Prirodni antioksidativni sastojci odabranog aromatičnog bilja i njihovo djelovanje protiv pojedinih patogenih mikroorganizama

Aromatic plants contain natural antioxidant constituents such as phenolic compounds, which have attracted a great deal of public and scientific interest because of their health-promoting effects as antioxidants. Five plants, Filipendula ulmaria (meadow sweet), Crataegus monogyna (hawthorn), Polygonum aviculare (polygonum), Potentilla anserina (silverweed),and Pelargonium purpureum (little robin), have been examined in order to determine their phenolic composition. Reversed-phase high performance liquid chromatography (RP-HPLC) was employed for the identification and quantification of phenolic compounds ofthe aforementioned plants. Gas chromatography–mass spectrometry method (GC-MS) was also used for identification of phenolic compounds after silylation. Analysis of the non-volatile and thermolabile phenolic compounds by GC-MS presupposes their conversion intovolatile and thermotolerant derivatives. The derivatization process was optimized againstreagents, temperature and reaction time. The antioxidant capacity was determined in driedplants and in their methanol extracts with the Rancimat test using sunflower oil as substrate. Both pulverized plants and extracts showed antioxidant capacity. Total phenoliccontent in the extracts was determined spectrometrically applying the Folin-Ciocalteu assay and it ranged from 7.2 to 28.2 gallic acid equivalents (GAE)/(mg/mL). Antimicrobial activity of the extracts against selected microorganisms was performed using the disk diffusion method. Gram-(+) bacteria were more sensitive to the plant extracts than Gram-(–) bacteria.Aromatično bilje sadrži prirodne antioksidanse poput fenolnih spojeva koji su zbog pozitivnog utjecaja na zdravlje privukli pozornost javnosti i znanstvenika. Istražen je fenolni sastav pet vrsta biljaka: končare (Filipendula ulmaria), bijeloga gloga (Crataegus monogyna), troskota (Polygonum aviculare), petoprsta (Potentilla anserina) i purpurne iglice (Pelargonium purpureum). Za određivanje koncentracije i sastava fenolnih spojeva upotrijebljena je visokodjelotvorna tekućinska kromatografija obrnutih faza, a za određivanje sastava fenolnih spojeva, nakon supstitucije vodikova atoma sa -SiMe3 skupinom, primijenjena je plinska kromatografija u kombinaciji s masenom spektrometrijom, kojom je utvrđeno da je došlo do konverzije iz nehlapljivih derivata u hlapljive derivate i iz termolabilnih derivata u termotolerantne derivate. Da bi se dobili derivati željenih svojstava, optimirani su koncentracija reagensa, temperatura i vrijeme reakcije. Primjenom Rancimat metode (kao supstrat je upotrijebljeno suncokretovo ulje) dokazana su antioksidativna svojstva sušenog bilja i ekstrakta dobivenog s metanolom. Primjenom Folin-Ciocalteau metode spektrofotometrijski je određen ukupni udjel fenola u ekstraktima, koji je iznosio 7,2-28,2 mg/mL (izraženo kao galna kiselina). Antimikrobna aktivnost ekstrakata dokazana je disk-difuzijskom metodom, pri čemu je ustanovljeno da su ekstrakti više utjecali na rast Gram-(+) bakterija nego na rast Gram-(-) bakterija

Prirodni antioksidativni sastojci odabranog aromatičnog bilja i njihovo djelovanje protiv pojedinih patogenih mikroorganizama

Aromatic plants contain natural antioxidant constituents such as phenolic compounds, which have attracted a great deal of public and scientific interest because of their health-promoting effects as antioxidants. Five plants, Filipendula ulmaria (meadow sweet), Crataegus monogyna (hawthorn), Polygonum aviculare (polygonum), Potentilla anserina (silverweed),and Pelargonium purpureum (little robin), have been examined in order to determine their phenolic composition. Reversed-phase high performance liquid chromatography (RP-HPLC) was employed for the identification and quantification of phenolic compounds ofthe aforementioned plants. Gas chromatography–mass spectrometry method (GC-MS) was also used for identification of phenolic compounds after silylation. Analysis of the non-volatile and thermolabile phenolic compounds by GC-MS presupposes their conversion intovolatile and thermotolerant derivatives. The derivatization process was optimized againstreagents, temperature and reaction time. The antioxidant capacity was determined in driedplants and in their methanol extracts with the Rancimat test using sunflower oil as substrate. Both pulverized plants and extracts showed antioxidant capacity. Total phenoliccontent in the extracts was determined spectrometrically applying the Folin-Ciocalteu assay and it ranged from 7.2 to 28.2 gallic acid equivalents (GAE)/(mg/mL). Antimicrobial activity of the extracts against selected microorganisms was performed using the disk diffusion method. Gram-(+) bacteria were more sensitive to the plant extracts than Gram-(–) bacteria.Aromatično bilje sadrži prirodne antioksidanse poput fenolnih spojeva koji su zbog pozitivnog utjecaja na zdravlje privukli pozornost javnosti i znanstvenika. Istražen je fenolni sastav pet vrsta biljaka: končare (Filipendula ulmaria), bijeloga gloga (Crataegus monogyna), troskota (Polygonum aviculare), petoprsta (Potentilla anserina) i purpurne iglice (Pelargonium purpureum). Za određivanje koncentracije i sastava fenolnih spojeva upotrijebljena je visokodjelotvorna tekućinska kromatografija obrnutih faza, a za određivanje sastava fenolnih spojeva, nakon supstitucije vodikova atoma sa -SiMe3 skupinom, primijenjena je plinska kromatografija u kombinaciji s masenom spektrometrijom, kojom je utvrđeno da je došlo do konverzije iz nehlapljivih derivata u hlapljive derivate i iz termolabilnih derivata u termotolerantne derivate. Da bi se dobili derivati željenih svojstava, optimirani su koncentracija reagensa, temperatura i vrijeme reakcije. Primjenom Rancimat metode (kao supstrat je upotrijebljeno suncokretovo ulje) dokazana su antioksidativna svojstva sušenog bilja i ekstrakta dobivenog s metanolom. Primjenom Folin-Ciocalteau metode spektrofotometrijski je određen ukupni udjel fenola u ekstraktima, koji je iznosio 7,2-28,2 mg/mL (izraženo kao galna kiselina). Antimikrobna aktivnost ekstrakata dokazana je disk-difuzijskom metodom, pri čemu je ustanovljeno da su ekstrakti više utjecali na rast Gram-(+) bakterija nego na rast Gram-(-) bakterija

Non-thermal methods for ensuring the microbiological quality and safety of seafood

A literature search and systematic review were conducted to present and discuss the most recent research studies for the past twenty years on the application of non-thermal methods for ensuring the microbiological safety and quality of fish and seafood. This review presents the principles and reveals the potential benefits of high hydrostatic pressure processing (HHP), ultrasounds (US), non-thermal atmospheric plasma (NTAP), pulsed electric fields (PEF), and electrolyzed water (EW) as alternative methods to conventional heat treatments. Some of these methods have already been adopted by the seafood industry, while others show promising results in inactivating microbial contaminants or spoilage bacteria from solid or liquid seafood products without affecting the biochemical or sensory quality. The main applications and mechanisms of action for each emerging technology are being discussed. Each of these technologies has a specific mode of microbial inactivation and a specific range of use. Thus, their knowledge is important to design a practical application plan focusing on producing safer, qualitative seafood products with added value following today’s consumers’ needs

Antimikrobni učinak ekstrakta biljke Filipendula ulmaria na patogene bakterije i uzročnike kvarenja na laboratorijskoj podlozi, te u ribljem mesu i ikri

Water-methanol extract from Filipendula ulmaria contains a variety of phenolic compounds, such as caffeic, p-coumaric and vanillic acid, myricetin, etc, which demonstrate antibacterial activity. Monitoring this activity in the broth using absorbance measurements showed that species of the Enterobacteriaceae family were more resistant than other Gram-negative and Gram-positive bacteria tested. Acidic environment enhanced the antibacterial activity of Filipendula ulmaria extract when it was tested against Salmonella Enteritidis PT4 and Listeria monocytogenes Scott A. The efficacy of Filipendula ulmaria extract against selected foodborne psychrotrophic bacteria was also tested using solid laboratory media and low incubation temperatures for better simulation of food preservation conditions. Higher concentrations of the extract, compared to minimum inhibitory concentration determined in the broth, were needed for satisfactory inhibition of spoilage bacteria. Potential use of Filipendula ulmaria extract as natural food preservative was also examined against natural spoilage flora and inoculated pathogenic bacteria on fish flesh and fish roe product (tarama salad). No significant differences of viable populations of spoilage or pathogenic bacteria were found between the treated samples and controls. Further trials of Filipendula ulmaria extract should be carried out in acidic foods with low fat and protein content, supplemented with additional adjuncts, in order to explore its potential as effective natural food antimicrobial agent.Ekstrakt biljke Filipendula ulmaria sadržava različite fenolne spojeve, npr. kafeinska, p-kumarinska i vanilinska kiselina, miricetin i drugo, koji imaju antibakterijski učinak. Mjerenjem apsorbancije praćena je aktivnost tih spojeva u bujonu, te je utvrđeno da su bakterije iz porodice Enterobacteriaceae puno otpornije od ostalih Gram-negativnih i Gram-pozitivnih bakterija. Kisela je sredina pojačala antibakterijski učinak ekstrakta biljke Filipendula ulmaria na bakterije Salmonella Enteritidis PT4 i Listeria monocytogenes Scott A. Ispitan je učinak ekstrakta na odabrane psihrotrofne mikroorganizme na čvrstoj laboratorijskoj podlozi pri niskim temperaturama. Za uspješnu inhibiciju uzročnika kvarenja bila je potrebna veća koncentracija ekstrakta od minimalne inhibicijske koncentracije. Pri prirodnom konzerviranju hrane ispitana je mogućnost primjene ekstrakta na uzročnicima kvarenja i inokuliranim patogenim bakterijama u ribljem mesu i ikri (tarama salata). Nije utvrđena značajna razlika u broju živih stanica uzročnika kvarenja ili patogenih bakterija između obrađenih i kontrolnih uzoraka. Da bi se istražila mogućnost prirodnog konzerviranja hrane dodatkom ekstrakta biljke Filipendula ulmaria, potrebno je provesti daljna istraživanja u tzv. kiseloj hrani, s malim udjelom proteina i masti

Volatilome of chill-stored European Seabass (Dicentrarchus labrax) fillets and Atlantic Salmon (Salmo salar) slices under modified atmosphere packaging

Fish spoilage occurs due to production of metabolites during storage, from bacterial action and chemical reactions, which leads to sensory rejection. Investigating the volatilome profile can reveal the potential spoilage markers. The evolution of volatile organic molecules during storage of European seabass (Dicentrarchus labrax) fillets and Atlantic salmon (Salmo salar) slices under modified atmosphere packaging at 2 °C was recorded by solid-phase microextraction combined with gas chromatography-mass spectrometry. Total volatile basic nitrogen (TVB-N), microbiological, and sensory changes were also monitored. The shelf life of seabass fillets and salmon slices was 10.5 days. Pseudomonas and H2S-producing bacteria were the dominant microorganisms in both fish. TVB-N increased from the middle of storage, but never reached concentrations higher than the regulatory limit of 30–35 mg N/100 g. The volatilome consisted of a number of aldehydes, ketones, alcohols and esters, common to both fish species. However, different evolution patterns were observed, indicating the effect of fish substrate on microbial growth and eventually the generation of volatiles. The compounds 3-hydroxy-2-butanone, 2,3-butanediol, 2,3-butanedione and acetic acid could be proposed as potential spoilage markers. The identification and quantification of the volatilities of specific fish species via the development of a database with the fingerprint of fish species stored under certain storage conditions can help towards rapid spoilage assessment

The effect of organic and conventional production methods on sea bream growth, health and body composition: A field experiment

This study aimed to develop a better understanding of organic sea bream aquaculture production in Greece, in particular its consequences for fish growth, health and body composition, and to propose and update standards for sustainable organic sea bream farming. Gilthead sea bream were kept in sea cages at densities of 4 kg m–3 (organic) and 15 kg m–3(conventional), and were fed organically produced feed (45% crude protein, 14% fat) or conventional feed (46% crude protein, 17% fat). The amino acid profile of the conventional diet, particularly the lysine content, which is one of most important dietary amino acids for sea bream, appeared to be unsatisfactory. “Organic” sea bream stored less fat content in their white muscle than the conventional sea bream. The liver lipid content was lower and the hepatosomatic index was higher for the organic sea bream. The microbiological analysis showed that both Enterobacteriaceae and Escherichia coli on the skin were below the enumeration detection limit in both the organic and conventional sea bream. Total viable counts on the skin and muscle of both the organically and conventionally cultured sea bream were approximately 3 log cfu g–1, which is well below the acceptable limit (7 log cfu g–1) for marine species. The results showed that the combination of a low stocking density and feed with a different ingredient composition but similar nutritional value resulted in similar growth rates and nutrient profiles of the final product. Further research on nutrition is required to provide information on setting the appropriate standards for organic sea bream aquaculture to ensure that the final product is in line with the consumers’ preferences

Food ingredients from the marine environment. Marine biotechnology meets food science and technology.

Marine environment disposes a plethora of bioactive compounds with unique properties and remarkable potential for biotechnological applications. A lot of those compounds can be used by the food industry as natural preservatives, pigments, stabilizers, gelling agents, etc., while others exhibits beneficial effects and can be used as functional food ingredients, nutraceuticals, dietary supplements and prebiotics. Interdisciplinary approach is required to increase our knowledge, explore the potential of marine environment and produce value-added food for all

Bacterial injury and sensitisation of gram-negatives to nisin.

Nisin is a bacteriocin produced by Lactococcus lactis subsp. lactis, which is active against Gram-positive organisms including bacterial spores. It is not generally active against Gram-negative bacteria, yeasts and fungi. Gram negatives show nisin-sensitivity when their outer membrane permeability is altered by various means, such as treatments with chelators, e.g. EDTA, osmotic shock, heating, freezing, freeze-drying, high- pressure etc. Application of chelators and nisin is effective against Gram-negatives when exogenous nisin is added. Nisin produced in situ and chelators are not an effective combination, since nisin production follows the pH drop caused by sugar fermentation, and this interferes with the sequestering ability of the chelators. Presence of nisin during thermal inactivation of Gram-negatives though is effective. Bacteria become structurally injured during heating showing sensitivity to agents like SDS and deoxycholate and extended detection times by impedimetry. These injured bacteria are inactivated by nisin, with a concomitant reduction of the measured D-values. Low pH and the presence of small amount of chelators enhance the injury and inactivation and reduce D-values further. Gram-negative bacteria injured by chilling and freezing are also sensitive to nisin. The effectiveness of nisin is reduced in a food environment mostly of nisin binding to fat, and food particles. D-values were decreased less or not at all in egg white and liquid whole egg, respectively, and rapid chilling of bacteria attached to chicken skin in presence of nisin did not give the effect seen in laboratory media. Nisin is active against heat-, chill-, and freezing-stressed Gram-negatives only if it is present during the treatments. When the stress factor is removed, the bacteria recover their nisin resistance, implying transient susceptibility to nisin, but not to smaller molecules. This is probably due to rapid reorganisation and restoration of OM permeability damage, rather than biochemical repair. The LPS chain length influences the sensitisation of Gram-negatives to nisin, only in the case of freezing, where the strain with the shorter LPS chain was more sensitive than the wild type. Heat-, and freezing-stressed bacteria lost lipopolysaccharides and increased their cell surface hydrophobicity. This was not seen with chill-stressed bacteria, which were sensitive to nisin though. This indicates that release of LPS is not a prerequisite for nisin sensitivity in Gram-negatives

Food ingredients from the marine environment. Marine biotechnology meets food science and technology

Marine environment affords a plethora of bioactive compounds with unique properties and remarkable potential for biotechnological applications. A lot of those compounds can be used by the food industry as natural preservatives, pigments, stabilizers, gelling agents, and others, while others exhibit beneficial effects and can be used as functional food ingredients, nutraceuticals, dietary supplements and prebiotics. Interdisciplinary approach is required to increase our knowledge, explore the potential of marine environment and produce value-added food for all