H. Thippareddi

Control of Clostridium perfringens in cooked ground beef by carvacrol, cinnamaldehyde, thymol, or oregano oil during chilling.

Inhibition of Clostridium perfringens spore germination and outgrowth by carvacrol, cinnamaldehyde, thymol, and oregano oil was evaluated during abusive chilling of cooked ground beef (75% lean) obtained from a local grocery store. Test substances were mixed into thawed ground beef at concentrations of 0.1, 0.5, 1.0, or 2.0% (wt/wt) along with a heat-activated three-strain C. perfringens spore cocktail to obtain final spore concentrations of ca. 2.8 log spores per g. Aliquots (5 g) of the ground beef mixtures were vacuum-packaged and then cooked in a water bath, the temperature of which was raised to 60 degrees C in 1 h. The products were cooled from 54.4 to 7.2 degrees C in 12, 15, 18, or 21 h, resulting in 3.18, 4.64, 4.76, and 5.04 log CFU/ g increases, respectively, in C. perfringens populations. Incorporation of test compounds (> or = 0.1%) into the beef completely inhibited C. perfringens spore germination and outgrowth (P < or = 0.05) during exponential cooling of the cooked beef in 12 h. Longer chilling times (15, 18, and 21 h) required greater concentrations to inhibit spore germination and outgrowth. Cinnamaldehyde was significantly (P < 0.05) more effective (< 1.0 log CFU/g growth) at a lower concentration (0.5%) at the most abusive chilling rate evaluated (21 h) than the other compounds. Incorporation of lower levels of these test compounds with other antimicrobials used in meat product formulations may reduce the potential risk of C. perfringens germination and outgrowth during abusive cooling regimes.

Inhibition of Clostridium perfringens Spore Germination and Outgrowth by Lemon Juice and Vinegar Product in Reduced NaCl Roast Beef

UNLABELLEDnInhibition of Clostridium perfringens spore germination and outgrowth in reduced sodium roast beef by a blend of buffered lemon juice concentrate and vinegar (MoStatin LV1) during abusive exponential cooling was evaluated. Roast beef containing salt (NaCl; 1%, 1.5%, or 2%, w/w), blend of sodium pyro- and poly-phosphates (0.3%), and MoStatin LV1 (0%, 2%, or 2.5%) was inoculated with a 3-strain C. perfringens spore cocktail to achieve final spore population of 2.5 to 3.0 log CFU/g. The inoculated products were heat treated and cooled exponentially from 54.4 to 4.4 °C within 6.5, 9, 12, 15, 18, or 21 h. Cooling of roast beef (2.0% NaCl) within 6.5 and 9 h resulted in <1.0 log CFU/g increase in C. perfringens spore germination and outgrowth, whereas reducing the salt concentration to 1.5% and 1.0% resulted in >1.0 log CFU/g increase for cooling times longer than 9 h (1.1 and 2.2 log CFU/g, respectively). Incorporation of MoStatin LV1 into the roast beef formulation minimized the C. perfringens spore germination and outgrowth to <1.0 log CFU/g, regardless of the salt concentration and the cooling time.nnnPRACTICAL APPLICATIONnCooked, ready-to-eat meat products should be cooled rapidly to reduce the risk of Clostridium perfringens spore germination and outgrowth. Meat processors are reducing the sodium chloride content of the processed meats as a consequence of the dietary recommendations. Sodium chloride reduces the risk of C. perfringens spore germination and outgrowth in meat products. Antimicrobials that contribute minimally to the sodium content of the product should be incorporated into processed meats to assure food safety. Buffered lemon juice and vinegar can be incorporated into meat product formulations to reduce the risk of C. perfringens spore germination and outgrowth during abusive cooling.

Salmonella spp. risk assessment for cooking of blade tenderized prime rib

Prime rib is generally prepared by cooking to low temperatures for long times to attain the desired tenderness and juiciness. Destruction of Salmonella spp. in blade tenderized prime rib was examined by following cooking procedures commonly used by chefs. Beef ribs (boneless) were inoculated with Salmonella spp. to attain initial surface levels of about 5.75 log10 CFU/cm. The ribs were blade tenderized (one pass) using a Ross blade tenderizer. Each was split into two equal sections. One half was cooked to a target internal temperature of 110 and the other half to 120°F, then tempered at room temperature for up to 60 min and placed in a holding oven (120°F) for up to 120 min. Reductions of 4.54 and 4.80 log10 CFU/g were attained for roasts removed from the oven at 110 and 120°F, respectively. Even though prime rib preparation utilizes very low cooked product temperatures, the long cooking time and tempering period result in substantial process lethality and a safe final product.

Validation of process capabilities for directly acidified beef and venison containing beef snack sticks for control of E. Coli O157:H7

USDA/FSIS guidelines require sausage manufacturers to validate their processes to assure that they can achieve a five-log (99.999%) reduction of E. coli O157:H7. Some small meat processors use encapsulated acids instead of lactic acid starter cultures to produce directly acidified sausages. The objectives of this study were to determine 1) the effects of typical thermal processing temperatures and times on reducing E. coli O157:H7 in directly acidified all-beef and venisoncontaining beef snack sticks, 2) the effect of fat content (10 and 25%) on lethality, and 3) the effect of acid type (citric versus lactic) on lethality. For both all-beef and venisoncontaining beef snack sticks, E. coli O157:H7 reductions of approximately 3 log cycles (99.9%) were observed when product internal temperature reached 148 and 155oF. Reductions increased to more than 5 log cycles after 2 hours of slow drying in which the smokehouse temperature was sequentially decreased to 70°F. Encapsulated citric acid was slightly more effective at lowering product pH, compared with the encapsulated lactic acid. Similar pathogen reductions were observed with 10 and 25% fat content. This study demonstrates that the defined processing schedule used to manufacture beef and venison-containing beef snack sticks is adequate to provide microbiologically safe products and to meet USDA guidelines for pathogen reduction. The processing schedule must include an extended drying phase, in addition to the thermal step, to meet these requirements. Introduction

Effects of cetylpyridinium chloride treatment of roast beef on Listeria monocytogenes populations and quality attributes

The effectiveness of cetylpyridinium chloride (CPC) for reducing microbial populations, in particular Listeria monocytogenes, on ready-to-eat roast beef was evaluated. Roast beef slices inoculated with L. monocytogenes were dipped in a solution of 1% CPC for 1 minute. Samples were then vacuum packaged and stored at refrigeration temperature. The effects of CPC treatment on microbial populations, as well as on color and texture of the roast beef samples, was evaluated over a 42day period. Immediately after CPC treatment, L. monocytogenes populations were reduced by 99 to 99.99%, with the treatment being somewhat more effective on exterior than on sliced/cut surfaces. Throughout 42 days of refrigerated storage, populations of L. monocytogenes, total bacteria, and lactic acid bacteria remained lower on CPC-treated samples than on non-treated samples. Treatment with CPC did not significantly affect the color or texture of roast beef. Treatment with CPC, especially when applied to products before slicing, may serve as an effective antimicrobial intervention for ready-to-eat meat products.

Post-process steam pasteurization of packaged Frankfurters combined with acid/buffer treatments for control of Listeria monocytogenes

The efficacy of a saturated steam-based post-process pasteurization system to reduce/ eliminate Listeria monocytogenes on frankfurters was evaluated. Frankfurters were packaged individually or in a single layer format (4 per package, touching). Samples were surface treated with 2% lactic acid, 4% lactic acid, 2% buffered sodium citrate, or 2% buffered sodium lactate, vacuum packaged, and steam pasteurized to end-point surface temperatures of 160, 170 or 180°F using a Townsend Post-Process Pasteurization system (formerly Stork-RMS Protecon). Pasteurization of inoculated single layer franks to surface end point temperature targets of 160, 170, and 180°F resulted in L. monocytogenes reductions (P<0.05) of 0.92, 1.44 and 2.89 log colony forming units (CFU)/frank, respectively. Greater reductions in L. monocytogenes populations were observed for individually packaged frankfurters with 2.32, 4.62 and 6.52 log CFU/frank reductions at target surface end point temperatures of 160, 170, and 180°F, respectively. No differences (P>0.05) were noted between various surface acid treatments applied. Postprocess pasteurization of frankfurters (in-package) using the saturated-steambased Townsend system was effective in reducing numbers of L. monocytogenes.

Evaluation of consumer reheating methods fordestruction of Listeria monocytogenes in frankfurters

The USDA Food Safety and Inspection Service has issued a “zero tolerance” for Listeria monocytogenes in ready-to-eat meat and poultry products. The Food Safety and Inspection Service recommends that consumers “Reheat [hotdogs] until steaming” to reduce the risk of listeriosis. We evaluated L. monocytogenes survival on inoculated frankfurters after reheating using common, in-home consumer practices. Frankfurters were inoculated with a six-strain mixture of L. monocytogenes to an initial level of approximately 10 colony forming units (CFU)/gram. Eight inoculated franks for each treatment were cooked using boiling water, a conventional electric oven, or a microwave oven. L. monocytogenes recovery was calculated after plating on Modified Oxford Agar and Tryptose Phosphate Agar. L. monocytogenes reductions were 3.2 log10 CFU/gram on franks microwaved with or without water for 60 seconds or cooked in a conventional electric oven at 500°F for 2 or 5 minutes. Franks cooked in boiling water for 30 and 60 seconds achieved reductions of 4.3 and 4.9 log10 CFU/gram, respectively. Franks wrapped in a paper napkin and microwaved for 60 seconds resulted in a 6.8 log10 CFU/gram reduction, the most effective consumer reheating protocol.

Control of Listeria Monocytogenes in ready-to-eat meats using cetyl pyridinium chloride

Cetyl Pyridinium Chloride (CPC) spray using variable application temperatures, pressures, and times was evaluated for its effectiveness in reducing Listeria monocytogenes inoculated on the surfaces of commercial frankfurters and Polish sausage. Frankfurters and Polish sausage were inoculated with a five-strain cocktail of L. monocytogenes (101M, 109, 108M, serotype 4c ATCC, and serotype 3 ATCC) and subjected to no treatment, CPC treatment, and CPC followed by water treatment. CPC (1%) was applied to the frankfurters and Polish sausage by spraying in a cabinet using all combinations of 77, 104, and 131°F spray temperatures; 20, 25, and 35 psi spray pressures; and 30, 40, and 60 second times of exposure. No individual effect (P>0.05) of any particular application temperature, pressure, or time on the reduction of L. monocytogenes was observed. Hardness and color of the product was not affected when treated with 1% CPC. From initial inoculum levels of 8.20 log colony forming units (CFU)/gram, 1% CPC reduced L. monocytogenes by 1.19 to 2.39 log CFU/gram.

Steam based post-process pasteurization of beef salami for control of Listeria monocytogenes

We evaluated the destruction of Listeria monocytogenes on surfaces of artificially inoculated, vacuumpackaged beef salami by steam pasteurization (Stork RMA-Protecon Post-process Pasteurizer). Beef salami was inoculated with L. monocytogenes (initial concentrations of 4.36 log10 CFU/cm2 at the end and 4.49 at the middle), then pasteurized at 185, 194, or 203°F for 2 or 4 min. Only about 0.11 log10 CFU/ cm2 (detection limit) L. monocytogenes survived after pasteurization at 203°F for 2 and 4 min, for a kill rate? of over 99.99%. Post-packaging pasteurization reduces the threat of L. monocytogenes on the surfaces of cooked meat products.

Dakota Gold®-brand dried distiller’s grains with solubles in finishing cattle diets: a preharvest strategy against acid resistant Escherichia coli and coliforms?

Trial 1. Finishing beef heifers (345 head) were used in a 153-day finishing trial to evaluate the effects of feeding six levels of Dakota Gold-brand dried distiller’s grains with solubles (DDGS): 0%, 15%, 30%, 45%, 60%, 75% (dry basis), on the number of acid resistant E. coli and coliforms. Fecal grab samples were taken on day 65 and day 100, 2 and 20 hours after feeding, and were analyzed for acid resistant E. coli and total coliforms, as well as pH and VFA. There was a significant linear increase in fecal pH with increased DDGS at both 2 and 20 hours postfeeding (P 0.05). Total fecal VFAs were not affected by dietary treatment or hour sampled after feeding (P>0.05)