not surpass 20 mg/kg. Among the microorganisms isolated, Enterobacter cloacae, Aerococcus viridans, Kocuria varians, and Staphylococcus chromogenes were able to decarboxylate amino acids and produce biogenic amines in vitro. Most (70.59%) of the microorganisms identified were able to produce histamine, 23.53% were able to produce the diamines putrescine and cadaverine, and only 11.76% were able to produce tyramine, although this substance was the major biogenic amine found in anchovy samples.

A preliminary study of the evolution of histamine and tyramine during a brewing process was carried out. A clear formation of tyramine was observed during the main fermentation (from 2·5 to 40·5 mg/litre), but histamine formation was negligible in this same period. Good correlations (p < 0·001) were found between formation of tyramine and alcoholic content, and between this amine and apparent extract during the main fermentation. In addition, a statistical comparison was done of the biogenic amine contents in 64 samples corresponding to the four types of beer established by the Spanish law on the basis of their extract of original wort and their alcoholic content. No significant statistical differences were found between the histamine and tyramine contents in the four types of beer (p = 0·05).

Histamine and tyramine contents in 226 and 186 Spanish wine samples, respectively, have been studied employing spectrofluorometric methods. The average content of histamine in red wines (4·07 mg/liter) proves to be higher than in white wines (0·81 mg/liter) and rose wines (0·86 mg/liter). The average content of tyramine was also higher in red wines (3·03 mg/liter) than in white (1·49 mg/liter) and rose ones (1·66 mg/liter). Relationships are studied between the contents of these amines and that of total sulfur dioxide and volatile acidity, as well as with the intensity of malo-lactic fermentation. Our results, in general, show that (a) the highest levels of both amines occur in red wines with low concentrations of total sulfur dioxide, (b) white and rose wines with high volatile acidity show higher levels of these amines than wines with low volatile acidity, and (c) in all wines highest levels of amines correspond to wines with a stronger malo-lactic fermentation.

Biogenic amines in processed meat products can be useful as indices of poor-quality raw material, but they can also be related with microbial activity involved in fermentation processes. This paper provides new data on this topic. Histamine, tyramine and pH changes were followed during storage/spoilage of beef and pork at both room and refrigerated temperatures. A notable increase in the content of amines was observed at both temperatures studied. A greater and more rapid formation of histamine and tyramine took place in pork than in beef. The increase in the amines occurred before the increase in pH value. A preliminary study about the influence of ripening on histamine and tyramine contents was also carried out. This process seems to exert a greater influence on histamine than on tyramine content. Finally, the histamine and tyramine contents of 63 Spanish meat products were determined. Both amines were detected in all samples, but concentrations varied greatly. Uncooked and ripened meats showed statistically significant higher amounts of both amines than cooked meat products. In cooked meat products, histamine values ranged from 0·25 to 3·90 mg/kg and tyramine from 0·50 to 25·6 mg/kg. For uncooked and ripened meat products, the range of histamine was from 0·25 to 249 mg/kg and of tyramine from 0·45 to 510 mg/kg.

Biogenic amines and polyamines were studied in 18 market samples of spinach. Histamine and spermidine were detected in relatively high amounts in all samples within the ranges of 9.5-69.7 and 15.6-53.0 mg/kg, respectively. Other biologically active amines were either detected at low levels or not found at all. Changes in amine content during storage at 6 degrees C were studied. The content of most of the amines remained constant during storage, with the exception of spermidine and histamine. Spermidine showed a clear decreasing trend, whereas histamine significantly increased in all trials, but decreased at the end of the storage in two of the trials. Trials showing a decrease in histamine content also showed the highest spermidine decrease and recorded the highest pH values. Microbial loads throughout storage were also followed, with Pseudomonadaceae and Enterobacteriaceae being the predominant bacterial groups. Trials with higher microbial loads in initial samples also showed the highest histamine content in these samples. Potential explanations for both the formation and the degradation of histamine during storage are discussed.

Se define, identifica y explica para qué sirven y cómo funcionan en nuestro organismo los alimentos funcionales, y se alerta contra los abusos publicitarios. Cataluña ESP

Resumen del autor en catalán Se reflexiona sobre que los escándalos alimentarios debidos al mal uso de las tecnologías convencionales hacen que se reitere la conveniencia de obtener alimentos según aquello que se entiende por procesos naturales, que muchos llaman biológicos. Hace falta precisar términos. Todos los alimentos son biológicos, ya que resultan procesos ligados a la vida, aunque se hayan utilizado pesticidas, por ejemplo. Nadie puede, desde una perspectiva científica, reclamar para sus productos el uso exclusivo del término biológico, orgánico o ecológico. Cataluña ESP

The reliability of flow injection/gas diffusion (FIGD) methods to determine trimethylamine (TMA-N) and total volatile basic nitrogen (TVB-N) in hake was studied in order to find an alternative and accurate, simple, cheap, and rapid method for non-protein nitrogen determination. FIGD methods involved extracting volatile amines with 7.5% trichloroacetic acid, followed by the injection of the extracts into the FIGD manifold, previously adjusted for TMA-N or TVB-N determinations. Each determination took approximately 2 min. Reliability was satisfactory in linearity, precision, recovery, and sensitivity. There was good correlation (p0.001) between FIGD and the classic official methods, for both TMA-N and TVB-N determinations, and also between FIGD and the gas chromatographic procedure described for TMA-N. These results proved that FIGD methods are simpler, cheaper, and faster than current official procedures. To check the suitability of FIGD procedures over a wide range of analyte concentrations, changes of both TMA-N and TVB-N and the P ratio values throughout the ice storage of hake were monitored. The usefulness of each of these potential freshness indicators for hake is discussed.

The stability of the water-soluble B vitamins and the fat-soluble vitamins A and E of three liquid infant milks was followed throughout 12 months of storage at 20, 30 and 37 °C. Two samples were ‘follow-on’ milks from two different manufacturers and the other a ‘junior’ milk from one of these. The levels of water-soluble vitamins and vitamin E remained constant during storage at the three temperatures. In contrast, vitamin A decreased in samples from one manufacturer at all storage temperatures, and in samples from the other only at 37 °C. A kinetic equation was derived that made it possible to predict the influence of storage temperature on the shelf life of these kinds of products, together with the storage period during which levels of vitamin A recommended as adequate would remain.

A method has been developed for spectrofluorometric determination of histamine in fish and meat products. After a perchloric extract Is obtained from samples, histamine Is extracted with n-butanol and transferred to hydrochloric acid. Finally, histamine Is subjected to a condensation reaction with o-phthalaldehyde (OPT). The method was tested for lack of interference from other amines. Precision of the method In fish products was 6.60% CV; recovery was 96.50%. In meat products, precision was 5.42% CV; recovery was 96.20%. By analysis of variance (P = 0.05), no significant statistical differences were found for recovery values vs histamine content In both foods.

This article examines the origins of the Mediterranean diet, tracing them back to the great classic cultures of ancient times. It then describes what we understand today as being the Mediterranean diet and analyses the nutritional value of the foods that make up the diferent types of Mediterranean diet. Finally, while not suggesting that this diet is a panacea, it is argued that it is suflciently balanced and varied to make it a healthy option., Se realiza un análisis de los orígenes de la dieta mediterránea, los cuales se remontan a las grandes culturas clásicas de la Edad Antigua. Además, se describe lo que hoy en dia cabe entender como dieta mediterránea y se analiza el valor nutritivo de los alimentos que integran los diversos tipos de dietas mediterráneas. Finalmente, se realizan algunas consideraciones sobre la bondad de la dieta mediterránea, que, sin ser una panacea, es lo suficientemente equilibrada y agradable para considerarla saludable.

A rapid, simple and reliable liquid chromatographic method has been developed for the simultaneous determination of nicotinamide, thiamin, riboflavin, pyridoxine, pyridoxal, pyridoxamine, cyanocobalamine and folic acid in liquid and powdered infant milk. Ion-pair chromatography with a reversed-phase C18 column is used. Six vitamins were resolved in a single analysis; total analysis time never exceeded 55 min. A mobile phase of methanol-water (15:85), 5 mM octanesulfonic acid, with 0.5% triethylamine at pH 3.6 and a flow-rate of 1.0 ml/min gave the most satisfactory separation of these vitamins using a UV detector set at different wavelengths. Sample preparation involves acidification to precipitate proteins, and centrifugation followed by gravity filtration. Linearity, precision, recovery and sensitivity were always satisfactory. Detection limits ranged from 0.02 to 0.10 microgram/ml and determination limits ranged from 0.03 to 0.25 microgram/ml.

A high-performance liquid chromatographic (HPLC) method was developed for the determination, in one run, of retinol and alpha-tocopherol in infant milk formulae. The method involved saponification at room temperature and a later extraction of vitamins with n-hexane. The vitamins were resolved with a C18 reversed-phase column and they were detected by UV spectrophotometry. Linearity, precision, recovery and sensitivity were satisfactory. The main advantage of the method proposed is the simultaneous determination of both vitamins using a common extraction procedure and UV detection with a variable-wavelength spectrophotometer.