DEVELOPMENT OF A CARCASS SANITIZING SPRAYING SYSTEM FOR SMALL 

AND VERY SMALL SLAUGHTERHOUSES 

Final Report to FSIS/TPDS 

By 

Gabriel Rodriguez, Gary R. Acuff and Alejandro Castillo 

Department of Animal Science 

Texas A&M University 

College Station, TX 77843-2471 

October 2004 
Introduction 

Although the meat industry has new tools to fight bacteria at all levels from farm 

to table, contamination of carcasses can still occur. With the implementation of United 

States regulations requiring plant operation under the HACCP system, meat processing 

plants employ various technologies for improving the microbiological quality of 

carcasses. Antimicrobial intervention methods are designed to reduce microbial 

contamination on the carcasses. 

Carcass decontamination utilizing organic acids is a sanitation process that is 

widely used in the industry, and has been studied deeply. Spraying with organic acid 

solutions and/or hot or cold water is increasingly applied as sequential interventions for 

meat decontamination (Stopforth et al, 2003). Lactic acid cabinets are available on the 

national market, but they represent a significant investment and are available only for 

large establishments, which usually have higher financial resources in comparison to 

small and very small establishments. 

Small and very small establishments represent approximately the 70% of the total 

slaughter plants in the U.S. (FSIS, 2003), and this large amount of establishments 

represents an important field of work where implementation of affordable technologies 

is needed to ensure the national public health. These establishments, if thjey apply 

organic acid sprays, usually achieve this treatment using a hand sprayer, which 

represents an economic tool. However, this method make the process time-consuming 

and unreliable, since an even spray is not achieved, leaving some areas of the carcass 

untreated. Our Sanitizing Halo, a carcass spraying system, was designed having in 

consideration three main parameters. The first parameter was cost effectiveness; small 

and very small slaughterhouses do not have the same investment capacity as the large 

establishments do. Therefore an inexpensive design is very important. The second 

parameter was convenience; small slaughterhouses are located generally out of the urban 

perimeter. Searching and purchasing materials can become a time consuming and 

discouraging task. To overcome this problem the system was designed so that it casn be 

built from materials purchased from any home improvement retail store. The third 

parameter was simplicity. The Sanitizing Halo can be assembled in a house garage or 

small shop utilizing common and basic tools available in the market. 

The sanitizing spraying system has three main components. A PVC square frame 

(Picture 1) where the nozzles are located, serves to help the lactic acid solution to get to 

the nozzles. A large handle (Picture 2), which is attached to the square permits the 

displacement of the equipment from bottom to top of the carcass reaching the easily the 

highest and furthest points of the carcass. Finally a water pump is included for 

conveying the lactic acid solution from an insulated tank to its final destination on the 

surface of the carcass. 

This project is aimed to help small and very small beef and pork slaughterhouses 

to comply with food safety regulations through the development of a sanitizing system 

with high performance of spray distribution at low cost. 
Background 

The contamination of beef during the slaughter and processing of carcasses is a 

major risk for subsequent food-borne infection in humans. It’s estimated that food borne 

diseases cause approximately 76 million illnesses, 325,000 hospitalizations, and 5,000 

deaths in the United States each year (Mead et al, 1999). Modern Meat, reported that it 

is estimated that at least one third of the 5,000 deaths each year from food-borne illness 

can be attributed to meat and poultry (Frontline, 2002). 

Beef carcasses, which are initially sterile, become contaminated with bacterial 

pathogens via transmission of organisms from the exterior of the live animal, and/or 

from the environment to the product surface (Belk, 2001). Microbial contamination of 

beef carcasses occurs during the conversion of live animals to meat. After killing and 

evisceration, most of the microbial characteristics of the carcass remain unaltered. In a 

healthy animal it is expected that that inner layers of muscle tissue are free of any 

contamination from air, soil and water. However a large number of microorganisms find 

their way to the carcass surface during the cleaning operations from the intestine and by 

contact with knives, hooks, walls, floors as well as by human contact (Guerrero and 

Taylor, 1994). Main sources of bacterial contamination include feces from the hide, 

hair, and hooves of the animals (Mies et al 1999). During processing workers and 

equipment may spread bacterial contamination from the hide to the product. 

Integration of sanitizing methods, such as knife trimming in combination with other 

antimicrobial decontamination methods such as steam vacuuming, hot water and acid 

sprays systems and steam pasteurization can help to improve the microbial safety of 

carcasses after slaughter (Gorman et al 1995, Castillo et al, 1998, Castillo et al 1999, 

Pipek et al 2004). Medynsky, Pospiech,and Kniat (2000) found that an increase of the 

lactic acid concentration in meat above the level of 0.5% enhanced water holding 

capacity and reduced thermal loss. In other study Jimenez-Villarreal et al (2003) found 

that lactic acid treatments on beef trimmings before grinding could improve or maintain 

the same sensory and instrumental color, sensory odor, lipid oxidation, sensory taste, 

shear characteristics and cooking characteristics as traditionally processed ground beef 

patties. Therefore the use of these antimicrobial treatments could be used in industry as a 

measure of safety improvement without negatively impacting the fresh product. 

Carcass decontamination utilizing organic acids is a sanitation process that is widely 

used in the industry, and has been studied deeply. In 1995 (Netten, Mossel and Veld, 

1995), found that lactic acid decontamination was capable of eliminating salmonellae 

from pork, veal and beef carcasses, and that this compound is also likely to be effective 

against C jejuni. This bacterium is at least 10-fold more sensitive to lactic acid than 

Salmonella. Furthermore, counts of C. jejuni on freshly slaughtered veal, pork and beef 

carcasses are also up to l00-fold lower than those of Salmonella. Castillo et al., (1998) 

compared the effect of different decontamination interventions on E. coli O157:H7 

inoculated on beef carcasses. Lactic acid rinses in combination with water wash, 

trimming and hot water reached reductions from 4.2 to 5.0 log CFU/cm2

. Lactic acid is 

frequently used for beef carcass decontamination. Its ability to reduce pathogens or 

other organism of fecal origin has been studied extensively showing that lactic acid have 

a strong antibacterial effect. Besides the antimicrobial effect, the studies reviewed show 
that the use of lactic acid as a meat sanitizer does not have a significant impact on 

sensory and/or physic-chemical characteristics. 

Components and characteristics of the Sanitizing spraying system 

Square frame: The sanitizing spraying system has two squares frames; one 

square frame is for spraying beef carcasses, and the second and smallest square frame is 

used for spraying the pork carcasses. Difference in size of the square frames is due to 

the fact that beef carcasses are much wider than pork carcasses. Delivery of the solution 

is made through a series of nozzles that are arranged in such a way that all regions of the 

carcass will receive the same amount of solution. The square frame used to spray the 

pork carcasses has total number of eight nozzles and the square frame used for spraying 

beef carcasses has 12 nozzles. 

The square frame is attached to a large handle. This handle permits the displacement of 

the square frame from bottom to top of the carcass. The large handle permits the 

operator to reach easily the furthest points of the carcass. The handle is attached to a 

pumping system, which impels the lactic acid solution from an isolated Rubbermaid 

cooler. 

System adjustment: 

Temperature. The lactic acid solution should be heated to 55°C and then 

transferred to an insulated tank. In this study a Rubbermaid® water container was used. 

This container was used to hold the lactic acid solution. Since it is insulated, it was able 

to keep the temperature for about 1 1⁄2 hour. After that, a decrease of 3 to 5°C was 

detected. It is recommendable to prepare the lactic acid minutes before the system is to 

be used. 

Spraying Pressure. The pumping system utilized in the Sanitizing Halo system 

delivers the lactic acid solution at a maximum pressure of 40 psi. FSIS has no current 

requirements concerning the minimum and maximum pressure for organic acids (i.e., 

lactic acid, acetic, and citric acid) when they are applied onto livestock carcasses. 

However, the rescinded FSIS Directive 6340.1—Acceptance and Monitoring of PreEvisceration Carcass Spray (PECS) Systems, dated 1/24/92, stated that the spray 

pressures should be limited to 50 psi. 

Spraying time and amount of solution delivered: Each carcass was sprayed for a 

total time period of 20 seconds. Starting from the bottom, to the Highest point for 10 

seconds, and coming down and spraying for 10 more seconds. During the spraying time 

the system delivers 1.5 gal of lactic acid solution on each carcass side. 
System testing: 

Methods. The system was tested at the Texas A&M University Rosenthal Meat 

Science and Technology Center (RMSTC). The testing objective was to compare the 

effectiveness of the spray system to routine hand spraying on bacterial reduction of beef 

carcasses. Lactic spraying at RMSTC is done utilizing a pressure washer gun, which is 

attached to a pumping system. 

Carcass sampling. After spraying, each carcass side was sampled using a sponge 

to collect 100-cm2

 samples each from the rump, brisket and clod regions following FSIS 

procedure (FSIS, 1996). The sponge was placed in a plastic bag and added with 25 ml 

of sterile 0.1-peptone water and transported to the food Microbiology laboratory located 

in 313 Kleberg building at Texas A&M University. 

Plating. Each sample was plated on E. coli and Aerobic Plate Count PetrifilmTM 

plates for counts of coliforms and E. coli as well as counts of mesophilic aerobes. 

System Validation 

Methods. The sanitizing halo was validated for carcass decontamination at two 

selected small slaughter plants producing beef carcasses and pork carcasses. The system 

was taken to the slaughter floor and used for treating 24 carcass halves. A set of 24 

untreated carcass halves were used as a control. 

Sampling. After application of the lactic acid solution both, treated and untreated 

carcasses were sampled following FSIS sampling requirements (FSIS 1996) as it was 

done at the implementation stage. A total of 300 cm2

 per carcass were collected from the 

rump, brisket and clod regions of the beef carcasses, and jowl, bacon and ham regions of 

the pork carcasses. The sponges were placed in a refrigerated container and transported 

to the laboratory 313 at Kleberg building in Texas A&M University for analysis within 

one day. 

Plating. Each sample was plated on E. coli and Aerobic Plate Count PetrifilmTM 

plates for counts of coliform and E .coli as well as counts of mesophilic bacteria. Each 

sample was tested for counts of E. coli, coliforms and mesophilic aerobic bacteria. 

Statistical analysis: 

Microbiological data were transformed logarithmically before statistical analysis. 

Means for each treatment were analyzed by analysis of variance (ANOVA) procedure of 

SPSS 11.5 for Windows. Least square means were separated when treatment effect was 

significant in the ANOVA table (p<0.05). 
Results 

Temperature and pH. Data in Table 1 show that the pH was reduced on the 

carcass surface from 7.1-7.6 to 2.8-3.2. Since the lactic acid solution was applied at 

55°C, the temperature at the carcass surface increased by approximately 3°C; but the 

temperature was rapidly lowered at the subsequent chilling step. 

System implementation. The counts of aerobic and mesophilic bacteria obtained 

from the carcasses sprayed with the sanitizing spraying system were significantly lower 

than the counts on the carcasses sprayed with the hand spraying method (Table 2). 

Bacterial counts for coliforms were below to the detectable limit for both treatments. 

The bacterial counts for coliforms obtained the control were between 1.0 

logCFU/100cm2

.and 1.5 0 log CFU/100cm2. These results confirm the efficacy of the 

sanitizing spraying system on reducing coliforms, aerobic and mesophilic bacteria. 

System Validation. All bacterial counts obtained from sprayed carcasses were 

significantly lower than the bacterial counts on the non-sprayed carcasses, with overall 

reductions of mesophilic bacteria by 2.9 log cycles for beef carcasses and 1.9 log cycles 

on pork carcasses (Tables 2 and 3, Fig 1 and 2). A relevant finding in this study was 

the usefulness of our spraying system for meeting the bacterial counts required in the 

FSIS standard for E. coli. This was true for beef carcasses. As shown in Table 4, 16 of 

24 non-sprayed beef carcasses produced E. coli counts above the acceptance limit set in 

the FSIS rule, whereas only 1 of 24 carcasses subjected to lactic acid spray produced 

unacceptable E. coli counts. For pig slaughter, neither control nor sprayed carcasses 

produced unacceptable E. coli counts. This indicates that our spraying system can help 

small processors in meeting current food safety standards. However, care must be taken 

to encourage good hygiene before using the sanitizing halo, which should be a 

complement and not a substitute for good manufacturing practices. 

References: 

Belk K. E. 2001. National Cattlemen’s Association. Beef decontamination 
 

techniques. Available at www.beef.org
 

Castillo A., L.M. Lucia, K.J. Goodson, J.W. Savell and G.R. Acuff. 1999. 

Decontamination of beef carcass surface tissue by steam vacuuming alone and 

combine with hot water and lactic acid sprays. Journal of food protection, Vol 

62, No 2, 1999, Pages 146-151 

Castillo A., L.M. Lucia, K.J. Goodson, J.W. Savell and G.R. Acuff. 1998. 

Comparison of water wash, trimming and combined hot water and lactic acid 

treatments for reducing bacteria of fecal origin on beef carcasses. Journal of 

food protection Vo 61, No 7, 1998, Pages 823-828. 

Castillo A., L.M. Lucia, K.J. Goodson, J.W. Savell and G.R. Acuff. 1998. Use of 

hot water for beef carcass decontamination. Journal of food protection, Vol 61, 

No 1, Pages 19-25. 
Food Service and inspection service (FSIS), 2003. HCC database. 

Frontline, 2002. Modern meat. Available at 

http://www.pbs.org/wgbh/pages/frontline/shows/meat/safe/foodborne.html

Gorman, B.M., J.N. Sofos, J.B. Morgan, G.R. Schmidt, and G.C. Smith. 1995. 

Evaluation of hand trimming, various sanitizing agents, and hot water spraywashing as decontamination interventions for beef brisket adipose tissue. Journal 

of food protection 58: 899-907. 

Guerrero I., A.J. Taylor. 1994. Meat surface decontamination using lactic acid from 

chemical and microbial sources. Lebensm, - Wis. U. - Technol., 27, 201-209 

(1994). 

Jimenez-Villareal J.R., F.W. Pohlman, Z.B. Johnson, and A.H. Brown. 2003. 

Effects of chlorine dioxide, cetylpyridinium chloride, lactic acid and trisodium 

phosphate on physical, chemical and sensory properties of ground beef. Meat 

Science1055-1062 

Netten P.V., D.A. Mossel, and J.H. Veld. 1995. Lactic acid decontamination of fresh 

pork carcasses: a pilot plant study. International Journal of Food Microbiology. 

25:1-9. 

Mead P.S., L. Slutsker, V. Dietz, L.F. McCaig, J.S. Breese, C.Shapiro, P.M. Griffin, 

and R.V. Tauxe. 1999 Food-related illness and death in the United States. 

Emerging Infectious Diseases. Vol. 5, No 5. 

Medynski A., E. Pospiech, R. Kniat. 2000. Effect of various concentrations of lactic 

acid and sodium chloride on selected physico-chemical meat traits. Meat Science 

(2000) 285-290. 

Mies P.D., B.R. Covington, K.B. Harrys, L.M. Lucia, G.R. Acuff, and J.W. Sawell.. 

Commercial and laboratory application of cattle washes with and without 

antimicrobial agent as decontamination strategies for hides. Department of 

Animal Science, Texas A&M University 

Pipek P., M. Houska, J. Jelenikova, K. Kyhos, K. Hoke, and M. Sikulova. 2004. 

Microbial decontamination of beef carcasses by combination of steaming and 

lactic acid spray. Journal of food engineering. 2004, Article in press, Available 

at www.elsevier.com/locate/jfoodeng 

Stopforth J.D, J. Samelis, J.N. Sofos, P.A. Kemdall, and G.C. Smith. 2003. Influence 

of organic acid concentration on survival of Listeria monoytogenes and 

Escherichia coli 0157:H7 in beef carcass wash water and other model equipment 

surfaces. Food microbiology 20 (2003) 651-660. 
Table 1. Surface pH and temperature for beef and pork carcasses with or without 

lactic acid spray 

Treatment 

Type of carcass Determination 

Control Sprayed 

Surface temperature (°C) 30.9 33.7 

Beef 

Surface pH 7.1 2.8 

Surface temperature (°C) 27.0 29.3 

Pork 

Surface pH 7.6 3.2 
Table 2. Comparison between the sanitizing spraying system and traditional hand 

spraying method 

Log cfu/100 cm2 ± SD (N = 

13) Counta 

Control1 RMSTC2 Sanitation 

Halo2 

Mesophilicb 2.1 ±0.40Ac 1.7 ± 0.83B 1.2 ± 0.66C 

Rump APC* 2.3 ± 0.40A 2.0 ± 0.66 1.4 ± 0.68C 

Coliforms 1.0 ± 0.92 0.6 ± 0.23 0.5 ± 0.14 

Mesophilic 2.4 ± 0.36A 2.1 ± 0.81 1.2 ± 0.77C 

Clod APC 2.7 ± 0.20A 2.3 ± 0.53 1.5 ± 0.69C 

Coliforms 0.5 ± 0.00 0.5 ± 0.00 0.6 ± 0.40 

Mesophilic 2.8 ± 1.00A 2.1 ± 0.71 1.5 ± 0.66C 

Brisket APC 2.9 ± 0.85A 2.4 ± 0.61 1.5 ± 1.18C 

Coliforms 1.5 ± 0.96 0.6 ± 0.31 0.5 ± 0.00 

1 Control: Samples taken after trimming and hot water wash before application of 

2% lactic acid solution at 55 °C. 

2 RMSTC: Samples taken after applying the lactic solution using the traditional 

spray method in Rosenthal Meat Science and Technology Center. 

3 Sanitation Halo: Samples taken after applying the lactic acid solution using the 

proposed spray system. a Mesophilic aerobes: Aerobic Plate Count PetrifilmTM plates incubated at 37 

°C/24 hr; Total Coliforms: Total lactose-fermenting colonies on E. coli 

PetrifilmTM incubated at 37 °C for 24 h; E. coli: Glucuronidase-positive on E. 

coli PetrifilmTM incubated at 37 °C for 24 h. 

b Values within rows with same letter are not different (P>0.05) 
c 

Table 3. In-plant validation of the Sanitizing spraying system for reducing bacterial 

numbers on beef carcassesa 

 Countb 

Log cfu/100 cm2 ± SD (N = 24) Log reduction 

Control Sanitizing Halo 

Rump Mesophilic aerobesb 4.9 ± 0.9Ac

 2.2 ± 1.0B 2.7 

Total Coliforms 3.6 ± 1.2A 1.1 ± 1.1B 2.5 

E. coli 3.0 ± 1.4A <1.0 ± 0.8B >2.0 

Clod Mesophilic aerobes 4.3 ± 0.8A 2.2 ± 0.8B 2.1 

Total Coliforms 3.0 ± 1.1A <1.0 ± 0.5B >2.0 

E. coli 2.2 ± 1.3A <1.0 ± 0.3B >1.1 

Brisket Mesophilic aerobes 5.1 ± 0.7A 1.9 ± 0.9B 3.2 

Total Coliforms 3.7± 1.2A <1.0 ± 0.5B >2.7 

E. coli 3.2 ± 1.1A <1.0 ± 0.0B >2.2 

Overall Mesophilic aerobes 4.8 ± 0.8A 1.9 ± 0.9B 2.9 

Total Coliforms 3.4± 1.2A <1.0 ± 0.7B >2.4 

E. coli 2.8 ± 1.3A <1.0 ± 0.4B >1.8 

a Beef carcasses sampled by the FSIS sponge method at the end of the processing line, 

before chilling

b

 Mesophilic aerobes: Aerobic Plate Count PetrifilmTM plates incubated at 37 °C/24 hr; 

Total Coliforms: Total lactose-fermenting colonies on E. coli PetrifilmTM incubated 

at 37 °C for 24 h; E. coli: Glucuronidase-positive on E. coli PetrifilmTM incubated at 

37 °C for 24 h. 

Mean values within rows followed by same letter are not significantly different (P > 

0.05) 
c 

Table 4. In-plant validation of the Sanitizing spraying system for reducing bacterial 

numbers on pork carcassesa 

Countb Log cfu/100 cm2 

± SD (N = 24) 

Control Sanitizing Log 

Halo reduction 

Jowl Mesophilic aerobesb 4.8 ± 0.3Ac 2.8 ± 0.7B 2.0 

Total Coliforms 2.0 ± 0.8A <1.0 ± 0.4B >1.0 

E. coli 1.7 ± 0.8A <1.0 ± 0.2B >0.7 

Ham Mesophilic aerobes 4.1 ± 0.3A 2.4 ± 0.6B 1.7 

Total Coliforms 1.9 ± 0.9A <1.0 ± 0.6B >0.9 

E. coli 1.5 ± 0.7A <1.0 ± 0.4B >0.5 

Bacon Mesophilic aerobes 4.3 ± 0.5A 2.3 ± 0.6B 2.0 

Total Coliforms 2.2 ± 1.0A <1.0 ± 0.3B >1.1 

E. coli 2.0 ± 0.9A <1.0 ± 0.2B >1.0 

Overall Mesophilic aerobes 4.4 ± 0.4A 2.5 ± 0.6B 1.9 

Total Coliforms 2.0 ± 0.9A <1.0 ± 0.4B >1.0 

E. coli 1.7 ± 0.8A <1.0 ± 0.3B >0.7 

a Pork carcasses sampled by the FSIS sponge method at the end of the processing line, 

before chilling

b

 Mesophilic aerobes: Aerobic Plate Count PetrifilmTM plates incubated at 37 °C for 

24 hr; Total Coliforms: Total lactose-fermenting colonies on E. coli PetrifilmTM 

incubated at 37 °C for 24 h; E. coli: Glucuronidase-positive on E. coli PetrifilmTM 

incubated at 37 °C for 24 h. 

Mean values within rows followed by same letter are not significantly different (P > 

0.05) 
c 

Table 4. Effect of lactic acid spray using the Sanitizing spraying system on the ability of 

a small beef and a small pork slaughterhouse to meet current E. coli FSIS standards 

No. carcasses 

Mean E. coli cfu/cm2a No. carcasses between m 

and Mb 

sampled Controlc Sprayed Controlc Sprayed 

Beef 24 150 0.5 16 1 

Pork 24 3 <0.2 0 0 

a For each carcass, the E. coli count represents the average count from the rump, clod 

and brisket regions in beef or the jowl, ham and belly regions in pork, an area of 100 

cm2

 from each region was sampled using a sponge to follow the FSIS method. 

b The FSIS standards stipulates N = 13, c = 3, m = not detectable, M = 100 cfu/cm2 

for beef carcasses and N = 13, c = 3, m = 10 cfu/cm2

, M = 10,000 cfu/cm2 for pork 

carcasses. 

Control carcasses were sampled after trimming and washing, immediately before 

chilling 
0 

0.5 

1 

1.5 

2 

2.5 

3 

3.5 

4 

4.5 

5 

5.5 

Mesophilic*

E.coli

Total

Coliforms

Mesophilic

E.coli

Total

Coliforms

Mesophilic

E.coli

Total

Coliforms 

Log CFU/100cm2

l 

i 

Figure 1. Effect of the sanitazing spraying system 

on microbial loads on beef carcasses 

Rump Clod Brisket 

Contro 

Sanitaz ng syst 
0 

1 

2 

3 

4 

5 

Mesophilic*

E.coli

Total

Coliforms

Mesophilic

E.coli

Total

Coliforms

Mesophilic

E.coli

Total

Coliforms 

Jowl 

Log CFU/100cm2

l 

i 

Bacon 

Figure 2. Effect of the sanitazing sprying system 

on microbial loads on pork carcasses 

0.5 

1.5 

2.5 

3.5 

4.5 

5.5 

Ham 

Contro 

Sanitaz ng syst 
Picture 1. Square frame 
Picture 2. Large handle 
Picture 3. Pumping system components 
Conclusions and recommendations 

The sanitizing halo reduced considerably the bacterial loads on the surface of 

beef and pork carcasses. It is an important tool that can help small and very small 

slaughterhouses to comply with government regulations and at the same time to assure 

the safety of their products. 

The use of a wheel cart to move the sanitizing spraying system to different areas 

of the plant is complicated. Kill floors at small and very small establishments have no 

space for a wheel cart. Hoses, water, fat and meat pieces are other obstacles that make 

difficult the use of the wheel cart. Instead of setting the sanitizing spraying system in a 

wheel cart a larger hose (large of the hose depends on the area of the killing floor) 

connecting the sanitizing spraying system to the pumping system can be used, and 

system can be hung from a hook located strategically in one of the walls, so it would not 

contact the floor and become contaminated.