According to the Pork Checkoff, pork is the number one consumed meat animal protein in the world. Many factors contribute to the steady annual increase in pork consumption around the world.

Over the past few decades, the pork industry has shifted from outdoor production to a confinement setting. Currently, 52% of global pork production is produced in an indoor setting. In the United States, about 91% of market pigs are raised indoors. Utilizing indoor production, farmers have greater control over the environment, temperature, air flow, and exposure to disease. Indoor pork production, helps to eliminate the risk of contaminations via Trichinella sprilis, allowing for pork to be safely consumed at lower internal cooking temperatures.

Genetic improvements have also attributed to more efficient production of pigs with better feed to weight gain conversion. Nutrition has not deviated much from a corn and soybean-based diet, but additional alternative feed sources have a positive contribution to pork production. Nutritional requirements of growing-finishing pigs have not changed, but energy sources have become more expensive. So, alternative energy sources are sought which increases the need to monitor fat quality. With improvements and changes in production practices, genetics, and nutrition, the meat industry works to ensure improvements made on the live pig provide positive improvements to pork products.

The industry must constantly evolve to meet the consumers’ needs and demands, as the consumer makes the final estimation of quality for all meat products. Consumers’ perception of the meat industry is important and helps to guide the type of research that meat scientists need to focus on. Consumers desire a pleasant eating experience every time they sit down to their kitchen table. Making pork tender, juicy, and flavorful is influenced by several quality factors that can occur before, during, and after the harvest process.

Consumers use visual color and marbling as indicators of an expected eating experience. In the past several researchers used visual color and marbling to develop a pork quality grading system. In general, a darker colored pork chop with more marbling is perceived as greater quality than a lighter colored pork chop with less marbling. Some consumers prefer a dark color chop, others may appreciate a chop with a paler color. Additionally, consumers have different preferences for the amount of marbling within a chop. Some prefer a chop with a lot of marbling and others prefer a chop that is leaner appearing. Using the combination of visual marbling and visual coloring scores allows chops to be assigned to different quality grades for evaluation by trained panelists and then later recognized by consumers.

A retail audit conducted in 2013 assessed two types of pork chops. The two types included enhanced chops (chops that were infused with water and other ingredients) and non-enhanced chops. These were used for visual marbling and color assessment. The majority (53%) of enhanced chops were rated a visual color score of 3 which is described as reddish pink color. Only 15% of enhanced chops were described as grayish pink as indicated by a color score of 2. While 25% of enhanced chops received a color score of 4, which is described as dark reddish pink, non-enhanced chops followed a similar distribution of color scores of 2, 3, and 4 (19%, 48%, and 26%, respectively). A majority of enhanced and non-enhanced chops scored a 2 for visual marbling (45% and 47% respectively). Visual marbling scores are intended to represent the percentage of lipid in a pork chop. As an example, a chop with a visual marbling score of 2 should have 2% lipid. Only 14% of enhanced chops and 9% of non-enhanced chops had a visual marbling score of 1. A marbling score of 3 represented 31% of both enhanced and non-enhanced chop populations. Variation within a retail case can lead to confusion on which chop will provide the best eating experience for a consumer. Research is needed to continue to improve producing chops that meet consumers’ expectations of what they want to buy.

Genetic potential of pigs to have darker colored meat can be correlated to muscle fiber type that a pig possesses at birth. However, proper handling and harvesting of pigs will have a greater impact on pork color regardless of the genetic potential. In addition, accelerated chilling methods are used to ensure pork carcasses are cooled quickly, to prevent pale-colored, lean, and poor water holding capacity. Research has been conducted using trained panelists to determine differences in eating experiences attributed to different quality grades (combination of visual color and marbling). In one study, trained panelists were unable to detect sensory tenderness differences among high, average, and low-quality grade chops cooked to 160˚F. However, high quality chops when tested with instruments were more tender than average and low-quality chops cooked to 160˚F. Trained panelists were able to detect differences in sensory juiciness, where high quality chops were juicier, compared to average and low-quality chops cooked to 160˚F.

Additionally, the color of chops that consumers see in a retail case is influenced by the pH of the pork chop. The ultimate pH is the pH of pork 24 hours after harvest. Normal pH is approximately 5.70. Chops that appear darker in color tend to have a greater ultimate pH, and chops with a lighter color will have a lower ultimate pH. Generally, pigs that are handled calmly, provided adequate rest at the abattoir, and have carcasses that are properly chilled tend to have a greater ultimate pH.

Studies have shown that chops with a high ultimate pH have improved sensory tenderness and juiciness when cooked to 160˚F. According to one study, as ultimate pH increased from a lower pH (5.05-5.50) to a higher pH (6.68-5.95) tenderness scores increased by 14% and juiciness scores increased by 12%. This study emphasized that a chop with a greater ultimate pH will result in superior eating experience than a chop with a lower ultimate pH when chops are cooked to 160˚F.

Even though consumers define quality differently, final cooking temperature seems to universally improve eating experience. In 2013, the USDA lowered the recommended final internal cooking temperature of whole pork muscles from 160˚F to 145˚F. Pork is now safe to cook to a lower degree of doneness without compromising food safety. Lowering the cooking temperature of pork chops will increase tenderness and juiciness scores by a trained sensory panelist. Additionally, chops cooked to 145˚F were about 7% more tender measured by instruments, than chops cooked to 160˚F.

Data on tenderness based on instruments, was supported by consumer data, with more consumers rating chops cooked to 145˚F as tender compared to chops cooked to 160˚F. Emerging research has utilized the revised internal cooking temperature and different quality grades on trained sensory panelists. Trained panelists were unable to detect differences in tenderness or juiciness among chops of different quality grades when cooked to 145˚F. Additionally, color and marbling did not influence sensory traits independently when chops were cooked to 145˚F. Therefore, a study using chops with specific visual marbling and visual scores to represent different quality chops were served to consumers. Chops were cooked to either 145˚F or 160˚F to determine consumer preferences. Consumers were unable to identify differences between chops considered high or average quality; however, consumers rated chops cooked to 145˚F as more tender, juicy, flavorful, and overall more acceptable compared to chops cooked to 160˚F regardless of the quality of pork chop.

An additional consumer study, using pork loin chops with high ultimate pH values (5.88-6.23) and chops with low ultimate pH values (5.36-5.56) were served to consumers cooked to 145˚F, 160˚F, or 180˚F. A greater percentage of consumers rated chops in the high ultimate pH category juicier, compared to chops in the low ultimate pH category regardless of the final internal cooking temperature. However, tenderness, flavor, and overall acceptability were not influenced by ultimate pH categories.

These studies indicate that it is the final internal temperature that impacts overall eating experience, regardless of visual marbling, visual color, or ultimate pH. Educating consumers on proper cooking temperatures will ensure positive eating experiences for consumers regardless of the type of chop they select from the retail case. The regular use of a meat thermometer will help to ensure the correct internal cooking temperature is achieved.

In conclusion, cooking whole pork muscles to 145˚F rather than 160˚F will improve tenderness, juiciness, flavor, and consumer acceptability. Neither ultimate pH nor the combination of visual color and marbling impacted consumer sensory ratings of pork loin chops cooked to 145˚F. Regardless of the visual color or marbling of a pork chop in the retail case, preparation of the chop by the consumer has a greater impact on the pork chop than its visual appearance. Education of proper preparation methods need to be emphasized to all consumers to ensure positive eating experiences with pork.

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Lauren Honegger
Lauren Honegger is a graduate research assistant at the University of Illinois, working on her Master’s degree in Meat Science. Lauren is originally from Forrest, Illinois and earned her Bachelor’s degree in Animal Sciences from the University of Illinois in 2015. Her thesis research is focused on pork quality factors influencing consumers’ pork preferences. During her time as a master’s student, Lauren has executed several research projects and was the assistant manager of one of the University of Illinois farrow to finish commercial/research farms. She facilitated and supervised multiple projects, from four separate lab groups, encompassing genetics, nutrition, and meat science. Lauren has also served as a teaching assistant.

Dustin Boler
Dr. Boler is an associate professor in the Animal Sciences department at the University of Illinois. Originally from Spencer, Indiana Dustin Boler earned degrees in Animal Sciences and Agricultural Economics from Purdue University (BS ’04) and Animal Sciences degrees at the University of Illinois (MS ’08, PhD ’11). Prior to Illinois, he was an assistant professor at The Ohio State University. His research activities focus on fresh and processed meat quality of beef, swine, and poultry. He interacts with various industry partners to evaluate the effects of onfarm practices on carcass characteristics and cutability. Additionally, he investigates further processed meat quality, especially, issues relating to fat quality and bacon production.

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