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Food Safety, Quality, and Nutritional Composition of Foods of Animal Origin

Harris, Kerri
Texas A&M University
Start date
End date

To provide data related to the safety of food products of animal origin, including the efficacy of antimicrobial treatments or processes on the production of non-intact meat products, methods for reducing microbial contamination of meat products, the ability of pathogens to survive in various processing condition.
To provide collect data on current quality characteristics of beef in the retail cases, and on factors, such as dry vs. wet aging and days of aging, that influence the quality of meat.
To provide data that will be used to update the USDA National Nutrient Database for Standard Reference for beef.

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NON-TECHNICAL SUMMARY: Foods of animal origin are an important component of the diet in the United States. Consumers demand and expect that their food supply will be safe, of acceptable quality, affordable, and provide desired nutritional/health benefits. Illnesses and deaths caused from both food safety and diet related issues can have a major economic impact on society by 1) affecting public health through lost productivity, increased medical expenses, and death, as well as 2) the loss of food product sales. Agriculture and animal production practices continue to change; and therefore, the nutritional composition of meat is dynamic and evolving. There have been tremendous strides in the beef sector to produce leaner livestock that better meet the demands of today's consumers. Nutritional data have not been collected to reflect the beef products currently available in the marketplace; therefore, the available nutrient composition data is not accurate. Gerber et al. (2009) reported meat suffers a bad image, and that it is overlooked meat contains many essential nutrients. This image has caused consumers to use less red meat instead of just avoiding the high-fat meats they have been taught to keep away from (Swize et al., 1992). Therefore, data on nutritional composition of beef products should be collected on an ongoing basis to update the USDA's National Nutrient Database for Standard Reference (SR).

Many health organizations and private industries rely on information housed by federal agencies to develop educational materials related to diet and health issues and for proper nutritional labeling of products. The SR provides referencing data for national nutrition policies, diet therapy, nutrition education programs, guidance for pediatric, obstetric, and geriatric populations, as well as a source of information for menu calculations for schools, nursing homes and hospitals. Information in the SR also is used to provide nutrition information for on-pack labels related to nutrient claims. These data are also extremely important to consumers who are trying to make educated decisions about the foods they consume. While consumers may use nutritional information to make purchasing decisions about the types of foods they will consume, the have an expectation that the food will be safe and not cause illness. However, according to the Centers for Disease Control and Prevention (CDC), approximately 48 million people get sick from foodborne illness and 3,000 people die of foodborne disease each year in the U.S. Over 2,000 different Salmonella serotypes have been identified, and all have been determined to be pathogenic to humans (D'Aoust, 1997). Approximately 40,000 cases of salmonellosis are reported (CDC) in the United States each year. Children, the elderly, and the immunocompromised are the most likely to suffer severe conditions. Foodborne disease and contaminated foods can also cause serious economic disruption at the local, national, and international levels. It is estimated that foodborne diseases costs billions of dollars in healthcare-related and industry expenses annually, and the "preventing a single fatal case of E. coli O157 infection would save an estimated $7 million" (CDC, 2014). Foodborne outbreaks and recalls decrease consumer confidence, and threaten the continuous supply of foods for human consumption, as well as the job stability and economic vitality of food producing corporations and national economies. Beef has been shown to represent a potential source of contamination for the consumer (Dorsa et al., 1998; Hinton et al., 1998; and Payne et al., 1991). Studies have documented the effect of diet on E. coli populations (Russell et al., 2000), and the presence in feces at the feedlot (Dargatz et al., 1997; Elder et al., 2000; and Smith et al., 2001). Contamination containing E. coli O157:H7 on the hide is one source of carcass contamination, and may be contributing to the overall incidence rate of E. coli O157:H7 in today's beef products. Because both Salmonella and E. coli O157:H7 are human pathogens and natural inhabitants of cattle, the presence of these organisms in cattle at slaughter and in associated products, poses a potential risk in raw beef products. Processes, such as tenderizing, enhancing and marinating may further increase the risks associated with these hazards. Therefore, it is important that establishments have validated interventions to reduce microbial contamination. Interventions (hot water, steam pasteurization, and organic acid sprays) have been used during harvest, and some interventions are applied to chilled carcasses, cuts, and trimmings. Along with food safety expectations and nutritional concerns, consumers have expectations for desirable quality characteristics, like tenderness, juiciness and flavor. Therefore, it is important that scientific research continues to address nutritional composition, methods for improving the safety, and quality characteristics of food of animal origin. This project is designed to address all of these issues.

APPROACH: To address gaps in food safety knowledge, in-plant validation data will be collected in commercial processing establishments. Establishments will be selected based on the processing aids and interventions currently being applied, as well as the types of products (intact, non-intact, and ground beef) being produced. A minimum of 4 different combinations of processing aids/interventions and application methods will be evaluated for this project. Data will be collected at the establishments on the specific processing procedures, as well as the operational parameters of the antimicrobial interventions currently being applied in the operation. For each intervention, in-plant application parameters (i.e., concentration, pH, temperature, pressure, volume, etc.) will be recorded. For intact products, surface antimicrobials/interventions will be evaluated. For non-intact products, surface antimicrobials/interventions will be evaluated as well as internal contamination of the finished product. For ground products, treatment of surface antimicrobials/interventions for trimmings will be evaluated as well as finished ground beef. Background bacterial levels will be determined for each beef product by obtaining microbiological samples before inoculation to evaluate possible natural presence of the marker organisms. For each sample, counts of surrogate microorganisms will be determined by plating appropriate serial dilutions on tryptic soy agar (TSA) supplemented with ampicillin (100 ug/L). Additional microbial data will be collected as needed to ensure appropriate control throughout the project. To provide data related to the quality of food products of animal origin, researchers will conduct a national survey evaluating the tenderness of retail beef cuts. This project will include collaborators from additional universities to assist with collection of cuts from retail stores in at least four major metropolitan areas across the United States. In-store data will include quality grade, enhanced/non-enhanced, brand name, package weight, price/pound, steaks per package, package date, sell by date, and packaging material type. Product will be selected from the retail cases and shipped to the universities for tenderness evaluation using Warner-Bratzler Shear force determination and consumer panel. For Warner-Bratzler Shear force determination frozen steaks will be thawed in a 4C cooler for 48 h before cooking. Steaks will be cooked on a grated, non-stick electric grill (Hamilton Beachâ„¢ Indoor/Outdoor Grill, Southern Pines, NC). All steaks were turned will be removed from the grill upon reaching an internal temperature of 70C, and will then be cooled for approximately 16 h at 2 to 4C. After cooling, visible fat and heavy connective tissue will be trimmed to expose muscle fiber orientation. At least six 1.3 cm cores will be removed from each steak at locations from the medial, middle, and lateral portions. Cores will be removed parallel to the muscle fibers and sheared once, perpendicular to the muscle fibers, on a United Testing machine at a cross-head speed of 500 mm/min using an 11.3 kg load cell, and a 1.02 cm thick V-shape blade with a 60 angle and a half-round peak. The peak force (N) needed to shear each core will be recorded, and the mean peak shear force of the cores will be used for statistical analysis.

The consumer sensory panelists will be recruited from surrounding communities by randomly calling participants, and through email list serves. A consent form and demographic questionnaire will be completed by each participant. Steak samples will be randomly assigned to panelists for evaluation. Each panelist will receive two 1.27 cm cubes of each sample and evaluate four random samples during each session. Samples will be characterized using a 10-point hedonic scales. To provide data to update the USDA National Nutrient Database for Standard Reference beef products will be collected from commercial beef plants across the country. Carcasses will be selected based on sex class, USDA Quality grade, yield grade, weight, and genetics to best represent cattle that contribute to the US beef supply. Carcass data will be collected on each animal, and both sides of the carcass will be utilized. Beef will be fabricated 5-7 d postmortem into retail cuts. Retail cuts will be vacuum packaged, boxed, and stored in a cooler 0-4C. Retail cuts then will be transferred to a -18C freezer 21 d postmortem. Retail cuts will be dissected into separable lean, separable fat, and refuse using trained dissectors. Following the procedures in Wahrmund-Wyle et al. (2000), separable lean includes all muscle, intramuscular fat, and any connective tissue trained dissectors considered inedible. After each dissection, technicians are to record the weights of all dissected components ensuring a 99% recovery of each initial cut weight. Lean and fat components will be homogenized and composited for subsequent nutrient analyses. Cooking method of braised, grilled, or roasted will be assigned to the retail cuts that are designated for the cooked treatment. Meat will be thermocoupled in the geometric center, or thickest portion of the cut, and the internal temperature will be recorded. After cooking, samples will be chilled in refrigeration (0-4C) uncovered 12-24 h post-cooking in preparation for dissection. Beef samples (cooked and raw) will be homogenized using the Robot Coupe Blixer 7 BX 6V batch processor following dissection. The separable lean from the sample will be cut into 2.5 cm pieces. Samples will be placed in liquid nitrogen until completely frozen. Pieces will be transferred to the Robot Coupe 7. The sample will be blended at 1500 rpm for 10 seconds, sides of the bowl will be scraped, and the sample then will be blended at 3500 rpm for 30 seconds. After homogenization, 60 g of powder will be weighed out and aliquot into a Whirlpak bag for proximate analysis and 100 g will be weighed out and aliquot into a Whirlpak bag as a back up sample. All samples will be stored in a -80C freezer. Percentage of moisture will be determined using AOAC (1990) air, oven-dry method 950.46. Approximately 5 g of powdered sample from each cut and animal will be added to dried, pre-weighed aluminum tins and weights recorded. Analysis of the samples will be performed in triplicate. Samples will be oven dried at 100C for 16-18 h then removed and placed in a dessicator for cooling. Percentage of moisture will be calculated by taking the initial weight of the sample, subtracting the dried weight, dividing by the initial weight and multiplying by 100. Crude Protein will be determined using AOAC methods using a Rapid N Cube. Total nitrogen will be determined using a furnace temperature of 1100C. Before analysis, the instruction manual instructed the use of three blank standards to calibrate the machine. For calibration, aspartic acid will be used. Approximately 250 mg of sample will be weighed into a foil weigh sheet and a pellet will be made, weighed, and entered. Crude protein levels will be determined by multiplying the total nitrogen by a factor of 6.25. Percentage of ash will be determined using the ash oven method 920.153 AOAC (1990). Total lipid will be extracted using a modified Folch et al. (1957) method. Samples weighing approximately 0.5 g will be homogenized with 20 mL choloroform:methonal (2:1). The homogenate will be filtered through a Buchner funnel with slight suction into a clean tube. The filtrate will receive 8 mL of a 0.74% KCl solution. The two phases will be separated in a centrifuge for 20 min. The upper phase will be siphoned off and the lower phase will be transferred into pre-dried, pre-weighed 100 mL glass scintillation vials. The lower phase will be evaporated using a nitrogen evaporator. Samples will be dried for 20 min at 100C, cooled in a dessicator, and weighed to calculate total fat.

Funding Source
Nat'l. Inst. of Food and Agriculture
Project source
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Project number
Accession number
Bacterial Pathogens
Natural Toxins
Food Defense and Integrity
Escherichia coli
Meat, Poultry, Game