Bioactivity of Microencapsulated Cell-Free Supernatant of Streptococcus thermophilus in Combination with Thyme Extract on Food-Related Bacteria.

The bioactive properties of the combination of microencapsulated cell-free supernatant (CFS) from Streptococcus thermophilus and thyme extract on food-related bacteria (Photobacterium damselae, Proteus mirabilis, Vibrio vulnificus, Staphylococcus aureus ATCC29213, Enterococcus faecalis ATCC29212, and Salmonella Paratyphi A NCTC13) were investigated. The microencapsulated CFS of S. thermophilus, in combination with ethanolic thyme extract, had a particle size in the range of 1.11 to 11.39 µm. The microencapsulated CFS of S. thermophilus had a wrinkled, spherical form. In the supernatant, especially at 2% (v/w), the thyme extract additive caused a decrease in the wrinkled form and a completely spherical structure. A total of 11 compounds were determined in the cell-free supernatant of S. thermophilus, and acetic acid (39.64%) and methyl-d3 1-dideuterio-2-propenyl ether (10.87%) were the main components. Thyme extract contained seven components, the main component being carvacrol at 67.96% and 1,2,3-propanetriol at 25.77%. Significant differences (p < 0.05) were observed in the inhibition zones of the extracts on bacteria. The inhibitory effect of thyme extract on bacteria varied between 25.00 (P. damselae) and 41.67 mm (V. vulnificus). Less antibacterial activity was shown by the microencapsulated CFS from S. thermophilus compared to their pure form. (p < 0.05). As a result, it was found that microencapsulated forms of CFS from S. thermophilus, especially those prepared in combination with 2% (v/w) thyme extract, generally showed higher bioactive effects on bacteria.

Physical, chemical, and sensory properties of water kefir produced from Aronia melanocarpa juice and pomace.

Water kefir is widely consumed all over the world due to its potential health benefits. The aim of this current study was to compare non-fermented juice and fermented beverage of water kefir produced from Aronia melanocarpa juice and pomace in terms of chemical, physical and sensory quality as well as valorisation of pomace in the production of water kefir. When compared to water kefir made with aronia juice, less reduction in total phenolic content (TPC), total flavonoid content (TFC) and total anthocyanin content (TAC) was observed in samples made with aronia pomace during the fermentation process. Similarly, greater antioxidant activity was demonstrated in water kefir made with aronia pomace than juice. Based on sensory evaluation, no difference was found in overall acceptability, taste, aroma/odor, and turbidity of water kefir made with aronia pomace before and after fermentation. Results indicated that aronia pomace has potential in water kefir production.

Formulation with sage tea-loaded fish oil-based microcapsules to delay oxidation.

Fish (Engraulis encrasicolus) oil was successfully microencapsulated using sage essential oils prepared in three different concentrations as 1% (S1), 2% (S2) and 3% (S3). The microencapsulated fish oil powders fabricated with spray drying were stored at room temperature (24 ± 1 °C) in order to determine the oxidative deterioration for 12 weeks. The highest microencapsulation efficiency was observed in the S3 (60.17%) as compared with other groups. Although the changes in free fatty acid (FFA) values were defined between 6.04 and 9.29% at the end of the storage period, the lowest FFA value was found in S2 samples (p < 0.05). Among the microencapsulated samples, the highest peroxide value (PV) was measured as 20.24 meq O2/kg for S1 at the 11th week of the experimental period. Moreover, statistical differences between the control (25.93 meq O2/kg) and S1 samples were observed (p < 0.05). The rapid increase in the thiobarbituric acid (TBA) value of fish powders was delayed by microencapsulation technique fabricated with spray drying. The use of sage essential oils within this combination effectively retarded the oxidation in fish oil powders at ambient storage, indicating cost-effective for the food industry. Therefore, encapsulation of fish oils with sage oil using the spray drying technique has improved oxidation stability of fish oil and can be used for food applications.

Recent developments in the use of cold plasma, high hydrostatic pressure, and pulsed electric fields on microorganisms and viruses in seafood.

Non-thermal processing methods, such as cold plasma (CP), high pressure processing (HPP) and pulsed electric fields (PEF), have been proposed for natural and fresh-like foods to inactivate microorganisms at nearly-ambient or moderate temperature. Since natural, safe, and healthy foods with longer shelf-life are increasingly demanded, these requests are challenging to fulfill by using current thermal processing technologies. Thus, novel preservation technologies based on non-thermal processing methods are required. The aim of this article is to provide recent developments in maintaining seafood safety via CP, HHP, and PEF technologies, as well as their mechanisms of action regarding contamination with food-borne microorganisms. Their application to control parasites, spores and the possibility to eradicate the hazard of SARS-CoV-2 transmission through seafood products are also discussed. CP, HHP, and PEF have been applied to inactivate food-borne microorganisms in the seafood industry. However, the drawbacks for each emerging technology have also been reported. To ensure safety and maintain quality of seafood products, the combination of these processing techniques with natural antimicrobial agents or existing thermal methods may be more applicable in the case of the seafood industry. Further studies are required to examine the effects of these methods on viruses, parasites, and SARS-CoV-2 in seafood.

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.

The Impact of Thyme, Rosemary and Basil Extracts on the Chemical, Sensory and Microbiological Quality of Vacuumed Packed Mackerel Balls.

The effect of natural extracts (0.05%) and vacuum packaging on the sensory, chemical, and microbiological quality of mackerel balls were evaluated at refrigerated (4 ± 2 °C) storage. Natural extracts thyme (38.13 mg GAE/g), rosemary (81.85 mg GAE/g) and basil (21.08 mg GAE/g) were evaluated. Natural extracts imparted stability to lipids (TBA, FFA, and PV), and the ability was further improved by vacuum packaging. Biochemical changes (TVB-N, pH) and microbiological quality (total viable count) were also retained. Control samples packed under vacuum were found to cross over acceptable limits on day 28. Based on sensory quality evaluation, samples treated with rosemary and thyme extracts showed superior sensory quality over control, whilebasil-treated samples were not found acceptable at day 28. Consequently, the inclusion of thyme and rosemary extracts exhibits preservative quality when combined with vacuum packaging, retaining biochemical, microbial, and sensory quality.

The impact of aromatic plant-derived bioactive compounds on seafood quality and safety.

Plant-derived bioactive compounds have been extensively studied and used within food industry for the last few decades. Those compounds have been used to extend the shelf-life and improve physico-chemical and sensory properties on food products. They have also been used as nutraceuticals due to broad range of potential health-promoting properties. Unlike the synthetic additives, the natural plant-derived compounds are more acceptable and often regarded as safer by the consumers. This chapter summarizes the extraction methods and sources of those plant-derived bioactives as well as recent findings in relation to their health-promoting properties, including cardio-protective, anti-diabetic, anti-inflammatory, anti-carcinogenic, immuno-modulatory and neuro-protective properties. In addition, the impact of applying those plant-derived compounds on seafood products is also investigated by reviewing the recent studies on their use as anti-microbial, anti-oxidant, coloring and flavoring agents as well as freshness indicators. Moreover, the current limitations of the use of plant-derived bioactive compounds as well as future prospects are discussed. The discoveries show high potential of those compounds and the possibility to apply on many different seafood. The compounds can be applied as individual while more and more studies are showing synergetic effect when those compounds are used in combination providing new important research possibilities.

Contribution of polysaccharides from crustacean in fermented food products.

Fermented foods are of great importance for their role in preserving nutrients and enriching the human diet. Fermentation ensures longer shelf life and microbiological safety of food. Natural bioactive compounds have been paid attention as nutraceuticals or functional ingredients, which have health-promoting components since polysaccharides, especially chitosan, chitin and their derivatives, are biocompatible and biodegradable, biorenewable, without toxic properties and environmentally friendly. They have been applied in several fields such as medicine, agriculture, and food industry. This chapter provides information on polysaccharides obtained from crustacean as bioactive compounds as well as their effects in fermented foods.

Antioxidant and Antimicrobial Activity of Hydroethanolic Leaf Extracts from Six Mediterranean Olive Cultivars.

Phenolic profiles, antioxidant, and antimicrobial activities of hydroethanolic olive leaf extracts from six Mediterranean olive cultivars (Croatian: Lastovka, Levantinka, Oblica; Italian: Moraiolo, Frantoio, Nostrana di Brisighella) were investigated. As expected, various distributions of phenolic levels were observed for each cultivar and the total phenolic content showed high variability (ranging from 4 to 22 mg GAE/g of dry extract), with the highest amount of phenolics found in the Oblica sample, which also provided the highest antiradical (ORAC) and reducing activity (FRAP). The screening of individual compounds was performed by HPLC-PDA-ESI-QTOF-MS and the main detected compounds were oleuropein, hydroxytyrosol, oleoside/secologanoside, verbascoside, rutin, luteolin glucoside, hydroxyoleuropein, and ligstroside. While the antioxidant activity of the samples was relatively high, they showed no bactericidal and bacteriostatic activity against E. coli and S. Typhimurium; weak activity against Staphylococcus aureus, Bacillus cereus, and Listeria innocua; and inhibitory effects against Campylobacter jejuni at 0.5 mg dry extract/mL. The obtained results support the fact that olive leaf extracts, and especially those from the Oblica cultivar, could potentially be applied in various industries as natural preservatives and effective and inexpensive sources of valuable antioxidants.

Recent developments in industrial applications of nanoemulsions.

Nanotechnology is being utilized in various industries to increase the quality, safety, shelf-life, and functional performance of commercial products. Nanoemulsions are thermodynamically unstable colloidal dispersions that consist of at least two immiscible liquids (typically oil and water), as well as various stabilizers (including emulsifiers, texture modifiers, ripening inhibitors, and weighting agents). They have unique properties that make them particularly suitable for some applications, including their small droplet size, high surface area, good physical stability, rapid digestibility, and high bioavailability. This article reviews recent developments in the formulation, fabrication, functional performance, and gastrointestinal fate of nanoemulsions suitable for use in the pharmaceutical, cosmetic, nutraceutical, and food industries, as well as providing an overview of regulatory and health concerns. Nanoemulsion-based delivery systems can enhance the water-dispersibility, stability, and bioavailability of hydrophobic bioactive compounds. Nevertheless, they must be carefully formulated to obtain the required functional attributes. In particular, the concentration, size, charge, and physical properties of the nano-droplets must be taken into consideration for each specific application. Before launching a nanoscale product onto the market, determination of physicochemical characteristics of nanoparticles and their potential health and environmental risks should be evaluated. In addition, legal, consumer, and economic factors must also be considered when creating these systems.

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.

Nano-technological approaches for plant and marine-based polysaccharides for nano-encapsulations and their applications in food industry.

Novel food preservation methods, along with preservatives have been employed to prevent food products from spoilage. There is an increasing demand to substitute synthetic preservatives with natural bioactive compounds since they are safe and environmentally friendly. Bioactive compounds with functional and therapeutic properties are found in foods and have also beneficial physiological and immunological health effects. However, there are some issues associated with bioactive compounds, such as low stability, solubility, and permeability. Encapsulation techniques, especially nano-encapsulation, are a promising technique to overcome these restrictions. A range of the plants' constituents can be converted into bio-nanomaterials. Major plant constituents are polysaccharides which have good biocompatibility properties and therapeutic activities, such as antioxidant, antiviral, anti-inflammatory, anti-allergic, and anti-tumor. Among plant and marine-based polysaccharides, cellulose, starch, alginates, chitosan, and carrageenans have been used as carrier materials to preserve core material. Moreover, many studies indicated that favorable sources such as plant and marine based polysaccharides are emerging. This chapter will cover plant and marine-based polysaccharides for nano-encapsulation and their application in the food industry.

Nucleotide degradation, biogenic amine level and microbial contamination as quality indicators of cold-stored rainbow trout (Oncorhynchus mykiss) gravad.

The extent to which the transformation of nucleotides, biogenic amines, and microbiological changes affect the quality and shelf life of vacuum packaged low processed rainbow trout (Oncorhynchus mykiss) gravad during storage at 7 ± 1 °C for 42 days was investigated. Although total viable counts increased slowly up to 6 log CFU g-1 at the end of storage, coliform bacteria disappeared. The histamine concentration and the biogenic amine index increased up to 45.2 ± 1.62 mg kg-1 and 100 mg kg-1 respectively. The highest concentration of inosine monophosphate was achieved in freshly prepared gravad, whereas the hypoxanthine level increased with storage time up to 28 days. Among nucleotide ratios, the G value is more suitable for the determination of gravad quality than K, Ki and H values. Once the gravad obtained the limit of acceptability by the panelists (35 days) the G value rose to 470%.

Use of Spectroscopic Techniques to Monitor Changes in Food Quality during Application of Natural Preservatives: A Review.

Consumer demand for food of high quality has driven research for alternative methods of food preservation on the one hand, and the development of new and rapid quality assessment techniques on the other hand. Recently, there has been a growing need and interest in healthier food products, which has led to an increased interest in natural preservatives, such as essential oils, plant extracts, and edible films and coatings. Several studies have shown the potential of using biopreservation, natural antimicrobials, and antioxidant agents in place of other processing and preservation techniques (e.g., thermal and non-thermal treatments, freezing, or synthetic chemicals). Changes in food quality induced by the application of natural preservatives have been commonly evaluated using a range of traditional methods, including microbiology, sensory, and physicochemical measurements. Several spectroscopic techniques have been proposed as promising alternatives to the traditional time-consuming and destructive methods. This review will provide an overview of recent studies and highlight the potential of spectroscopic techniques to evaluate quality changes in food products following the application of natural preservatives.

The function of nanoemulsion on preservation of rainbow trout fillet.

This study was conducted to investigate the effects of nanoemulsions prepared with various concentrations of olive oil on the sensory, chemical and microbiological quality of rainbow trout fillets. The results showed that the shelf life of rainbow trout fillets were determined as 10 days for the control, 12 days for tween 80 group, 14 days for the 15% olive oil nanoemulsion group (O15) and 16 days for both 30% (O30) and 45% olive oil nanoemulsion groups (O45). It was determined that the use of olive oil suppressed the fish smell and improved the organoleptic quality of fish fillets, extending shelf life. Best sensory results were obtained from O30 and O45 treatment groups. The use of nanoemulsion had a positive effect on the biochemical parameters (TVB-N, PV, FFA, TBARs and pH), as well as inhibiting bacterial growth compared to the control group. Among nanoemulsion groups, the lowest bacteria content was found in O45 group. As a result, O30 and O45 treatment groups can be recommended for the preservation of fish fillets.

Antimicrobial influence of nanoemulsified lemon essential oil and pure lemon essential oil on food-borne pathogens and fish spoilage bacteria.

The antimicrobial activities of lemon oil based nanoemulsion and two different concentrations of lemon essential oil (100% and 10%) on food-brne pathogens (Staphylococcus aureus, Klebsiella pneumoniae, Enterococcus faecalis and Salmonella Paratyphi A) and fish spoilage bacteria (Photobacterium damselae, Enterococcus faecalis, Vibrio vulnificus, Proteus mirabilis, Serratia liquefaciens, and Pseudomonas luteola) were compared in terms of disc diffusion, minimum inhibition concentration (MIC) and minimum bactericidal concentration (MBC). The constitutes of extracted lemon essential oil were identified by using GC-MS. Viscosity, the mean droplet size, thermodynamic stability and refractive index of nanoemulsions were determined. The main components detected in the lemon essential oil were d-limonene, p-cymene, ß-pinene with percentages of 52.85%, 14.36%, and 13.69%, respectively. It was found that lemon nanoemulsion was more effective on food-borne pathogens except K. pneumoniae than 100% lemon essential oil. 10% lemon essential oil showed the highest inhibition effect on S. Paratyphi A. The conversion of the essential oil into nanoemulsion improved antimicrobial activity. According to value of MIC, both nanoemulsion and 100% essential oil inhibited bacterial growth of all of the pathogen bacteria tested whereas they were less effective on inhibition of fish spoilage bacteria. However, 10% essential oil was more effective on spoilage bacteria than pathogens. MBC showed that nanoemulsion and 100% lemon essential oil presented a noticeable bactericidal activity against S. paratyphi A whereas 10% lemon essential oil was found as ≥25 mg/mL against pathogens and spoilage bacteria. Therefore, the use of nanoemulsion based on lemon essential oil can have potential as a natural antimicrobial agent against food-borne pathogen and spoilage bacteria for fish processing industry.

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.

First report on TTX levels of the yellow spotted pufferfish (Torquigener flavimaculosus) in the Mediterranean Sea.

The differences of tetrodotoxin (TTX) levels in various parts of pufferfish (Torquigener flavimaculosus) were examined in conjunction with the seasonal and sexual variations. The TTX levels in gonads, liver, intestines, skin and muscle tissue were determined using the Q-TOF LC/MS. Instrumental analysis revealed that all examined tissues from T. flavimaculosus contained high TTX concentrations. TTX levels in the gonads, liver, intestines, skin and muscle tissue of pufferfish were within the range of 5.03-100.71, 7.04-106.80, 12.59-86.30, 33.95-139.88 and 15.88-86.07 (µg/g), respectively. It was determined that in all seasons, except for summer, female individuals had higher TTX levels than males. Among all seasons, the highest level of TTX was found in winter and the lowest in autumn. Consequently, T. flavimaculosus is a highly toxic pufferfish that is dangerous for human consumption and should not be consumed under any circumstances.