Detection of key factors in the extraction and quantification of lycopene from tomato and tomato products

The analytical process of lycopene extraction and photometrical determination was critically examined for raw tomato and processed tomato products by means of a 2 IV (15-10) Plackett-Burman experimental design in order to identify the key factors (KFs) involved. Fifteen apparent key factors (AKFs) reported in the literature were selected: sample weight (X1); volume of extraction solution (X2); antioxidant concentration (BHT, X3); neutralizing agent concentration (MgCO 3, X4); light presence during lycopene extraction (X5), homogenization velocity (X6) and time (X7), agitation time (X8), and temperature (X9) during the extraction process; water volume for separation of polar/nonpolar phases (X11); presence of inert atmosphere throughout the process (X12); time (X13), temperature (X14), and light presence (X10) during separation of phases and time delay for reading (X15). In general, higher lycopene concentrations in samples led to a higher number of key factors (KF). Thus, for raw tomato (lycopene range 1.22-2.29 mg/100 g) no KF were found, whereas for tomato sauce (lycopene range from 5.80 to 8.60 mg/100 g) one KF (X4) and for tomato paste (lycopene range from 35.80 to 51.27 mg/100 g) five KFs (X1, X2, X4, X11, and X12) were detected. For lycopene paste, X1 and X2 were identified as the KFs with the greatest impact on results, although in fact the X1/X2 ratio was the real cause. The results suggest that, with increased processing, the physical and chemical structure of lycopene becomes less important since the identified KFs explain almost 90% of variability in tomato paste but only 32% in raw tomato.     

Characterization of high purity lycopene from tomato wastes using a new pressurized extraction approach

In this paper, a method for the extraction of high purity lycopene from tomato wastes is presented. The method is based on a pressurized extraction that uses the Extractor Naviglio, and it is performed in the 0.7-0.9 MPa range. Tomato skin, the byproduct deriving from manufacturing of tomato, in a water dispersion, are used as starting material. Lycopene is transferred, for the effect of the high pressure used, in the form of molecular aggregates into the water as a dispersion, while apolar compounds remain in the matrix. The aggregates are easily purified in a single subsequent step by using methanol, thus, obtaining lycopene at 98% chromatographic purity or higher. A new stationary phase, phenyl-hexyl silicone, and a simple water/acetonitrile gradient were used for HPLC analysis of lycopene. The extract was characterized by UV-Vis spectrophotometry, (1)H NMR, (13)C NMR, and electrospray ionization mass spectrometry. An average recovery of 2.8 mg lycopene/kg tomato waste can be obtained after 4 hours of extraction and using tap water as the extracting liquid. The recovery percentage was of about 10%. The exhausted tomato byproduct can be easily dried and used in agriculture or as feeding for animals.     

Seasonal variations in the level of plant constituents in greenhouse production of cherry tomatoes

The content of selected plant constituents was measured in cherry tomatoes (Lycopersicon esculentumMill. cv. Jennita) during conventional Norwegian tomato production in a greenhouse from May until October 2004. Samples were collected according to standard production procedure with orange-yellow colored fruits at weight in the range of 12.4-19.3 g and size in the range of 28.9-33.0 mm (diameter). The content of selected compounds based on 100 g FW were found to vary in the following range during the season: 7.38-28.38 mg of chalconaringenin, 0.32-0.92 mg of rutin, 0.24-1.06 mg of chlorogenic acid, 5.60-20.02 mg of ascorbic acid, 1.60-5.54 mg of lycopene, and 0.37-0.55 mg beta-carotene. Only minute amounts of naringenin together with kaempferol 3-rutinoside and caffeic acid, which previously have been reported from tomatoes, were detected. The content of chalconaringenin to rutin and that of lycopene to beta-carotene showed a strong correlation during the season (p < 0.001). The content of total phenolics and methanol-soluble antioxidants also showed a correlation (p < 0.001), and were found in the range 14.6-32.6 mg of gallic acid equivalents (GAE)/100 g fresh weight (FW) and 445-737 micromol of Fe(II)/100 g FW, respectively. Seasonal variation in the level of plant constituents is shown to be related to photon flux density and fertilization level.     

Browning indicators in bread

Bread is the most important food in the Spanish household and represents the largest proportion of products produced by commercial bakeries. The browning indicators furosine, hydroxymethylfurfural (HMF), and color were determined to evaluate heat effects induced during manufacture of these foods. The breads analyzed were common, special, sliced toasted, and snack breads. Identical sample preparation and HPLC conditions were used to determine HMF in all breads. The precision tested at high and low HMF concentration in breads was 2.60% and 1.57%, respectively. Recovery of HMF was 96.2%. The HMF values ranged from 2.2 to 68.8 mg/kg. Color index (100 - L) ranged from 17.0 to 38.2. The linear correlations (r(2)) between 100 - L/HMF were above 0.70 for common, special, and snack breads. Similar correlation was obtained between 100 - L/HMF in a dough baking at different times. The furosine content in common bread ranged between 125 and 208 mg/100 g of protein. No linear correlation was found between furosine and HMF. Moreover, HMF and furosine were also determined in crumb and crust. Levels of HMF had a wide range (0.9-1.76 mg/kg) and furosine was between 43 and 221 mg/100 g of protein.     

Liquid chromatography-mass spectrometry of cis- and all-trans-lycopene in human serum and prostate tissue after dietary supplementation with tomato sauce

Several epidemiological studies suggest a lower incidence of prostate cancer in men who routinely consume tomato products. Tomatoes are the primary dietary source of lycopene, which is among the most potent antioxidants of the carotenoids. Men with clinical stage T1 or T2 prostate adenocarcinoma were recruited (n = 32) and consumed tomato sauce based pasta dishes for 3 weeks (equivalent to 30 mg of lycopene per day) before radical prostectomy. Prostate tissue from needle biopsy just before intervention and prostectomy after supplementation from a subset of 11 subjects was evaluated for both total lycopene and lycopene geometrical isomer ratios. A gradient HPLC system using a C(18) column with UV-vis absorbance detection was used to measure total lycopene. Because the absorbance detector was insufficiently sensitive, HPLC with a C(30) column and positive ion atmospheric pressure chemical ionization mass spectrometric (LC-MS) detection was developed as a new assay to measure the ratio of lycopene cis/trans isomers in these samples. The limit of detection of the LC-MS method was determined to be 0.93 pmol of lycopene on-column, and a linear response was obtained over 3 orders of magnitude. Total lycopene in serum increased 2.0-fold from 35.6 to 69.9 microg/dL (from 0.664 to 1.30 microM) as a result of dietary supplementation with tomato sauce, whereas total lycopene in prostate tissue increased 3.0-fold from 0.196 to 0.582 ng/mg of tissue (from 0.365 to 1.09 pmol/mg). all-trans-Lycopene and at least 14 cis-isomer peaks were detected in prostate tissue and serum. The mean proportion of all-trans-lycopene in prostate tissue was approximately 12.4% of total lycopene before supplementation but increased to 22.7% after dietary intervention with tomato sauce. In serum there was only a 2.8% but statistically significant increase in the proportion of all-trans-lycopene after intervention. These results indicate that short-term supplementation with tomato sauce containing primarily all-trans-lycopene (83% of total lycopene) results in substantial increases in total lycopene in serum and prostate and a substantial increase in all-trans-lycopene in prostate but relatively less in serum.     

Determination of vitamin B(6) in cooked sausages

A reverse-phase high-performance liquid chromatography (HPLC) method has been described for the determination of various active forms of vitamin B(6) in meat products. Different extracting agents were tested to solubilize fully the analyte for quantification. The best data were obtained by extracting the samples with 5% (w/v) metaphosphoric acid. Separation by HPLC was performed with fluorescence detection (excitation, 290 nm; emission, 395 nm), on a 10 cm x 0.46 cm i.d. Hypersil BDS C(18) 5 microm column using a mixture of 50 mM phosphate buffer (pH 3.2) and acetonitrile (99:1, v/v) as mobile phase. Precision of the method was 0.5% (within a day) and 4.3% (between days). The detection limits were 0.020 mg/100 g for pyridoxal and pyridoxamine, 0.017 mg/100 g for pyridoxamine phosphate, 0.500 mg/100 g for pyridoxal phosphate, and 0.033 mg/100 g for pyridoxol, with a signal-to-noise ratio of 3. The recovery ranged from 92.0 to 100.0%.     

Anthocyanin quantification and radical scavenging capacity of Concord, Norton, and Marechal Foch grapes and wines

The anthocyanin content and the radical scavenging capacity of three non-Vitis vinifera grapes (Marechal Foch, Norton, and Concord varieties) were determined. Analyses of anthocyanins in the skin (S) and wine (W) of these grape varieties were performed by spectrophotometry, HPLC with electrochemical detection, and matrix-assisted laser desorption ionization (MALDI). The total anthocyanin contents of S samples were 258 +/- 37 mg/100 g of wet weight for Foch, 888 +/- 78 mg/100 g for Norton, and 326 +/- 5.9 mg/100 g for Concord grapes. The malvidin 3,5-diglucoside content quantified by HPLC indicated that Norton S had the highest amount of the compound (327 +/- 110 mg/100 g). The MALDI mass spectrometric analysis indicated an abundance of malvidin glucosides in W of Foch grapes and in S and W of Norton grapes and of cyanidin aglycon in S and W of Concord grapes. S samples were subjected to a radical scavenging capacity test using the 2,2-diphenyl-1-picrylhydrazyl radical and compared to Trolox. The radical scavenging capacity for Foch S was 0.78 mM Trolox equiv, that of Concord S, 0.80 Trolox equiv, and that of Norton S was highest at 0.95 Trolox equiv. The higher concentrations of malvidin 3,5-diglucoside in S of grape varieties were associated with greater radical scavenging capacity.     

Phenolic acids in berries, fruits, and beverages

The contents of soluble and total phenolic acids were analyzed in samples of 29 berries and berry products, 24 fruits and fruit peels, and 12 beverages. Variation of phenolic acids in berries was also studied. Soluble phenolic acids were extracted with methanolic acetic acid, and a tentative quantification was performed by high-performance liquid chromatography (HPLC). The total phenolic acid content was determined by HPLC after alkaline and acid hydrolyses. The content of total phenolic acids as aglycones in the above samples varied from 0 (pear cider) to 103 mg/100 g fresh weight (rowanberry). Besides rowanberry, the best phenolic acid sources among berries were chokeberry (96 mg/100 g), blueberry (85 mg/100 g), sweet rowanberry (75 mg/100 g), and saskatoon berry (59 mg/100 g). Among fruits, the highest contents (28 mg/100 g) were determined in dark plum, cherry, and one apple variety (Valkea Kuulas). Coffee (97 mg/100 g) as well as green and black teas (30-36 mg/100 g) were the best sources among beverages. Caffeic acid dominated in all of these samples except in tea brews. Variation in the phenolic acid contents of the berries was either small or moderate.     

Lycopene production using Blakeslea trispora in the presence of 2-methyl imidazole: yield, selectivity, and safety aspects

The potential role of 2-methyl imidazole in improving lycopene production by Blakeslea trispora with regards to yield, selectivity, and safety aspects was investigated in batch culture. Optimization of the bioprocess conditions in terms of (a) (+) and (-) strain ratio in the inoculum, (b) initial crude soybean oil (CSO) addition level, and (c) the amount of 2-methyl imidazole was based on response surface methodology to achieve maximum lycopene production. The dependence of growth kinetics, lycopene yield, and selectivity of the bioprocess on the above factors was clear. 2-Methyl imidazole at 50 mg/L was found equally active in terms of lycopene cyclase inhibition with that at 200 or 100 mg/L; in all cases, lycopene accounted for 94% of the total carotenoids. The highest yield was observed at a 50 mg/L level of addition (24 mg/g of biomass dry weight,) in a substrate supplemented with CSO (48 g/L of culture medium) and inoculated with 1(+)/7(-) strain ratio.     

Monoclonal enzyme immunoassay for the analysis of carbaryl in fruits and vegetables without sample cleanup

The N-methylcarbamate pesticide carbaryl is one of the most important insecticides used worldwide. In the present work, the validation of a monoclonal antibody-based enzyme immunoassay (ELISA) for the determination of this compound in fruits and vegetables is described. The immunoassay is a competitive heterologous ELISA in the antibody-coated format, with an I(50) value for standards in buffer of 101.0 +/- 26.9 ng/L and with a dynamic range between 31.6 and 364.0 ng/L. For recovery studies, peppers, cucumbers, strawberries, tomatoes, potatoes, oranges, and apples were spiked with carbaryl at 10, 50, and 200 ppb. After liquid extraction, analyses were performed by ELISA on both extracts purified on solid-phase extraction (SPE) columns and crude, nonpurified extracts. Depending on the crop and the fortification level, recoveries in the 59.0--120.0% range were obtained for purified samples and in the 70.0--137.7% range for crude extracts. The carbaryl immunoassay performance was further validated with respect to high-performance liquid chromatography (HPLC) with postcolumn derivatization and fluorescence detection (EPA Method 531.1). Samples were spiked with carbaryl at several concentrations and analyzed as blind samples by ELISA and HPLC after SPE cleanup. The correlation between methods was excellent (y = 1.04x + 0.71, r(2) = 0.992, n = 33), with HPLC being more precise than ELISA (mean coefficients of variation of 5.2 and 12.0%, respectively). The immunoassay was then applied to the analysis of nonpurified extracts of the same samples. Results also compared very well with those obtained by HPLC on purified samples (y = 1.28x - 0.59, r(2) = 0.987, n = 33) while maintaining similar precision. Therefore, the developed immunoassay is a suitable method for the quantitative and reliable determination of carbaryl in fruits and vegetables even without sample cleanup, which saves time and money and considerably increases sample throughput.     

Atomic absorption spectrophotometric determination of calcium and magnesium and colorimetric determination of phosphorus in cheese: collaborative study

The determination of calcium, phosphorus, and magnesium in cheese was collaboratively studied. The sample is dried and ashed and the residue is dissolved in an acidified aqueous solution. Calcium and magnesium are determined by atomic absorption spectrophotometry and phosphorus is determined by colorimetry. The study was repeated 3 times because of high within- and between-laboratory relative standard deviations (RSDr and RSDR, respectively). Poor precision in the first 2 studies was caused by a number of factors, including use of contaminated glassware, improperly maintained instruments, and impure reagents as standards. In each study, 5 varieties of cheese were distributed as 10 blind duplicate samples along with a practice sample. Thirteen laboratories participated in the third study, which was generally problem-free. The range of results and the average RSDr and RSDR found in the cheeses were: calcium, 608-1107 mg/100 g. 1.5%, 2.6%; magnesium, 23.9-50.6 mg/100 g, 2.8%, 3.8%; phosphorus, 444-695 mg/100 g, 1.2%, 1.6%. The method has been adopted official first action by AOAC.     

Flavanols and methylxanthines in commercially available dark chocolate: a study of the correlation with nonfat cocoa solids

Intake of flavanols, a subgroup of dietary polyphenols present in many fruits and vegetables, may be associated with health benefits, particularly with reducing the risk of coronary diseases. Cocoa and chocolate products are rich in flavanol monomers, oligomers, and polymers (procyanidins). This study used normal phase HPLC to detect, identify, and quantify epicatechin, catechin, total monomers, procyanidin oligomers and polymers in 14 commercially available chocolate bars. In addition, methylxanthines (theobromine and caffeine) were also quantified. Nonfat cocoa solids (NFCS) were determined both gravimetrically and by calculation from theobromine contents. The flavanol levels of 12 commonly consumed brands of dark chocolate have been quantified and correlated with % theobromine and % NFCS. Epicatechin comprised the largest fraction of total chocolate flavonoids, with the remainder being catechin and procyanidins. Calculated NFCS did not reflect epicatechin (R(2) = 0.41) or total flavanol contents (R(2) = 0.49). Epicatechin (R(2) = 0.96) was a reliable marker of total flavanols, catechin (R(2) = 0.67) to a lesser extent. All dark chocolate tested contained higher levels of total flavanols (93.5-651.1 mg of epicatechin equiv/100 g of product) than a milk or a white "chocolate" (40.6 and 0.0 mg of epicatechin equiv/100 g, respectively). The amount and integrity of procyanidins often suffer in the manufacturing of chocolate, chiefly due to oxidation and alkalinization. In this study, the labeled cocoa content of the chocolate did not always reflect analyzed levels of flavonoids. Increasingly, high % NFCS is being used commercially to reflect chocolate quality. If the flavanol content of chocolate is accepted to be a key determinant of health benefits, then continued monitoring of flavanol levels in commercially available chocolate products may be essential for consumer assurance.     

Flavonoids and antioxidant capacity of Georgia-grown Vidalia onions

Vidalia onion varieties Nirvana, DPS 1032, Yellow 2025, King-Midas, and SBO 133 grown at Vidalia, Georgia, were analyzed for flavonoid content. A high-performance liquid chromatographic (HPLC) method with photodiode array detection was used for quantification. Compounds were analyzed as aglycons after acid hydrolysis with 1.2 M HCl. Identification of each compound was based on comparison of its retention time and UV spectra with those of pure commercial standards. Three major flavonoids, kaempferol, myricetin, and quercetin, were identified and quantified. Quercetin was the major flavonoid (7.70-46.32 mg/100 g fresh weight, FW) present in all varieties, followed by myricetin (2.77-4.13 mg/100 g FW). Minor quantities of kaempferol (1.10-1.98 mg/100 g FW) were also detected. The total polyphenols and Trolox equivalent antioxidant capacity (TEAC) ranged from 73.33 to 180.84 mg/100 g FW and 0.92-1.56 microM TEAC/g FW, respectively. A positive but weaker correlation was obtained for total polyphenols versus antioxidant capacity. Nevertheless, a stronger correlation (r(2) = 0.34) was obtained between flavonoid content versus antioxidant capacity. The data indicate that Vidalia onions are a rich source of quercetin, and they also contain myricetin and kaempferol.     

Content of chalconaringenin and chlorogenic acid in cherry tomatoes is strongly reduced during postharvest ripening

The contents of chalconaringenin, chlorogenic acid, rutin, ascorbic acid, lycopene, and beta-carotene were analyzed during postharvest and vine ripening of cherry tomatoes (Lycopersicon esculentumMill.) (cv. Jennita) produced in a greenhouse. A remarkable decrease in the content of chalconaringenin took place during postharvest ripening. The tomatoes were found to contain 15.26 mg 100 g(-1) fresh weight (FW) at harvest but held only 0.41 mg after 3 weeks at 20 degrees C in darkness. Chalconaringenin did not convert into naringenin. The content of chlorogenic acid fell from 0.51 to 0.06 mg 100 g(-1) FW at the same conditions. The content of rutin and that of total phenolics remained stable during postharvest ripening. The amounts of lycopene as well as beta-carotene and ascorbic acid increased during postharvest ripening. No significant change in the amount of methanol soluble antioxidants or total soluble solids was found during postharvest ripening of the tomato fruits. During vine ripening, the total amount of phenolics and that of soluble solids (% Brix) increased. The content of phenolics correlated well with the content of methanol soluble antioxidants (p < 0.001). The amount of ascorbic acid increased from 9.7 mg in green-yellow tomatoes to 17.1 mg 100 g(-1) FW in red tomatoes. The amount of chalconaringenin decreased to 8.16 mg 100 g(-1) FW, whereas no significant change was observed for chlorogenic acid or rutin. Possible causes for the decrease in chalconaringenin are discussed.     

Evaporative light-scattering analysis of sulforaphane in broccoli samples: Quality of broccoli products regarding sulforaphane contents

Broccoli sulforaphane has received attention as a possible anticarcinogen. Sulforaphane analysis is difficult due to the lack of a chromophore for spectrometric detection. Hence, we developed a method for determining sulforaphane by using high-performance liquid chromatography (HPLC) coupled with an evaporative light-scattering detector (ELSD). Sulforaphane was extracted from acid-hydrolyzed broccoli samples, followed by solid-phase extraction and reversed-phase HPLC. Sulforaphane was detected by ELSD and concurrently identified by electrospray ionization time-of-flight mass spectrometry. The recovery of sulforaphane from broccoli samples was above 95%. The detection limit was 0.5 mug. The present method was sensitive enough to determine sulforaphane in mature broccoli, broccoli sprouts, and commercial broccoli products. Sulforaphane concentration in broccoli sprout (1153 mg/100 g dry weight) was about 10 times higher than that of mature broccoli (44-171 mg/100 g dry weight). Therefore, the broccoli sprout is recommended as a source of sulforaphane-rich products. In contrast, we found that sulforaphane could not be detected in most of broccoli products, suggesting present commercial broccoli products having low quality.     

Multivariate analysis of FTIR and ion chromatographic data for the quality control of tequila

Principal component analysis (PCA) was applied to the chromatographic and spectroscopic data of authentic Mexican tequilas (n = 14) and commercially available samples purchased in Mexico and Germany (n = 24). The scores scatter plot of the first two principal components (PC) of the anions chloride, nitrate, sulfate, acetate, and oxalate accounting for 78% of the variability allowed a classification between tequilas bottled in Mexico and overseas; however, no discrimination between tequila categories was possible. Mexican products had a significantly (p = 0.0014) lower inorganic anion concentration (range = 1.5-5.1 mg/L; mean = 2.5 mg/L) than the products bottled in the importing countries (range = 3.3-62.6 mg/L; mean = 26.3 mg/L). FTIR allowed a rapid screening of density and ethanol as well as the volatile compounds methanol, ethyl acetate, propanol-1, isobutanol, and 2-/3-methyl-1-butanol using partial least-squares regression (precisions = 5.3-29.3%). Using PCA of the volatile compounds, a differentiation between tequila derived from "100% agave" (Agave tequilana Weber var. azul, Agavaceae) and tequila produced with other fermentable sugars ("mixed"tequila) was possible. The first two PCs describe 89% of the total variability of the data. Methanol and isobutanol influenced the variability in PC1, which led to discrimination. The concentrations of methanol and isobutanol were significantly higher (methanol, p = 0.004; isobutanol, p = 0.005) in the 100% agave (methanol, 297.9 +/- 49.5; isobutanol, 251.3 +/- 34.9) than in the mixed tequilas (methanol, 197.8 +/- 118.5; isobutanol, 151.4 +/- 52.8).     

Antioxidant activity of indigenous edible mushrooms

The current study was undertaken to measure the antioxidant potential from water and methanolic extracts of fruiting bodies of 23 species of mushrooms naturally grown in different geographic locations of India. The antioxidant ability of each species was analyzed for the total antioxidative status, employing multimechanistic antioxidative assays such as inhibition of lipid peroxidation, determination of reducing power, and free radical scavenging ability, in addition to determination of total phenolics and identification of phenolic acids by HPLC analysis, because the phenolics are known to contribute largely to antioxidant potential. The antioxidant potential of these varieties of mushrooms was determined by summing the antioxidative activity (AOA) of each variety by varied antioxidant assays followed by determining the relative percent of AOA defined as the "antioxidant index" (AI). On the basis of the AI, the mushroom species were graded as very high, high, moderate, and low. Termitomyces heimii was identified as the best variety, which showed 100% AI with 37 mg of phenolics/g of sample, 418 units of reducing power ability (RPA)/g, and an IC50 of approximately 1.1 mg (dry weight)/mL, free radical scavenging activity (FRS) in the water extract followed by 11.2 mg of phenolics/g, 275 units of RPA/g, and an IC50 of approximately 2.7 mg (dry weight)/mL of FRS in the methanolic extract. Following T. heimii, Termitomyces mummiformis exhibited an AI of 86% within the "very high" group. Potent inhibitions of lipid peroxidation of approximately 100 and 69% was also observed in T. heimii and T. mummiformis, respectively. Water extracts ranged from 34 to 49% and methanolic extracts varied from 20 to 32% on dry weight of mushroom fruiting body. Total phenolic compounds were higher in the water extracts (2-37 mg/g) than in methanolic extract (0.7-11.2 mg/g). The AOA measured in the water extract was better than that from the methanolic extract. HPLC analysis of phenolic acids in the two mushroom species, namely, T. heimii and T. mummiformis, displaying maximum AOA potential indicated a preponderance of tannic acid, gallic acid, protocatacheuic acid, and gentisic acid. Studies thus provide the precise antioxidant status of 23 indigenous species of mushrooms, which can serve as a useful database for the selection of mushrooms for the function of preparation of mushroom-based nutraceutics.     

Determination of sarafloxacin residues in fortified and incurred eggs using on-line microdialysis and HPLC/programmable fluorescence detection

Isolation of sarafloxacin (SAR) from fortified and incurred chicken eggs was done by a combination of liquid-liquid extraction and aqueous on-line microdialysis performed on an automated trace enrichment of dialysates (ASTED) system. The ASTED system coupled a sample cleanup procedure with HPLC and programmable fluorescence detection. Overall recoveries of 87-102% for SAR were obtained from samples fortified over a range of 1-100 ng/g. The relative standard deviation values ranged from 22 to 26% for samples fortified between 1 and 5 ng/g and from 2 to 12% for samples fortified between 10 and 100 ng/g. The limits of detection and quantitation were 0.2 and 1 ng/g, respectively. Eggs containing incurred SAR, which were collected over a 3-day dosing period and for 5 consecutive days thereafter, also were analyzed by using this technique. Because the method is automated, 35 samples can be processed within a 24-h period, which enables large data sets to be acquired over a short time period.     

Extraction of lycopene from tomato skin with supercritical carbon dioxide: effect of operating conditions and solubility analysis

Supercritical carbon dioxide (SCCO2) extraction of lycopene from waste tomato skins was investigated. The experiments were carried out at pressures and temperatures ranging from 20 to 50 MPa and 313 to 373 K, respectively, without any modifiers. The flow rate of CO2 was maintained at 2.5 mL/min for 330 min extraction time. Solvent flow rate effect was examined for CO2 flow rates from 1.5 to 4.5 mL/min. The extracts were analyzed by high-performance liquid chromatography and UV-visible spectroscopy. The results showed that with optimized operating conditions, the maximum yield of lycopene (1.18 mg of lycopene/g of sample) was obtained at 40 MPa, 373 K, and 2.5 mL of CO2/min. Chromatographic analysis indicated that lycopene was extracted from tomato skin with negligible degradation at the optimum conditions and the amount extracted represented more than 94% of the total carotenoid content of the sample. The solubility of lycopene was modeled by use of the Chrastil equation.     

Determination of thiamin in cooked sausages

A reliable and rapid high-performance liquid chromatography (HPLC) method has been set up for the determination of total thiamin in difficult sample matrices such as cooked sausages. Different hydrolysis conditions and enzymes were tested to release the vitamin from its phosphate ester. The best data in the enzymatic digestion were obtained by incubating the samples with 6% clara-diastase at 50 degrees C for 3 h. After oxidation of thiamin to thiochrome, the sample extracts were purified by using a C(18) Sep-Pak cartridge. Final determination was performed by reversed-phase HPLC with fluorescence detector (excitation 360 nm, emission 430 nm), on a low-cost 25 cm x 4 mm i.d. Spherisorb C(8) cartridge using a mixture of 5 mM phosphate buffer pH 7.0 and acetonitrile (70:30, v/v) as mobile phase. Precision of the method was 1.5% (within a day) and 5. 2% (between days). The detection limit was 0.015 mg/100 g. All the recoveries from the different cooked sausages were better than 90% of thiamin hydrochloride added to samples of meats. In the samples analyzed, the mean value for thiamin was between 0.039 and 0.508 mg/100 g fresh weight.