The research from the University of Sakarya, Turkey, found that immersing the sausages in SSP slurry for 10 minutes prior to packing inhibits growth of the foodborne bacteria.
The study - Inhibition of Listeria Monocytogenes and E.coli 0157:H7 on Frankfurters using Scallop-shell Powder – said the treatment also cut the natural flora of frankfurters “without changing any sensory or chemical properties” of the meat. The paper has been published in the Journal of Food Safety.
Authors Tulay Bodur et al concluded the method could be used as an alternative process to producing safer frankfurters with a longer shelf life.
The team said it had carried out the research after the issue of LM and E.coli growth on the sausages was highlighted by the United States Department of Agriculture as a problem. Around 500,000 pounds of cooked, ready-to-eat meats were recalled in the US from April 2006 to March 2009 due to Listeria contamination. E.coli has also been flagged as an issue with frankfurters because of improper heat processing or possible cross-contamination after processing, said the team.
Frankfurters containing 70 per cent beef and 30 per cent turkey were surface inoculated with LM or E.coli at the concentration of 8 logs cfu/g. Initial levels of the bacteria were undetectable.
The inoculated samples were dried for 10 minutes and then immersed in 0, 0.05 or 0.10 per cent of SSP and stirred for 10 or 30 minutes – with only one sample placed in each SSP slurry. The sausages were examined for levels of the inoculum following the treatment and again after seven days refrigerated storage at 4°C.
Frankfurters were also added to 90ml of sterile water and homogenised for three minutes.
The team found that populations of LM on frankfurters fell from 8.4 logs to 3.5 and 3.8 logs respectively (a fall of 4.9 and 4.6 log) after a 10 minute and 30 minute immersion in 0.05 and 0.10 per cent SSP treatment. In contrast, sausages dipped in sterile water for 10 or 30 minutes showed a fall in LM populations of 2.5 and 2.7 log respectively.
During the seven days, LM populations were 0.5 and 1.0 logs cfu/g lower on the 0.05 and 0.10 per cent SPP treated frankfurters compared to the controls. Remaining SSP residue could continue to hamper bacterial growth during storage, said the group.
E.coli populations of 9.2 logs cfu/g on the frankfurter were reduced by 4.6, 5.0 or 5.9 logs following 10-minute exposure to 0, 0.05 and 0.10 respectively. After 30-minute treatment with SSP E.coli populations fell from 9.2 logs cfu/g to 5.1, 4.2 or 3.5 logs cfu/g respectively, said the group.
No significance difference was seen between the effects of 0.10 per cent and 0.05 per cent SSP.
E.coli populations decreased on the frankfurters by 1.3 and 1.5 logs after exposure to 0.05 per cent SSP for 10 and 30 minutes compared to the control during the time period. But the 0.10 per cent SSP inhibited E.coli growth by 0.6 and 0.8 logs compared to the control.
The research concluded that populations of LM and E.coli on frankfurters can be “significantly reduced” by immersion in SSP slurry during a seven-day storage period in a refrigerator, without affected sensory properties, ascorbic acid content or pH of the meat.
Source: Journal of Food Safety
Title: Inhibition of Listeria Monocytogenes and E.coli 0157:H7 on Frankfurters using Scallop-shell Powder by Tülay Bodur, Güliz Yaldirak, Osman Kola and Arzu Cağri-Mehmetoğlu