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.     

Effects of Sodium Chloride Reduction and Polyphosphate Addition on Clostridium Botulinum Toxin Production in Turkey Frankfurters

Mechanically deboned turkey meat emulsions were made with 1.0, 1.5, 2.0, 2.5, or 3.0% salt (NaCl), or with combinations of 1.5% or 2.0% salt with 0.4% sodium tripolyphosphate (TPP), sodium hexametaphosphate (HMP), or sodium acid pyrophosphate (SAPP). Sodium nitrite levels were constant at 150 ppm. Emulsions were inoculated with a mixture of 10 strains of C. botulinum (10³/g) and incubated at 27°C. Increasing NaCl content from 1.0% to 3.0% delayed toxin production by 3 days on the average. Toxin production was detected earlier when TPP was added, HMP had no effect, and SAPP delayed toxin production.     

Effects of Polyphosphates on Cell Numbers, Enterotoxin A, and Extracellular Protein in Staphylococcus aureus 196E

Effects of sodium salts of pyro- (SAPP), tripoly- (STPP), and hexametaphosphate (SHMP) on cell numbers, enterotoxin A (SEA) and extracellular protein production (ECP) of Staphylococcus aureus strain 196A were studied in 4% N-Z amine broth plus 1% yeast extract after 24 hr at 30°C. At pH 7.0, concentrations lower than 56 mM (1.2%) SAPP, 27 mM (1%) STPP or 3 mM (0.4%) SHMP had no antibacterial effects and a bacteriostatic effect showed at slightly higher concentrations. SAPP was the least effective inhibitor at neutral pH, but displayed enhanced inhibitory effects at pH 5.5. Reduction in SEA and ECP paralleled cell growth suppression; their concentrations were 1400 ng/mL and 1.5 mg/mL, respectively, in phosphate free broth (9 × 10⁹ CFU/mL), and nondetectable when cell numbers were ≤10⁶ per mL.     

Interaction of Reduced NaCl, Sodium Acid Pyrophosphate and pH on the Antimicrobial Activity of Comminuted Meat Products

Meat (beef-pork) batters were formulated with NaCl (2.3% and 4.1% brine) and with 0.5% sodium acid pyrophosphate (SAPP) in combination with 2.3% brine. The adjusted pH of raw batters resulted in cooked meat pH values of 5.7, 6.0, and 6.3. Inoculated (Clostridium sporogenes spores) and uninoculated batters in cans were cooked to 70°C and stored for abuse at 27°C. Microbial growth was delayed and the short shelf-life of low brine (2.3%) products was extended with SAPP in the formulation. The antimicrobial properties of treatments with SAPP were due to both declining pH and presence of phosphate in the formulation. Potential mechanisms of microbial inhibition by SAPP are discussed.     

Effect of Phosphates on Bacterial Growth in Refrigerated Uncooked Bratwurst

The effects of 0.5% sodium acid pyrophosphate (SAPP), sodium tripolyphosphate (STPP), tetrasodium pyrophosphate (TSPP) and sodium polyphosphate glassy (SPC) on aerobic mesophilic and psychrotrophic bacterial growth and on survival of inoculated Stuphylococcus aureus Z 88 were investigated in uncooked bratwurst stored at 5°C for 7 days. No significant microbial inhibition by phosphates was found, although SAPP addition resulted in consistently lower total aerobic plate counts. Phosphate-induced pH differences in the sausages had no effect on bacterial numbers. The possible role of meat enzymes in the hydrolysis of condensed phosphates to microbiologically inactive species is discussed.     

Staphylococcus aureus Growth and Toxin Production in Imitation Cheeses

The ability of eleven imitation (or substitute) cheeses to support the growth and toxin production of Staphylococcus aureus at 26°C was evaluated. All established enterotoxin serotypes were tested by inoculating suspensions of the requisite strains into 100-g samples of cheese (about 30 staphylococci/g). Water activity (a_w) of the cheese samples ranged from 0.942–0.973; pH values ranged from 5.33–6.14. Seven cheeses supported extensive growth of S. aureus; one or more serotypes of enterotoxin were produced in six cheeses. Enterotoxin in the cheese was detected in 4 days at 3 × 10⁶ staphylococci/g. However, the ability of some cheeses to support growth and toxin production of S. aureus could not be correlated with pH, a_w, or product formulation.     

Recovery of Selected Bacteria in Media Containing 0.5% Food Grade Poly- and Pyrophosphates

Pure cultures of Salmonella typhimurium, Pseudomonas aeruginosa, Staphylococcus aureus and two lactic starters were plated with laboratory media containing 0.5% of a food grade poly- or pyrophosphate. Heated or unheated tetra sodium pyrophosphate (TSPP) was highly inhibitory or lethal to all cultures tested, followed by unheated sodium tripolyphosphate (STPP) and sodium polyphosphate glassy (SPG), while sodium acid pyrophosphate (SAPP) was not inhibitory or enhanced recoveries. Heating reduced the effectiveness of phsophates as inhibitors.     

Effect of various antimicrobials on the growth kinetics of foodborne pathogens in ready-to-eat, pyeonyuk (cooked and pressed pork)

This study investigated the antimicrobial effects of garlic, potassium lactate and sodium diacetate (PL/SDA) mixture, ?-polylysine, and potassium sorbate (PS) alone or in combinations of them on the growth of foodborne pathogens and production of staphylococcal enterotoxin A (SEA) in ready-to-eat (RTE) pyeonyuk at various temperatures. Lag times (LTs) of Salmonella Typhimurium were longer than those of Staphyloccus aureus at all tested temperatures, regardless of antimicrobial agent. The growth of S. Typhimurium and S. aureus were not observed in pyeonyuk made with 3% PL/SDA mixture or 1.5% ?-polylysine at 10°C. The 0.2% of PS, which is the permitted level for meat products, did not inhibit the growth of S. Typhimurium and S. aureus. Although growth of S. aureus in RTE pyeonyuk with 3% PL/SDA mixture and 1.5% ?-polylysine was observed, SEA was not produced at 17, 24, and 30°C, suggesting the application of PL/SDA mixture or ?-polylysine to reduce the risk related to the consumption of pyeonyuk.     

Molecular and phenotypic characterization of Staphylococcus aureus strains isolated from carcass swabs and carcass drips of chickens slaughtered in the informal market in Gauteng Province,South Africa

The study was conducted to characterize Staphylococcus aureus strains from swabs and drips of dressed chicken carcasses sold at outlets in six townships in the informal market in Gauteng province, South Africa, using molecular and phenotypic methods. Seven genes (6 toxins and 1 antimicrobial resistance) comprising staphylococcal enterotoxin A (SEA), B (SEB), C (SEC), D (SED), exfoliative toxin A, toxic shock syndrome toxin, and MecA encoding methicillin resistance were assayed using polymerase chain reaction. The resistance of the S. aureus strains to 18 antimicrobial agents was determined using the disk diffusion method. The frequency of detection of the six toxin genes was sea (52.2%), followed by seb (10.9%), sec (6.5%), sed (2.2%), eta (93.5%), and tst (19.6%). The mecA gene was detected in 4.3% of the isolates. The predominant profiles of toxin genes detected were sea-eta (37.0%). All 63 isolates of S. aureus were resistant to one or more antimicrobial agents. The frequency of resistance was high to spectinomycin (98.4%), nalidixic acid (85.7%), and penicillin (84.1%), but low to gentamycin (1.6%) and cefotaxime (1.6%). The high frequency of toxin genes and antimicrobial resistance gene observed in S. aureus isolates from chicken could pose a challenge to food safety and may have therapeutic and zoonotic implications.     

Effect of the Parabens With and Without Nitrite on Clostridium botulinum and Toxin Production in Canned Pork Slurry

Antimiciobials were evaluated in thioglycollate broth at pH 6.5 for the ability to inhibit growth and toxin production by C. botulinum 12885A and ATCC 7949 (Type B). Methyl, ethyl, propyl, and butyl parabens (0.1%) and sorbic acid (0.2%) were effective in inhibiting growth of C. botulinum 12885A and ATCC 7949 in broth. Ethyl, propyl, and butyl parabens (0.1%) and sorbic acid (0.2%) inhibited toxin production by both strains in culture medium. Ethyl, propyl, butyl parabens (0.1%) and sorbic acid (0.2%) were individually added to a comminuted pork slurry having salt and sugar, with or without 40 ppm sodium nitrite. Cans were inoculated with a mixture of C. botulinum 12885A and ATCC 7949 spores. The canned product was abused by holding at 27°C and was observed over a 3-month period for swollen cans. Swollen cans were examined for botulinal toxin by the mouse bioassay. Propyl and butyl paraben did not inhibit or delay toxin production. Ethyl paraben with or without nitrite delayed toxin production for 4 wk. Sorbic acid inhibited toxin for 3 wk; when 40 ppm nitrite was added to the sorbic acid treatment, toxin production was delayed for 4 wk.     

Effect of Poly- and Pyrophosphates on the Natural Bacterial Flora and Inoculated Clostridium sporogenes PA 3679 in Cooked Vacuum packaged Bratwurst

Survival and growth of inoculated Clostridium sporogenes PA 3679 and of natural aerobic and anaerobic bacterial flora were studied in cooked, vacuum packed bratwurst containing 0.5% phosphates during refrigerated (5°C) and subsequent temperature abuse storage (24°C). Sodium acid pyrophosphate (SAPP), sodium tripolyphosphate (STPP), tetrasodium pyrophosphate (TSPP) and sodium polyphosphate glassy (SPG) were tested. No significant bacterial inhibition by any phosphate was observed during refrigerated storage, nor was there appreciable growth in the control bratwurst. However, SAPP significantly inhibited aerobic and anaerobic bacteria (including C. sporogenes) upon temperature abuse, followed in effect by TSPP and STPP. Cooking to 65.5°C helped retain antimicrobial properties of phosphates to some extent. Enzymatic hydrolysis of phosphates is postulated as a major factor in loss of antimicrobial properties of phosphates in processed meats.     

Genetic Diversity and Antibiotic Resistance Patterns of Staphylococcus Aureus Isolated from Leaf Vegetables in Korea

Staphylococcus aureus is an important foodborne pathogen on global basis. The current study investigated the genetic patterns in S. aureus isolates from leaf vegetables (n = 53). Additional isolates from livestock (n = 31) and humans (n = 27) were compared with the leaf vegetable isolates. Genes associated with toxins, antibiotic resistance, and pulsed‐field gel electrophoresis (PFGE) patterns were analyzed. At least 1 enterotoxin‐encoding gene (sea, seb, sec, sed, and see) was detected in 11 of 53 (20.75%) leaf vegetable isolates. When the agr (accessory gene regulator) grouping was analyzed, agr II was the major group, whereas agr IV was not present in leaf vegetable isolates. All S. aureus isolates from leaf vegetables were resistant to more than one of the antibiotics tested. Nineteen of 53 (35.85%) isolates from leaf vegetables exhibited multidrug‐resistance, and 11 of these were MRSA (methicillin‐resistant S. aureus). A dendrogram displaying the composite types of S. aureus isolates from 3 origins was generated based on the combination of the toxin genes, agr genes, antibiotic resistance, and PFGE patterns. The isolates could be clustered into 8 major composite types. The genetic patterns of S. aureus isolates from leaf vegetables and humans were similar, whereas those from livestock had unique patterns. This suggests some S. aureus isolates from leaf vegetables to be of human origin.     

Growth and enterotoxin production of Staphylococcus aureus in Iranian ultra‐filtered white cheese

This study aimed to investigate the growth and enterotoxin production of Staphylococcus aureus during the ripening and storage of Iranian ultra‐filtered white cheese (IUFWC). According to the results, the addition of starter culture had significant inhibitory effects on the growth and enterotoxin production of S. aureus. Moreover, prolong survival and enterotoxin production were observed in the samples with the highest inoculum (5 log CFU/g) of S. aureus. It was concluded that proper activity of the starter culture together with the refrigeration storage of IUFWC was the key element in inhibiting the growth and enterotoxin production of S. aureus.     

Production of enterotoxin A by Staphylococcus aureus in food

The relationship between growth of Staphylococcus aureus and enterotoxin A production in various cooked foods at 22°C was determined. Although production of enterotoxin A in artificial media occurs under most conditions that support growth of S. aureus, such a correlation was not found in foods. In meat products and vanilla custard enterotoxin A was detected when ? 7.2 log₁₀ colony forming units/g were present. In vegetables (peas, spinach) however, production of enterotoxin A was markedly delayed despite excellent growth of S. aureus. Production of the toxin was observed when the count of S. aureus had reached ? 8.9 log₁₀ colony forming units/g.     

Staphylococcus aureus Identification Characteristics and Enterotoxigenicity

Enterotoxigenicity and conventional tests for identification of Staphylococcus aureus were correlated for strains of staphylococci isolated from foods. These strains were examined for enterotoxin production, colonial morphology on Baird-Parker agar, coagulase activity with rabbit and pig plasma, thermostable nuclease (TNase) production, lysostaphin sensitivity and anaerobic utilization of glucose and mannitol. Enterotoxins A,B,C,D, and E were produced singly or in combination by 100 of the S. aureus strains; 51 strains produced no enterotoxin. False-negative rates in identifying the enterotoxigenic group as typical S. aureus were as follows: 11% for colonial morphology on Baird-Parker agar, 8% for coagulase activity with Difco rabbit plasma, 7% for TNase production, 4% for lysostaphin sensitivity and 2% and 4%, respectively, for the anaerobic utilization of glucose and mannitol. Consequently, none of these tests was reliable for differentiating toxigenic from nontoxigenic S. aureus..     

Inhibition by gamma-irradiation and antimicrobial food additives of aflatoxin B1 production by Aspergillus flavus in poultry diet

The effect of gamma-irradiation and the antimicrobial food additives on growth and aflatoxin B₁ production by A. flavus NRRL 5520 in poultry diet was investigated. By increasing the irradiation doses the viable population as well as aflatoxin B₁ production decreased greatly. No growth and no detection of aflatoxin production occurred in poultry diet after treatment with 6 kGy. The addition of the antimicrobial food additives resulted in a significant decrease in aflatoxin B₁. Growth and toxin production was completely inhibited by 0.64% sodium propionate, 0.134% potassium sorbate and 0.1% sodium bisulfite. The combination treatments between gamma-irradiation (3 kGy) and sodium propionate (0.48%), potassium sorbate (0.022% and 0.044%) and sodium bisulfite (0.0334% and 0.0667%) inhibited completely the fungal growth and aflatoxin B₁ production. At 5 kGy, no growth was recorded and aflatoxin B₁ production was completely inhibited at all tested levels of priopionate, sorbate and bisulfite. The combined effects between gamma-irradiation and the antimicrobial agents had a synergistic effect on the mould growth and aflatoxin production in poultry diet.     

Inhibition of Clostridium botulinum by Antioxidants and Related Phenolic Compounds in Comminuted Pork

Antioxidants, esters of p-hydroxybenzoic acid and gallic acid, and related phenolic compounds were evaluated for their activity against growth and toxin production of C. botulinum types A and B in comminuted pork. With an inoculum level of 8,000 spores/g of meat most of the chemicals at a concentration of 1,000 ppm delayed first swell formation for less than 3 days beyond the control. For most compounds, the time to first swell formation beyond that of the control increased as the spore level per g of meat decreased. 8-Hydroxyquinoline at a concentration of 200 ppm or in combination with sodium nitrite (40 ppm) inhibited the growth and toxin production of C. botulinum in comminuted pork for 60 days at 27°C. 8-Hydroxyquinoline was more active in inhibition of growth and toxin production of C. botulinum in comminuted pork than in prereduced Thiotone-yeast extract-glucose broth.     

Extension of the Shelf-Life of Fresh Ground Pork with Polyphosphates

The antimicrobial effects of 1.0% sodium acid pyrophosphate (SAPP) and sodium orthophosphate monobasic (ORTHO), alone or combined, were studied in fresh ground pork held at 2–4°C for 6 days. Addition of 1.0% SAPP to the meat inhibited psychrotrophic bacterial growth (P<0.01) and resulted in 50% longer meat shelf-life (equivalent to 2 days) in relation to control samples or to meat treated with 0.5% or 1.0% ORTHO. Addition of a 0.5% SAPP/0.5% ORTHO combination was less inhibitory to meat bacteria than 0.5% SAPP alone. Bacterial inhibition did not correlate with soluble orthophosphate content in ground pork.