Impacto de diferentes niveles de nisina como agente bioconservador en la calidad química, sensorial y microbiológica de filetes de lubina (Dicentrarchus labrax) envasados al vacío y almacenados a 4 ± 2 °C.

Nisin is produced by Lactococcus lactis subsp. lactis and is also known as an antimicrobial agent especially effective against gram-positive bacteria. It has long been used as a preservative in foods and beverages and is generally regarded as safe (GRAS). In the present work, the effects of different concentrations of nisin (0.2, 0.4 and 0.8%) on the sensory, chemical and microbiological quality and shelf-life of vacuum-packed sea bass (Dicentrarchus labrax) fillets were investigated during chilled (4 ± 2 °C) storage. The sensory points for raw and cooked fillets increased with time during the storage period (p < 0.05). The control group, with scores of 9.08, was rejected by panelists on day 12; whereas nisin-treated groups were rejected on day 14 with scores ranging from 9.00-9.17 score. As a result of chemical analyses, lower values (p < 0.05) were obtained from the nisin groups with low oxidative rancidity. Moreover, nisin inhibited microbial growth, which shows antimicrobial activity. Consequently, it was concluded that the application of nisin (especially 0.8%) preserved the organoleptic quality and extended the shelf-life of sea bass fillets.La nisina es producida por Lactococcus lactis subsp. lactis y conocida como agente antimicrobiano, especialmente contra las bacterias grampositivas. Se ha utilizado como conservante en alimentos y bebidas durante mucho tiempo y generalmente se considera seguro (GRAS). En el presente trabajo, se investigaron los efectos de diferentes concentraciones de nisina (0,2, 0,4 y 0,8%) sobre la calidad sensorial, química y microbiológica y la vida útil de los filetes de lubina (Dicentrarchus labrax) envasados al vacío durante el enfriamiento y almacenamiento (4 ± 2 °C). La puntuación sensorial de los filetes crudos y cocidos aumentó con el tiempo durante el período de almacenamiento (p <0,05). El grupo de control con puntuación de 9,08 fue rechazado por los panelistas el día 12, mientras que los grupos de tratamiento con nisina fueron rechazados el día 14 con un rango de puntuación de 9,00-9,17. Como resultado de los análisis químicos, se obtuvieron valores más bajos (p < 0,05) de los grupos de nisina con baja rancidez oxidativa. Además, la nisina inhibió el crecimiento microbiano que muestra actividad antimicrobiana. En consecuencia, se evaluó que la aplicación de nisina (especialmente 0,8%) conservó la calidad organoléptica y prolongó la vida útil de la lubina

Maximizing the antioxidant capacity of Padina pavonica by choosing the right drying and extraction methods

Marine algae are becoming an interesting source of biologically active compounds with a promising application as nutraceuticals, functional food ingredients, and therapeutic agents. The effect of drying (freeze-drying, oven-drying, and shade-drying) and extraction methods (shaking at room temperature, shaking in an incubator at 60 \ub0C, ultrasound-assisted extraction (UAE), and microwave-assisted extraction (MAE)) on the total phenolics content (TPC), total flavonoids content (TFC), and total tannins content (TTC), as well as antioxidant capacity of the water/ethanol extracts from Padina pavonica were investigated. The TPC, TFC, and TTC values of P. pavonica were in the range from 0.44 \ub1 0.03 to 4.32 \ub1 0.15 gallic acid equivalents in mg/g (mg GAE/g) dry algae, from 0.31 \ub1 0.01 to 2.87 \ub1 0.01 mg QE/g dry algae, and from 0.32 \ub1 0.02 to 10.41 \ub1 0.62 mg CE/g dry algae, respectively. The highest TPC was found in the freeze-dried sample in 50% ethanol, extracted by MAE (200 W, 60 \ub0C, and 5 min). In all cases, freeze-dried samples extracted with ethanol (both 50% and 70%) had the higher antioxidant activity, while MAE as a green option reduces the extraction time without the loss of antioxidant activity in P. pavonica

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

The effects of slaughtering methods on the freshness quality of rainbow trout

WOS: 000223261700002The effects of slaughtering methods (percussive stunning and death in ice slurry) on the quality of rainbow trout stored in ice and modified atmosphere packing (MAP) (40% CO2, 30% N-2 and 30% O-2) were investigated in terms of sensory, chemical and microbiological analysis. Sensory analysis showed that the demerit points of fish slaughtered by percussive stunning were higher than those slaughtered by the ice slurry method, but there were no significant differences in demerit points (P>0.05). In addition, the rate of increase in demerit points in fish in MAP was significantly (P>0.05) higher at 6 and 10 days of storage than that in fish in ice for each slaughter method, which was due to increased drip, the appearance of slime and the odour of the fish in MAP packing. The mean K values of rainbow trout slaughtered by percussive stunning in this study were significantly lower (P0.05), but higher concentrations of biogenic amines were found for the ice slurry slaughter method and for fish stored in ice. There were no significant differences (P>0.05) in total viable count of fish stored in ice and MAP, regardless of the different slaughter methods used. However, fish packed in MAP showed reduction in bacterial counts compared to fish held in ice throughout study. The results of this study showed that slaughter by percussive stunning improved the quality of trout compared to the ice slurry method

Effects of aluminium foil and cling film on biogenic amines and nucleotide degradation products in gutted sea bream stored at 2 +/- 1 degrees C

WOS: 000233043000002Biogenic amines and nucleotide degradation products of sea bream stored in ice, wrapped in aluminium foil (WAF) and in cling film (WCF) at 2 +/- 1 degrees C were investigated by using a rapid HPLC method. Results obtained from this study showed that for household purposes packing fish in different materials has a little effect on the biogenic amines formation and nucleotide degradation products. The highest decrease of IMP content was observed for sea bream in WAF, followed by WCF. INO values showed a fluctuation and remained below the levels of 5.5 mu mol/g for all storage conditions. Hx value constantly increased with the storage time during chilled storage. For all of the storage condition, K and Ki value increased linearly with storage time. At the end of the storage period, K, Ki, H and G value reached 60-76%, 65-81%, 30-54% and 89-173%, respectively. Among biogenic amines, (trimetylamine) TMA, putrescine, cadaverine, spermidine, spermine, tryptamine, tyramine, beta-phenylalanine and histamine were detected during storage period. TMA and putrescine were observed to increase linearly during storage period. Histamine production was only found at the end of storage period. The highest histamine values for fish wrapped in aluminium foil were 6.4 mg/100 g and fish wrapped in cling film was 4.6 mg/100 g

Production of biogenic amines by Morganella morganii, Klebsiella pneumoniae and Hafnia alvei using a rapid HPLC method

WOS: 000224613200005The histidine decarboxylating activity and production of biogenic amines by Morganella morganii (NCIMB, 10466), Klebsiella pneumoniae (NCIMB, 673) and Hafnia alvei (NCIMB, 11999) were investigated using a rapid HPLC method. Derivatisation of the bacterial samples was carried out using benzoyl chloride. A gradient elution system was used for analysis with a mixture of acetonitrile and HPLC grade water. Bacterial strains not only produce histamine in histidine-enriched broth but also the other biogenic amines. The chromatographic results show that bacterial strains are also capable of producing spermine and spermidine in histidine-enriched broth. Bacterial ammonia production by all three strains was clearly detected since ammonia is generated during the degradation of histidine. The study demonstrates that the highest histamine production was obtained by Morganella morganii, followed by Klebsiella pneumoniae, and the lowest with the Hafnia alvei. Therefore, Morganella morganii and Klebsiella pneumoniae have strong histidine decarboxylase activity since they are prolific histamine-forming bacteria

Effects of combining of smoking and marinating on the shelf life of anchovy stored at 4°C

The quality of smoked and marinated anchovy was investigated in terms of sensory, chemical [total volatile basic nitrogen (TVB-N), thiobarbituric acid (TBA), peroxide value (PV), fatty acids, free fatty acids (FFA), and pH] and microbiological parameters (total aerobic count (TVC), coliform, Escherichia coli, Salmonella, Staphylococcus aureus) during 7 months of storage. The results of sensory analyses showed that the total appearance, odor-taste, and texture scores decreased gradually during storage period. The results of the chemical analyses also correlated well with the sensory analyses apart from TVBN value. TBA significantly increased (p<0.05) from 1.9 to 4.25 MA/kg after the storage of 6 month. Peroxide value (POV) showed significant fluctuations (p<0.05) during the storage period. Initial TVC of 3.8 log CFU/g increased to 6.2 log CFU/g at the end of storage period. According to results obtained from sensory, chemical, and microbiological analyses, shelf life of this product was about 6 month. © KoSFoST and Springer 2010

Sterol Content of Fish, Crustacea and Mollusc: Effects of Cooking Methods

Sterol contents (desmosterol, cholesterol, stigmasterol, and sitosterol) of 36 fresh and cooked seafood and four freshwater fish species were investigated by high performance liquid chromatography (HPLC) method. Cholesterol and sitosterol were main sterols in seafood and freshwater fish species. Raw shellfish and molluscs contained cholesterol above 18.92 mg/100 g fish muscle, while the cholesterol content of marine fish ranged from 6.5 to 78.40 mg/100 g fish muscle. The cooking process resulted in significant effects on the sterol contents of seafood and freshwater species (p < 0.05). A remarkable increase in sitosterol (more than 3-4 fold compared to raw fish) was recorded for some fish species cooked in the oven. The highest desmosterol content was observed for fried fish, whereas the frying process resulted in a significant loss in cholesterol and sitosterol contents of marine fish (p < 0.05). The impacts of cooking methods on sterol content of seafood and their form varied depending on fish species and the cooking method used. Copyright © Taylor & Francis Group, LLC