Inhibition of Clostridium sporogenes PA 3679 and Natural Bacterial Flora of Cooked Vacuum-Packaged Bratwurst by Sodium Acid Pyrophosphate and Sodium Tripolyphosphate With or Without Added Sodium Nitrite

Survival and growth of inoculated Clostridium sporogenes PA3679 and natural aerobic and anaerobic bacterial flora were studied in refrigerated (5°C) and subsequently temperature abused (24–25°C), cooked, vacuum-packaged bratwurst containing 0.5% sodium acid pyrophosphate (SAPP) or sodium tripolyphosphate (STPP) with or without sodium nitrite. Phosphates alone or combined with nitrite did not affect aerobic bacterial counts but resulted in reduced clostridial and anaerobic counts at 5°C. Upon temperature abuse, inhibition of all bacteria by SAPP was significant (P<0.05) for up to 48 hr and greatly enhanced by 100 ppm but not by 50 ppm sodium nitrite, whereas STPP lost its antimicrobial properties after 24 hr. Soluble orthophosphate levels had a positive correlation with bacterial inhibition in SAPP-treated bratwurst.     

Effect of Sodium Acid Pyrophosphate in Combination with Sodium Nitrite or Sodium Nitrite/Potassium Sorbate on Clostridium botulinum Growth and Toxin Production in Beef/Pork Frankfurter Emulsions

Combinations of sodium acid pyrophosphate (SAPP) with added sodium nitrite and/or potassium sorbate were tested at various pH levels to determine effectiveness in delaying Clostridium botulinum growth and toxin production in frankfurter emulsions. Formulations containing sodium nitrite (40 ppm), potassium sorbate (0.26%) and SAPP (0.4%) resulted in a greater delay of toxin production (12–18 days) than other combinations (6–12 days) having similar pH values. Treatments containing 0.4% SAPP appeared to be more inhibitory than their counterparts without SAPP, displaying less numbers of toxic samples during the 53-day storage period at 27°C. Aerobic mesophilic colony counts and residual nitrite data showed little difference among treatments.     

Inhibition of Clostridium botulinum Growth from Spore Inocula in Media Containing Sodium Acid Pyrophosphate and Potassium Sorbate with or without added Sodium Chloride

The effects of sodium acid pyrophosphate (SAPP), sodium chloride (NaCl) and/or potassium sorbate (PS) on the growth from heat-activated spores of three individual strains or a mixture of ten strains of Clostridium botulinum in peptone-yeast extract-glucose broth at pH 5.55 or 5.85 were measured spectrophotometricalty at A_630nm. Growth ratios (GR = treatment/control) based on time to reach A₆₃₀= 0.35 or 0.04 were calculated and used to compare effects of additives on strains. SAPP, NaCl, PS, and pH exhibited independent significant main effects (p≦0.01) on delaying growth in most C. botulinum strains tested. Combinations of additives without NaCl consistently caused an increase in the GR and an increase in organism sensitivity to additives in the medium. Treatments containing SAPP (0.2 or 0.4%) and PS (0.13 or 0.26%) were more effective for delaying growth than other formulations tested.     

Effect of Mechanically Separated Pork, Sodium Erythorbate and Sodium Nitrite Combinations on Clostridium sporogenes Survival and Growth in Liver Sausage

Liver sausage formulated with 50 or 75% mechanically separated pork (MSP), 75 or 150 ppm sodium nitrite and 0, 550 or 1100 ppm sodium erythorbate was examined for Clostridium sporogenes PA3679 survival and growth during refrigerated temperature storage (5°C, 6 days) and during subsequent exposure to elevated temperatures (22–24°C, 2 d). Sodium nitrite at 150 ppm inhibited clostridial growth in sausage held at 22–24°C, regardless of MSP content, if 550 ppm sodium erythorbate were also present. Sodium nitrite at 75 ppm combined with erythorbate at 550 and 1100 ppm did not inhibit C. sporogenes growth during simulated temperature mishandling of liver sausage. Residual nitrite decreased (P<0.05) with erythorbate addition but was unaffected by MSP.     

The effect of pH on the thermal resistance of Clostridium sporogenes (PA 3679) in asparagus purée acidified with citric acid and glucono-delta-lactone.

The influence of type of acid, pH and temperature on heat resistance of Clostridium sporogenes (PA 3679) spores were investigated in white asparagus pureé acidified with citric acid and glucono-delta-lactone (GDL). The pH values studied were: 4.5, 4.8, 5.1 and 5.4 at temperatures of 110, 115, 118 and 121 degrees C. The addition of citric acid and GDL to reduce pH significantly diminished heat resistance of the spores. The two acids investigated differed in their effect on heat resistance at the various pH-levels. The most pronounced effect was observed at the lower heat treatment temperatures investigated. The z values ranged from 10.24 to 13.09 degrees C in the asparagus purée with acids added and with significant differences between the two acids and the various pH levels.     

Gas Permeability and Permselectivity of Poly(L‐Lactic Acid)/SiOx Film and Its Application in Equilibrium‐Modified Atmosphere Packaging for Chilled Meat

A layer of SiO_x was deposited on the surface of poly(L‐lactic acid) (PLLA) film to fabricate a PLLA/SiO_x layered film, by plasma‐enhanced chemical vapor deposition (PECVD) process. PLLA/SiO_x film showed Young's modulus and tensile strength increased by 119.2% and 91.6%, respectively, over those of neat PLLA film. At 5 °C, the oxygen (O₂) and carbon dioxide (CO₂) permeability of PLLA/SiO_x film decreased by 78.7% and 71.7%, respectively, and the CO₂/O₂ permselectivity increased by 32.5%, compared to that of the neat PLLA film. When the PLLA/SiO_x film was applied to the equilibrium‐modified atmosphere packaging of chilled meat, the gas composition in packaging reached a dynamic equilibrium with 6% to 11% CO₂ and 8% to 13% O₂. Combined with tea polyphenol pads, which effectively inhibited the microbial growth, the desirable color of meat was maintained and an extended shelf life of 52 d was achieved for the chilled meat.     

Active Packaging of Fresh Chicken Breast,with Allyl Isothiocyanate (AITC) in Combination with Modified Atmosphere Packaging (MAP) to Control the Growth of Pathogens

ABSTRACT: Listeria monocytogenes and Salmonella typhimurium are major bacterial pathogens associated with poultry products. Ally isothiocyanate (AITC), a natural antimicrobial compound, is reportedly effective against these pathogenic organisms. A device was designed for the controlled release of AITC with modified atmosphere packaging (MAP), and then evaluated for its ability to control the growth of L. monocytogenes and S. typhimurium on raw chicken breast during refrigerated storage. In order to obtain controlled release during the test period, a glass vial was filled with AITC and triglyceride. It was then sealed using high-density polyethylene film. The release of AITC was controlled by the concentration (mole fraction) of AITC in the triglyceride and by the AITC vapor permeability through the film. The fresh chicken samples were inoculated with one or the other of the pathogens at 10⁴ CFU/g, and the packages (with and without AITC-controlled release device) were flushed with ambient air or 30% CO₂/70% N₂ before sealing, and then stored at 4 °C for up to 21 d. The maximum reduction in MAP plus AITC (compared to MAP alone) was 0.77 log CFU/g for L. monocytogenes and 1.3 log CFU/g for S. typhimurium. The color of the chicken breast meat was affected by the concentration of AITC. Overall, a release rate of 0.6 μg/h of AITC was found to not affect the color, whereas at 1.2 μg/h of AITC the surface of the chicken was discolored.