Alaskan flatfishes on the German market: part 1: identification by DNA and protein analytical methods

North Pacific flatfishes are gaining increased popularity on the German market. Isoelectric focusing of sarcoplasmic proteins and PCR-based DNA analysis were applied to identify fillets of nine Alaskan Flatfish species: Artheresthes stomias (Arrow-tooth flounder), Limanda aspera (Yellowfin sole), Isopsetta isolepis (Butter sole), Lepidopsetta bilineata (Southern rock sole), Lepidopsetta polyxystra (Northern rock sole), Hippoglossus stenolepis (Pacific halibut), Hippoglossoides elassodon (Flathead sole), Platichthys stellatus (Starry flounder), and Glyptocephalus zachirus (Rex sole). Characteristic protein patterns were obtained for raw fillets of several species. Reactivity of flatfish DNA against five pairs of primers was tested, amplifying segments of the mitochondrial cytochrome b, cytochrome oxidase subunit I, 16S rRNA gene, as well as the nuclear parvalbumin gene. Amplicons of the cytochrome b gene were sequenced and used for single-strand conformation polymorphism analysis. The survey of deep-frozen commercial yellowfin sole fillets resulted in the detection of 17% of the fillets being mislabelled; Northern rock sole, butter sole and flathead sole had been used as substitutes.     

Application of cold oxygen plasma for the reduction of Cladosporium cladosporioides and Penicillium citrinum on the surface of dried filefish (Stephanolepis cirrhifer) fillets

This study was conducted to investigate the effects of cold oxygen plasma (COP) on the reductions of Penicillium citrinum and Cladosporium cladosporioides on the surface of dried filefish fillets (Stephanolepis cirrhifer). The counts were significantly (P < 0.05) reduced with the increase in the treatment time (3–20 min) of COP on the fillets. However, no significant (P > 0.05) differences were observed in the counts between 3 and 5 min of COP. The average decrease in the counts of C. cladosporioides and P. citrinum caused by 3–20 min of COP was 0.91 and 1.04 log₁₀ CFU g^?1, respectively. A reduction of >1‐log₁₀ CFU g^?1 was observed on the fillets treated with COP for >10 min. Decimal reduction time (d_R) by Weibull model was 9.32 and 7.42 min of COP for C. cladosporioides and P. citrinum, respectively. The fillets exposed to 20 min of COP displayed increased thiobarbituric acid reactive substance (TBARS) and decreased overall sensory acceptance. However, the fillets treated with 10 min of COP received satisfactory TBARS and consumer acceptance. Therefore, a 10‐min COP could be effective in reducing >90% and inactivating of the mould without causing any deleterious changes to the physicochemical and sensory qualities of the fillet.     

Comparison of nutritional value and microbiological status of new imported fish species on the German market

Proximate composition, fatty acid profile, other nutritional values and spoilage indicators were examined in the muscle meat of five species: barramundi (Lates calcarifer) from various origins, tilapia (Oreochromis spp.) of different qualities, cobia (Rachycentron canadum) and leather jacket (Aluterus monoceros) from the Pacific Ocean and Patagonian grenadier (Macruronus magellanicus) from South America. Lowest lipid contents (0.4% and 0.8%) were found in leather jacket and cobia. Leather jacket fillets had lowest protein (16.2%) and highest sodium chloride content (4.9%). Concentrations of ∑EPA + DHA were 0.1 g 100 g^?1 for tilapia and leather jacket, 0.2 g 100 g^?1 for barramundi and cobia and 0.7 g 100 g^?1 for Patagonian grenadier. Barramundi and tilapia were characterised by high taurine content (215 and 276 mg 100 g^?1 ww.), and cobia had only low levels (41 mg 100 g^?1 ww.). Iodine contents were low and selenium levels varied between 303 and 570 μg kg^?1 ww. No sign of spoilage was detected.     

Antioxidative and antimicrobial activities of shrimp chitosan on gilthead sea bream (Sparus aurata) during refrigerated storage

This study aims to determine the effects of chitosan obtained from Metapenaeus stebbingi shells on the shelf life of refrigerated gilthead sea bream. It was determined that 1% chitosan‐coated samples had the lowest thiobarbituric acid (TBA) (3.05 mg malondialdehyde (MDA) kg^?1) and free fatty acids (FFA) value (2.79% oleic acid), while the control group had the highest TBA (5.08 mg MDA kg^?1) and FFA value (6.13% oleic acid) on the 27th day of storage. In the last day of storage, TVB‐N was found higher in control group (25.62 mg 100 g^?1) than chitosan‐coated samples (14.57 mg 100 g^?1). Total viable count value of the control group exceeded maximum permissible limit on the 27th day of storage. However, it was lower than 7.0 log CFU/g in chitosan‐coated samples during the refrigerated storage. As a result of this study, it was determined that shelf life of refrigerated gilthead sea bream can be increased up to 27 days with chitosan.     

The influence of different plasticisers and fatty acids on functional properties of basil seed gum edible film

In this study, the influence of different concentrations of plasticisers and fatty acids on functional properties of basil seed gum (BSG) films was investigated. The results revealed that glycerol and sorbitol were effective plasticisers for BSG films. Glycerol‐plasticised films exhibited hydrophilic nature with high moisture content (27–49%) and water vapour permeability (4.2–6.5 × 10^?11 g Pa^?1 m^?1 s^?1), moisture uptake higher than 100%, solubility ranging 39–50% and moderate mechanical properties. The films containing sorbitol showed lower moisture content, moisture uptake and percentage elongation compared with glycerol‐plasticised samples. Presence of fatty acids promoted an increase in hydrophobicity of samples, characterised by lower moisture uptake, solubility, water vapour permeability and higher contact angles. Among investigated fatty acids, oleic acid efficiency on improving the characteristics of films was higher than saturated fatty acids (palmitic and stearic acid). Concluding, BSG films showed a substantial potential to be incorporated into food packaging applications, especially for those that require less hydrophilic films.     

Seasonal changes of proximate composition and fatty acids of farmed dusky grouper (Epinephelus marginatus Lowe, 1834)

The aim of this work was to determine the seasonality of nutrient profiles of dusky grouper (Epinephelus marginatus Lowe, 1834) cultured in a cage to improve knowledge on its nutritional composition. Fish (n = 735) were reared in a circular polyethylene floating cage for a 19‐month experimental period and provided a commercial pelleted feed once a day with a total daily ration of 1% wet body weight. Fish were sampled every 3–4 months, and biometric parameters as well as muscle composition were determined. The edible proportion of fish increased slightly with culture time. The flesh showed low lipid content, similar to those reported for wild grouper. Biometric indices, muscle proximate composition and fatty acid profiles were significantly affected by seasonality, that is lipids and monounsaturated fatty acids increased during summer, in parallel with the decline of polyunsaturated fatty acids.     

Production of Agaricus brasiliensis mycelium from food industry residues as a source of antioxidants and essential fatty acids

Agaricus brasiliensis is a medicinal mushroom traditionally employed in prevention and treatment of cancer, used as immunostimulant and as a source of antioxidants. We investigated the chemical composition of the mycelium produced by submerged (SF) and solid‐state fermentation (SSF), using residues from food industry as substrates. After fermentation, antiradical activity and levels of antioxidants were enhanced, indicating that the micro‐organism produces these metabolites. For myceliated substrate (mushroom mycelia grown around and into the substrate particles) obtained by SSF, phenolics ranged from 18.57 to 70.46 mg g^?1 and flavonoids from 0.83 to 4.51 mg g^?1. For myceliated substrate obtained by SF, the variation was 27.19 to 66.99 mg g^?1 and 0.75 to 5.34 mg g^?1 for phenolics and flavonoids, respectively. The fatty acid profile determined by FT‐ICR MS and UPLC‐MS showed predominance of palmitic, linoleic, linolenic and oleic acids. Our findings indicated that mycelium has nutraceutical potential and can be incorporated in food supplements.     

Bacterial inactivation and quality changes of fresh‐cut avocados as affected by intense light pulses of specific spectra

Intense light pulses (ILP) treatments have good prospects for becoming an alternative to traditional thermal methods for decontamination of food surfaces. The aim of this work was to evaluate which ranges of the light spectrum are responsible for bacterial inactivation and their effect on the quality of fresh‐cut avocado. Results show that the effectiveness of ILP treatment decreases when the ultraviolet (UV) spectral region is blocked (particularly UV‐C). ILP treatments without UV‐C light (305–1100 nm) and an overall fluence of 10.68 J cm^?2 caused reductions of 2.47 and 1.35 log CFU g^?1 in the initial counts of inoculated Escherichia coli and Listeria innocua, respectively, in comparison with those treated using only VIS–NIR light (0.83 and 0.68 log CFU g^?1, respectively). Treatments applying light of a wavelength between 305 and 1100 nm had a more pronounced impact on colour, texture and headspace gas composition than treatments that did not contain UV light (400–1100 nm).     

Original article: Extraction of lipid from scallop (Patinopecten yessoensis) viscera by enzyme‐assisted solvent and supercritical carbon dioxide methods

In the present study, lipid was extracted from scallop (Patinopecten yessoensis) viscera by using the enzyme‐assisted solvent method and the supercritical carbon dioxide (SC‐CO₂) method. Soxhlet extraction with ethyl ether produced a yield of 23.7 ± 0.6 g of lipid 100 g^?1 of dry matter. Enzyme‐assisted solvent extraction allowed recovering 60.6 ± 1.5% of P. yessoensis viscera lipid from the samples treated with papain, whereas a lipid recovery rate of 78.3 ± 0.6% was achieved by SC‐CO₂ extraction. The lipid extracted was divided into the unsaponifiable fraction (sterol) and the saponifiable fraction (fatty acid) and analysed by gas chromatography mass spectrometry. Results indicated that the fatty acid composition and sterol composition for lipids extracted by different methods were slightly different. Eicosapentaenoic acid and docosahexaenoic acid were dominant polyunsaturated fatty acids accounting for 35–40% of the total fatty acid.     

Lipid quality and filleting yield of reared meagre (Argyrosomus regius)

Reared meagre (Argyrosomus regius) of average weight 1278 g was evaluated for its filleting yield and fillet lipid quality. Filleting yield averaged 42.2%, while very low levels of muscle fat deposits were measured (1.06%). Analysis of lipid classes revealed a high proportion of polar lipids (48.3–59.1%) and low levels of neutral fatty acids (40.9–51.7%) when compared to corresponding values of other farmed fish species. Phosphatidyl‐choline (PC) was the dominant polar lipid (2.92 mg g^?1 muscle), while cholesterol the most abundant neutral lipid (1.68 mg g^?1 muscle). The fatty acid composition of meagre fillet generally reflects the dietary fatty acids. Among n‐3 fatty acids, eicosapentaenoic (4.58%) and docohexaenoic (15.0%) were measured to be the most abundant ones, and 18:2n‐6 (11.9%) was the most common n‐6 fatty acid. The fatty acid profiles of polar and neutral fractions differ, with monounsaturated fatty acids being predominant in the neutral and n‐3 polyunsaturates in the polar lipids. The high polar lipid contents and n‐3 fatty acids and the low atherogenic and thrombogenic indexes indicate a high quality of this species’ lipids.     

Sacha inchi (Plukenetia volubilis L.) shell: an alternative source of phenolic compounds and antioxidants

Sacha inchi seed (SI) is known as a rich source of oil with high content of polyunsaturared fatty acids of the ω‐3 and ω‐6 type (~85% of total fatty acids). However, few studies have focused on the use of by‐products from the seed. The aim of this study was to characterise the main phenolic families present in SI shell and to evaluate the best extraction solvent for the extraction of phenolic compounds (PC) and antioxidant capacity (AOXC). The PC content corresponded to 74.5 ± 5.1 mg g^?1 of which 93.1% were condensed tannins and the remaining compounds corresponded to free and bound phenolic acids, hydrolyzable tannins, flavonoids and flavanoids. Protocatechic and p‐coumaric acids but also hydroxycinammic acid derivatives of ferulic and o‐coumaric type and lignan derivatives were identified. Acetone containing solvents favoured the extraction of higher amounts of total PC and AOXC. This study highlights the potential use of SI shell as a novel and alternative source of PC antioxidants for the nutraceutical and/or functional food industries.     

Effects of Pseudomonas chlororaphis and gaseous chlorine dioxide on the survival of Salmonella enterica on tomatoes

Control of Salmonella enterica on tomatoes is important for food safety. The aim of this research was to evaluate the survival of Salmonella enterica serovars Montevideo (SM) and Typhimurium (ST) on tomatoes exposed to gaseous chlorine dioxide and Pseudomonas chlororaphis (Pc). Pc was applied to stem scars of tomatoes prior to inoculations with SM and ST. Tomatoes were treated with gaseous ClO₂ at 0.4 mg L^?1 for 2 and 4 h (90% R.H. 13 °C), respectively. At 4 h of ClO₂ treatment, SM and ST populations were reduced to 0.82 and <0.30 log CFU g^?1, respectively. Tomatoes treated with SM and ST had 5.42 and 5.37 log CFU g^?1 of Salmonella. Tomatoes treated with Pc + Salmonella count was 2.59 (treated) and 5.83 log CFU g^?1 (control). Salmonella survival was similar at 2 and 4 h of ClO₂ treatment. Application of ClO₂ and Pc may reduce contamination of tomatoes by Salmonella serovars.     

Physicochemical characterisation and oxidative stability of refined hoki oil,unrefined hoki oil and unrefined tuna oil

Physicochemical characterisation and oxidative stability of refined hoki oil, unrefined hoki oil and unrefined tuna oil were carried out in the present study. Tuna oil contains a higher percentage of polyunsaturated fatty acids (42.57%) than the hoki oils (28.79–30.13%), which have higher percentages of monounsaturated fatty acids (45.02–47.16%). All oils showed a good ratio of n‐3 to n‐6 fatty acid (7.01–8.10). Cholesterol contents in the unrefined hoki (5149.40 μg g^?1) and tuna (2045.48 μg g^?1) oils were higher than the refined hoki oil (1411.27 μg g^?1). Tuna has a higher concentration of natural α‐tocopherol (752.49 μg g^?1) but lower concentration of vitamin A (110.99 μg g^?1) than unrefined hoki oil (151.44 μg g^?1 and 997.60 μg g^?1, respectively). Higher percentages of unsaponifiable matter were found in the hoki oils (4.90–7.24%) compared with the tuna oil (0.56%). The hoki oils appear more yellow than the tuna oil, which is darker by comparison. Moisture, p‐anisidine value and free fatty acid contents in the hoki oils were lower than the tuna oil. Other indicators of oxidative stability showed that the hoki oils were more stable than the tuna oil.     

Development and validation of a SYBR‐Green I Real‐Time PCR test to detect bivalves including Mytilus species in foods

The incidence of allergy to seafood, and in particular to molluscs is second only to that of nuts. To protect consumers, the regulators of food products insisted on identifying molluscs as allergens. The aim was to develop quantitative assay for the presence Mytilus species in processed food products. The chosen platform was real‐time PCR (qPCR) targeting either the gene encoding mitochondrial cytochrome C oxidase I or the nuclear gene encoding β‐actin. Recombinant plasmids containing each of target regions were used as a reference for quantification purposes. Limit of detection (LOD) and of quantification (LOQ) were determined. Spiked food samples containing 50–500 μg g^?1 of Mytilus chilensis were analysed both by qPCR and by ELISA. The former assay gave a positive outcome over this range, whereas the latter was sensitive down to a concentration of 125 μg g^?1.     

Shelf life and quality of probiotic yogurt produced with Lactobacillus acidophilus and Gobdin

This study evaluated the effect of dry white mulberry and walnut paste (Gobdin, a traditional Turkish food) in probiotic yogurt on the survival of Lactobacillus acidophilus and yogurt properties. Six different yogurts were produced with 0%, 5% and 10% Gobdin using Lactobacillus bulgaricus + Streptococcus thermophilus and with 0%, 5% and 10% Gobdin using L. bulgaricus + S. thermophilus + L. acidophilus. The physical, chemical, microbiological and sensorial properties of the yogurts were evaluated based on storage at 4 ± 1 °C. Probiotic shelf life and the most suitable combinations were determined. The highest L. acidophilus count (8.65 log cfu g^?1) was found in the 5% Gobdin‐supplemented yogurt on the 7th day of storage, while the lowest count (8.11 log cfu g^?1) was found in the probiotic control yogurt on the 21st day. Although the L. acidophilus counts in the probiotic yogurts declined during storage, all values found throughout the 21‐day storage period were >8 log cfu g^?1. This is above the level necessary to provide the desired therapeutic effect in probiotic products (10⁶–10⁷ cfu g^?1). The highest overall acceptability score was obtained on the first day from the yogurt with 5% Gobdin. However, all yogurt samples had general acceptability scores between 7 and 8 points from a 9‐point maximum. Thus, this study determined that a new functional yogurt can be produced using L. acidophilus with 5% Gobdin.     

Quantitative UPLC‐MS/MS analysis of chlorogenic acid derivatives in antioxidant fractionates from dandelion (Taraxacum officinale) root

While qualitative studies have identified chlorogenic acids in antioxidant extracts, particularly ethyl acetate‐derived extracts, of Taraxacum officinale, quantitative analysis of these phenolic compounds remains largely unreported for this species. In this study, bioactivity‐guided fractionation of an antioxidant crude ethyl acetate extract (DPPH = 295.481 ± 0.955 mg TE g^?1 extract) from T. officinale root resulted in a number of reverse‐phase fractions that demonstrated high antioxidant activity (DPPH = 1058.733–1312.136 mg TE g^?1 extract), stronger than that of the synthetic antioxidant Trolox^®. UPLC‐MS/MS screening of these fractions for the presence of selected mono‐ and di‐caffeoylquinic acids revealed large quantities of 1,5‐dicaffeoylquinic acid present in several fractions (853.052–907.324 μg mg^?1), respectively. Due to the antioxidant potency and high levels of 1,5‐dicaffeoylquinic acid observed in these fractions, it was concluded that specifically this chlorogenic acid derivative is a major contributor to the antioxidant efficacy of dandelion root.     

Assessment of thermo‐oxidative rancidity in sunflower oil and fried potato chips stabilised with oleoresin sage (Salvia officinalis L.) and ascorbyl palmitate by altered triglycerides and electronic nose

Oleoresin sage (Salvia officinalis) (SAG) (200–1500 mg kg^?1), ascorbyl palmitate (AP) (100–300 mg kg^?1) and TBHQ (200 mg kg^?1) were assessed for delaying the thermo‐oxidation in sunflower oil (SO) during 18 h of frying (180 °C). Electronic nose compared the global aroma fingerprints of potato chips fried in oils. The chemical rancidity indices viz., fatty acids, total polar compounds (TPC), altered triglycerides (dimers, polymers, oxidised monomers, diglycerides), free fatty acids, conjugated dienes and induction periods were monitored along with physical indices viz., viscosity and colour. SO_SAG+AP (1309.62 + 270.71 mg kg^?1) outperformed SO_TBHQ by preserving polyunsaturated fatty acids (60.48% vs. 56.23%), retarding TPCs (28.16% vs. 29.91%), triglyceride dimers (90.24 vs. 95.82 mg g^?1) and polymers (25.40 vs. 26.98 mg g^?1) concomitantly extending the oil disposal time (basis 25% TPC) (15.9 vs. 14.7 h). The postfrying viscosity, colour values and global aroma fingerprints of fried chips indicate a close match between SO_SAG+AP and SO_TBHQ.     

Polyphenolic and phytochemical content of Cucumis sativus seeds and study on mechanism of preservation of nutritional and quality outcomes in enriched mayonnaise

Oxidative rancidity in food emulsions leads to a reduction in shelf life. Synthetic antioxidants are widely used in food industry to prevent the development of rancidity. The present study was focussed on investigating the antioxidant potential of Cucumis sativus seeds (CSS) and correlates these findings with mayonnaise enrichment and extends its shelf life. CSS exhibited the highest abundance in phenolic compounds (93.5 ± 0.1 mgGAE g^?1), flavonoids (57.4 ± 0.1 mgQE g^?1), β‐carotene (19.46 ± 0.4 mg carotenoids per 100 g) and high free radical scavenging activity. CSS (200 ppm) and butylated hydroxyanisole (200 ppm) were incorporated in mayonnaise and the oxidative stability was evaluated by peroxide, p‐anisidine and TBARS values during storage at different temperatures. Organoleptic evaluations indicated that CSS enriched sample was recorded the highest overall acceptability. The results from our study will provide scientific basis for CSS as natural preservative against lipid oxidation or food enrichment while developing functional foods.     

Thermo‐rheological and functional properties of gamma‐irradiated wholewheat flour

The effects of different doses (0, 0.5, 1, 2.5, 5 and 10 kGy) of gamma irradiation on the thermal, rheological and functional properties of the wholewheat flour were evaluated. Water and oil absorption capacity of the flour increased from 85.92% to 91.44% and 1.10 to 1.91 g g^?1 of flour, respectively, with increase in irradiation dose. The dough development time decreased with dose from 4.0 to 3.0 min. The transition temperatures (T_o, T_p and T_c) decreased as the dose increased; enthalpy of gelatinisation (?H) decreased from 5.18 to 4.27 J g^?1 with dose. The flow behaviour showed a shear‐thinning behaviour, and the hysteresis area decreased with dose. The structural recovery decreased with dose. FTIR did not show formation of any new chemical groups.     

Effect of high‐pressure treatments on microbial loads and physicochemical characteristics during refrigerated storage of raw milk Serra da Estrela cheese samples

This work studied the effect of high pressure processing (HPP) at 400, 500 and 600 MPa during 10, 5 and 3 min, respectively, on samples ewe cheese manufactured from raw milk, during storage (100 days) at 5 °C. Total aerobic mesophilic and lactic acid bacteria were slightly affected, decreasing by about 1.0 and 0.82 log CFU g^?1, respectively, immediately after HPP treatment at 600 MPa for 3 min, while Enterobacteriaceae, yeasts and moulds, and Listeria innocua were reduced to below the quantification limits. Lactic acid bacteria decreased further during storage, showing increasing inactivation as the pressure level increased. Physicochemical parameters (water activity, moisture content, pH and titratable acidity) were generally not affected by HPP, while lipid oxidation increased throughout storage, with HPP samples showing lower values (50–66%) at 100 days of storage. The results indicated that HPP has potential to improve cheese microbial safety and shelf‐life, with a lower lipid oxidation level than nonpressurised cheese.