Stimulation of Cadaverine Production by Foodborne Pathogens in the Presence of Lactobacillus,Lactococcus, and Streptococcus spp.

Abstract: The effect of Lactobacillus plantarum (FI8595), Lactococcus lactis subsp. cremoris MG 1363), Lactococcus lactis subsp. lactis (IL 1403), and Streptococcus thermophilus on cadaverine and other biogenic amine production by foodborne pathogens was investigated lysine decarboxylase broth. Both of lactic acid bacteria and foodborne pathogens used (especially Staphylococcus aureus, E. coli, Lc. lactis subsp. lactis and Lb. plantarum) had an ability to convert aminoacids into biogenic amine. The conversion of lysine into cadaverine was the highest (167.11 mg/L) by Lactobacillus spp. Gram‐positive bacteria generally had a greater ability to produce cadaverine with corresponding value of 46.26, 53.76, and 154.54 mg/L for Enterococcus faecalis, S. aureus, and Listeria monocytogenes, respectively. Significant variations on biogenic amine production were observed in the presence of lactic acid bacteria strains (P < 0.05). The role of lactic acid bacteria on biogenic amine production by foodborne pathogens varied depending on strains and specific amine. Cadaverine accumulation by Enterobactericeae was increased in the presence of lactic acid bacteria strains except for St. thermophilus, which induced 2‐fold lower cadaverine production by S. Paratyphi A. Lc. lactis subsp. lactis and Lc. lactis subsp. cremoris induced 10‐fold higher increases in histamine for E. coli and K. pneumoniae, respectively. Lactic acid bacteria resulted in strong increases in cadaverine production by P. aeruginosa, although remarkable decreases were observed for histamine, spermidine, dopamine, agmatine, and TMA in the presence of lactic acid bacteria in lysine decarboxylase broth . The result of the study showed that amine positive lactic acid bacteria strains in fermented food led to significant amine accumulation by contaminant bacteria and their accumulation in food product may be controlled by the use of proper starters with amine‐negative activity. Practical Application: Foodborne pathogens and certain lactic acid bacteria are particularly active in the production of biogenic amines. Most of the strains of bacteria possess more than 1 amino acid decarboxylase activity under lysine enrichment culture conditions. Lactic acid bacteria strains had a significant role on increase putrescine accumulation by foodborne pathogens. The increased production of biogenic amines in mixed culture is the result of presence of amine positive lactic acid bacteria strains. The addition of a proper selected starter culture with amine‐negative activity is advisable to produce safer fermented food with low contents of biogenic amines.     

The impact of applying natural clinoptilolite (zeolite) on the chemical,sensory and microbiological changes of vacuum packed sardine fillets

Different doses (1% and 5%) of natural zeolite were applied to determine quality changes in vacuum packaged sardine fillets during 19 days at 4 ± 1 °C. Zeolite had an effect to improve sensory quality of sardine especially for removing off‐odour. The acceptable shelf life of vacuum packaged sardine was 8 days for control and 12 days for groups treated with 1% and 5% zeolite. The zeolite application resulted in significant reduction in total volatile basic nitrogen values, except for group treated with 5% zeolite at 15 days. Although the effect of zeolite depended on dose and specific storage days, application of zeolite had no effect on free fatty acid analysis. The use of zeolite significantly reduced ammonia and biogenic amine accumulation, especially for histamine and tyramine. The result of the study showed that the efficacy of zeolite as natural antimicrobials was high and lower dose of zeolite has to be applied to get maximum preservation effect.     

Effect of the Icing with Rosemary Extract on the Oxidative Stability and Biogenic Amine Formation in Sardine (Sardinella aurita) During Chilled Storage

The effect of icing with the rosemary extract on the quality and safety of sardines (Sardinella aurita) was assessed through the chemical, sensory and microbiological methods. The sensory acceptability limit was 12?days for sardine stored in traditional ice and 15?days for sardine stored in ice prepared from rosemary extract solution. There were no significant differences between sardine stored in ice with both 0.05% and 0.1% rosemary extract in terms of sensory acceptability. Storage of sardine in ice containing rosemary extract improved the sensory and some of the chemical quality parameters as compared with the traditional icing, which resulted in a significant extension in the shelf life of sardine. Eleven biogenic amines were determined for food quality and safety. Icing containing rosemary extract had a positive effect, causing low biogenic amine content, especially histamine and putrescine. Histamine content of sardine also increased rapidly with time when the number of bacteria reached above 10⁶ cell/g, which is a good correlation between histamine content and number of bacteria. Consequently, the application of ice containing rosemary extract improved the quality and safety of sardine, which can be explored by the food industry.     

Sensory,microbiological and chemical assessment of the freshness of red mullet (Mullus barbatus) and goldband goatfish (Upeneus moluccensis) during storage in ice

The shelf life of red mullet and goldband goatfish during ice storage were studied in terms of sensory, microbiological and chemical changes. The sensory acceptability limit was 8 days for goldband goatfish (Upeneus moluccensis) and 11 days for red mullet (Mullus barbatus) stored in ice. The TVC level was correlated with sensory assessment. The TVC exceeded 7 log cfu g⁻¹ after 8 days for goldband goatfish, and 11 days for red mullet. At the end of storage period, pH, TVB-N, TBA, FFA and PV for red mullet were 7.84, 47.19 mg/100 g, 0.69 mg MA kg⁻¹, 1.17% oleic acid and 1.58 meq O₂/kg and for goldband goatfish they were 7.53, 43.97 mg/100 g, 0.74 mg MA kg⁻¹, 1.62% oleic acid and 1.68 meq O₂/kg, respectively. In red mullet, agmatine, serotonin, histamine and dopamine became the dominant amines, reaching 7.30, 5.97, 2.52 and 2.31 mg/100 g, respectively. Also the dominant amines for goldband goatfish were 4.37, 3.88, 3.38 and 2.00 mg/100 g for histamine, agmatine, dopamine and putrescine, respectively.     

Synergistic and antagonistic effect of lactic acid bacteria on tyramine production by food-borne pathogenic bacteria in tyrosine decarboxylase broth

The effect of lactic acid bacteria (LAB) strains on tyramine (TYR) and also other biogenic amines (BA) production by eight common food-borne pathogen (FBP) in tyrosine decarboxylase broth (TDB) was investigated by using a rapid HPLC method. Significant differences were observed among the FBP strains in ammonia (AMN) and BA production apart from tryptamine, histamine (HIS) and spermine formation (p < 0.05). Salmonella paratyphi A was characterised as the main amine producer. LAB had an important synergetic role in some BA production by food-borne pathogenic bacteria, although the effect of some LAB strains on BA production was strain-dependent. Lactococcus spp. and Streptococcus spp. resulted in significantly higher TYR accumulation by Aeromonas hydrophila and Enterococcus faecalis in TDB. The presence of Lactococcus and/or Lactobacillus in TDB significantly increased HIS production by A. hydrophila, Escherichia coli, Ent. faecalis, Klebsiella pneumoniae and Pseudomonas aeruginosa, whereas HIS accumulation was significantly reduced by Staphylococcus aureus, S. paratyphi A and Listeria monocytogenes.     

Hydrolysis and oxidation of European eel oil during frozen storage for 48 weeks

The quality assessment of the wild European eel (Anguilla anguilla) stored at −20 °C was assessed by sensory, chemical (total volatile basic nitrogen (TVB-N), peroxide value (PV), free fatty acid (FFA), thiobarbituric values (TBA) and pH) methods. The sensory analysis of showed that European eels were acceptable by panellists and can be stored for more than 48 weeks at −20 °C. No effects of frozen storage were observed on the proximate composition of eel. The level of TVB-N showed fluctuations (7.09–14.72 mg TVB-N/100 g) during frozen storage period, thus TVB-N could not be used as an indicator of frozen eel quality. FFA, PV and TBA values showed fluctuations during frozen storage period but remained low at the end of storage period, PV reached to the maximum level of 13.20±1.73 meq/kg, which did not exceed the maximum recommended value for human consumption (20 meq/kg). The release of FFA slightly increased (P>0.05) from the initial value of 0.88 to 2.14 (expressed as % of oleic acid) until 32 weeks of frozen storage while TBA increased from the initial value of 0.085 mg MA/kg to maximum level of 0.7696 mg MA/kg after week 40. After that, their values decreased to 1.82 and 0.5577 at week 48, respectively. This study showed that off-flavour and off-odour was not detected and frozen European eels were still acceptable by panellists and can be stored for more than 48 weeks at −20 °C.