Concentrations of biogenic amines in fish,squid and octopus and their changes during storage

The concentrations of seven biogenic amines (BA) were simultaneously determined in 74 samples of fish, squid and octopus, by the method of HPLC coupled with pre-column derivatisation. The relationship between the formation of BA in aquatic products and the growth of microbial flora during storage was also investigated. Results showed that putrescine, cadaverine, histamine and tyramine were the dominant BA in the studied samples, but the concentrations of histamine and tyramine were mostly less than 50 and 100 mg kg⁻¹, respectively. Freezing can effectively prevent the formation of BA, but the levels of putrescine, cadaverine, histamine and tyramine significantly increased (p < 0.05) during storage at 4 and 25 °C. The growth of mesophilic or psychrophilic bacteria in blue scad and octopus strongly and positively correlated with the formation of amines (such as putrescine, cadaverine, histamine and tyramine) during storage, except for histamine in octopus.     

Trace element content of Boletus tomentipes mushroom collected from Yunnan,China

The contents of As, Cd, Cr, Cu, Fe, Hg, Mg, Mn, Ni, Pb, and Zn in eleven fruiting bodies of Boletus tomentipes were determined. The results showed the values of the studied elements decreased in the order: Mg (208–279 mg kg⁻¹) > Fe (106–137 mg kg⁻¹) > Mn (29.5–46.8. mg kg⁻¹) > Zn (18.7–23.1 mg kg⁻¹), > Cu (11.4–15.8 mg kg⁻¹) > Cr (3.36–4.78 mg kg⁻¹) > Pb (1.38–3.88 mg kg⁻¹) > Ni (1.68–3.01 mg kg⁻¹) > Cd (0.16–0.32 mg kg⁻¹) > As (0.10–0.24 mg kg⁻¹) > Hg (<0.06 mg kg⁻¹).     

Investigation on the presence of sulphites in fresh meat preparations: estimation of an allowable maximum limit

Sulphiting agents are commonly used food additives. They are not allowed in fresh meat preparations. In this work, 2250 fresh meat samples were analysed to establish the maximum concentration of sulphites that can be considered as “natural” and therefore be admitted in fresh meat preparations. The analyses were carried out by an optimised Monier-Williams Method and the positive samples confirmed by ion chromatography. Sulphite concentrations higher than the screening method LOQ (10.0 mg · kg^− 1) were found in 100 samples. Concentrations higher than 76.6 mg · kg^− 1, attributable to sulphiting agent addition, were registered in 40 samples. Concentrations lower than 41.3 mg · kg^− 1 were registered in 60 samples. Taking into account the distribution of sulphite concentrations obtained, it is plausible to estimate a maximum allowable limit of 40.0 mg · kg^− 1 (expressed as SO₂). Below this value the samples can be considered as “compliant”.     

Determination of metal contaminations in sea foods from Marmara,Aegean and Mediterranean seas: Twelve fish species

The concentrations of cadmium, cobalt, chromium, copper, iron, manganese, nickel, lead and zinc were determined by ICP-AES in muscles and livers of 12 fish species sampled from the Marmara, Aegean and Mediterranean seas of Turkey. Iron showed the highest levels in examined tissues of all fish species. Following Fe, Zn generally showed the second highest levels. Metal concentrations in edible parts of fish species were 0.02–0.37 mg kg⁻¹ for cadmium, 0.04–0.41 mg kg⁻¹ for cobalt, 0.04–1.75 mg kg⁻¹ for chromium, 0.32–6.48  mg kg⁻¹ for copper, 7.46–40.1 mg kg⁻¹ for iron, 0.10–0.99  mg kg⁻¹ for manganese, 0.02–3.97 mg kg⁻¹ for nickel, 0.33–0.86 mg kg⁻¹ for lead, 4.49–11.2 mg kg⁻¹ for zinc, respectively. All metal concentrations in livers were higher than those in muscles. In some stations, cadmium and chromium concentrations in both muscles and livers, and lead levels in livers of the examined species were higher than permissible safety levels for human uses.     

Flavonols (kaempeferol,quercetin, myricetin) contents of selected fruits,vegetables and medicinal plants

The concentrations of flavonols (kaempeferol, quercetin, myricetin) were determined in 22 plant materials (9 vegetables, 5 fruits, and 8 medicinal plant organs). The materials were extracted with acidified methanol (methanol/HCl, 100:1, v/v) and analyzed by reverse phase high-performance liquid chromatographic (RP-HPLC) with UV detection. The total flavonols contents varied significantly (P < 0.05) among vegetables, fruits and medicinal plant organs ranged from 0 to 1720.5, 459.9 to 3575.4, and 2.42 to 6125.6 mg kg⁻¹ of dry matter, respectively. Among vegetables, spinach and cauliflower exhibited the highest amounts of flavonols (1720.5 and 1603.9 mg kg⁻¹, respectively), however, no flavonols were detected in garlic. Within fruits, highest level of flavonols was observed in strawberry (3575.4 mg kg⁻¹), whereas, the lowest in apple fruit (459.9 mg kg⁻¹). Of the medicinal plant organs, moringa and aloe vera leaves contained the highest contents of flavonols (6125.6 and 1636.04 mg kg⁻¹), respectively, whereas, lowest was present in barks (2.42–274.07 mg kg⁻¹). Overall, leafy green vegetables, soft fruits and medicinal plant leaves exhibited higher levels of flavonols.     

Metal content determination in four fish species from the Adriatic Sea

Concentrations of As, Cd, Cu, Hg and Pb were measured by atomic absorption spectrometry (AAS) in muscle tissues of four fish species: anchovy (Engraulis encrasicholus), mackerel (Scomber japonicus), red mullet (Mullus surmuletus) and picarel (Spicara smaris) from the Croatian waters of the Adriatic Sea during 2008 and 2009. Metal levels measured in anchovy were in the following ranges (mg kg⁻¹): As 0.01–54.8, Cd 0.001–0.02, Cu 0.001–6.29, Hg 0.001–0.52 and Pb 0.001–0.34 mg kg⁻¹. Metal ranges in red mullet were (mg kg⁻¹): As 0.01–70.9, Cd 0.002–0.85, Cu 0.001–57.3, Hg 0.001–2.07 and Pb 0.001–0.27 mg kg⁻¹. Metal level ranges measured in mackerel were (mg kg⁻¹): As 0.01–36.4, Cd 0.001–0.1, Cu 0.001–15.9, Hg 0.001–0.78 and Pb 0.002–0.24 mg kg⁻¹. In picarel, metal level ranges were (mg kg⁻¹): As 0.01–54.6, Cd 0.001–0.1, Cu 0.08–32.9, Hg 0.001–0.207 and Pb 0.001–0.46 mg kg⁻¹. Significant differences in metal concentrations were found among fish species. The results presented on metal contents in the examined species give an indication of the environmental conditions. Concentrations of Cd, Cu, Hg and Pb obtained were far below the established values by the European Community regulations. However, arsenic levels found in red mullet were higher than the recommended legal limits for human consumption and as such may present a human health issue.     

HPLC–MS identification and quantification of flavonol glycosides in 28 wild and cultivated berry species

Berries and red fruits are rich dietary sources of polyphenols with reported health benefits. More than 50 different flavonols (glycosides of quercetin, myricetin, kaempferol, isorhamnetin, syringetin and laricitrin) have been detected and quantified with HPLC–MSⁿ in fruits of blueberry, bilberry, cranberry, lingonberry, eastern shadbush, Japanese wineberry, black mulberry, chokeberry, red, black and white currants, jostaberry, red and white gooseberry, hardy kiwifruit, goji berry, rowan, dog rose, Chinese and midland hawthorn, wild and cultivated species of blackberry, raspberry, strawberry and elderberry. The phenolic constituents and contents varied considerably among the analyzed berry species. Elderberry contained the highest amount of total flavonols (450–568 mg kg⁻¹ FW), followed by berry species, containing more than 200 mg kg⁻¹ FW of total: chokeberry (267 mg kg⁻¹), eastern shadbush (261 mg kg⁻¹), wild grown blackberry (260 mg kg⁻¹), rowanberry (232 mg kg⁻¹), american cranberry (213 mg kg⁻¹) and blackcurrants (204 mg kg⁻¹). Strawberry (10.5 mg kg⁻¹) and white currants (4.5 mg kg⁻¹) contained the lowest amount of total flavonols. Quercetins represent the highest percentage (46–100%) among flavonols in most analyzed berries. In wild strawberry and gooseberry the prevailing flavonols belong to the group of isorhamnetins (50–62%) and kaempferols, which represent the major part of flavonols in currants (49–66%). Myricetin glycosides could only be detected in chokeberry, rowanberry and species from the Grossulariaceae, and Adoxaceae family and Vaccinium genus. Wild strawberry and blackberry contained from 3- to 5-fold higher total flavonols than the cultivated one.     

5-Hydroxymethylfurfural content in foodstuffs determined by micellar electrokinetic chromatography

Micellar electrokinetic chromatography (MEKC) has been applied for the determination of 5-hydroxymethylfurfural in several foodstuffs. A 75 mM phosphate buffer solution at pH 8.0 containing 100 mM sodium dodecylsulphate was used as background electrolyte (BGE), and the separation was performed by applying +25 kV in a 50 μm I.D. uncoated fused-silica capillary. Good linearity over the range 2.5–250 mg kg⁻¹ (r² ? 0.999) and run-to-run and day-to-day precisions at low and medium concentration levels were obtained. Sample limit of detection (0.7 mg kg⁻¹) and limit of quantification (2.5 mg kg⁻¹) were established by preparing the standards in blank matrix. The procedure was validated by comparing the results with those obtained with liquid chromatography coupled to tandem mass spectrometry (LC–MS/MS). Levels of HMF in 45 different foodstuffs such as breakfast cereals, toasts, honey, orange juice, apple juice, jam, coffee, chocolate and biscuits were determined.     

Determination of organochlorine pesticide residues in rice and human and fish fat by simplified two-dimensional gas chromatography

The residue levels of four hexachlorocyclohexane (HCH) isomers (α-HCH, β-HCH, γ-HCH and δ-HCH), 4 dichloro-diphenyl-trichloroethane (DDT) congeners (p,p-DDE, o,p-DDT, p,p-DDD, and p,p-DDT), heptachlor, heptachlor epoxide, aldrin, dieldrin and endrin in rice and its bran from Jiangsu Province, PR China, were investigated by simplified two-dimensional gas chromatography, coupled with micro-electronic capture detector (μECD). Concentrations of organochlorine pesticides (OCPs) for ∑HCH ranged from 0 to 0.039 mg kg⁻¹ in the rice and 0 to 0.057 mg kg⁻¹ in its bran. For ∑DDT, the concentrations ranged from 0 to 0.053 mg kg⁻¹ in the rice and 0 to 0.051 mg kg⁻¹ in its bran. The five other OCPs, except HCH and DDT, were not detected. The major HCH isomers and DDT, congeners detected, both in the rice and its bran, were β-HCH and p,p′-DDE. Compared with the residue levels in the rice, the OCPs levels in fish and human fat were detected at higher residue levels. It is necessary to investigate the OCP residues in foodstuffs of the food chain in order to evaluate the potential health risk to humans.     

Chemical composition of cultivated seaweed Ulva clathrata (Roth) C. Agardh

Samples of cultivated Ulva clathrata were collected from a medium scale system (MSS, 1.5 × 1.5 m tank), or from a large scale system (LSS, 0.8 ha earthen pond). MSS samples were dried directly while the LSS sample was washed in freshwater and pressed before drying. Crude protein content ranged 20–26%, essential amino acids accounting for 32–36% of crude protein. The main analysed monosaccharides were rhamnose (36–40%), uronic acids (27–29%), xylose (10–13%) and glucose (10–16%). Some notable variations between MSS and LSS samples were observed for total dietary fibre (26% vs 41%), saturated fatty acids (31% vs 51%), PUFAS (33% vs 13%), carotenoids (358 vs 169 mg kg⁻¹ dw) and for Ca (9 vs 19 g kg⁻¹), Fe (0.6 vs 4.2 g kg⁻¹), Cu (44 vs 14 mg kg⁻¹), Zn (93 vs 17 mg kg⁻¹) and As (2 vs 9 mg kg⁻¹). The chemical composition of U. clathrata indicates that it has a good potential for its use in human and animal food.     

Fish and food safety: Determination of formaldehyde in 12 fish species by SPME extraction and GC–MS analysis

The formaldehyde (FA) content in different fish products was evaluated using a solid phase microextraction (SPME)-GC–MS method based on fiber derivatisation with pentafluorobenzyl-hydroxyl-amine hydrochloride. LOD and LOQ values of 17 and 28 μg kg⁻¹, respectively were calculated. Fish quality was assessed by the analysis of 12 species (sea-fish, freshwater-fish and crustaceans), revealing variable FA levels. Fresh, deep frozen, canned, boiled and roasted fish were analysed; cooking always produced a decrease in the analyte content. Fish belonging to the Gadidae family were the samples with the highest FA concentration (from 6.4 ± 1.2 mg kg⁻¹ to 293 ± 26 mg kg⁻¹), in four cases out of 14 exceeding the value of 60 mg kg⁻¹ proposed by the Italian Ministry of Health. Storage on ice was also investigated, showing moderate FA production also at temperature around 0 °C. FA contents lower than 22 mg kg⁻¹ were finally found in all the other samples.     

Pharmacokinetics and residues of tetracycline in crucian carp muscle using capillary electrophoresis on-line coupled with electrochemiluminescence detection

A novel and sensitive determination for tetracycline (TC) in crucian carp muscle was developed by using capillary electrophoresis coupled with electrochemiluminescence (ECL) detection. The conditions affected separation and detection were examined in detail. The linearity range of TC concentration was from 0.005 to 10 μg mL⁻¹ with a correlation coefficient of 0.9992. The detection limit of TC (S/N = 3) was 1.8 ng mL⁻¹. The relative standard deviations of the ECL intensity and the migration time for eleven consecutive injections of 1.0 μg mL⁻¹ TC were 1.6% and 0.8%, respectively. The recovery of TC was 97.8% (n = 5). After administration of 75 mg kg⁻¹ TC, the maximum concentration and peak time of TC in crucian carp muscle were 7.33 mg kg⁻¹ and 8 h, respectively. After administration of TC, TC concentration demonstrated trivial variation in the period from 48 to 96 h.     

Determination of heavy metals (Cd,Pb) and trace elements (Cu,Zn) in sediments and fish of the Southeastern Aegean Sea (Turkey) by atomic absorption spectrometry

The Bay of Güllük in Southeastern Aegean Sea (Turkey) is very important by the potential of marine product in the Aegean Sea. There are various polluting elements in Güllük Bay. The current situation of the bay and impact of pollutants have became necessity. Dicentrarchus labrax are frequently used for human consumption. In this study, heavy metals (Pb, Cd) and trace elements (Cu, Zn) were analyzed in fish (D. labrax) and sediments in the Bay of Güllük by atomic absorption spectrometry. The average metal concentrations in the fish varied in the following ranges: Pb; <0.02–0.4, Cd; <0.01–0.04, Cu; <0.1, Zn; <0.5–7.2 mg kg⁻¹. In addition, seven sediment samples were analyzed and avarage concentrations of them were found as Zn; 80.8 ± 0.45, Cu; 25.2 ± 0.14, Pb; 20.0 ± 2, Cd; 0.560.08 mg kg⁻¹. The accuracy and precision of our results were checked by using International Certified Reference samples (fish: DORM-2, sediment: HISS-1).     

Flow injection analysis of nitrate-N determination in root vegetables: Study of the effects of cooking

Vegetables are the major vehicles for the entry of nitrate into the human system. Ever-increasing concern over nitrate toxicity has directed a number of countries to lay down maximum allowable threshold concentrations with regards to nitrate-N in vegetables. Fiji is an independent island nation, located in the southern Pacific Ocean, has a tropical oceanic climate and hence expected to have high nitrate-N levels in vegetables. Thus, the present study was devoted to establish a flow injection analysis (FIA) technique for nitrate-N determination in Fiji’s commonly consumed fresh and cooked root vegetables such as potato (Solanum tuberosum), dalo (Colocasia esculenta), sweet potato (Ipomoea batatas) and carrot (Daucus carota L.). Activated carbon extraction technique was applied to extract nitrate-N. FIA with colorimetric detection technique having linear dynamic range of determination 1.0–20.0 mg L⁻¹ and detection limit of 0.042 mg L⁻¹ (0.34 mg kg⁻¹), using sulphanilamide and N-(1-naphthyl)ethylenediamine dihydrochloride as colour reagents, was used to determine nitrate-N contents in selected fresh and cooked root vegetables. The samples throughput was 38 h⁻¹. The effects of various cooking (boiling, baking and frying) methods on nitrate-N contents in root vegetables have also been studied. The study shows that the nitrate content of fresh root vegetables ranges from 53.76–258.00 mg kg⁻¹ whereas boiling reduces nitrate content by 23.30–42.62%. The frying in soya bean oil elevates nitrate contents from 204.53–299.12% but after baking nitrate contents remains almost constant with slight increasing trend from 2.80–8.43%. A comparison of the nitrate obtained by standardised method and the nitrate contents in vegetables of other countries are also presented.     

Comparison of the cell wall composition for flesh and skin from five different plums

Cell walls were isolated from flesh and skin of five plum varieties corresponding to three species (Prunus domestica L., Prunus salicina Lindl. and Prunus insititia Lindl.) using the alcohol-insoluble solids (AIS) procedure. Yields varied from 83 to 114 g kg⁻¹ dry weight in the flesh and from 192 to 361 g kg⁻¹ dry weight in the skins. Their main sugars were uronic acid (224–322 mg g⁻¹ AIS), cellulosic glucose (139–170 mg g⁻¹ AIS), galactose and arabinose. Galactose and arabinose ratio were variable between the varieties. The degrees of methylation were high (62–84).     

Chemical characterization of a traditional honey-based Sardinian product: Abbamele

The first chemical characterization of abbamele, a traditional honey decoction from Sardinia (Italy) is hereby reported. Water content (from 17.7% to 27.7%), electrical conductivity (from 0.19 to 0.81 mS cm⁻¹), pH (from 3.21 to 3.92), free acidity (from 26.1 to 87.6 meq kg⁻¹), invertase activity (from 0 to 1.02 U kg⁻¹), 5-(hydroxymethyl)-2-furaldehyde, HMF (from 881 to 4776 mg kg⁻¹), total polyphenols (from 188 to 984 mg kg⁻¹) and free amino acid contents of thirteen abbamele samples, from industrial and traditional producers, were obtained in an attempt to compare this traditional product with honey and to study the relationship between its main features and the production procedures. The long thermal treatment involved in the production of abbamele has been identified as the main cause of very low (or absent) invertase activity and free amino acid content as well as the very high content of HMF.     

The effect of diets supplemented with thyme essential oils and rosemary extract on the deterioration of farmed gilthead seabream (Sparus aurata) during storage on ice

The effect on quality were assessed for gilthead seabream fed five different diets: control (basal diet); BHT (basal diet with 200 mg kg⁻¹ of butylated hydroxytoluene); rosemary (basal diet with 600 mg kg⁻¹ of rosemary extract - Rosmarinus officinalis); carvacrol (basal diet with 500 mg kg⁻¹ of essential oil of Thymbra capitata, carvacrol chemotype); and thymol (basal diet with 500 mg g⁻¹ of essential oil of Thymus zygis, subspecies gracilis, thymol chemotype). After 18 weeks of experimentation, the animals were stored on ice at 4 °C for 0, 7, 14, and 21 days. Physical-chemical, microbiological and sensory analyses were carried out at each sampling point to determine the degree of deterioration in the gilthead seabream. Lower indices of oxidation were observed in animals who were administered feeds supplemented with BHT, carvacrol and (to a lesser degree) rosemary. Lower bacteria counts were observed for the BHT and thymol groups, in addition to a slower deterioration in terms of sensory perception. Accordingly, the addition of natural antioxidants to the diet may have an added effect on fish quality, delaying post mortem deterioration.     

Occurrence of β-casomorphins 5 and 7 in commercial dairy products and in their digests following in vitro simulated gastro-intestinal digestion

The occurrence of β-casomorphin-5 (BCM5) and β-casomorphin-7 (BCM7) was investigated in commercial dairy products and in their digests, following in vitro simulated gastro-intestinal digestion (SGID), by means of HPLC–MS. The analysed dairy products were as follows: 10 cheeses (Gorgonzola, Caprino, Brie, Taleggio, Gouda, Fontina, Cheddar and Grana Padano 10-, 15- or 25-m ripened); 4 samples of drinking milk (unprocessed, pasteurised, UHT and in bottle-sterilised); 2 yoghurts and 4 fermented milks containing probiotics; 7 infant formulas; and 4 dried milk-derivatives (skim milk powder, calcium caseinate and milk protein concentrates). β-Casomorphin-5 was not detected in dairy products, either prior to or after SGID. β-Casomorphin-7 was detected only in cheeses with the exception of Taleggio, Caprino and Grana Padano samples. Peptide amount was in the range 0.01–0.15 mg kg⁻¹ the highest level being recovered in Brie sample. Following SGID, BCM7 formed in all dairy samples or increased up to 21.77 mg kg⁻¹ in digests of cheeses. The peptide level ranged from 0.29 to 1.23 mg kg⁻¹in fermented milks and from 3.46 to 22.18 mg kg⁻¹ in dried milk-derivatives. Digests of commercial infant formulas contained BCM7 at concentrations of 0.04–0.21 mg l⁻¹. For the first time, this work reports quantitative values for BCM5 and BCM7 in a range of dairy products providing evidence that, during processing, only proteolytic systems involved in manufacturing and ripening of cheese can potentially hydrolyse β-CN to BCM7. Nevertheless, formation or further release of BCM7 is mainly promoted by the action of gastrointestinal proteinases during in vitro digestion irrespective of the type of dairy product.     

Impact of resistance on the efficacy of binary combinations of spinosad, chlorpyrifos-methyl and s-methoprene against five stored-grain beetles

Laboratory experiments were conducted to determine the efficacy of spinosad (a biopesticide), chlorpyrifos-methyl (an organophosphorus compound (OP)) and s-methoprene (a juvenile hormone analogue) applied alone and in binary combinations against five stored-grain beetles in wheat. There were three strains of Rhyzopertha dominica, and one strain each of Sitophilus oryzae, Tribolium castaneum, Oryzaephilus surinamensis and Cryptolestes ferrugineus. These strains were chosen to represent a range of possible resistant genotypes, exhibiting resistance to organophosphates, pyrethroids or methoprene. Treatments were applied at rates that are registered or likely to be registered in Australia. Adults were exposed to freshly treated wheat for 2 weeks, and the effects of treatments on mortality and reproduction were determined. No single protectant or protectant combination controlled all insect strains, based on the criterion of >99% reduction in the number of live F₁ adults relative to the control. The most effective combinations were spinosad at 1 mg kg⁻¹+chlorpyrifos-methyl at 10 mg kg⁻¹ which controlled all strains except for OP-resistant O. surinamensis, and chlorpyrifos-methyl at 10 mg kg⁻¹+s-methoprene at 0.6 mg kg⁻¹ which controlled all strains except for methoprene-resistant R. dominica. The results of this study demonstrate the difficulty in Australia, and potentially other countries which use protectants, of finding protectant treatments to control a broad range of pest species in the face of resistance development.     

Study of flavonoids in aqueous spinach extract using positive electrospray ionisation tandem quadrupole mass spectrometry

The presence of three flavonols (quercetin, kaempferol, myricetin) and two flavones (apigenin, luteolin) were investigated in the extract of fresh spinach leaves. Aqueous spinach extracts were prepared with a leaf/water ratio of 1:2 at 80 °C for 30 min stirring. Ferric ammonium sulphate method was used for measuring total polyphenols in the extracts and expressed as catechins and tannic acid equivalents. The flavonoids glycosides in the extract were hydrolysed to their aglycons with 1.2 M HCl in boiling 50% water methanol solution. The resulting aglycons were identified and quantified by a C18 reverse phase high-performance liquid chromatography (RP-HPLC). Furthermore, the results were confirmed by HPLC coupled to an electrospray ionisation tandem triple-quadrupole mass spectrometer ESI-MS performing low-energy collision induced dissociation (CID-MS/MS) in the collision cell (HPLC-ESI-MS/MS). Analyses were made in the multiple reaction monitory (MRM) mode. Results showed that total polyphenols contents in fresh spinach leaves were 270 mg kg⁻¹ and 390 mg kg⁻¹ as tannic acid and catechin equivalents, respectively, in which, major flavonoids aglycons were apigenin (170 mg kg⁻¹), quercetin (50 mg kg⁻¹) and kaempferol (30 mg kg⁻¹).