Steers were slaughtered, dressed, and fabricated using conventional procedures or strict sanitary procedures. Strict sanitary procedures involved antemortem washing of steers, use of disposable gloves, careful handling of carcasses to prevent cross-contamination, and spraying of carcasses with hot (55°C) 1% L-lactic acid before evisceration and before entering the chill cooler. Mean aerobic plate counts (APC, log 10 /cm 2 ) of carcasses slaughtered under strict sanitary conditions and of subprimals (boneless strip loins and ribs) from animals handled under strict sanitary conditions and stored at 1°C in high-oxygen barrier (HOB) film (0 to 80 d) were lower than those of carcasses and subprimals from animals slaughtered and fabricated using conventional procedures. In most cases, APCs of steaks displayed in polyvinyl chloride (PVC) film for 0 to 6 d from animals and subprimals handled under strict conditions were lower than those of steaks from animals and subprimals handled under conventional procedures. Bacillus spp., Micrococcus spp., and yeasts were the dominant (50% or more of microflora) microbial types on carcasses that were slaughtered and dressed using strict sanitary conditions. For carcasses slaughtered using conventional procedures, Micrococcus spp. and to a lesser extent Streptococcus , coagulase-negative Staphylococcus and/or coryneform bacteria were the dominant microbial types. After 20 d of storage, there were no consistent differences in the percentage distribution of microbial types on the two groups of subprimals. Lactobacilli dominated the microflora of subprimals at that time. When scores for lean color, surface discoloration, fat color, overall appearance, and odor of steaks from subprimals handled under strict sanitary conditions were significantly different (P<0.05) from controls, treated steaks were more desirable than those of comparable steaks from control subprimals.

Commercial corn tortillas were assayed for pH, moisture, a w , aerobic plate count (APC) and mold and yeast count (MYC). The shelf life of commercial tortillas ranged from 3 to 60 days, depending on the amount and type of preservative added. High initial APCs of commercial tortillas were associated with poor sanitary conditions at the plants, airborne contamination and improper storage practices. Shelf life of tortillas was greatly enhanced by refrigerated storage with or without the use of antimicrobials. For tortillas stored at 25°C, substantial increases in shelf life were attained by acidification (0.45% fumaric acid) plus addition of K-sorbate or Ca-propionate, but particularly by combination of these two antimicrobials. For tortillas stored at 4°C, shelf life of non-acidified samples was somewhat enhanced by addition of parabens and combinations of K-sorbate and Ca-propionate. Shelf life of acidified tortillas at 4°C was somewhat enhanced by addition of parabens and K-sorbate but increased substantially by addition of Ca-propionate and combinations of K-sorbate and Ca-propionate.

Thirty packages (454 g) each of beef and chicken pre-marinated vacuum packaged fajitas were obtained from a commercial meat purveyor and placed in a retail case for 16 d. At days 1, 5, 9, 12 and 16, aerobic plate counts (APCs) and microbial types of three randomly selected samples of each product were determined. Samples were also evaluated for surface discoloration, overall appearance, immediate and cooked off-odor and off-flavor. As storage progressed, the pH of products declined, APCs increased and Lactobacillus spp. Became dominant in the microflora. Some packaged fajitas, especially chicken, exhibited gas formation in random packages throughout the storage periods. Products became “unacceptable” between 12 and 16 d of retail storage.

Steaks and roasts were fabricated from strip loins and top rounds that were held vacuum packaged for 10 d at 2°C. Steaks and roasts then were treated with 2–3% Dermatex R Food Grade (DFG), an acetylated monoglyceride, vacuum packaged and stored at 2 ± 2°C for up to 4 weeks (steaks) and 7 weeks (roasts). Aerobic plate counts (APC) and APT counts of control and DFG-treated steaks and roasts did not differ (P>0.05) during refrigerated storage. The microflora of steaks and roasts during storage was dominated by lactic acid bacteria. Treatment with DFG did not influence the microbiological characteristics of the steaks and roasts.

Vacuum packaged strip loins and top rounds were fabricated into loin steaks and round roasts and treated, respectively, with 3 and 2% Dermatex® Food Grade (DFG), an acetylated monoglyceride. Samples were then vacuum packaged and stored at 2 ± 2°C for up to 49 (steaks) and 56 (roasts) d. Mean lean color (vacuum packaged and oxygenated), surface discoloration and overall appearance scores were not consistently different between treated and control steaks and roasts regardless of storage time. No consistent differences were observed in pH values of the lean and purge, percentage moisture or sensory evaluations of steaks and roasts treated with DFG before storage.

In determining aerobic plate counts of surfaces of beef carcasses, green to brown-black colonies of an Acinetobacter sp. appeared on tryptic soy agar plates. Pigmentation was induced by indole-producing organisms in close proximity of or overlapping with the Acinetobacter sp. Addition of indole to culture media also supported pigmentation of the Acinetobacter sp. Indole appeared to be a key intermediate compound in pigment formation.

Seventy-two beef knuckles were packaged (n = 12) in each of six different bag types with oxygen transmission rates (OTR) of 1, 10, 12, 13, 30 and 400 cc/m 2 /24 h at 4°C and 100% relative humidity to study brown discoloration of knuckles during refrigerated storage. Knuckles in bag types of OTR of 1 and 12 cc did not discolor as compared to those in bags with higher OTR (30 and 400 cc) probably due to differences in oxygen tension in the package and in the types of bacteria present. Deterioration of lean color of knuckles in some bag types of low OTR appeared associated with large percentages of Leuconostoc mesenteroides in the microflora.

Two media, glucose salt teepol broth (GSTB) and salt polymyxin broth (SPB), were compared for their efficacy in enumerating Vibrio parahaemolyticus in naturally contaminated samples using the most probable number (MPN) procedure. Eleven laboratories in four countries participated, six of them using two analysts. One hundred ninety-six of 335 samples were found to contain V. parahaemolyticus . Neither enrichment medium was superior, and both media appeared necessary to prevent false-negative results. There was a high (52.5%) percentage of MPN patterns that were improbable with respect to Poisson distribution in those MPN tubes that yielded V. parahaemolyticus . Suspect colonies that developed on thiosulfate citrate bile salts sucrose (TCBS) plates streaked from GSTB were confirmed (1,438/1,929 = 75%) about as frequently as when streaked from SPB (2,155/3,038 = 71%).

Presence of Campylobacter jejuni was determined at various locations in turkey carcass processing and further processing of turkey products (wieners, ham and boneless breast). Contamination of turkey carcasses with C. jejuni , in most cases, occurred on the surface of the skin or on the surface of the abdominal cavity lining. No contamination of interior muscle tissue was observed. The percentage of turkeys containing C. jejuni upon entering the processing plant varied (50 to 100%). Large numbers of C. jejuni were killed during scalding of carcasses, but extensive recontamination occurred during mechanical defeathering. After scalding, numbers of C. jejuni peaked during evisceration, but dropped to lower levels after washing. Few or no C. jejuni were recovered from the carcasses after leaving the chill tank. No C. jejuni were detected on frozen turkey carcasses, including the drip, at the wholesale or retail level. However, Campylobacter coli was detected in the drip of a few carcasses that had been in frozen storage at the wholesale level for 2 wk and 3 months. Neither C. jejuni nor C. coli was detected on frozen turkeys at the retail level. Although, in some cases, C. jejuni were recovered from turkey meat during initial stages of further processing, no C. jejuni were recovered from heat-treated, further processed products.

Various cooking procedures (roasting, braising, stewing and microwave cooking) applied to turkey thighs, and washing procedures for contaminated utensils (knives and cutting boards) and food handlers' hands were evaluated for their effectiveness in removing Campylobacter jejuni . Roasting, braising and stewing were effective in destruction of C. jejuni on contaminated turkey thighs even when the meat was undercooked, reaching an internal temperature of 55°C. Destruction of C. jejuni by microwave cooking was assured more fully if a meat thermometer was used to check the internal temperature of the sample rather than by visual evaluation. Washing of utensils with water and detergent, either by hand or in a dishwasher, removed C. jejuni except from wooden cutting boards washed by hand. Minimal hand washing procedures may not assure complete removal of C. jejuni from contaminated hands.

The effect of various initial chilling treatments on the numbers and types of microorganisms of beef, pork and lamb tongues (n = 60) and livers (n = 60) packaged either in polyethylene (PE) film or in vacuum packages in Texas and transported fresh-chilled via transoceanic shipment to Antwerp, Belgium, was evaluated. Initial chilling treatments included: cooler-tempered (4 to 6 h at 2°C), cooler-chilled (24 h at 2°C) freezer-tempered (0.5 to 1 h at −20°C), freezer-chilled (2 h at −20°C), ice-chilled (2 h in ice water slush) and no prechilling (NPC) before packaging and subsequent refrigerated storage at 2°C. After the initial chilling treatments, the microflora was varied with Micrococcus spp. with or without coryneform bacteria being the predominant bacterial types of most samples. After refrigerated storage for 13 to 15 d, lactic acid bacteria became dominant in most vacuum-packaged samples and in pork and lamb samples stored in PE film. Brochothrix thermosphacta and Pseudomonas spp. constituted a greater part of the microflora of beef tongues and livers stored in PE film than that of comparable vacuum-packaged samples. Increases in aerobic plate counts (APC) of refrigerated vacuum-packaged samples nearly always were greatest for samples (NPC) that were not pre-chilled before packaging and usually were smallest for samples that were either freezer-chilled, freezer-tempered or ice-chilled.

The effects of chilling/tempering treatments on the pH, weight loss and quality characteristics of beef, pork and lamb variety meats (livers, hearts, tongues and kidneys) that were packaged either in polyethylene (PE) bags or vacuum packaged (VP) in the USA and transported fresh-chilled to Antwerp, Belgium, were evaluated. Product arrived at the final destination 11 d after departure from the United States seaport (13 to 15 d after packaging). Changes in pH during overseas shipment were generally small and suggested a lack of product quality deterioration resulting from major microbial proliferation during this period. Variety meats that were not prechilled before packaging generally had the lowest weight loss among chilling/tempering treatments. In general, fresh-chilled variety meats that were vacuum packaged incurred less weight loss than those that were packaged in PE bags. Livers lost a greater percentage of their weight during shipment than did other variety meats. Vacuum-packaged variety meats had more desirable quality characteristics after shipment than those that were packaged in PE bags. Shipping fresh-chilled variety meats in PE does not appear feasible. Although some statistical differences were noted, the chilling/tempering treatments appeared to have little appreciable effect on quality characteristics of variety meats, with two exceptions: (a) cooler-chilled variety meats packaged in PE bags had superior quality characteristics as compared to those that were not prechilled and packaged in PE bags; and (b) livers that were not prechilled before vacuum packaging did not maintain their qualitative characteristics as well as did those in other chilling/tempering treatments.

Pork loins were fabricated immediately (fresh) or stored in parchment paper for 6 d or stored in vacuum packages for 8 d. Chops were packaged in either a high oxygen-permeable (PVC) film or a high oxygen-barrier film (vacuum) to be displayed 4 d or 2, 6 and 10 d, respectively. High oxygen-barrier (HOB) film was superior to PVC film in maintaining desirable visual properties of chops. Chops had less off-odor in HOB film when they were held no longer than 3 or 4 d in HOB packages compared to extended periods of display. Pork loin chops packaged in high oxygen-barrier film can be displayed up to 6 d if chops are from fresh pork loins. Although visual scores for vacuum-packaged chops were acceptable for 10 d for all storage treatments, chops from the parchment paper and vacuum-packaged storage treatments had off-odors which were limiting factors in achieving long shelf life.

Pseudomonas spp. and Brochothrix thermosphacta were a major or dominant part of the microbial flora of normal and dark, firm and dry (DFD) beef steaks with or without added glucose, citrate or citrate plus lactic acid and displayed for 3 to 6 d in polyvinyl chloride (PVC) film. When normal and DFD steaks with or without the additives were displayed in high oxygen-barrier film, Lactobacillus and/or Leuconostoc spp. were dominant. Addition of glucose (50–500 μg/g meat) had little, if any, effect on the aerobic plate count (APC), pH, lean color, odor and surface discoloration scores of both normal and DFD steaks displayed in PVC or in high-oxygen barrier film. Addition of citrate or citrate plus lactic acid also had little effect on steaks except for lowering pH values and surface discoloration scores of steaks.

A flow-through controlled atmosphere packaging system using a number of different carbon dioxide-enriched gaseous compositions was demonstrated to be effective in retarding the growth of microorganisms on fresh swordfish steaks held at 2°C for 22 d. During the first 14 d of storage, Pseudomonas spp. either dominated or represented a major part of the microflora of steaks in all gaseous atmospheres tested. However, in atmospheres containing 70% CO 2 or in pure CO 2 , heterofermentative Lactobacillus spp. and Brochothrix thermosphacta were a major part of the microflora, particularly after the 14th day of storage. Both total volatile nitrogen and trimethylamine, often used as quality indicators for fresh seafoods, increased more slowly for swordfish steaks stored in CO 2 -enriched atmospheres than steaks stored in air. Advantages of using a controlled atmosphere flow-through system for storage of fresh seafoods include: (a) a stable gas composition, (b) individual portions can be removed from a master package without losing or disrupting the gaseous atmosphere, and (c) volatile off-odors which accumulate during storage in sealed CO 2 -enriched atmospheres are carried off with the flow-through gas.

Large increases in counts cf Leuconostoc spp., Lactobacillus coryneformis , Lactobacillus plantarum , Lactobacillus viridescens and Lactobacillus curvatus occurred over a 28-d display period when aseptically fabricated steaks were inoculated with 10 3 to 10 4 cells/cm 2 of these species and then were vacuum-packaged. With Lactobacillus cellobiosus 2, Serratia liquefaciens or Hafnia alvei as inoculum, increases in count were much smaller. Counts of L. cellobiosus 1, Brochothrix thermosphacta , a Moraxella sp. and Alteromonas putrefaciens of inoculated steaks decreased during display. With a higher inoculum (10 6 cells/cm 2 ), increases in counts of lactic acid bacteria usually were smaller. Some lactic acid bacteria caused marked decreases (0.2 to 0.5) in the pH of the meat surface. Changes in surface discoloration of uninoculated and inoculated steaks over a 28-d display period were not significant (P>0.05). Off-odor scores of both uninoculated and inoculated steaks were lower (more off-odor) after display but few of the differences were significant. Off-odors of steaks inoculated with lactic acid bacteria were described as “sour”, “buttermilk”, “sulfur-like” and “H 2 S”.

Lamb loins were allocated (30 loins/treatment) to three packaging treatments: (a) vacuum-packaged, (b) vacuum-packaged followed immediately by injection of a 20% CO 2 :80% N 2 atmosphere, and (c) vacuum-packaged followed immediately by injection of a 40% CO 2 :60% N 2 atmosphere. Loins in each packaging treatment were then assigned (6 loins/period) to one of five storage periods--0, 7, 14, 21 or 28 d. During storage, the CO 2 concentration increased in vacuum packages (initial vs. 21 d) and decreased in modified atmosphere packages (initial vs. 7 or 28 d); O 2 concentration was higher in vacuum packages than in modified atmosphere packages at every storage period. Vacuum packaging was superior to modified atmosphere packaging for maintaining desirable appearance of wholesale loins, particularly if the atmosphere contained a high CO 2 concentration. Appearance of retail chops was not substantively affected by the method used to package (vacuum vs. modified atmosphere) the wholesale loin from which they originated. Palatability of cooked chops was not affected by packaging method in 28 or 30 comparisons among product from loins that had been stored for 0 to 28 d before organoleptic testing.

A selective enrichment-plating procedure was tested for the recovery and enumeration of Campylobacter jejuni from turkey eggs and meat. Enrichment was in brucella broth with ferrous sulfate, sodium metabisulfite, sodium pyruvate and five antimicrobial agents. Plating was on brucella agar supplemented with equine blood and antimicrobial agents. Incubation of tubes and plates was at 42°C in an atmosphere of 5% O 2 :10% CO 2 :85% N 2 . C. jejuni could be recovered from the enrichment broth when calculated initial cell numbers per ml of broth were as low as 0.3 to 3.3

Campylobacter jejuni was not isolated from fertile turkey eggs or from newly-hatched poults. The organism was present in 16 to 76% of fecal swabs of 15-to 19-day old turkeys from two commercial brooder facilities, and was isolated from litter and drinking water. Extensive cleaning of a brooder house and application of new litter seemed to exclude litter, water, feed and grit as initial sources of contamination. Newly-hatched poults could be raised in a Campylobacter -free environment for 19 to 21 d without evidence of this organism in fecal swabs.

Swordfish ( Xiphias gladius ) steaks were held in retail packages containing 100% CO 2 and in mixtures of 40% and 70% CO 2 in combination with either oxygen or nitrogen. Controls were stored in air. Samples were removed for chemical and microbiological analyses after 2–22 d of storage at 3.5°C. The inhibitory effect of CO 2 on psychrotrophic, aerobic gram-negative spoilage bacteria was proportional to the CO 2 tension in the packages. Maximum inhibition of growth was achieved with 100% CO 2 . Except for steaks stored in 40% CO 2 :60% O 2 heterofermentative Lactobacillus spp. became a dominant part of the microflora of steaks stored in CO 2 -enriched atmospheres. Pseudomonas spp. continued to be a major part of the microflora of steaks stored in 40% CO 2 :60% O 2 . During the first 2 d of storage, there was a decrease in the surface pH of the swordfish steaks proportional to the CO 2 tension in the packages. Swordfish steaks stored in CO 2 -enriched atmospheres had lower total volatile nitrogen (TVN), trimethylamine (TMA) and total volatile acid (TVA) values than steaks stored in air. Oxidative rancidity was not a flavor problem of fish in any of the atmospheres after 20 d of refrigerated storage.