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USDA/AFRI Integrated Food Safety Project

Research Progress

Water Washing Studies

EO water washing studies (Dr. Hung)

  • Nalidixic acid adapted STEC has similar resistant electrolyzed oxidizing (EO) water treatment and will be used for our future inoculation studies.
  • Comparison of current and novel washing treatments to control Escherichia coli O157:H7, O26:H11 and Salmonella Typhimurium DT 104 on beef trims and ground beef patties were performed. All treatment achieved significant reduction than water and Blitz was the most effective treatment. Freezing and frozen storage on ground beef achieved additional reduction on STEC.
  • Effects of various chemicals treatments followed by 0, 1, 7 and 14 days freezing storage on survival of Escherichia coli O157:H7, O26:H11 and Salmonella Typhimurium DT 104 in ground beef patties were determined.
  • A new CIP meat grinder sanitization treatment has been developed and invention disclosure has been submitted to UGA.
  • Washing treatment for subprimal and trims may be limited due to original load, potential effect on quality and ability to penetrate the meat surface.

EO water washing studies (Dr. Bosilevac)

  • An EO water generator (Primacide Unit) has been installed in our cutting room with a new Ross needle tenderizer. This will allow sensory studies to be run in conjunction with microbiological studies, as the EO water can be transferred to microbiology laboratory for intervention efficacy studies without risk to sensory work.

LA-SDS washing studies (Dr. Bosilevac)

  • Levels of Levulinic Acid+SDS (5%/0.5%) were evaluated as an intervention for beef head and cheek meat to control contamination. The Levulinic Acid/SDS did not reduce the levels of non-O157 STEC, O157:H7 and Salmonella in the current studies to the extent expected. Exposure times were limited to 1, 2, and 5 minutes. The effects of exposure to the Levulinic Acic/SDS intervention on meat color (a*, b* and L*) were also determined.
  • Reduction of aerobic plate counts, non-O157 Shiga toxin-producing Escherichia coli, O157:H7 Shiga toxin-producing Escherichia coli and Salmonella enterica after immersion of inoculated cheek meat in an antimicrobial solution for 1, 2, and 5 min or in 80°C water for 10s were measured.
  • Effect of different antimicrobial solution treatment on cheek meat color were determined immediately after immersion.

UV and IR Studies

UV and IR studies (Dr. Hung)

  • E. coli O157:H7 (Strains 5,4,1, E932 and E009 individually), E. coli O104, cocktail of E. coli O157, E. coli O145, E. coli O103, E. coli O121, E. coli O111, E. coli O45, E. coli O26 and non-pathogenic surrogate (ATCC 1427 and ATCC 1428) on their resistant to ultra violet (UV) light were studied.
  • The strain 5 in the E. coli O157:H7 group was found to be the most resistant strain and E. coli O104 was the most resistant non O157 STEC. Among all the E. coli strains and serovars tested, E. coli O157:H7 strain 5 was the most resistant one to UV.
  • UV resistant of Nalidixic acid resistant strains were studied in comparison to the parent strains to determine whether they can be used for future studies to make enumeration easy by cutting down the background flora. It was found that nalidixic acid adaption significantly increased the sensitivity of the STEC strains except for strain E932 of E. coli O157:H7, hence would not be a suitable option for replacing parent strains in future studies with UV treatments.
  • UV inactivation data were analyzed to calculate D and Z values of different STEC strain so their resistant to UV can be easily compared. For example, the most resistant E. coli O157:H7 strain 5 had a D value of 87 sec at 1.04mW/cm2 and E. coli O104 had a D value of 66 sec at the same intensity. Based on the calculated Z value, for the same UV dosage we found there is a benefit of high-intensity-short-time than low-intensity-long-time treatment. Pulse UV treatment will be further investigated.

UV studies (Dr. Bosilevac)

  • The treatment of beef surfaces with UV energy has been increased to 7900 uW-sec/cm2 and the chamber has been modified to allow UV+ozone as treatment. When exposure was set at 75 seconds, between 0.5-0.6 J/cm2 of energy were applied to beef surfaces. At this level of treatment the inactivation with UV was 1.1, 1.2, and 0.9 log reduction for Sal, O157, and LM respectively. Preliminary observations indicate that a combination of UV and ozone has more inactivation to pathogenic bacteria.
  • The effects of the 75 s UV and UV-ozone treatments on the color of beef flanks were determined at time 0 and after 24 h storage at 4C. Color was determined as L* , a* , and b* values, where L* indicates whiteness, a* indicates red (positive value) or green (negative value), and b* indicates yellow (positive value) or blue (negative value). UV treatments had no effect on L* values compared to control (untreated) either at 0 or 24 h after treatment. UV treatment had no effect on redness and yellowness compared to control at 0 h, but the redness and yellowness increased after 24 h of storage at 4 C.
  • The UV unit will be further upgraded to increase the power output in an attempt to shorten the exposure time to that which is acceptable for beef processing industry use. It is anticipated that an exposure of less than 15 s is required for industry adoption. After UV unit is upgraded, the effects of 10, 15, and 20 s exposures will be determined on reducing the viability of E. coli O157:H7 and non-O157 EHEC. The efficacy of UV/ozone combination against pathogens, colors, and lipid oxidation will also be examined.

Radio frequency heating studies (Dr. Mohan)

  • Beef homogenate blends of varying lean to fat compositions (90/10, 85/15, 80/20, 73/27) behave distinctly during Radio frequency heating at individual initial temperatures (10°C, 25°C, 50°C) of the immersion medium (water).The homogenate blend types showed differences in heating times.
  • 85/15 homogenate blend reached the target temperature (50°C) faster than the 90/10 blend at initial water temperatures of 10°C and 50°C. Overall results suggest that beef homogenates containing lower fat ratios (90/10 and 85/15) get cooked sooner in RF compared to blends with higher fat ratios (80/20, 73/27).
  • The instrumental color measurements (L*, a*, b*-values) were different (P<0.05) among raw and RF heated homogenates for all 4 beef blends. L*, a*- values were found to be lower and b* values higher for RF heated samples compared to raw samples.
  • The instrumental color readings suggest that RF treatment impacted the color of the beef homogenates. RF heating was found to also influence the Metmyoglobin accumulation in the beef homogenates. % MMb values of RF heated samples were found be higher than those of raw samples for all the four beef blends (P< 0.05).
  • A sanitation protocols (Standard Operating Procedures) was developed and approved by the Institutional Biosafety Committee (IBC) forRadio Frequency Equipment Cleaning Standard Operating Procedure and Biosafety lab Transportation and Cleaning Standard Operating Procedure.
  • A time-temperature parameter for RF cooking of beef short loin steaks was performed using two samples at a time in two separate packages.
  • RF heating with antimicrobial is being used as an alternative process for pasteurizing beef trimming for ground beef production as final process. Effect of different RF heating rates, antimicrobial concentrations and in reducing pathogens on beef trimming is being investigated. Doctoral student Anuj Purohit is currently developing methods and protocol for RF pasteurization of beef trimming during ground beef production. Effect of RF heating on final product quality, color shelf-life and sensory characteristics will be studied.

Photocatalytic bactericidal nanoparticles studies (Drs. Hung and Zhao)

  • Studies have been conducted to determine the bactericidal activity of three different commercial titanium dioxide (TiO2) and two different iron oxide (Fe2O3; a commercial and a synthesized) nanoparticles. The bactericidal activity of nanoparticles in suspension was tested against a surrogate bacteria E.coli (ATCC 1428) under different nanoparticle concentrations, light intensities, reaction mixture volumes and treatment periods.
  • Nanoparticle photocatalytic reaction rate is depending on nanoparticle density/surface area, surface characteristics, and surface chemistry.
  • Optimum conditions for bactericidal activity evaluation on TiO2 nanoparticles were determined. This protocol will be used to evaluate different nanoparticles on their photocatalytic and bactericidal activities.
  • Most efficient commercial TiO2 sample showed up to a 5 log reduction in 2 hrs.
  • A dip coating protocol has been developed to test the compatibility and adherence behavior of different binders with nanoparticles on stainless steel and ceramic surfaces.

Noroviruses studies (Dr. Cannon)

Prevalence of viruses in cattle

  • Cattle fecal samples collected during the NAHMS 2011 Feedlot Study.
  • 969 samples were collected from 66 farms and tested for noroviruses/caliciviruses (P289/P290 primers; 400 samples originating from 28 farms; P289/P290 plus extended set of primers; 569 samples from 38 farms).
  • Of the 969 samples tested, 282 samples tested presumptive-positive by RT-PCR (9/400 from first set presumptive positives; all DNA sequenced. All 9 were garbage sequences).
  • Of 251/569 samples presumptive-positive; 53 were submitted for sequencing. Using P290 primer- all were negative (garbage sequences).

Sanitation of food processing environment

  • Sanitizer Efficacy against Murine Norovirus, a Surrogate for Human Norovirus, on Stainless Steel Surfaces when Using Three Application Methods. (Ref: Applied and Environmental Microbiology 2013. Feb; 79(4):1368-77.)

Economic and cost analysis (Dr. Rosson)

  • The economic baseline of the U.S. beef industry was updated using the input/output model IMPLAN. The beef industry, estimated at $44.1 billion in 2010, grew to $50.0 billion in 2011. As a result, total of economic support for the industry grew from $176.2 billion to $199.6 billion and total jobs grew from 943,000 to 1.07 million.
  • Research continued to better refine the cost and benefit categories to be included in the analysis. An analysis of each beef processing technology in this project will be analyzed using Net Present Value, Benefit-Cost Ratio, and Internal Rate of Return methodologies.

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