Before food enters the mouth, most consumers have formed a perception of what they will experience. One might expect a pinkish-reddish hued cured kosher beef hot dog in an all-natural casing to have a snap when bitten, followed by a salty, savory taste. A golden-brown cooked pork sausage patty will likely ooze juices when chewed and have the flavor of sage, with or without sweet hints of brown sugar or maple. Meat and poultry processors often rely on ingredient technologies to make sure their raw and fully cooked products possess the expected color and aroma, as well as deliver on anticipated or familiar flavor.
“Since our brains are wired to make judgments based on sight, most of our perceptions of food are based on visual appearance,” said Derek Hull, director of technical services, Wenda Ingredients, Naperville, Ill. “We are naturally attracted to foods that are visually appealing and appetizing. Once we get closer to the food, our sense of smell takes over, triggering memories and past experiences that shape our expectations, making it more enjoyable or not.”
It is important that processors understand the threats that exist to negatively impact color and flavor.
“Factors that increase risk include fat level and type, exposure to oxygen in the package and compounds that catalyze reactions,” said Rob Ames, director of business development, Corbion, Lenexa, Kan. “Understanding the threats and their order of events is important to risk mitigation.”
Fresh meat challenges
Compared to frozen and fully cooked meat, fresh meat is most susceptible to undesirable color changes. This is primarily due to exposure to oxygen.
“Consumers generally seek bright white poultry, pink pork and cherry-red beef when considering raw meat and poultry products,” said Michael Cropp, technical service manager, Kemin Food Technologies, Des Moines, Iowa.
Fresh meat exposed to oxygen kicks off the chemical reaction known as oxidation. In general, ground meat is the most susceptible of all raw meats, as the grinding process increases the meat’s surface area, resulting in more exposure to the environment and more contact with oxygen. This may accelerate the oxidation process.
“Oxidation occurs when myoglobin, the pigment responsible for meat’s red or pink color, binds to oxygen,” Hull said. “This turns the meat into a dull brownish-gray color that is not visually appealing to consumers.”
The more time the meat is exposed, the greater the discoloration. It is most common in red meat products, as they contain the highest myoglobin content. While poultry has the least amount of myoglobin, it still is prone to oxidation from microorganisms.
“Microbes break down muscle tissue,” Hull said. “This leads to a grey or yellowish discoloration. Improper storage conditions, such as exposure to light and temperature fluctuations, can further contribute to color deterioration.
“Color degradation generally occurs before microbial spoilage,” Hull added. “While these items are typically safe to eat, microbially speaking, the color change can diminish their visual appeal.”
Ron Ratz, senior vice president, Wixon, St. Francis, Wis., added, “A fresh, mild odor is expected, whereas any sour or off-putting smells are a clear warning sign of some sort of oxidation or spoilage.”
Flavor changes
Lipid oxidation can also take place in raw meats. It is most common in ground poultry, because of its fatty acid profile.
“This reaction occurs over time due to oxygen reacting with unsaturated fatty acids, giving rise to secondary products, such as aldehydes and ketones, which result in off-flavors and odors in meat products,” Cropp said. “Products with a longer shelf life, such as fully cooked and frozen products, and a higher degree of unsaturated fatty acids are most susceptible.
“Just like with fresh meat color, oxygen content speeds up the oxidation rate,” Cropp added. “Storage temperature, light exposure and transition metals also play critical roles.”
Frozen meats are also susceptible to color and flavor changes as a result of freezer burn.
“This impacts the finished product by creating a warmed-over flavor,” Hull said. “Fully cooked and refrigerated sliced deli meats, particularly cured products, are not immune to this color change. This is caused by insufficient cure color conversion, often resulting from inadequate curing ingredients and poor dispersion, leaving a cure color that fades to a dull gray color over time.”
Antioxidant ingredients like green tea extract and rosemary extract are easy-to-use and low-cost solutions. (Source: ©INNAFOTO2017 - STOCK.ADOBE.COM)Ingredients to the rescue
Antioxidant ingredient technology can help prevent premature color and flavor changes caused by oxidation. Traditional synthetic antioxidants, such as butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT) and tertiary butylhydroquinone (TBHQ), are time-tested ingredients that protect color, flavor and overall freshness in various meat applications. They are easy to use and low cost; but being chemically derived, they are undesirable in today’s clean-label food environment. A growing number of meat and poultry processors are exploring clean label alternatives to protect product quality during shelf life.
Plants in the Lamiaceae family, such as rosemary, contain phenolic diterpenes that can serve as effective molecules to scavenge free radicals and delay oxidation in food applications. When rosemary extract is combined with green tea extract, a source of molecules known as catechins, the resulting natural plant extract blend can provide superior performance to stabilize meat and poultry products during shelf life.
“Olessence is an olive-derived antioxidant that is a natural source of hydroxytyrosol, a phenolic compound,” Cropp said. “The mode of action is free radical quencher, which functions in the same manner as rosemary and green tea, with a more bland flavor profile. It works great for fresh poultry. This antioxidant offers greater application versatility and offers a variety of product options based on needs.”
The olive extract is naturally water soluble, often combined with rosemary, which is inherently oil soluble. The combination of olive and rosemary offers great synergistic benefits for getting into product matrices.
Acerola cherry extract provides a clean-label natural source of the free-radical quencher ascorbic acid. It is best for beef and pork applications.
“Clean-label, natural mushroom extract is a source of chitosan, which helps maintain fresh meat’s red color under frozen conditions,” Cropp added. “Chitosan helps keep the muscle protein oxygenated during storage. It is best suited for pre-rigor meat applications with products sold fresh-frozen and/or frozen and slacked out later.”
Applying a chelator to the surface of fresh meat and poultry may also assist with maintaining desirable color. Chelators, a class of secondary antioxidants, work by complexing metals, which marginalize their reactivity. They eliminate the initial oxidation step. Common chelators used in the food industry include ethylenediaminetetraacetic acid (EDTA), citric acid and some phosphates.Chelators help keep transition metals, such as heme iron in myoglobin, at a reduced state for longer periods of time,” Cropp said.
“This is very beneficial for products stored in an oxygen environment.”
The role of packaging
Proper packaging also helps minimize color and flavor degradation. It helps to eliminate oxygen within the package by vacuum.
“Shelf life is further enhanced by modifying the atmosphere in the package with gases to optimize storage conditions,” Hull said.
Common gases used include carbon dioxide, carbon monoxide and nitrogen. Ratios can be optimized by protein and desired shelf life.
“Some fresh meat sold in polyvinyl chloride (PVP) packaging, commonly called overwrap, is often placed into a carbon dioxide mother bag during transport to prolong the fresh meat color life at the retail establishment,” Cropp said. “Occasionally, fresh raw beef and pork is vacuum-packaged in nitrite-embedded film. In a raw state without oxygen, the resulting color of the meat is nitric oxide myoglobin (bright cherry red). Compared to oxygen-containing environments, this packaging environment is excellent for microbial stability shelf life extension — due to lack of oxygen — but is relatively expensive compared to other packaging solutions.”
Acerola cherry extract is a clean-label natural source of ascorbic acid that works best for beef and pork applications. (Source: ©NIKCOA - STOCK.ADOBE.COM)Issues with fully cooked meats
Deli-style luncheon meats, ready-to-eat meats and poultry and fully cooked sausages come with different color and flavor challenges. Oxygen exposure, along with light and temperature abuse, can create a challenging environment that negatively impacts meat and poultry product quality.
“With cooked meats, we also assess the texture visually, such as, is it moist and inviting, or dry and unappetizing,” Ratz said. “After the visual check, our sense of smell kicks in, confirming the meat’s freshness and proper preparation. Meat processors manufacturing further processed fresh and fully cooked meat products must prioritize the use of ingredients that extend shelf life while preserving and maintaining both color and flavor to help meet consumer expectations.”
Cropp added, “Tightly sealed packages that are free of air pockets will help limit oxygen exposure. However, sous vide cooking, which typically involves processing at lower cooking temperatures and holding for extended periods, has unique challenges. The extended period of time at higher temperatures can increase the oxidation rate. Products should contain free radical quenchers to reduce oxidation impacts.”
Another common discoloration is known as greening. This has to do with the way light bounces off the surface of the deli meat. It is a phenomenon known as diffraction and may produce an almost rainbow-like iridescent color.
Diffraction involves the fibrous strands of protein in the meat and white light, which is composed of a spectrum of different colors of varying wavelengths. After meat is sliced, the cut ends of the tightly packed strands form a series of grooves.
When light hits these grooves, some of the light is absorbed and some of it is diffracted. These color waves bend at a different angle, producing an iridescent effect. Diffraction depends on the grooves being structurally intact and perfectly aligned. This is why iridescent discoloration is more common on firmer, processed deli-style meat.
This shimmer is also more noticeable in darker cooked meats, such as roast beef and ham. Turkey and chicken are too pale to showcase the reflected light bends. It also matters if the deli product is restructured or whole muscle. In the latter, the ground and reformed fibrous proteins are no longer aligned and therefore cannot diffract light.
There’s not much a meat processor can do to prevent this shimmering effect. However, slicing and packaging have an impact. Only cuts that are sliced against the grain, or perpendicular to the direction of the fibrous proteins, show iridescence. Blade sharpness may also influence the development of the grooves that diffract the light waves. Sharper blades produce cleaner cuts with smoother surfaces, which are better for refracting light. Blunt blades, though more challenging to slice with, yield rough surfaces, which are too disrupted to produce iridescence.
Proper color development in certain cooked or smoked meats is just as important as color retention in fresh meat. When the meat is processed, the balance between red myoglobin and bright red oxymyoglobin gets disturbed. These molecules suffer from oxidative stress and are reduced to brown metmyoglobin. In pork, for example, nitrogenous compounds such as nitrates and nitrites, are added to the pork via traditional cures to ensure a desirable pink color. Select plant and spice extracts are also able to deliver desirable pink color to uncured pork products.
“While cultured celery juice powder is the most common option used in the industry, Wenda Ingredients also supplies cultured beet juice and Swiss chard cure ingredients,” Hull said. “When combined with our acerola cherry powders, which are natural sources of ascorbic acid (vitamin C), these ingredients create a very stable cure color conversion that lasts throughout the product’s shelf life. The reaction also creates a strong antioxidative effect, protecting the flavor of the finished product during its longer refrigerated shelf life.
These ingredients also are simply labeled as “cultured celery powder (celery powder, sea salt),” “natural flavor, sea salt,” “cultured beet juice powder,” “cultured Swiss chard” or “acerola cherry powder.” Organic versions of some are available.
Prosur Inc., Naperville, Ill., offers a fruit and spice blend that is rich in polyphenols and helps prevent the browning of myoglobin of meat during cooking and drying. When used at the suggested levels, residual nitrites are below the detectable limit.
Colorful and tasty meat and poultry are possible with ingredient and packaging technologies. By incorporating these interventions, processors can extend shelf life and reduce food waste.
