Effects of citrus essential oils on the oxidative stability of microencapsulated fish oil by spray-drying

The effects of citrus essential oils (orange, lemon, mandarin, and grapefruit) on the oxidative stability of microencapsulated fish oil by spray-drying were evaluated. The encapsulation efficiency of microcapsules was in the range of 42.25 and 62.43%. Twelve active substances were determined as major volatile components of citrus essential oils. The highest phenolic content was obtained from grapefruit essential oil (44.32 mg GAE/g). Lower values of thiobarbituric acid reactive substances (TBARs) were obtained for microencapsulated fish oils with essential oils compared to control. At the end of storage, the highest peroxide value (PV) was observed in the control group (25.30 meq O₂/kg oil) while the lowest value was in the lemon (13.40 meq O₂/kg oil) and orange group (13.91 meq O₂/kg oil). The results of this study showed that citrus essential oils can be used to improve the oxidative stability of fish oil microcapsules.

Antimicrobial effect of laurel essential oil nanoemulsion on food-borne pathogens and fish spoilage bacteria

This research aimed to apply nanotechnology for nanoformulation of Laurus nobilis essential oil (EO) by ultrasonic emulsification method and characterization of nano-form: particle size, viscosity, polydispersity index, thermodynamic stability, and surface tension. The antimicrobial activity of laurel EO nanoemulsion (LEON) and laurel EO was also investigated against a panel of ten food-borne pathogens and fish spoilage bacteria. The GC-MS analysis of EO revealed that 1,8-Cineole was the main volatile compound. According to disc-diffusion results, LEON was more effective against Gram-positive pathogen bacteria of Staphylococcus aureus and Enterococcus faecalis than EO. Laurel oil demonstrated a higher inhibitory effect against fish spoilage bacteria (6.19 to 18.5 mm). The MICs values of LEON and laurel EO ranged from 6.25 to >25 mg/mL and from 1.56 to >25 mg/mL, respectively. Nanoemulsion and oil exhibited the best bactericidal activity against Pseudomonas luteola. Therefore, LEON can be developed as a natural antimicrobial agent in food industry.

Recent advances in industrial applications of seaweeds

Seaweeds have been generally utilized as food and alternative medicine in different countries. They are specifically used as a raw material for wine, cheese, soup, tea, noodles, etc. In addition, seaweeds are potentially good resources of protein, vitamins, minerals, carbohydrates, essential fatty acids and dietary fiber. The quality and quantity of biologically active compounds in seaweeds depend on season and harvesting period, seaweed geolocation as well as ecological factors. Seaweeds or their extracts have been studied as innovative sources for a variety of bioactive compounds such as polyunsaturated fatty acids, polyphenols, carrageenan, fucoidan, etc. These secondary metabolites have been shown to have antioxidant, antimicrobial, antiviral, anticancer, antidiabetic, anti-inflammatory, anti-aging, anti-obesity and anti-tumour properties. They have been used in pharmaceutical/medicine, and food industries since bioactive compounds from seaweeds are regarded as safe and natural. Therefore, this article provides up-to-date information on the applications of seaweed in different industries such as pharmaceutical, biomedical, cosmetics, dermatology and agriculture. Further studies on innovative extraction methods, safety issue and health-promoting properties should be reconsidered. Moreover, the details of the molecular mechanisms of seaweeds and their bioactive compounds for physiological activities are to be clearly elucidated.

Tetrodotoxin levels of three pufferfish species (Lagocephalus sp.) caught in the North-Eastern Mediterranean sea

Tetrodotoxin (TTX) levels in Lagocephalus sceleratus (Silverstripe blaasop), Lagocephalus spadiceus (Half-smooth golden pufferfish) and Lagocephalus suezensis (Suez puffer) caught in Mersin Bay in the Northeastern Mediterranean Sea were analysed using Q-TOF LC/MS. Pufferfish were caught using trawl fishing, longlining and fishing line from December 2015 to October 2016. The TTX changes in the gonads, livers, intestines, skins and muscle tissues were evaluated according to sex and season. TTX levels for L. sceleratus and L. suezensis for all tissues were in the range of 0.69-35.6 μg/g and 0.67-3.09 μg/g, respectively. The highest TTX levels were observed in the gonads of female L. sceleratus caught in the autumn, and in the skin of L. suezensis caught in the spring but no quantifiable levels of TTX were found for L. spadiceus. In conclusion, L. sceleratus and L. suezensis species caught in the North-Eastern Mediterranean are toxic, and their consumption is unsafe.

Effect of Natural Zeolite (Clinoptilolite) on in vitro Biogenic Amine Production by Gram Positive and Gram Negative Pathogens

The effect of two levels of clinoptilolite (1 and 5%) on the production of biogenic amines (BA) and ammonia (AMN) by Gram positive (Staphylococcus aureus, Enterococcus faecalis, and Listeria monocytogenes) and Gram negative bacteria (Aeromonas hydrophila, Klebsiella pneumoniae, Escherichia coli, Pseudomonas aeruginosa, and Salmonella Parathypi A), in tyrosine decarboxylase broth (TDB) was studied. A. hydrophila and E. coli produced the highest amounts of amines which were 1223.06 and 2627.90 mg/l, respectively. All strains were able to decarboxylate tyrosine to tyramine (TYR) with E. coli being the highest (1657.19 mg/l). A. hydrophila formed >50 mg/l histamine (HIS) while the other strains produced none or very low concentrations (<4 mg/l). Among Gram-positive pathogens, E. faecalis was characterized as the main amine producer (478.23 mg/l). Although dependent on bacterial strain and level used, the natural zeolite clinoptilolite can be used to decrease BA and AMN production by bacterial strains that are of health concern. Practical Applications: Uses of natural prodcuts for biogenic amines inhibition. Clinoptilolite was used to reduce the amounts of amines such as spermine, putrescine, and dopamine produced by pathogenic and spoilage bacteria.

Technological Factors Affecting Biogenic Amine Content in Foods: A Review

Biogenic amines (BAs) are molecules, which can be present in foods and, due to their toxicity, can cause adverse effects on the consumers. BAs are generally produced by microbial decarboxylation of amino acids in food products. The most significant BAs occurring in foods are histamine, tyramine, putrescine, cadaverine, tryptamine, 2-phenylethylamine, spermine, spermidine, and agmatine. The importance of preventing the excessive accumulation of BAs in foods is related to their impact on human health and food quality. Quality criteria in connection with the presence of BAs in food and food products are necessary from a toxicological point of view. This is particularly important in fermented foods in which the massive microbial proliferation required for obtaining specific products is often relater with BAs accumulation. In this review, up-to-date information and recent discoveries about technological factors affecting BA content in foods are reviewed. Specifically, BA forming-microorganism and decarboxylation activity, genetic and metabolic organization of decarboxylases, risk associated to BAs (histamine, tyramine toxicity, and other BAs), environmental factors influencing BA formation (temperature, salt concentration, and pH). In addition, the technological factors for controlling BA production (use of starter culture, technological additives, effects of packaging, other non-thermal treatments, metabolizing BA by microorganisms, effects of pressure treatments on BA formation and antimicrobial substances) are addressed.

Tetrodotoxin levels in pufferfish (Lagocephalus sceleratus) caught in the Northeastern Mediterranean Sea

The toxicity of tetrodotoxin (TTX) in pufferfish (Lagocephalus sceleratus) from Mersin Bay in the Northeastern Mediterranean Sea was measured using a mouse bioassay (MBA) and LC-MS-MS. Pufferfish were caught by trawl fishing, longlining and fishing line from December 2012 to October 2013. Changes in the levels of TTX in the gonads, livers, intestines, skins and muscles as a function of season and sex were determined. The gonads of female fish were toxic in all seasons (>2μg/g), whereas the gonads of male fish were only toxic in the spring and autumn. The highest TTX levels in gonads, livers, intestines and skins of female fish were 52.1, 46.2, 7.64 and 3.43μg/g, respectively, using LC-MS-MS. The TTX level in the muscle of female fish in winter was 2.83μg/g but was otherwise below the toxic limit. Consequently, it can be dangerous to consume pufferfish, including the edible muscle, from the Eastern Mediterranean Sea.

Quality Changes of Marinated Tench (Tinca tinca) during Refrigerated Storage

The quality control of marinated tench with sauce stored at 4 °C was investigated in terms of sensory, chemical (total volatile basic nitrogen (TVB-N), trimethylamine (TMA), thiobarbituric values (TBA), peroxide value, free fatty acids, biogenic amines, fatty acids, and pH and microbiological parameters (total aerobic count, coliform, Escherichia coli, and Salmonella) during 6 months of storage. The use of alcohol vinegar and salt in marinated tench caused the TVB-N, TMA to decrease. The maximum TVB-N and TMA values were found to be 12.77 mg/100 g and 4.68 mg/100 g after 150 days and 180 days storage period, respectively. Oxidative rancidity in marinated tench was found to be low (2.81 mg MA/kg) and rancid flavor was not detected even after a storage period of 180 days. As storage time progressed, putrescine, cadaverine, and serotonine became the dominant amines. Salmonella, coliform, E. coli, and Staphylococcus aureus were not detected during the storage period of 6 months. Total bacteria count increased to 4.3 log CFU/g at the end of the storage period. Data obtained from this study showed that marinated tench can be stored for more than 6 months.