Progress 07/01/04 to 06/30/09
Outputs
OUTPUTS: During the past 5 years our work assuring palatability and safety of meat products has included investigations of microbial attachment and destruction on surfaces in meat plants, thermal destruction of Porcine Respiratory and Reproductive Syndrome virus in bacon, lipid oxidation in snack food containing meat and utilization of Near Infrared Spectroscopy to evaluate gel strength in meat batters. Findings of our microbial attachment work indicate a microbial reduction of up to one log cfu/square cm after a 24 hour chilling and drying period. This work indicates that bacteria inoculated onto meat plant surfaces attach to and remain on those surfaces but do not increase in numbers. Surface desiccation may lead to slight reduction in microbial numbers. However, findings showing a reduction in microbial numbers on equipment surfaces during cooling and desiccation may have be confounded by development of microbial attachment during the process. Thermal treatment is effective at destroying microorganisms in foods. In our work with PRRS virus internal temperatures of 110-136C were observed in bacon cooked using microwave heating. Heating, at above 110C, produced up to 6.8 log reduction of viral titer for inoculated bacon. Typical bacon manufacturing involves heating to 53C and produces a 3.1 log reduction of viral titer of PRRS virus in inoculated pork bellies. Low occurrence of PRRS virus in bellies of infected pigs coupled with greater than 3 and 6 log reductions during bacon manufacture and microwave heating, respectively, lead to high confidence that no active virus remains in microwave cooked bacon. Production of shelf stable foods containing meat is beneficial in communities where nursing children and their mothers are among the most at-risk for undernourishment. Nutribusiness cooperatives run by women have been established in developing countries to produce food products for local consumption and regional sale. One meat-containing product, called Chiparoo, is being developed with the intent that it can be manufactured in a developing country by a Nutribusiness cooperative. Chiparoos are made from ground meat, cooked potatoes, salt, lime juice, nitrite, and phosphate. This batter is either cooked in a chub and sliced into "chips" or extruded into "strips". Both product forms are dried in an oven or smokehouse and placed in plastic bags for storage. The purpose of this experiment was to examine the effects of two meat sources, rabbit and chicken, and three levels of phosphate on Chiparoo properties. Rabbit Chiparoos had a lower cook yield and final product pH while having an increased ease of rehydration, resistance to breaking and a higher Thiobarbituric acid (TBA) value, a measure of lipid oxidation. The phosphate levels showed no significant effect for any of the tests performed. There were negative correlations between the pH of the raw batter and the TBA value for the extruded strips after two weeks and between the water activity and the TBA value for the extruded strips after two weeks. This work shows that Chiparoos, made from different meats, experience differing amounts of lipid oxidation and thus require varied control measures. PARTICIPANTS: Participants in this project included research leader Dr. Edward Mills, PSU, Department of Dairy and Animal Science. Laboratory work and product manufacturing were conducted by Mr. Barrie Moser, PSU, Department of Dairy and Animal Science. TARGET AUDIENCES: Benefits of this work will accrue to undernourished children and mother in developing countries. International aid agencies and governments might adopt this technology or model other products on the concepts developed here. Meat or food processors in developed countries may gain insights or novel product or process ideas from findings reported from this work. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Our work involving palatability and safety of meat products several areas. It includes emphasis on microbial destruction during normal chilling as well as thermal destruction during microwave heating. Palatability of shelf stable meat snacks is addressed in our work with Chiparoos made under low-tech conditions typical of manufacturing in Sub-Saharan Africa. The results of these projects have been shared with the scientific community in peer reviewed publications and with broader audiences in posters and presentations at national meetings. The technologies and concepts developed in this work may be useful to local community groups in developing countries or to small or large manufacturers of meat products or snack foods for developed countries such as the U.S.
Publications
- Sami, A.S., C.R. Raines, E.W. Mills, B.W. Infantolino, T.L. Ott, and A.N. Gipe. 2009. Effects of electrical stimulation and postmortem aging on RNA integrity and DNAJA1 mRNA in two beef muscles. Proceedings of Reciprocal Meat Conference 62:64. #57. (Abstract).
- Mills, E.W. 2009. Meat Product Safety. J. Anim. Sci. Vol. 87. E-Suppl. 2/J. Dairy Sci. Vol. 92. E-Suppl. 1:537.
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Progress 10/01/07 to 09/30/08
Outputs
OUTPUTS: In developing countries, nursing children and their mothers are among the most at-risk for undernourishment and may benefit greatly from the addition of even a small amount of animal products to their diets. Nutribusiness cooperatives run by women have been established in developing countries to produce food products for local consumption and regional sale. One meat-containing product, called Chiparoo, is being developed with the intent that it can be manufactured in a developing country by a Nutribusiness cooperative. Chiparoos are made from ground meat, cooked potatoes, salt, lime juice, nitrite, and phosphate. This batter is either cooked in a chub and sliced into "chips" or extruded into "strips". Both product forms are dried in a solar drier, oven or smokehouse and placed in plastic bags for storage. The purpose of this experiment was to examine the effects of two meat sources, rabbit and chicken, and three levels of phosphate, 0.2%, 0.3%, and 0.4% on Chiparoo properties. Rabbit Chiparoos had a lower cook yield and final product pH while having an increased ease of rehydration, resistance to breaking and a higher Thiobarbituric acid (TBA) value, a measure of lipid oxidation. The phosphate levels showed no significant effect for any of the tests performed. Positive residual correlations were found between the pH of the raw batter and the water activity of the strips and between the pH of the dried strips and their water activity. There were negative correlations between the pH of the raw batter and the TBA value for the extruded strips after two weeks and between the water activity and the TBA value for the extruded strips after two weeks. This work shows that Chiparoos, made from different meats, experience differing amounts of lipid oxidation and thus require varied control measures. PARTICIPANTS: Participants in this project included research leader Dr. Edward Mills, PSU, Department of Dairy and Animal Science. Laboratory work and product manufacturing were conducted by Mr. Barrie Moser, PSU, Department of Dairy and Animal Science. TARGET AUDIENCES: Benefits of this work will accrue to undernourished children in developing countries. International aid agencies and governments might adopt this technology or model other products on the concepts developed here. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
The current research focused on Chiparoos made under low-tech conditions typical of manufacturing in Sub-Saharan Africa. This product could be made by local women's NutriBusiness cooperatives and sold in periurban areas as part of a value-added processing enterprise. Continued success of such an enterprise would depend in part on controlling product texture and lipid oxidation during storage. Ingredient and manufacturing variables influence these properties. Additional trials are required before reliable guidance can be offered for optimum formulations. The unique combination of meat and starchy vegetable represented by Chiparoos might also has potential as a nutrient dense snack food for developed countries such as the U.S.
Publications
- Valderrama, W.B., E.W. Mills, and C.N. Cutter. 2008. Efficacy of chlorine dioxide against Listeria monocytogenes in brine solutions. Proceedings of the International Association for Food Protection. Columbus, OH. pg.81. Abstract: P2-39.
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Progress 01/01/07 to 12/31/07
Outputs
OUTPUTS: During typical manufacture bacon is heated only to about 53C thus it must still be fully cooked before consumption. For purposes of export smoked bacon is treated as a raw pork product. Importation of smoked bacon into some countries is restricted due to the possibility that pathogens such as the Porcine Respiratory and Reproductive Syndrome (PRRS) virus may not be destroyed. Many meat processors conduct additional microwave cooking of sliced bacon in order to offer fully-cooked, ready-to-eat bacon. USDA regulations for precooked, sliced bacon require that the weight loss during cooking should reach or exceed 60% of the starting weight. USDA does not specify a final internal temperature for microwave cooked bacon. Previous work in this laboratory showed that the internal temperature of microwave heated bacon sometimes peaks at above 130C and consistently surpasses 110C. The current investigation is designed to assess the deactivation of PRRS virus during manufacture and
microwave cooking of bacon. Internal cooking temperatures of bacon were measured and used as a guide for evaluating thermal deactivation of virus in growth media and in bacon. Thermal deactivation of virus was assessed in commercial bacon samples, as well as bacon manufactured in the pilot plant and bacon manufactured from hogs inoculated with the virus. Internal temperature of 110-130C was observed in bacon cooked using microwave heating. In trials using commercial sliced bacon, a log reduction of virus of 6.74 log was achieved for bacon heated by microwave to 110C. Bacon manufacturing trials with samples heated by convection to 53C, produced a log reduction of virus of 3.12 log. A PCR based technique revealed the presence of virus in the bellies of infected hogs, but the concentration was too low to detect within the standard methods of assessment which are based on observed cytopathic effects in sensitive cells. The low occurrence of PRRS virus in bellies of infected pigs coupled
with greater than 3 and 6 log reductions during bacon manufacture and microwave heating, respectively, leads to high confidence that no active PRRS virus remains in microwave cooked bacon.
PARTICIPANTS: Participants in this project included research leaders Dr. Edward Mills (PSU, Department of Dairy and Animal Science) and Dr. Suzanne Myers (PSU, Department of Veterinary and Biomedical Sciences) who designed and conducted the project. Laboratory work and animal care were conducted by Mr. Barrie Moser (PSU, Department of Dairy and Animal Science).
TARGET AUDIENCES: Benefits of this work will accrue to US Pork producers who will have improved demand for their hogs, meat processors especially pre-cooked bacon manufacturers who will gain access to additional markets, and buyers and consumers of pre-cooked bacon in importing countries and within the US who will have increased confidence in the safety of pre-cooked bacon.
Impacts
Bacon is among the highest value-added products produced from pork. The results of this work will allow animal health officials and regulators to state with confidence that microwave cooked bacon should be considered fully-cooked for the purpose of importing into countries that are free of PRRS virus. Results to date indicate microwave cooking of bacon should be more than sufficient for destruction of PRRS virus and other pathogens. Successful demonstration that microwave cooking destroys the PRRS virus will help remove barriers to import of precooked bacon into a number of countries and improve profitability for the US pork industry.
Publications
- Mills, E.W. and M. Koushik. 2007. A NutriBusiness strategy for processing and marketing animal-source foods for children. J. Nutr. 137:1115-1118.
- Mills, E.W. 2007. Aging the Beef for Tenderness and Flavor. How much is enough? Proceedings from the National Grass-fed Beef Conference. Grantville, PA. pp. 290-294.
- Yoder, S.F., E.W. Mills, W.R. Henning, N. Ostiguy, S. Doores, and C.N. Cutter. 2007. The efficacy of microbiological diluents for the recovery of foodborne pathogens associated with homogenized beef tissue. IFT Abstract Number: 098-11
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Progress 01/01/06 to 12/31/06
Outputs
During typical manufacture bacon is heated only to about 53C thus it must be fully cooked before consumption. Many meat processors conduct additional microwave cooking of sliced bacon in order to offer fully-cooked, ready-to-eat bacon. Bacon is sliced onto a conveyor that moves the slices through one or more microwave chambers until it reaches the desired degree of doneness, crispness. During the microwave heating process fat and water are rendered out of the bacon and water is evaporated. USDA regulations for precooked, sliced bacon require that the weight loss during cooking should reach or exceed 60% of the starting weight. USDA does not specify a final internal temperature for microwave cooked bacon. The exact temperature achieved in the bacon during microwave cooking is not well known. The rendering and evaporation of water from about 40% moisture down to less than 10% moisture suggests that the temperature is at or above 100C. However, most temperature measuring
devices are not compatible with the microwave cooking environment. Infrared measurements can be used to evaluate the surface temperature of the bacon while cooking. Specialized fiber optic temperature probes are also compatible with the microwave heating environment. Considering the very thin, less than 2 mm, dimension of the bacon slice the surface and internal temperatures should not differ greatly. The purpose of this work is to document the temperatures achieved during commercial microwave heating of bacon and to determine if those heating conditions are adequate to assure destruction of pathogens or other infectious agents such as Porcine Respiratory and Reproductive Syndrome (PRRS) virus that might affect safety or marketability of the product. Surface and internal bacon slice temperature were monitored during microwave heating using a Fluoroptic thermometer (TruTemp 790, Luxtron Inc. Santa Clara, CA) equipped with fiber optic probes inserted into the bacon slice or applied to
the surface. Bacon was determined to be done cooking when cook loss exceeded 60% and some surface browning was observed. In the first trial surface temperature was measured in fat and lean areas of the bacon slice. Peak average surface temperature observed (averaging lean and fat tissue high temperatures) was 102C. The temperature of the lean portion of the bacon slice initially rose most rapidly then slowed as the temperature approached 100C while the temperature of fat portion continued past 100C. The peak surface temperature was recorded about 29 seconds after the end of microwave cooking indicating some equalization of temperatures following heating and possibly some lag in the temperature monitoring equipment. It was found that measurement of bacon surface temperature using an infrared thermometer was not effective, probably due to considerable color change of the surface during cooking. In a subsequent trial peak internal bacon slice temperature was found to exceed surface
temperature by about 1.7C (101.6C and 99.9C, respectively). Trials are under way to assess the thermal destruction of PRRS virus upon heating in conditions that mimic those observed in microwave cooking of bacon.
Impacts
Bacon is among the highest value-added products produced from pork. The results of this work will allow animal health officials and regulators to decide if microwave cooked bacon should be considered fully-cooked for the purpose of importing into countries that are free of PRRS virus. Results to date indicate microwave cooking of bacon should be more than sufficient for destruction of PRRS virus and other pathogens. Successful demonstration that microwave cooking destroys the PRRS virus will help remove barriers to import of precooked bacon into a number of countries and improve profitability for the US pork industry.
Publications
- Flowers, S.L. 2006. Identification and validation of antimicrobial interventions for red meat carcasses processed in very small meat establishments. Ph.D. Thesis. Pennsylvania State University, University Park, PA. 446 pp.
- Maretzki, A.N., Seetharaman, K., and Mills, E.W. 2005. A NutriBusiness Strategy for Empowering Rural Women and Improving Children(s) Health. South African J. of Clinical Nutrition. Abstract presented at 18th International Congress of Nutrition, Food-based Approaches to Combating Micro-Nutrient Deficiencies in Children of Developing Countries, Durban South, Africa. (Suppl. 1) 18:11.
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Progress 01/01/05 to 12/31/05
Outputs
The purpose of this study was to determine the relationship between NIR spectra and storage modulus (log G-prime), the elastic component) of low-fat meat batters made with beef or trout muscle, with or without NaCl. Skinned rainbow trout fillets or beef knuckles (IMPS 167) were minced and formulated to contain 10 percent fat using beef fat, 30 percent added water, and either 0 or 2 percent NaCl. Batters were stuffed into molds and cooked to 72 degrees C in a water bath. Gels were removed when the internal temperature reached 50, 60, and 72 degrees C. The NIR spectra between 800 to 1700 nm were collected on these gels. The dynamic rheological property of the initial batter was assessed on a rheometer at 50-Pa stress and 0.1-Hz frequency. The batter was heated from 10 to 72 degrees C at the temperature ramp of 1 degrees C/min and the rheological property was expressed in terms of the storage modulus. Partial least squares (PLS) analysis was used to predict the storage
modulus from NIR spectra of the gels from 96 data sets. A PLS cross-validation model used log (1/R) and log G-prime. The experiment was conducted with 8 replications. The optimal model conditions for PLS regression occurred with 6 PLS factors at standard error of calibration (SEC) = 0.56 and r = 0.89 (n = 64). When the PLS model was tested against the validation subset, similar performance was obtained at standard error of prediction (SEP) = 0.52 and r = 0.91 (n = 32). During thermal processing, NIR can be used to predict the storage modulus of low-fat meat batters prepared from muscle of two species and at differing salt levels.
Impacts
Real time assessment of textural changes in low-fat meat batters using near-infrared reflectance (NIR) spectroscopy during thermal processing could allow optimization of cooked sausage texture and stability. This work demonstrates the potential for on-line assessments of meat product gel strength, texture or other physical properties that could lead to new approaches for process control of meat manufacturing operations. Application of NIR spectroscopy to texture assessment during thermal processing will facilitate the design of new muscle food products and manufacturing procedures.
Publications
- Jittinandana, S., Slider, S.D., Kenney, P.B., Mills, E.W. and Irudayaraj, J.M.K. 2005. Prediction of storage modulus in low-fat, comminuted meat products using near-infrared spectroscopy. Institute of Food Technologists, New Orleans, LA. Abstract 89F-27.
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Progress 01/01/04 to 12/31/04
Outputs
Microbial attachment to meat plant surfaces provides a mechanism for bacteria to stay in place and resist sanitation procedures. However, such attached bacteria may be of limited risk to products if they are not disturbed while the product is present. The current work examines the attachment and survival of bacteria on a bare metal surface corresponding to the transport rail in a meat plant. A mixed culture of unknown bacteria recovered from overhead structure and rail surfaces in pork processing plants was incubated to a concentration of 100 million cfu/mL before inoculating onto an untreated steel surface. The volume of inoculum spread on a 3cm x 3cm area was 0.7 mL. Following inoculation, the surface was subjected to 24 hours of chilling and warming similar to the temperature cycle that occurs in a pork carcass cooler during one day of operations. When swab sampling was used to assess microbial numbers initially and after 24 hours a reduction of about one log
cfu/mL was observed after the 24 hour period. However, when the surface was scraped vigorously using a razor blade to remove attached bacteria a greater number of bacteria were recovered so the apparent reduction in bacterial numbers on the surface was about 0.28 log cfu/mL. This work indicates that bacteria inoculated onto meat plant surfaces attach to and remain on those surfaces but do not increase in numbers. Previous findings showing a reduction in microbial numbers on equipment surfaces during cooling and desiccation may have been confounded by development of microbial attachment during the treatment.
Impacts
During normal operations in pork processing plants bacteria are inoculated onto clean surfaces. This work shows that many of those bacteria survive for at least 24 hours on those surfaces but do not increase in numbers. Work in this lab has shown that condensate forming on overhead and rail surfaces is less contaminated than the surfaces where it forms. The process of microbial attachment to the surface likely prevents the bacteria from separating into the condensate. Researchers and regulators who involved with condensate risk assessment and control should find this work useful.
Publications
- No publications reported this period
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