Biogenic amines in dry sausages during shelf-life storage

 Supercritical fluid extraction (SFE) with subsequent HPLC analysis was performed in order to determine the amount of capsaicinoids in paprika and chillie powder samples. The extraction yields obtained by SFE were compared to those obtained by organic solvent extraction and were found to be comparable or slightly lower. The advantages of SFE are shorter extraction times, less sample preparation needed prior to HPLC analysis and fewer interfering peaks in the chromatograms. In addition, the SFE method developed (extraction temperature=80 ^°C, density= 0.75 g/ml, modifier=20 μl water) was shown to be suitable for analysis of capsaicinoids (capsaicin, dihydrocapsaicin, nordihydrocapsaicin) that are present over a wide range of concentrations (10–1400 μg/g) in the samples. Received: 12 July 1996/Revised version: 26 August 1996     

HPLC determination of trimethoprim in meat and milk with an SPE preseparation procedure

 An HPLC method in combination with solid-phase extraction and dual wavelength detection has been developed in order to monitor trimethoprim residues in meat and milk. The extraction recoveries for the maximal residual limit concentration in food (50 ng/g) were 86±5% for meat and 73±6 % for milk samples. The limits of determination of trimethoprim were 5 ng/g at 229 nm and about 15 ng/g at 280 nm. The method has been developed in response to specific needs of food control laboratories. This publication introduces the assay for milk and meat samples. Received: 27 March 1996/Revised version: 23 July 1996     

Parameters affecting the quality of processed cocoa powder: acidity fraction

 Total, free and fixed, volatile and non-volatile acids, as well as lactic and phosphoric acid contents were determined in six samples of three batches of cocoa beans subjected to various stages of fermentation (1–6 days), in 37 samples of non-alkalinized low-fat cocoa powder and in 15 samples of instant cocoa powder. The physico-chemical data obtained were related to sensory evaluation and submitted to analysis of variance, multivariate distribution (Mahalanobis distance) and the Pearson Chi-squared test. From the results obtained we can infer that optimally fermented cocoa samples should have a maximum total fixed acidity of 39 mEq NaOH/100 g, a non-volatile fixed acidity of 35 mEq NaOH/100 g, and a lactic acid content of 0.50 g/100 g (5.5 mEq/100 g). No correlation was found to occur between other acidities, the phosphoric acid content, and sensory data. These parameters are related to the sensory properties of cocoa and can be used to confirm deficiencies. Received: 12 February 1996 / Revised version: 17 June 1996     

Supercritical carbon dioxide extraction of sea buckthorn (Hippophae rhamnoides L.) pomace

BACKGROUND: The goal of this work was to utilize the sea buckthorn pomace, which is the by‐product of a sea buckthorn juice process. Pilot plant supercritical fluid extraction (SFE) experiments were performed in a 5 × 10^?3 m³ volume high‐pressure vessel. The effects of pressure and temperature on extraction yield and recoveries of biologically active components were studied using a 3² full factorial design. The pressure and temperature were varied over the ranges of 30–46 MPa and 313–353 K, respectively. The extract samples were analysed by TLC‐densitometry, UV/VIS spectrofotometry and HPLC methods. RESULTS: The obtained yields changed between 142–164 g kg^?1, according to the solvent power of the supercritical fluid. The recoveries of the different minor components were (g minor components kg^?1 dried raw material): 2.50–4.25 sitosterol, 0.20–1.60 ursolic acid, 0.04–0.18 carotenoid, 0.35–0.42 total tocopherol. CONCLUSION: By evaluation the designed experiments 46 MPa and 333 K were chosen as the optimum conditions. Copyright © 2007 Society of Chemical Industry     

HPLC-integrated solid-phase extraction with photochemical post-column derivatization for the determination of oxacillin, cloxacillin and dicloxacillin in raw milk

 An automated reversed-phase high-performance liquid chromatography (HPLC) method with UV detection at 300 nm after on-line coupled solid-phase extraction (SPE) and photochemical post-column derivatization was developed for the residue analysis of oxacillin, cloxacillin and dicloxacillin in raw milk. After a centrifugation step for defatting and ultrafiltration, a HPLC-integrated SPE using a restricted access sorbent, is performed. By operating the system in parallel mode, SPE and HPLC run are performed simultaneously. The procedure allows the analysis of about 30 samples within 24 h and was used to investigate the milk of cows which had been treated with oxacillin. The detection limit was 3 μg/kg for oxacillin and cloxacillin and 5 μg/kg for dicloxacillin. The recoveries were between 66% and 81% with coefficients of variation between 3.3% and 7.7%. Using an acetonitrile extraction procedure better recoveries of ≥90% were obtained with fortified samples, but more or less identical results were obtained for the samples with incurred residues after correction for recovery. Received: 16 February 1998     

Quality characteristics of different red pepper cultivars (<Emphasis Type="Italic">Capsicum annuum</Emphasis> L.) for hot paprika production

Twelve hybrids obtained by crossing of different Hungarian cultivars and the Spanish ‘Jaranda’, ‘Jariza’ and ‘Jeromín’ have been studied. The aim of this work was to select those peppers with high capsaicinoids content, and good agronomic and industrial characteristics, as ‘Jeromín’, the only local cultivar used for pungent (hot) paprika, has a low and irregular pungency depending on the year. The crop productive characteristics, ASTA colour, carotenoid pigment content and pungency of the paprika has been studied and elaborated following the traditional procedure of La Vera (Extremadura, Spain). The productive characteristics and pigment concentration of the crossings were, in general, similar to that of local cultivars, and all of them could be suitable for hot paprika production, because their capsaicinoid content was higher than that of ‘Jeromín’ (78 mg kg⁻¹ dwt of total capsaicinoids). The most pungent hybrids were Kibedicsipos × Jariza, Jeromín × Szegedi178 and Jaranda × Szegedi179, with a total capsaicinoid content of 1,240, 1,107, and 997 mg kg⁻¹ dwt, respectively. Their paprikas showed a carotenoid pigment content higher than that of ‘Jaranda’, which is considered as a high quality paprika.     

Analysis of biotin in Korean representative foods and dietary intake assessment for Korean

Biotin is an important vitamin functioning as coenzyme in several carboxylase-mediated metabolic reactions. Total 105 foods were selected as the target samples, of those 75 samples were highly and frequently consumed by Korean and the others were potently high biotin content foods. HPLC with the triple column system had been optimized and applied for the analysis of biotin in various food samples. The foods with the biotin concentration over 0.10 μg/g were 13 kinds of foods such as soybean (2.037 μg/g), soy milk (0.591 μg/g), pork liver (0.455 μg/g), etc. The total daily biotin exposure per person via average and the 95^th percentile food intake was 44.656 and 169.416 μg, respectively. The Korean staple food, rice contributed as fifth diet for biotin intake (3.433 μg/person/day) following soybean (9.167 μg/person/day) > milk (6.018 μg/person/day) > soy milk (4.433 μg/person/day) > beer (4.428 μg/person/day).     

Beverage iodine levels in Germany

Sales of iodized table salt (household use, bulk containers) have been flat in Germany since 1996/1997. Nevertheless, the amount of iodide excreted with the urine has been steadily increasing in the German population since 1993. We investigated the beverage iodine levels as possible source of the increased input of iodine into the food chain. No systematic studies on this topic have yet been carried out in Germany. A total of 510 samples were drawn from large grocery discounters who supply all German states with their products (35% fruit and vegetable juices, 35% beers, 10% pooled milk and yoghurt drinks, 10% mineral water, 10% soda). (1) Water-based beverage samples are prepared by solid-phase extraction and iodine concentration is determined by HPLC and electrochemical detection, (2) the samples of milk and milk products are prepared by trichloroacetic acid precipitation and centrifugation, and iodide concentration is determined by HPLC and electrochemical detection. Because the iodine concentrations in the beverage samples showed a left-skewed distribution, all expressed values are median values. Low iodine concentrations were observed in the water-based beverages: fruit and vegetable juices 2.92 μg I⁻/l, beers 2.91 μg I⁻/l, mineral waters 0.5 μg I⁻/l, sodas 0.5 μg I⁻/l. The median value measured in pooled milk and its derived products was 117 μg I⁻/l and 126 μg/l, respectively. As expected, the iodine was lower in summer milk than winter milk (and respectively). Although not statistically significant, beers from Northern Germany had higher concentrations of iodine than from Southern Germany (). In conclusion, based on our results, milk and milk products (117 μg I⁻/l and 126 μg/l, respectively) contribute significantly to the increased nutritional iodine supply of the German population.     

Ethanol modified supercritical fluid extraction and antioxidant activity of cajaninstilbene acid and pinostrobin from pigeonpea [Cajanus cajan (L.) Millsp.] leaves

Supercritical fluid carbon dioxide (SF-CO₂) extraction (SFE) of cajaninstilbene acid (CSA) and pinostrobin (PI) from pigeonpea leaves and antioxidant activity were investigated for the first time. SFE gave higher extraction yields than conventional heat-refluxing extraction (HRE) because of the severe breakage of cell morphology caused by SF-CO₂, which was observed by scanning electron microscopy (SEM). CO₂ flow rate, modifier composition and liquid to solid ratio were firstly optimised, 12 kg/h, and 80% EtOH with a liquid to solid ratio of 10 ml/g raw material exhibited better extraction performance. Then a central composite design (CCD) combined with response surface methodology was used to study the effects of extraction pressure, temperature and time on the extraction yields of CSA and PI, the optimal parameters were 30 MPa, 60 °C and 2 h. An antioxidant activity investigation showed SFE extracts exhibited better free radical-scavenging activity than HRE extracts with an IC₅₀ value of 0.2259 mg/ml.     

Determination of oxacillin, cloxacillin and dicloxacillin in milk, meat and cheese samples using HPLC and precolumn derivatization

 The objective of this work was to develop a confirmatory HPLC method for the determination of oxacillin, cloxacillin and dicloxacillin residues in milk, meat and cheese samples. The assay presented involves the extraction of the compounds to be studied from the sample, with an acidic solution of sodium tungstate, followed by solid-phase extraction and precolumn derivatization. The derivatization of the samples was achieved by the formation of mercury mercaptide derivatives in the presence of imidazole. Chromatographic separations were realized using linear gradient elution and separated compounds were detected at 345 nm. The recoveries of the preparation step were higher than 80% and the limits of detection were lower than the maximal residual limits (MRL) as determined by the Commission of the European Communities. Received: 27 March 1996/Revised version: 16 October 1996     

Content of selected bioactive components and antioxidant properties of broccoli (<Emphasis Type="Italic">Brassica oleracea</Emphasis> L.)

To evaluate individual variations in broccoli VOLTA F1 plants, the bioactive components of 15 florets that were cultivated in identical agricultural and climatic conditions were analyzed. Glucosinolates were analyzed by HPLC; total phenolic compounds, ascorbic and dehydroascorbic acids (vitamin C) and the DPPH^• and OH^• radical-scavenging activities of samples were also determined. Florets were characterized by particularly high glucoraphanin content, 17.95 μmol/g dry weight on average, which comprised about 50% of total glucosinolates. High individual variation was observed for several bioactive compounds, as well as for DPPH^• and OH^• radical-scavenging activity. Coefficients of variability (CVs) were high, and except for one case, exceeded 10%. Among glucosinolates, the highest CVs were noted for progoitrin (34.22%), 4-hydroxyglucobrassicin (27.32%) and neoglucobrassicin (24.44%). High CVs were also observed for vitamin C (29.11%), including dehydroascorbic acid (26.72%), and for OH^• (25.76%) and DPPH^• (21.77%) radical-scavenging activities. Smaller variations were found for glucoraphanin (CV = 14.84%) and polyphenols (CV = 14.95%).     

Capsaicinoids,Tocopherol, and Sterols Content in Chili (Capsicum sp.) by Gas Chromatographic-Mass Spectrometric Determination

A gas chromatography-mass spectrometry method was developed for the quantitative determination of capsaicinoids, vitamin E, and phytosterols in chili peppers using a simple extraction technique for rapid screening. These components were extracted with acetonitrile and were injected into gas chromatography attached with mass spectrometry. The mean recovery values for triplicate analysis were between 90.6–99.7%. Besides major capsaicinoids (capsaicin, dihydrocapsaicin, nordihydrocapsaicin), four more minor capsaicinoids (nonivamide, nornordihydrocapsaicin, homodihydrocapsaicin I and II) were detected in chili samples. α-Tocopherol was also detected in the same run along with three phytosterols (campesterol, γ-sitosterol, and stigmasterol). Variations were observed across the chili sample in all of the constituents except a few minor capsaicinoids. The method was suitable for simultaneous estimation of capsaicinoids, vitamin E, and phytosterols in a single run from any types of pepper. Thus, the method is effective for rapid screening of peppers for its nutraceutical composition using single solvent extraction.     

Distribution of microbes in supercritical CO2 extraction of sea buckthorn (Hippopha? rhamnoides) oils

 The distribution of vegetative microbial cells and their spores in a supercritical CO₂ extraction process was studied. The seed and flesh/skin fractions of the press residue of sea buckthorn berries (Hippopha? rhamnoides) from a juice factory were used as raw materials. A pilot-scale extraction plant was operated at 30 MPa at temperatures of 40 and 60°C. The number of yeasts, moulds and bacteria in the pulp/skin fraction, in the extraction residues, in the extracted oils as well as in the water phases separated from the extracted oils was estimated by the spread plate technique. The microbial content of the flesh/skin material was increased in some extractions by the addition of bacterial spores. In general, the extraction process led to a decrease in the bacterial count of the extracted material, whereas no microbial growth was detected in the oils extracted or in the water phases separated from them. Neither yeasts nor moulds were found in any samples after the extraction process. The microbial status of seed oil and flesh/skin oil obtained by industrial-scale CO₂ extraction at 40°C and at 30 MPa before and after gelatine encapsulation remained unchanged. This proves that supercritical CO₂ can be used to manufacture edible oil products free of living micro-organisms and their spores. Received: 14 May 1996     

Detection and quantification of pentosidine in foods

 Pentosidine, a crosslink amino acid in which one arginine and one lysine residue are linked together by a pentose, has been detected in foods for the first time using ion-exchange chromatography with direct fluorescence detection and subsequent ninhydrin derivatization. The method allows the simultaneous quantification of pentosidine along with all other amino acids of acid hydrolyzates at levels lower than 50 μg kg protein. Levels of pentosidine in all food samples investigated were very low (milk products between not detectable and 2–5 mg/kg protein; roasted coffee and some bakery products up to 35 mg/kg protein), indicating that pentosidine does not play a major part in the polymerization of food proteins. Received: 26 March 1996     

Detection and quantification of pentosidine in foods

 Pentosidine, a crosslink amino acid in which one arginine and one lysine residue are linked together by a pentose, has been detected in foods for the first time using ion-exchange chromatography with direct fluorescence detection and subsequent ninhydrin derivatization. The method allows the simultaneous quantification of pentosidine along with all other amino acids of acid hydrolyzates at levels lower than 50 μg kg protein. Levels of pentosidine in all food samples investigated were very low (milk products between not detectable and 2–5 mg/kg protein; roasted coffee and some bakery products up to 35 mg/kg protein), indicating that pentosidine does not play a major part in the polymerization of food proteins. Received: 26 March 1996     

Occurrence of Aflatoxins and Ochratoxin A in Baby Foods in Portugal

Infants have a more restricted diet and they generally consume more food on a body weight basis than adults. Therefore, the significance and potential health risk of any contaminant in foods consumed by infants is increased and diligent attention must be paid to this particular area. The present study aims to determine the occurrence of aflatoxin M₁ (AFM₁), aflatoxin B₁ (AFB₁) and ochratoxin A (OTA) in processed cereal-based foods (flours) and infant formulae (milk powder) available in the Portuguese market, both sold as conventional and organic origin. Mycotoxin determination was carried out using a method previously applied to duplicate diet samples. This method employed chloroform extraction, liquid–liquid extraction, immunoaffinity column (IAC) cleanup and HPLC analysis with fluorescence detection after post-column derivatisation. Quantification limits were 0.014, 0.004 and 0.028 μg kg⁻¹ for AFM₁, AFB₁ and OTA, respectively. These toxins could only be quantified in 12 of 27 analysed samples (15 positive results): two samples with AFM₁, two samples with AFM₁ and OTA, one sample with AFB₁ and OTA and seven samples with OTA. Positive results concerned four for AFM₁ (26%), one for AFB₁ (7%) and ten for OTA (67%). For these samples, contents ranged between 0.017–0.041 μg AFM₁ kg⁻¹, 0.034–0.212 μg OTA kg⁻¹, and one sample had a value of 0.009 μg AFB₁ kg⁻¹. Considering the presented results, we could provisionally conclude that the presence of these mycotoxins in baby foods does not constitute a public health problem. These are the first results concerning the occurrence of mycotoxins in marketed baby foods in Portugal and this is the first study using the HPLC method, proposed for duplicate diets, in baby food sample analysis.     

Application of response surface methodology and central composite design for the optimisation of supercritical fluid extraction of essential oils from Myrtus communis L. leaves

Essential oils of Myrtus communis L. leaves were obtained using supercritical fluid extraction (SFE) and hydrodistillation methods. The experimental parameters of SFE such as pressure, temperature, modifier volume, static and dynamic extraction time were optimised using a central composite design after a 2ⁿ⁻¹ fractional factorial design. The chemical compositions of the SFE extract were identified by GC–MS and determined by GC–FID. The major components of essential oils obtained by hydrodistillation were α-pinene (31.8%), 1,8-cineole (24.6%), limonene (14.8%), linalool (8.3%) and α-terpinolene (4.8%). However, by using the supercritical carbon dioxide in optimum conditions, only three components represented more than 85% of the extract. Therefore, by using the proper SFE conditions, the supercritical extraction is more selective than the conventional hydrodistillation methods. The oil yields based on the hydrodistillation was 0.47% (v/w). Extraction yields based on the SFE varied in the range of 0.5–6.3% (w/w) under different conditions.     

HPLC determination of stevioside in plant material and food samples

 An HPLC method for the determination of sweet-tasting stevioside (STS) in the leaves of the plant Stevia rebaudiana and in some beverages (e.g. tea, orange juice) was developed. The pre-separation procedure consisted of extraction of STS from the plant material using boiling water and a solid-phase extraction (SPE). Recovery rates of the SPE for the analysed matrices ranged from 92.8% to 97.8% (for concentrations of STS of 105, 210 and 300 μg/ml; Relative Standard Deviation (RSD)≤3.3%). The chromatographic separations were realized using a C₁₈ column, the mobile phase consisting of methanol and water, and with UV detection at 210 nm. The limits of determination of STS were 5 μg/ml for the leaf extracts and the tea sample and 8 μg/ml for the juice sample. Received: 7 April 1998     

Supercritical fluid and solid–liquid extraction of phenolic antioxidants from grape pomace: a comparative study

Distilled white grape pomace (Vitis vinifera var. Garnacha) was subjected to extraction by using two different methods: (1) solid–liquid extraction (SLE) employing 96% ethanol and water and (2) supercritical extraction (SFE) by running carbon dioxide coupled with ethanol as a modifier. Higher phenolic concentrations of extracts were attained by SFE (∼400 ppm), doubling those obtained by SLE. In the latter, increasing values of both temperature (from 25 to 50 °C) and contact time (from 30 to 90 min) and lower solvent-to-solid ratios (from 5:1 to 1:1) resulted in an enhancement of extraction efficiency. In SFE, the addition of the modifier (8%) was also found to favour the release of phenolic compounds. Antiradical activity values—evaluated by the ability to scavenge DPPH radicals—were, as general, also higher for SFE extracts, although maximum values reached at were similar (73% inhibition versus 68%). Chromatographic profiles confirmed the diverse nature of phenolic species occurring in extracts obtained from both extraction methods. Extracts from SLE contained more proanthocyanidins, whereas SFE ones contained basically gallic acid, catechin and epicatechin. Protection against oil oxidation assayed with two samples confirmed these results.     

HPLC determination of stevioside in plant material and food samples

 An HPLC method for the determination of sweet-tasting stevioside (STS) in the leaves of the plant Stevia rebaudiana and in some beverages (e.g. tea, orange juice) was developed. The pre-separation procedure consisted of extraction of STS from the plant material using boiling water and a solid-phase extraction (SPE). Recovery rates of the SPE for the analysed matrices ranged from 92.8% to 97.8% (for concentrations of STS of 105, 210 and 300 μg/ml; Relative Standard Deviation (RSD)≤3.3%). The chromatographic separations were realized using a C₁₈ column, the mobile phase consisting of methanol and water, and with UV detection at 210 nm. The limits of determination of STS were 5 μg/ml for the leaf extracts and the tea sample and 8 μg/ml for the juice sample. Received: 7 April 1998