title: Effects of diacetyl and carbon dioxide on spoilage microflora in ground beef.
abstract: The effect of CO2 and diacetyl, alone or in combination, on spoilage microflora in ground beef was determined. Ground beef was treated with 20, 30, or 40% CO2 for 22 days (study I); 20, 50, or 100 microg/g diacetyl for 26 days (study II); or a combination of 20% CO2 and 100 microglg diacetyl for 40 days (study III). Antimicrobial effectiveness was determined by aerobic plate counts (log10 CFU/g) using plate count agar (total aerobic bacteria), deMan Rogosa Sharpe (MRS) Lactobacillus agar (gram-positive bacteria), MacConkey agar (gram-negative bacteria), pH, and informal organoleptic assessments (by appearance and by odor). In study I, total bacteria and pH increased by day 4 in control meat samples. For all CO2 levels, gram-negative bacteria decreased and gram-positive bacteria increased compared with untreated controls. The pH remained constant for CO2-treated meat. Control samples had an off-odor and a brown appearance, while CO2-treated samples had no off-odor but did have a brown appearance. For samples treated with diacetyl (study II), spoilage was evident by day 7 for samples treated with 0, 20. and 50 microg/g diacetyl for all parameters examined. Ground beef treated with 100 microg/g diacetyl was spoiled on day 12. Diacetyl was detected (by odor) in samples that were treated with 100 microg/g diacetyl and had a brown appearance. Meat samples treated with the combination of CO2 and diacetyl (study III) showed that the addition of diacetyl did not have an additive effect on microbial growth. Combination-treated meat maintained a red appearance and no off-odor. Diacetyl and CO2 could be used in combination to maintain a red color and inhibit spoilage microorganisms.
authors.affiliation: US Department of Agriculture, Agricultural Research Service, Beltsville, Maryland 20705, USA. acampbel@anri.barc.usda.gov
authors.forename: Anisha M
authors.initials: AM
authors.lastname: Williams-Campbell
authors.forename: James M
authors.initials: JM
authors.lastname: Jay
mesh_terms: D000818:Animals; D002245:Carbon Dioxide / Q000494:pharmacology*; D002417:Cattle; D015169:Colony Count, Microbial; D003116:Color; D003931:Diacetyl / Q000494:pharmacology*; D005516:Food Microbiology; D018857:Food Packaging / Q000379:methods; D005519:Food Preservation / Q000379:methods; D006090:Gram-Negative Bacteria / Q000187:drug effects / Q000254:growth & development*; D006094:Gram-Positive Bacteria / Q000187:drug effects / Q000254:growth & development*; D006863:Hydrogen-Ion Concentration; D008461:Meat Products / Q000382:microbiology* / Q000592:standards; D009812:Odorants; D013997:Time Factors
chemical_list: D002245:Carbon Dioxide; D003931:Diacetyl