Kelly J.K. Getty, Ph.D. Kansas State University

 Packaging effects on jerky, snack sticks, kippered beef steak, and turkey tenders  Intrinsic factors in sliced deli turkey roast  Effect of salts

J. Food Prot. (2011) 74: Support provided by the USDA CSREES under agreement , the Kansas Department of Commerce and Housing, Agriculture Marketing Division, and Oberto Sausage Company

 A “zero” tolerance policy is applied by USDA to Lm in ready-to-eat meat and poultry products  USDA defines a post lethality treatment as a process that reduces Lm by at least 1 log  Research has shown packaging can generate a 1 log Lm reduction following 1 or more weeks of storage at ambient temperature

 To determine the effect of packaging environment and storage time on reducing Listeria monocytogenes on whole muscle beef jerky and pork and beef smoked sausage sticks

Jerky cut into square pieces Dipped into Lm inoculum Dry Jerky ~ 1 h Measure Water Activity Four packaging treatments applied Hold for 24, 48, 72 h and 30 days Plates incubated for 24 hours at 35˚C Enumeration of initial level of Lm Enumeration after storage periods Plates incubated for 24 hours at 35˚C

 Five strains of Lm were used to prepare a cocktail inoculum.  One loopful of each strain placed into 9 mL test tubes of tryptic soy broth (TSB). Incubated for 24 hours at 35˚C.  From the test tubes, 0.5 mL was pipetted into 200 mL jars of TSB. Incubated for 24 hours at 35˚C  Contents of jars were combined to create 1 L 5 strain cocktail

 Jerky was aseptically cut into 4 x 4 cm 2 pieces.  Dipped for 1 minute in 5 strain cocktail of Lm.  Allowed to air dry for 1 hour.  Packaged using four treatments: - Nitrogen Flush with - Vacuum (VAC) oxygen scavenger (NFOS) - Heat Seal with- Heat seal (HS) oxygen scavenger (HSOS)  Samples held for 0, 24, 48, 72 h and 30 days

 4 x 4 cm 2 was placed in a stomacher bag and 34 mL of peptone water was added.  Samples were stomached for 1 minute.  Serial dilutions were prepared.  0.1 mL of each dilution was spread plated onto modified Oxford medium (MOX) plates.  Plates were incubated at 35˚C for 24 hours.

a bc f f a cd c bc de e f f f f Mean Log Reduction of Lm on Beef Jerky Packaged in Different Packaging Environments and Stored at Ambient Temperature abcde Means having a different superscript differ (P<0.05)

a b b b Mean Lm Log Reduction (CFU/cm 2 ) on Smoked Sausage Sticks Packaged in Different Packaging Environments

a ab b c Mean Lm Log Reduction (CFU/cm 2 ) on Smoked Sausage Sticks During Ambient Temperature Storage

 Jerky - Using these packaging environments in conjunction with at least a 48 h storage time is a Lm post lethality control treatment.  Snack Sticks - Using these packaging environments in conjunction with at least a 24 h storage time is a Lm post lethality control treatment.

J. Food Sci. (accepted)

 Determine the effect of packaging environment and short term storage time on reducing Listeria monocytogenes in meat or poultry snacks

 Two commercially obtained products:  Kippered Beef Steak:  Lean beef components, ground and formed  Cured Product  Turkey Tenders:  Whole muscle turkey breast, sliced and marinated  Uncured Product

 4 packaging treatments X 4 storage times X 2 samples/treatment X 3 replications  Packaging treatments:  Heat sealed (HS)  Heat seal with oxygen scavenger (HSOS)  Nitrogen flushed with oxygen scavenger (NFOS)  Vacuum (VAC)  Storage times:  0, 24, 48, or 72 h

Product cut into squares or used as intact strips Dip into Lm inoculum for 1 min Dry Product ~1 h at ambient temperature Measure a w Package in 1 of 4 treatments Hold for 24, 48, or 72 h at ambient temperature Incubate plates for 48 h at 35˚C Spread plate for initial Lm level (time 0 h) Spread plate following storage time

Kippered Beef SteakTurkey Tenders SOIMPR ≤ 2.03:1 Moisture (%) Protein (%) Fat (%) Salt (%) MPR awaw pH6.05.6

Kippered Beef SteakTurkey Tenders Time (h)Mean a w Time (h)Mean a w Prior to Dip0.81Prior to Dip Mean a w During Ambient Time Storage

Mean log reductions (CFU/cm 2 ) of Listeria monocytogenes in kippered beef steak

Mean log reductions (CFU/cm 2 ) of Listeria monocytogenes in turkey tenders

 Processors of these products could use a combination of vacuum or nitrogen flushing and a hold time of 24 h prior to shipping to reduce potential Lm by at least 1 log.  However, processors should be encouraged to hold product for at least 72 h to enhance the margin of safety.

We acknowledge Cargill Meat Solutions for support of this project.

 Evaluate how sodium nitrite concentration, percent pump, and salt type affect the growth of L. monocytogenes in vacuum packaged sliced turkey deli roast stored at 4°C for up to 91 days.

 Sliced turkey deli roasts were formulated with 1.5% sodium chloride (NaCl) or 0.75% NaCl and 0.75% potassium chloride, 10% or 45% pump, and 0 ppm or 200 ppm sodium nitrite (NaNO 2 ) for a total of eight treatments.  Turkey slices were inoculated with a 5-strain Lm cocktail (inoculated) or peptone water (control) and then vacuum packaged.

 After 0, 7, 14, 21, 28, 42, 63, and 91 days of 4  C storage, treatments were sampled for Lm populations on modified oxford media (MOX) and aerobic plate count (APC).  pH, water activity (a w ), residual nitrite, and percent fat, moisture, protein, and sodium was measured using control treatments for each sampling day.

 Lm populations in turkey deli roast slices containing 200 ppm NaNO 2 were 0.70 to 2.39 log CFU/cm 2 lower (P<0.05) compared with products formulated with 0 ppm NaNO 2.  Using 10% pump reduced (P<0.05) Lm populations by 0.62 to 1.50 log CFU/cm 2 on days 7 to 28 and at day 63 compared with products pumped to 45%.

 Incorporating 1.5% NaCl or 0.75% NaCl and 0.75% KCl into turkey formulations did not affect (P>0.05) Lm or APC growth during 91 days of 4  C storage.

 Growth of Lm and APC were reduced with higher nitrite concentrations and lower percent pump, while salt type did not affect Lm growth during 4°C storage.

Nigel Harper, Ph.D. candidate

 To determine the effect that different salts have on the growth of L. monocytogenes  NaCl  KCl  CaCl 2  MgCl 2  Replacement salt  Sea salt

 Four chemical salts [sodium chloride (NaCl), potassium chloride (KCl), calcium chloride (CaCl 2 ) and magnesium chloride (MgCl 2 )] and two industrial salts (replacement salt and sea salt) at 0.5%, 1%, and 2.5.  Listeria enrichment broth used in this study was made without the sodium chloride and dipotassium phosphate.

 Results showed that MgCl 2 actually induced growth (P > 0.05) compared to control (no salt) and other salt solutions.  The industrial salts both yielded greater (P > 0.05) populations than the controls.  These results show that replacing pure NaCl with a salt that contains magnesium could cause outgrowth of Lm.

 Effect of salts on ground beef, ground turkey, and ground pork  Effects of salts in more complex meat systems

 Dr. Elizabeth Boyle  Dr. James Higgins  Dr. Ann Brackenridge, Cargill Meat Solutions  Bruce Barry, Oberto Sausage Company  Kim Uppal, Oberto Sausage Company  Tyler Axman  Shayne Lobaton-Sulabo  Nigel Harper  Tawnya Roenbaugh  Dr. Melissa Weber

 Referencec :