Bacterial growth in refrigerated, vacuum-packed luncheon meats

Abstract

The shelf life of vacuum-packed luncheon meats during refrigerated storage was not related to "total" counts since the only organisms that multiplied in this environment were lactic acid bacteria, which formed only a small proportion of the initial population.Bacterial growth curves obtained from several Canadian products were remarkably similar, but the spoilage patterns differed. For example, wiener spoilage was a function of bacterial growth while bologna spoiled from the accumulation of bacterial end products. After 15 weeks at 5 °C, the meats contained 0.6 to 0.8% lactic acid and the pH of comminuted meats dropped below 5.0. Cooked ham contained much less carbohydrate than comminuted meats, and the pH remained above 6.0. Under these conditions, ham is susceptible to putrefaction although this was not observed during this study.It was found that cooking can eliminate all lactic acid bacteria present in the raw meats but the products become recontaminated during slicing and packaging. The cleaning and sanitizing procedure used by the Company that cooperated in this study was efficient, but it was recommended that the packaging room be cleaned more often, and that a selective medium for lactic acid bacteria be used in sanitation surveys.

Microbiological Spoilage and Contamination of Vacuum-Packaged Cooked Sausages

“…Lactic acid bacteria form the major component of th e microbial population on various types of vacuum-package d cooked sausages (2,3,10,33,44,56,72,88) . A grea t diversity of lactic acid bacteria can be found in differen t types of spoiled cooked sausages (12,22,24,44) .…”

“…DNA-DNA hybridization Sourness has shown Leuconostoc mesenteroides subsp . mesenteroiSpoilage lactic acid bacteria produce mostly lactic and des, Leuconostoc paramesenteroides and Leuconostoc gelacetic acid during logarithmic growth and especially at th e idum (former Leuconostoc amelibiosum) constitute the spoilstationary phase of growth (33,74) . As the counts of age strains (22,55) .…”

“…OF THE PRODUCT S of the sausages during vacuum storage has been observe d (33). In some cases the slime formation has been very Survival of spoilage bacteria during heat treatmen t copious and the product was judged to be unacceptable (12) .…”

Identification of Lactic Spoilage Bacteria from Vacuum-packed Cooked Luncheon Meat and Induction of Repairable Injury By Mild Thermal Stress

“…In other work with coliforms injured in pasteurized milk, repair was complete in 6 h at 37 °C but required up to 14 days at 4 °C (15). The extent of injury induced in Lactobacillus sake and Lactobacillus curvatus by mild thermal stress (53 to 55°C for ≤ 12 min) was significant and may explain in part why the delay before growth of lactic bacteria was seen in vacuum-packaged cooked cured meats stored at refrigerator temperatures (10). It was also of interest that stationary phase cells of Lactobacillus sake were more resistant to thermal lethality but were as susceptible to thermally induced injury as more rapidly growing cells; however, the older cells could repair these injuries more quickly ( Table 2).…”

“…Even though many of these organisms initially serve a protective function, following exhaustion of easily fermentable carbohydrates, secondary substrates are attacked, which yields metabolic end-products that are organoleptically undesirable and compromise shelf-life (7)(8)(9). Correlations between the number of lactic organisms present on these products and their eventual spoilage at refrigerator temperature are poor (10)(11)(12), but spoilage occurs more frequently at very high levels of lactic bacteria (5,11). There is good reason to expect that any reduction in the rate at which these organisms grow will have a positive impact upon product shelf-life.…”