Dairy & Animal Science
Non Technical Summary
Meat quality, safety and sustainability are three strongly interrelated factors that directly affect the image, profitability and overall survivability of animal agriculture. Sensory attributes of meat are affected by the systems in which they were produced, starting at livestock conception and ending at final consumption. Interrelated factors of genetics, environment, diet, housing, transportation, slaughter, and postmortem handling all affect the quality of meat. As emphasis on sustainable livestock production grows, the opportunity for the introduction of previously unknown or unmanaged (in the current production systems) will emerge, leading to new sources of quality variation. Hence, identifying technologies to help manage this variability is essential. As well, investigations into the application of biotechnology to sustainable systems will address the environmental need for more efficient livestock production practices. This addresses potential changes in livestock production due to societal concerns about its environmental impact, and the well-being of livestock in general. Presently, meat packaging systems consist of non-recyclable, petroleum-based polymer films, plastics, or also Styrofoam. Although some packaging materials developed from renewable resources have been developed, they go widely unused due to added cost and potentially adverse interactions with meat on meat quality. Packaging materials and treatments during packaging can also improve the safety of fresh meat. The identification of safety intervention technologies that improve (or have no effect on) meat quality are essential to the adoption and growth of alternative meat packaging materials. Enhancing food safety while addressing and improving the sustainability of meat production and retailing practices can directly impact public welfare. The project addresses possible concerns faced by the meat-eating public in terms of meat's impact on the environment and the safety of meat. Meat animal producers and processors comprise a very small proportion of the population, and the survivability of that industry is directly tied to the rural communities in which they live.
Animal Health Component
Research Effort Categories
Goals / Objectives
The outward appearance of fresh meat is perceived to be indicative of both its quality and safety. However, there are variations among the meat itself and the type of packaging for meat used which each affect the products appearance. As a result, the U.S. meat industry experiences multi-million dollar losses each year due to poor color management of fresh meat. There are a variety of technologies available that can be applied to fresh meat that can affect its color; however, the effects of these technologies, including different lighting and packaging systems for retail display, as well as a deeper basic understanding of meat color chemistry, are not known and are the intent of this work. Retail display conditions and color: The light used in meat display cases directly affects the perceived color of fresh meat, thereby affecting its implied freshness, as well as alter meat biochemistry by accelerating oxidation (photooxidation). Entering the market are low-energy lights with different light spectra and energy properties that may affect the color of meat, particularly light-emitting (LED) lights. Optimizing retail meat case display for the use of LEDs will result in a lower energy use of meat retailers and also may improve the color stability and ultimately profitability of fresh meat. Meat packaging and color: Meat packaging is the interface between fresh meat and the consumer, and also heavily affects the appearance of fresh meat. Various combinations of gases, films and added ingredients working synergistically have been used to improve and (or) lengthen meat color life by improving meat color management (biochemically), retarding the growth of spoilage organisms, or both. There are great opportunities to use recyclable or renewable resources for meat packaging, and those resources need to be indentified and manufactured into a meat packaging material. Efficacy of meat packaging technology also includes its ability to improve or maintain fresh meat safety. Managing to prevent discoloration: Also related to meat color management is the biochemistry of what is occurring in the muscle, beneath the lights and beyond the packaging film. Metmyoglobin (MMb) is the brown meat pigment associated with spoiled meat. The maintenance of proper electron balances is essential to managing and optimizing fresh meat color. One of the critical elements is an enzyme complex referred to as MMb reductase. Problematically, this is a complicated series of events (for MMb reduction) and not all proteins are that participate in this series are understood. The identification of the specific proteins associated with MMb reductase will result in better color management opportunities. Expected outcomes: 1) Recommendations for low-energy lighting alternatives for meat retail display will be developed, 2) Meat packaging materials will be developed that increased the color stability of fresh meat, and 3) Further understanding of the mechanism of metmyoglobin reduction will be reached.
Display Case Conditions and Meat Color: A simulated retail environment will be used to evaluate the influences of lighting type, display temperature, and packaging type on the color life properties of fresh meat. To assess the effect of LED light versus conventional fluorescent light, different cuts of fresh beef and pork, whole-muscle and ground, will be displayed in retail display cases that simulate a retail environment. Cured meat products, which are often subject to color fading due to light, will also be evaluated in a mock retail environment. Fresh beef and pork, and cured meat products, will be displayed in vacuum, PVC film overwrap, or modified atmospheres. A spectrophotometer will be used to assess the L*, a*, and b* of the products over time. Standard equations for calculating both fading and metmyoglobin development using spectrophotometric data will be used (AMSA, 1991). Data will be used to characterize the color of meat displayed under LED or fluorescent lighting over time. Bacterial growth on the surface of meat as related to the type of light and subsequent UV conditions will be evaluated by enumerating aerobic plate counts (APC) during the display period. Meat Packaging Systems: Meat can be packaged in different gases or in vacuum. While the desirable red color of meat develops in the presence of CO or O2, it does not develop when vacuum packaged. Different treatments with CO prior to vacuum packaging will conducted and vacuum packaged beef and pork will be displayed under simulated retail conditions. Throughout display, microbial survival or outgrowth (spoilage and pathogenic microorganisms) will be evaluated by evaluating APC. If a system in identified that significantly reduces APC, challenge studies with specific microorganisms may be developed to demonstrate the ability of the system to protect against pathogen outgrowth. Packaging films containing natural components that can cause meat to turn red, such as celery extract, will be incorporated into a polymer and used as a vacuum package. The ability of the vacuum packaged product to retain its red color will be evaluated a spectrophotometer and L*, a* and b* values, along with spectral data (300-700 nm) will be used to evaluate the redness of meat displayed in a modified vacuum environment according to AMSA (1991) color evaluation guidelines. Metmyoglobin reducing ability: The complex associated with metmyoglobin reducing ability (MRA) is not well understood, though it is one of the critical factors associated with maintaining fresh meat color. Comparing muscles of differing color stabilities using a functional proteomic approach may reveal protein differences in the muscles that are related to color. The semimembranosus muscle, which has moderately good color stabilities on the outside portion and somewhat poor color stability on the inside portion, will be used to identify possible protein differences related to color within one muscle. A 2-dimensional PAGE will be conducted on muscle extract, and differences in spot intensity related to color stability will be determined and related to protein identification.