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.

Assessment of the safety of dietary fish oil supplements in terms of content and quality.

The fatty acid composition of top-selling fish oil dietary supplements in the markets was compared with the content stated on product label, and their oxidative qualities and heavy metal contents were evaluated in this study. While all the capsule groups (C) confirmed the label information, it was observed that one-third of the syrup groups (S) had less than the specified content. Capsule groups generally had richer EPA and DHA contents than syrup groups in the samples examined. The peroxide values (PV) of all fish oil capsules and syrups were found in the range of 1.97-2.89 mEq/kg and 2.22-18.30 mEq/kg, respectively. As for free fatty acids (FFA) values, the C4, S6, S9, and S10 groups were above the 3% oleic acid limit recommended for high-quality oils. However, thiobarbituric acid reactive substances (TBARs) values were found below 1 mg MA/kg in all groups. All fish oil supplements were within the limits specified in terms of As (0.50-4.19 µg/g), Cd (0.14 µg/g detected for one group, C5), Cu (not detected), Fe (0.32-15.7 µg/g), and Hg (≤ 0.1 µg/g). On the other hand, two fish oil supplements from the capsule group (0.17 for C6 and 1.01 µg/g for C8) and one group from the syrup group (0.29 µg/g for S10) exceeded the recommended limit in terms of Pb (0.1 mg/kg). As a result of the research, it can be concluded that the chemical quality of fish oils in syrup form needs to be improved and their reliability in terms of fatty acid content should be increased. Considering the heavy metals, it seems significant to follow up the fish oil products more strictly.

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.

Metal Bioaccumulation in the Gill, Liver, and Muscle of Bluefish (Pomatomus saltatrix) From the Northeastern Mediterranean and Human Health Risk Assessment Associated with Their Seasonal Consumption.

Heavy metals are continuously released into the oceans from both natural and anthropogenic sources. They are serious threats to both ecosystem and human health because of their toxicity, persistence, bioaccumulation, and biomagnification. We present metal concentrations in the economically important bluefish from Iskenderun Bay, providing valuable information on Northeastern Mediterranean aquatic ecosystem health, as well as the human health risk. The concentrations of manganese, iron, copper, zinc, selenium, cadmium, lead, and mercury were determined in the gill, liver, and muscle tissues of bluefish (Pomatomus saltatrix) caught in Iskenderun Bay (Turkey) during four seasons. Samples were analysed via inductively coupled plasma mass spectrometer. Fe and Zn were detected in the highest concentrations during all four seasons. The ranges of Fe concentrations were 61.15-108.76, 229.78-377.02, and 6.35-8.63 and those of Zn were 25.21-44.25, 42.25-76.08, and 6.27-13.59 in the gills, livers, and muscles, respectively. In contrast, Hg and Cd were not found in the bluefish tissues in any season with the exception of Cd in the gills during the spring (0.757 mg/kg, above the legal limit of 0.5 mg/kg). On a seasonal basis, no meaningful accumulation trend was observed for the muscles or gills, while the highest concentrations of Mn, Fe, Cu, Zn, and Se in the liver were found in the spring. Liver tissues possessed higher metal concentrations than gill and muscle tissues. Estimated daily and weekly intakes of the metals due to human consumption of the bluefish were considerably lower than the provisional tolerable intake. In this study, there was an inflow of metals into Iskenderun Bay; however, no significant metal accumulation was found in bluefish tissues at a rate that would harm human health.

The Role of Selected Lactic Acid Bacteria on Organic Acid Accumulation during Wet and Spray-Dried Fish-based Silages. Contributions to the Winning Combination of Microbial Food Safety and Environmental Sustainability.

Organic acid contents of acidified and fermented fish silages made from gibel carp (Caracius gibelio) and klunzinger's ponyfish (Equulites klunzingeri) fishes, and from fish processing residues or by-products, were determined and studied. The silages were undertaken in wet and spray-dried fish-based raw-materials for 3 weeks at room temperature (ca. 25 °C). Selected lactic acid bacteria (LAB) of Enterococcus gallinarum, Lactobacillus brevis, Lactobacillus plantarum, Pediococcus acidilactici, and Streptococcus spp. were employed to produce fermented fish-based silages, while acidified silage was prepared resorting to the addition of formic acid (3%, v/v). Lactic and propionic acids were the dominant produced organic acids, while succinic acid was formed at the smallest amounts in fermented silages. In the acidified silage, lactic and formic acids were produced in amounts higher than 800 and 1000 mg organic acid/100g sample, respectively. Among the fermented fish-based silages, LAB strains unfolded considerable ability to presumptively produce propionic acid in gibel carp silage (>2370 mg organic acid/100g sample). Spray-dried fermented silages displayed significantly higher organic acid content than wet silages. Propionic acid accumulation was found at the highest levels in gibel carp silage fermented with L. plantarum (6335.40 mg propionic acid/100g sample). This research effort pointed out the good capability of various selected lactic acid bacteria strains to produce significant amounts of organic acids-especially lactic, acetic, and propionic acids-during the fermentation of fish-based silages. In terms of food safety and quality, such a production of relatively high amounts of organic acids in wet and spray-dried fish-based silages clearly indicated their suitableness to be used for animal feed.

Pesticide residues in muscles of some marine fish species and seaweeds of Iskenderun Bay (Northeastern Mediterranean), Turkey.

Pesticide residues in muscles of nine marine fish and four seaweed species of Iskenderun Bay (Northeastern Mediterranean) have been investigated. In sampled fish species, two herbicides, three insecticides, two fungicides, and one synergist were identified and quantified. Metribuzin DADK, propamocarb HCl, and piperonyl butoxide (PBO) were detected in all the muscles of sampled fish species. Metribuzin DADK was the most abundant pesticide residue in fish muscles and the highest metribuzin DADK concentration was found in sardine (311.20 µg/kg). Propamocarb HCl concentrations varied greatly among species; from 0.530 ± 0.020 µg/kg in striped sea bream to 34.170 µg/kg in sea bass. The level of PBO ranged from 0.001 µg/kg for fourlined terapon to 0.013 µg/kg for sardine. No measurable oxamyl residue was found in any of the muscles of sampled fish species (except sardine). In seaweeds, two herbicides and two insecticides were identified and quantified. Metribuzin DADK was the most abundant and found in Cystoseira corniculata (5.01 mg/kg), Corallina elongata (0.703 mg/kg), and Jania rubens (3.85 mg/kg). Molinate was a minor contaminant and only found in Corallina elongata (0.002 mg/kg). Pyrethrin I was determined only in Padina pavonia to be 0.567 mg/kg. Pyrethrine II was found in Padina pavonia and Corallina elongate to be 1.214 and 0.229 mg/kg, respectively. The most hazardous pesticide residues of organochlorines and organophosphorus were not detected in both sampled fish muscles and seaweeds. There are no clear maximum residue limits for the detected eight pesticide residues declared for fish muscle by European Union MRL (2017). In conclusion, it can be considered that observed concentrations of pesticides in sampled nine marine fish species do not have a potential health risk for consumers. Some of the detected pesticide residues can be toxic for algae and aquatic life and regular monitoring studies are therefore essential to control the pesticide concentrations of aquatic biota in the region.

Fatty acid composition and biogenic amines in acidified and fermented fish silage: a comparison study.

In the presented study, ensiling of discard fish by acidification or fermentation was evaluated. Klunzinger's ponyfish which is a discard fish was used for the production of fish silage by acidification (3% formic acid for Method FA; 1.5% formic and 1.5% sulphuric acid for Method FASA) and fermentation (Lactobacillus plantarum for Method LP and Streptococcus thermophilus for Method ST). The chemical, microbiological and nutritional properties of the differently preserved fish silages were estimated during a storage period of 60 d at ambient temperature. Compared to the raw material, a slight increase in saturated fatty acids and a slight decrease in polyunsaturated fatty acids were observed in all silages. At the end of the storage period, the aerobic bacteria counts after applying Methods FA, FASA, LP and ST amounted to 2.35, 2.39, 5.77 and 5.43 log cfu/g, respectively. The analysis of thiobarbituric acid revealed that acidification of silages accelerated the lipid oxidation. Nine biogenic amines were found in raw fish and different silages. The initial histamine concentration in raw fish was 0.17 mg/100 g and in all silages it remained at low levels during the storage period. The initial tyramine content was found to be 1.56 mg/100 g in raw fish and increased significantly in all silages. The increase of the tyramine content in fermented silages was considerably higher than in acidified silages (23-48 mg/100 g and 5-10 mg/100 g, respectively). It can be concluded that acidified or fermented fish silage should be considered as potential feed component for animals because of its high nutritional value and appropriate microbiological and chemical quality.

Comparative seasonal sterol profiles in edible parts of Mediterranean fish and shellfish species.

The effect of different seasons on sterol content of seafoods was investigated. There were four sterols (cholesterol, sitosterol, desmosterol and stigmasterol) identified, with cholesterol being the predominant sterol. Stigmasterol was a minor component in fish muscle, whilst sitosterol was one of the main phytosterols found in fish muscle. Cholesterol content of fish consisted of 38-100% of total sterols in fish and 54-80% of total sterols in shellfish. The highest cholesterol content of fish muscle was found in summer and the lowest in autumn, whereas season did not have any effect on cholesterol level of green tiger prawn and speckled shrimp. Total sterol content of fish muscle ranged from 49 to 110 mg/100 g, although the range of total sterols in shrimp muscle was between 62 and 91 mg/100 g. The result of the study showed that total sterols in fish were generally found at lower levels in winter compared with other seasons.

Nutritional composition of frog (Rana esculanta) waste meal.

In the present study, the waste obtained from the frozen frog leg industry was used for the production of frog waste meal, and its proximate, amino acids, fatty acids, mineral and vitamin compositions were evaluated to determine the nutritional quality. In addition, the total bacterial count, Salmonella, total volatile basic nitrogen (TVB-N, mgN/100g) and thiobarbituric acid (TBA, mg malonaldehyde/kg) were also measured to determine the microbiological and chemical quality of frog waste meal (FWM). The crude protein, fat and ash content of FWM on a dry weight basis were 68.6%, 17.0% and 13.2%, respectively. The amino acid profiles were found to be fairly close to those of fish meal in terms of protein sources and rich in the glutamic acid, glycine, proline, arginine, and methionine. The proportions of fatty acid composition in FWM were analysed and findings were 26.7% for total saturated fatty acid (SFA), 42.5% for total monounsaturated fatty acid (MUFA), 17.0% for total n - 6 and 3.3% for n - 3 ratio. The major SFA, MUFA and PUFA in FWM were palmitic acid (19.1%), oleic acid (26.0%) and linoleic acid (16.7%), respectively. FWM was found to be high in mineral content, especially Zn, K, Cu, Mn, and Mg and high level of some vitamins such as folic acids and thiamin. The total bacterial count was found to be 2.9x10(4) CFU/g, and Salmonella was not observed. TVB-N and TBA in FWM was determined to be 157.4+/-5.8 mg N/100g and 1.2+/-0.1 mg malonaldehyde/kg, respectively.