Fresh, natural and simple are attributes today’s shoppers increasingly seek out in packaged foods. The challenge for meat and poultry processors is to deliver these attributes while also ensuring safety and allowing for shelf life that reduces waste and keeps product affordable. That’s because raw and cooked meat and poultry, with the latter including ready-to-eat (RTE) meats, sausages, hot bar foods and heat-and-eat products, are highly perishable. Their biological composition fuels the proliferation of pathogenic and spoilage microorganisms, with the former making them unsafe and the latter reducing product shelf life. Meat and poultry products are also a source of active enzymes and oxidation-prone compounds, which may negatively influence sensory attributes, such as color and flavor, rendering products unappealing. Processors will often include one or more processing, packaging and ingredient technologies to destroy pathogens, retard growth of spoilage microorganisms and reduce product breakdown.
These efforts are critical in the growing category of multi-component snack packs, which often include RTE meats combined with cheeses, crackers, nuts, fruits, chocolate pieces or even a hard-boiled egg. Consumers often fail to recognize that these are highly perishable products and cannot be treated like the shelf-stable granola bar or bag of pretzels that sits in a backpack or purse for hours on end. Further complicating this growing segment of products is the better-for-you positioning many meat snack marketers are making. They have found that organic, uncured and free of artificial preservative claims provide a healthful halo to RTE meats. With these claims, processed meats now appeal to many health and wellness shoppers; however, these claims require the elimination of powerful food safety ingredients.
The same is true for dried meat snacks, such as jerky, bars and sticks. While drying is a natural form of preservation, when these products are not cured, or have reduced sodium levels, it is often best to include additional methods to keep them safe and maintain quality during transport until the time of consumption.
Below are seven technologies designed to maximize shelf life.
1. Sodium and Potassium Chloride
These simple salts do so much more than enhance the flavor of foods. In fact, sodium chloride is recognized as one of the earliest ingredients used to preserve and prevent microbial growth in meat and poultry.
Both salts, sometimes used together in order to keep sodium content down, may be injected into whole muscle via a brine solution or blended in as a dry ingredient in processed meats. They function by decreasing water activity, or conversely, increasing osmotic pressure. The increase in osmotic pressure in the environment causes water to move through the cell membrane and out of microorganisms. Basically, this dehydrates the cell and it loses viability.
In addition to making meat and poultry products safe and extending shelf life, these salts may also improve texture. This is the result of salt solubilizing some meat proteins, creating an emulsion with fat and water that produces a more favorable, tender and juicy product. The juiciness – a result of proteins binding water – also increases product yield, providing an economic advantage.
2. Organic Acid Salts
Acetic acid, lactic acid and propionic acid are the most common organic acids used to inhibit pathogenic and spoilage microbial growth. They are often used in a buffered or neutralized format (with a conjugate base). Their mode of action is the same, but their effectiveness varies by the organic acid, specifically the amount of undissociated or non-ionized acid. It is the undissociated acid that penetrates microbial cell walls. Once inside the microorganism, where the pH is near or above neutral, the acid dissociates, lowering the pH. The pathogens and spoilage microorganisms encountered in the meat and poultry processing and distribution environment are pH-sensitive; thus, this change in pH impairs or stops growth. Further, the anionic parts of the organic acid, which are the negatively charged ions, remaining in the microorganism will accumulate, disrupting metabolic functions. This leads to an increase in osmotic pressure that eventually destroys the microorganism.
It is the amount of undissociated acid that determines the organic acid salt’s effectiveness as an antimicrobial. Dissociation is dependent on pH and quantified by pKa value. The pKa of an acid is the pH where 50 percent of the acid is undissociated. Propionic acid has a pKa of 4.87 and acetic acid’s is 4.75. Lactic acid is much lower at 3.83. When pH is higher than pKa, the amount of undissociated acid decreases and the acid is less effective at destroying undesirable microorganisms.
Propionates have a reputation as being one of the most effective antimicrobials in meat and poultry; however, marketers often do not consider them a clean-label ingredient. Acetic acid, on the other hand, is the primary component of vinegar, and recognized as a familiar household staple. Lactic acid is also label friendly, as it is a product of carbohydrate fermentation.
Fermentation technology allows for the development of optimized-performance ingredients, such as buffered vinegar, which comes in dry and liquid formats and has a range of acetic acid concentrations and usage rates. There are low- and no-sodium options, too. Some suppliers include plant extracts to assist with shelf life extension.
3. Plant Extracts
Several plant extracts are associated with maintaining quality in meat and poultry. Rosemary and green tea extracts are both proven ingredients for their ability to positively impact the appearance, taste and quality of meat and poultry. Both contain phenolic compounds that function as antioxidants, preventing oxidative breakdown of meat pigments by being oxidized themselves.
The main difference between the two plant extracts is that green tea extract has a lower negative flavor contribution to the final product. Thus, using a lower level of rosemary extract in combination with green tea extract allows the manufacturer to increase the natural plant extract usage rate, often resulting in an extract blend that works better in the meat product than using rosemary alone.
Acerola cherry extract is also proving to be a highly effective ingredient in meat and poultry. Extracted from the namesake wild plant grown in tropical and subtropical regions, acerola extract contributes the antioxidant vitamin C. The ingredient has been shown to delay both lipid and myoglobin oxidation, thereby delaying the onset of color loss and maintaining the desirable color and quality of meat products. When used in combination with rosemary and green tea extracts, acerola is more effective at delaying early discoloration than either extract alone.
Some natural plant extracts, most notably those with high concentrations of polyphenols/flavonoids and antioxidants, have also been shown to be effective against specific pathogens. Suppliers customize blends for specific applications for both fresh and RTE meat and poultry in order to preserve color and flavor while providing protection against pathogens.
In addition to plant extracts, certain spices, fruits and vegetables are associated with preserving the color of meat. Dried plum ingredients are such an example. Not only are they a source of antioxidants, they contribute to a desirable red hue. Thus, they can be used to enhance color, often in conjunction with other ingredients.
4. Bioprotective Cultures
Building on the fermentation approach to food safety, bioprotective cultures have long been used to inhibit pathogen growth in meat and poultry. Think salami and other fermented sausages. The science here is to introduce competing microorganisms – mainly lactic acid bacteria – into the system. Through fermentation they reduce the acidity of the food, which in turn inhibits pathogens and spoilage microorganisms from growing.
While still used with traditional starter cultures to make fermented sausages, processors today often include bioprotective cultures in products such as bacon, cooked ham, cooked poultry strips and fresh sausages to provide an extra layer of safety.
5. Packaging Conditions
Oxygen and light barriers in packaging film may assist with maintaining product integrity through shelf life, in the refrigerator as well as freezer. With packaging that includes a clear window for product transparency, the colors used in printing should be considered, as some colors influence color perception of the protein.
The gas flush that goes into prepackaged meats should also be considered. The visual appeal of fresh meat and poultry may be improved when the correct mix of oxygen (to maintain desirable red color) and carbon dioxide (to impede microbial growth) is used in modified atmosphere packaging enclosures.
6. High Pressure Processing (HPP)
Also known as cold pressure technology, HPP is a method of preserving packaged food products using extremely high pressure. The process leads to the elimination of harmful bacteria while maintaining a higher yield of vitamins, minerals and enzymes, and preserving a fresher taste. The technology may be used on a variety of fresh food products, including meat and poultry, to increase shelf life without preservatives. It’s also possible to reduce sodium in HPP meat products, enabling sodium reduction claims.
The HPP system involves the loading of airtight/hermetically sealed packages into carrier baskets. These baskets are inserted into the HPP vessel, which then gets sealed by plugs. At this point, potable water gets pumped into the vessel creating isostatic pressure (equal pressure on all sides) on the packages. Product is held at a high pressure for up to six minutes, with pressures and times varying by product. This pressure disrupts the microbial biochemistry of pathogens and spoilage bacteria, which helps preserve freshness and increase shelf life.
In today’s regulatory environment, the technology is gaining importance. HPP allows food processors to achieve significant benefits in terms of food safety and extended shelf life. Meat and poultry, mostly in the form of ready-to-eat deli-type products, is one of the leading industries using HPP technology.
Interestingly, food manufacturers using HPP technology are not required to label or declare use on packaging or elsewhere. However, it makes sense to communicate use of the technology to consumers so they better understand why certain products have a long shelf life without the inclusion of preservatives.
7. Photohydroionization (PHI)
This new potential intervention to control pathogens in meat and poultry uses a combination of ultraviolet (UV) light and oxidizing gases and leaves no residual by-product on the product, thus, it may be considered a processing aid. Unlike HPP, the PHI technology does not require the use of water and uses less energy. It is recognized as a chemical-free, natural, green and environmentally friendly advanced oxidation technology that controls for pathogens, mold and yeast in meat and poultry, among other foods.
The science behind PHI is the use of non-penetrating radiation, which in the case of whole muscle meat and poultry, contamination is limited to the surface. Processors may apply PHI to whole muscle before grinding it to ensure safety. The PHI treatment does not affect the taste or appearance of the product.