Comparison of volatiles in raw and boiled potatoes using a mild extraction technique combined with GC odour profiling and GC–MS

Aromas of raw and boiled potatoes were compared using a mild extraction technique, ensuring preservation of the very labile composition of potato aroma during analysis. The extracts were evaluated by GC–MS and GC-sniffing using a panel of four judges. A total of 29 compounds were identified by GC–MS in raw potatoes and 25 in boiled. Twenty compounds were found in both raw and boiled potatoes, but most often in very different concentrations. During GC-sniffing, 33 odours were detected in boiled, and 27 in raw potatoes. Eight odours corresponded to compounds identified by GC–MS. Another four odours could be tentatively identified. It is concluded that the change in aroma during boiling of potatoes depends on compounds from lipid oxidation as well as compounds from other types of reactions, for instance the Strecker-degradation.     

Characterization of nutritionally important phytoconstituents in minimally processed ready-to-eat baby-leaf vegetables using HPLC–DAD and GC–MS

Ready-to-eat baby-leaf vegetable market has been rapidly growing and offering to consumers convenient and appealing products, rich in health beneficial bioactive compounds. In the present study, the composition of carotenoids, tocopherols, and fatty acids were analyzed in seven baby-leaf vegetables using HPLC–DAD and GC–MS. Among the vegetables, the maximum amount (μg/g FW) of All-E-violaxanthin (42.77), 9′-Z-neoxanthin (22.13), All-E-lutein (69.67), All-E-β-carotene (60.18), total carotenoids (195.21), γ-tocopherol (19.68) and total tocopherol (47.68) were found in Batavian lettuce (Lactuca sativa L. var. Acephala). In all the studied baby-leaf vegetables, α-linolenic acid (ALA, C18:3) was found in highest quantity (44.73–54.39 %) followed by palmitic acid (C16:0) (13.02–19.49 %), and linoleic acid (C18:2) (8.25–21.54 %). Significantly high amount polyunsaturated fatty acids (PUFA) were recorded in Batavian lettuce (74.33 %) and red Romaine (72.72 %), compared to other studied vegetables. In view of health benefits, baby-leaf vegetables contain a low amount of saturated fatty acids and high-mono and PUFA, which can enhance the health benefits of these vegetables. Carotenoids in most of these studied baby-leaf vegetables can be classified as very high. Knowledge of carotenoid, tocopherols and fatty acids composition in different baby-leaf vegetables will be useful to nutritional experts for selection of nutrient-dense plants for food fortification and proper diet recommendation. To our knowledge, this is the first report on fatty acids composition from baby-leaf vegetables.     

Finding of pesticides in fashionable fruit juices by LC–MS/MS and GC–MS/MS

Products labelled as containing extracts from two mushrooms (cordyceps plus reishi) and the juices from açaí, goji, mangosteen, noni, pomegranate, and sea buckthorn have been analysed for 174 different pesticides, using the validated QuEChERS method for sample preparation and electrospray LC–MS/MS in the positive ion mode for analysis. Pesticides were found in 10 of the 21 samples analysed. Most pesticides found were below the tolerance levels (1–6 μg/g, depending on the pesticide), but some were not. This included boscalid, dimethomorph, iprovalicarb, pyridaben, pyrimethanil, and imazalil, for which there is no tolerance reported or zero tolerance in any fruit. However, genuine açaí that was harvested in the state of Pará and lyophilised in Rio de Janeiro had no detectable pesticides, when analysed by both LC–MS/MS and GC–MS/MS, which can detect 213 more pesticides and industrial chemicals. Likewise no pesticides were found in one sample each of cordyceps plus reishi, sea buckthorn and noni.     

Quantification of folpet and phthalimide in tea and herbal infusions by LC– high-resolution MS and GC–MS/MS

Two methods based on a modified QuEChERS sample preparation and either LC coupled to atmospheric pressure ionisation and high-resolution MS or GC coupled to electron ionisation and tripled quadrupole MS have been assessed for the quantification of folpet and phthalimide in tea and other dry herbal infusions. Both methods have been fully validated in green tea and further checked in black tea, verbena and rooibos, and they performed according to the SANTE/11813/2017 criteria at the target LOQ concentration level (50 µg/kg). These methods allow the accurate quantification of folpet in the selected matrices according to the new EU residue definition, which includes phthalimide. Phthalimide is the main metabolite and degradation product of folpet, although according to recent studies, it could be generated from different sources than folpet breakdown, such as food processing or analysis by GC.     

Application of GC–MSD and LC–MS/MS for the determination of priority pesticides in baby foods in Serbian market

Babies and small children are especially sensitive population to the exposure to environmental contaminants. Their small mass and developing systems, including brain development may show adverse health effects from even low levels of contamination on a chronic or single dose case. In this paper one extraction method and two chromatographic techniques for the determination of pesticide residues in baby food were evaluated. A liquid chromatography–tandem mass spectrometry technique combined with electrospray ionization (ESI), (LC–MS/MS) and gas chromatography–mass spectrometry detection (GC–MSD) technique were applied in the detection of 50 pesticides in baby food. So-called QuEChERS (quick, easy, cheap, effective, rugged and safe) method was used as a sample preparation procedure. The recoveries were investigated at three levels (5, 10 and 50 μg/kg) and the results obtained showed compliance with the contemporary EU requirements with a few exceptions. LOQs for most of the tested pesticides were below the EU MRLs (10 μg/kg), except deltamethrin, cypermethrin, fenvalerate, phosalone and beta-cyfluthrin (LOQs were 10 μg/kg). Both techniques were applied in the analysis of 50 samples of baby food manufactured in Serbia.     

The analysis of saturated and aromatic mineral oil hydrocarbons in dry foods and from recycled paperboard packages by online HPLC–GC–FID

ABSTRACT

The purpose of this study was to determine the concentrations of mineral oil hydrocarbons in dry foodstuffs packed in recycled paperboard, which were imported from different foreign countries to Germany. After collection, mineral oil saturated hydrocarbons (MOSH) and mineral oil aromatic hydrocarbons (MOAH) in dry foodstuffs and recycled paperboard were analysed using online coupled high-performance liquid chromatography–gas chromatography–flame ionisation detection (online HPLC–GC–FID) far before the end of the shelf life of the samples. Our results showed that recycled paperboard has MOAH content higher than that of dry foodstuffs. The proportion of MOAH within total mineral oil hydrocarbons was determined to be 7–45% in dry foodstuffs and 4–48% in paperboard. In addition, 29% of the products were found to contain over 1.00 mg/kg MOAH, with a maximum of 2.72 mg/kg in oatmeal. White colour recycled paperboard contained lower amounts of MOSH and MOAH than that of brown and grey colour recycled paperboard. The MOSH concentration in dry foodstuffs ranged from 0.11 to 21.92 mg/kg (?C25 hydrocarbons), which may be an indication of rapid migration. The lowest determined MOSH concentrations (?C25 hydrocarbons) were found in sea salt and soda samples, even when their paperboard contained high mineral oil hydrocarbons. Our three samples in packages containing internal bags (for complete barriers) were found to have low mineral oil concentration due to reduced migration through plastic (acrylate-coated polypropylene). However, one sample, a ‘crispy’ product with an internal bag, contained the extreme amount of 21.92 mg/kg. Differences in contaminants observed in both dry foodstuffs and recycled paperboard may have been due to the different packaging and production techniques of the different countries. In addition, 8 of 24 dry foodstuff samples contained MOSH concentrations frequently exceeding the 2.0 mg/kg limit for MOSH C₂₀–C₃₅.     

A GC–FID Method to Determine Styrene in Polystyrene Glasses

The styrene levels of polystyrene (PS) glasses from the most consumed brands of disposable glasses intended for water and coffee in Brazil were determined. A GC–FID method was developed and validated, showing good precision and accuracy. The method was successfully used to determine styrene in 11 PS glass brands. The styrene levels ranged from 1.68 to 43.69 mg/100 g glass, depending on the kind of polymer, thickness, and glass brand. It could be used to control the content of styrene in the polymer. The migration of styrene from the glasses into water and 20 % ethanol was not detected.     

Determination of phthalate esters in non-alcoholic beverages by GC–MS and optimization of the extraction conditions

A quantificational method for 7 phthalate esters in non-alcoholic beverages was developed. Dimethyl phthalate, di-ethyl phthalate, di-propyl phthalate (DPP), di-butyl phthalate (DBP), benzyl butyl phthalate, di-(2-ethylhexyl) phthalate (DEHP), and di-octyl phthalate (DOP) were extracted from non-alcoholic beverages with the optimized solid-phase extraction method, and quantification was achieved by gas chromatography–mass spectrometry with isotope internal standard of d₄-di-(2-ethylhexyl) phthalate (DEHP-d₄). The inter-day method repeatability (RSD) was 8–13 %, whereas the intra-day method repeatability (RSD) was 9–15 %. The mean spiking recoveries were 84–105 %. A wide variety of phthalate concentrations was observed in 48 non-alcoholic beverages. DEHP was the most abundant phthalate compound followed by DBP, DPP, and DOP. DEHP was found in sport drinks (0.015–0.098 mg L^?1), tea (0.016–0.123 mg L^?1), coffee (0.028–0.159 mg L^?1), and fruit juices (0.022–0.126 mg L^?1).     

Analysis of volatile compounds in New Zealand unifloral honeys by SPME–GC–MS and chemometric-based classification of floral source

New Zealand unifloral honeys have a higher commercial value than polyfloral honeys; however identification of floral source can be difficult and time-consuming. In this study, we aimed to establish a rapid and semi-automated method for identifying the floral source of New Zealand honeys. Volatile compounds from ten types of New Zealand unifloral honeys (a total of 234 samples) were analyzed by solid-phase microextraction (SPME) and gas chromatography coupled to mass spectrometry (GC–MS). For 37 compounds, probability plots of log₁₀[GC–MS peak area] versus cumulative probability enabled visual identification of those that could be possible markers used to discriminate floral source. GC–MS peak areas were also analyzed by hierarchical cluster analysis and principal component analysis. Results showed data falling into groups based on floral source, indicating that supervised pattern recognition could be used to build a model with which to classify honeys based on floral source. A model was built using WEKA (Waikato Environment for Knowledge Analysis) machine-learning software. The logistic model tree algorithm in WEKA produced a model that classified 89.8 % of samples correctly. Overall, results show that the methods employed here have the potential to be used as a basis for routine testing and classification of New Zealand unifloral honeys.     

GC–MS quantification and sensory thresholds of guaiacol in orange juice and its correlation with Alicyclobacillus spp.

Guaiacol is a profoundly negative taint/off-flavour produced by the increasingly common microbial contamination of fruit juices with Alicyclobacillus spp. The objectives of this study included: determining sensory thresholds for guaiacol in orange juice (OJ), developing an analytical method whose detection limits were equivalent to sensory thresholds and determining levels of Alicyclobacillus spp. that would produce detectable levels of guaiacol. A 12 member trained panel was used to establish guaiacol detection and recognition thresholds. Guaiacol ortho and retro nasal detection thresholds in OJ were 0.70 and 0.53 μg/l respectively. Odour recognition threshold was 2.0 μg/l. A SPME GC–MS Selected Ion Monitoring (SIM) procedure was optimised to achieve analytical detection limits of 0.5 μg/l. Optimum guaiacol detection limit was achieved using only responses from m/z 109 and 124. Ion ratios (m/z 109/124) and linear retention index value matching were used to confirm the identification of guaiacol. Quantification was achieved using peak areas from standard guaiacol additions in orange juice between 0.5 and 100 μg/l. Alicyclobacillus growth of 2.2 log CFU/ml in OJ produced just detectable levels (0.7 μg/l) of guaiacol.     

Measurement of malonaldehyde in apple juice using GC–MS and a comparison to the thiobarbituric acid assay

Malonaldehyde (MA) in gamma-irradiated apple juice was measured using a GC–MS method and in comparison to the thiobarbituric acid (TBA) assay. The profiles of MA content as a function of radiation dose were similar using both methods, however, MA content was higher when measured with the TBA assay compared to the GC–MS method. The overestimation of MA using the TBA assay increased as the amount of MA decreased. Use of the GC–MS method demonstrated MA content in irradiated juice declined rapidly during storage at 5 °C. MA content appeared to decrease much less when the TBA assay was used. The GC–MS method also allowed measurement of formaldehyde and acetaldehyde in addition to MA.     

Volatile characteristics of 50 peaches and nectarines evaluated by HP–SPME with GC–MS

Using HS–SPME–GC–MS, characteristics of the volatiles of 50 peaches and nectarines representing different germplasm origins were investigated. Ten of these peaches and nectarines were studied in two successive years. Eighty-four compounds were identified. Volatile composition was relatively consistent, but the amount of total volatiles and certain individual compounds varied between years. Moreover, the composition of volatiles and their contents depended on genotypic background and germplasm origin. Total volatiles in wild peaches and a Chinese local cultivar ‘Wutao’ were much higher than in the other groups. All the peaches and nectarines could be classified into four groups by principal component analysis of the volatiles (excluding C₆ compounds): ‘Ruipan 14’ and ‘Babygold 7’ with high contents of lactones, Chinese wild peaches and ‘Wutao’ with high contents of terpenoids and esters, seven cultivars with American or European origins with high content of linalool, and others without characteristic composition of volatiles.     

Multiresidue method for determination of 88 pesticides in berry fruits using solid-phase extraction and gas chromatography–mass spectrometry: Determination of 88 pesticides in berries using SPE and GC–MS

A method using solid phase extraction (SPE) cleanup followed by gas chromatography–mass spectrometry (GC–MS) has been established for quantitative determination of 88 pesticide residues in berry fruits including raspberry, strawberry, blueberry and grape. Based on an appraisal of the characteristics of GC–MS, validation experiments were conducted for 88 pesticides. In the method, solid-phase extraction was carried out using Envi-Carb cartridge coupled with NH₂-LC cartridge with acetonitrile–toluene (3:1, v/v) as the eluted solvent. In the linear range of each pesticide, the correlation coefficient was R² ? 0.99. At the low, medium and high three fortification levels of 0.05–0.5 mg kg⁻¹, recoveries fell within 63–137%. The relative standard deviation was between 1% and 19% for all 88 pesticides. Low limits of detection (0.006–0.05 mg kg⁻¹) and quantification (0.02–0.15 mg kg⁻¹) were readily achieved with this method for all tested pesticides.     

Determination of patulin in apple and quince products by GC–MS using C5–7 patulin as internal standard

A reliable gas chromatographic mass spectrometric method has been validated for the determination of trace levels (<10 μgL⁻¹) of patulin in apple products and quince jam. The method was based on extraction of patulin with ethyl acetate-hexane, alkalinisation and silylation with N,O-bis-trimethylsilyltrifluoroacetamide with 1% of trimethylchloro-silane. The accurate determination of patulin was achieved by employing commercial ¹³C_5–7 patulin labelled as an internal standard, which allowed compensating target analyte losses and enhancement or suppression matrix effects. Limits of detection and quantification of method using real samples were 0.4 and 1.6 μgkg⁻¹, respectively. Recoveries of patulin from samples spiked at 8–50 μgkg⁻¹ levels ranged between 71% and 89%. The repeatability of measurements (expressed as relative standard deviation) was lower than 16%. The method was successfully applied to the determination of patulin in apple fruit and apple products including juice, cider and baby food, and also in quince fruit and quince jam. A new PCR system for the detection of Penicillium expansum in samples containing highly degraded DNA was developed which permitted the detection of the mould in 2/3 of the samples containing patulin, including juices and jams.     

A Comparative Study of the Ionization Modes in GC–MS Multi-residue Method for the Determination of Organochlorine Pesticides and Polychlorinated Biphenyls in Crayfish

A gas chromatography–mass spectrometry (GC–MS) multi-residue method with different ionization modes has been developed for the determination of 23 organochlorine pesticides and ten polychlorinated biphenyls (PCBs) in crayfish. The approach was based on an extraction with acetonitrile saturated by hexane (containing 0.1 % acetic acid), followed by a dispersed solid-phase extraction cleanup with primary secondary amine and octadecylsilane, and finally analyzed by GC–MS/MS operated in electron impact (EI) and positive chemical ionization (PCI), and GC–MS in negative chemical ionization (NCI), respectively. An isotope internal standard, DDT-D₈, was used for quantification. These three GC–MS procedures were validated and compared using crayfish samples fortified at three levels (5, 10 and 20 ng/g). Good linearity, accuracy, precision and sensitivity were achieved by all three ionization modes with recoveries in the range of 70 to 112 %, relative standard deviations (RSDs) below 10 % and limits of detection (LODs) in the range of 0.002 to 8 ng/g. Extremely high selectivity was obtained by both EI- and PCI-MS/MS, while PCI was more sensitive to compounds containing nitro and carbonyl groups, and EI was a better choice for dieldrin, endosulfan, and its metabolites. NCI-MS had the highest sensitivity but lower anti-interference ability and was not suitable for the determination of DDTs and PCBs. These three ionization modes can be used as complementary and alternative in routine GC–MS analysis of organochlorine pesticides and polychlorinated biphenyls in food.     

Mycotoxins in spices and herbs–An update

Spices and herbs have been used since ancient times as flavor and aroma enhancers, colorants, preservatives, and traditional medicines. There are more than 30 spices and herbs of global economic and culinary importance. Among the spices, black pepper, capsicums, cumin, cinnamon, nutmeg, ginger, turmeric, saffron, coriander, cloves, dill, mint, thyme, sesame seed, mustard seed, and curry powder are the most popular spices worldwide. In addition to their culinary uses, a number of functional properties of aromatic herbs and spices are also well described in the scientific literature. However, spices and herbs cultivated mainly in tropic and subtropic areas can be exposed to contamination with toxigenic fungi and subsequently mycotoxins. This review provides an overview on the mycotoxin risk in widely consumed spices and aromatic herbs.     

Determination of mineral oil paraffins in foods by on-line HPLC–GC–FID: lowered detection limit; contamination of sunflower seeds and oils

A method is described to lower the detection limit for mineral oil saturated hydrocarbons (MOSH) in foods as compared to the on-line HPLC–LC–GC–FID method described previously: samples are preseparated (enriched) by conventional liquid chromatography on activated silica gel and activated aluminum oxide. The silica gel retains up to 1 g of fat or oil, the aluminum oxide up to 2 mg n-alkanes of at least 24 carbon atoms, i.e. plant paraffins which may severely hinder the analysis of the mineral paraffins. The efficacy of the method is shown for an apple and sunflower oil. Oils extracted from manually harvested seeds grown in fields or gardens contained between 0.14 and 0.77 mg/kg MOSH. In the oils from seeds sampled in an oil mill, this value was increased to 3.3–9.3 mg/kg, indicating a contamination during harvest, transport and/or storage. Concentrations in commercial refined sunflower oils ranged between 2.7 and 32 mg/kg, averaging 11.2 mg/kg. Since deodorization removes a substantial part of the MOSH, this suggests a further contamination in the oil mill. The contamination affected all samples at a similar level, indicating that it occurs systematically by the presently used technology.     

Furan in the baby-food samples purchased from the Finnish markets – Determination with SPME–GC–MS

A method applying solid-phase microextraction followed by gas chromatography–mass spectrometric determination was in-house validated and used to study furan concentrations in baby-food samples purchased from the Finnish markets. The validation parameters showed that the method was well applicable for the reliable analysis of furan. Furan was analysed in 21 different baby-food samples as three independent replicates. The mean levels of furan varied between 4.7 and 90.3 μg kg⁻¹ being well in accordance with the levels reported in other studies. The mean concentrations of similar product formulas based on their ingredients were 9.2, 37.0 and 49.6 μg kg⁻¹ for fruit-, vegetables- and meat-containing baby-foods, respectively. According to the statistical analyses, fruit-based baby-food samples had significantly lower concentrations of furan as compared to other formulas. Based on our exercise, it seems that a low margin of safety exists between the extreme worst case infant exposures and the deduced NOAEL of furan on experimental animals, particularly for a clear rodent carcinogen.     

Volatile profiling of Ficus carica varieties by HS-SPME and GC–IT-MS

Aroma is one of the essential parameters for the evaluation of fruit quality, with volatile components being determinant for this characteristic. During this work, the volatile profile of fresh fruits (pulp and peel) and leaves of Portuguese Ficus carica L. white (“Pingo de Mel” and “Branca Tradicional”) and dark (“Borrasota Tradicional”, “Verbera Preta” and “Preta Tradicional”) varieties were characterised by HS-SPME/GC–IT-MS.     

Volatile profiles of aromatic and non-aromatic rice cultivars using SPME/GC–MS

Rice (Oryza sativa L.) is enjoyed by many people as a staple food because of its flavour and texture. Some cultivars, like scented rice, are preferred over others due to their distinctive aroma and flavour. The volatile profile of rice has been explored by other investigators, some of whom have also determined a corresponding aroma using GC/olfactometry. However, little research has been done to determine if different aromatic rice cultivars produce different flavour volatiles that would make them more desirable than others when cooked. In this study, seven aromatic and two non-aromatic cultivars were examined for their volatile profiles both before and after storage using solid phase microextraction (SPME) fibres in conjunction with gas chromatography/mass spectrometer (GC–MS). Ninety-three volatile compounds were identified, 64 of which had not been previously reported in rice. Differences were found in the volatile compounds of aromatic and non-aromatic rice besides 2-acetyl-1-pyrroline (2-AP). Most of the volatile compounds were present in freshly harvested rice and rice following storage, with very few new compounds being identified only after storage. Dellrose, an aromatic cultivar, and Cocodrie, a non-aromatic cultivar, had the most complex volatile profiles (over 64 volatiles). Sixteen compounds were found only in the aromatic cultivars, and some volatiles were found to be unique to specific aromatic cultivars. However, no distinctive pattern was observed that would identify a cultivar as being derived from Basmati, Khao Dawk Mali 105 (i.e. jasmine), or other sources of aroma. This study showed that there is a great diversity of volatiles in both aromatic and non-aromatic rice cultivars and, with further research, this may lead to a better understanding of the combination of compounds that gives a cultivar a unique flavour.