Photo courtesy of Jeff Sindelar

Casings are a critical component for successfully manufacturing processed meat products. By definition, they serve as a governing force in the conversion of a meat batter or meat mixture into a final sausage or processed meat product.

Without them, we simply cannot produce the variety of products found in the marketplace possessing important consistency and uniformity properties. The casings most commonly used today fall under the general classifications including cellulose (skinless), regenerated collagen, natural, fibrous, cloth or plastic.

Some of the casings listed have changed very little since their early development (i.e. natural) while others have been dramatically improved due to a host of reasons including better raw materials, improved casing manufacturing procedures or the advent of new casing technologies such as pre-coating/pre-treatments.

Although casings have been utilized in the meat industry for decades (cellulose and regenerated collagen technologies developed in late 1920s), the practice of pre-treating casings with a coating containing ingredients such as flavorings, colorings or antimicrobial ingredients is a new technology with widespread application occurring in just the last 30 years.

Pre-coating/treating is technology in which a manufactured casing is treated, modified or even newly developed to result in a characteristic or benefit which can lead to improvements in performance or functionally that the original version could not provide.

Several options exist when reviewing the technology of pre-coating/treating including the casing type being coated/treated (i.e. collagen, fibrous, cloth, etc.), casing configuration (i.e. tubed, flat stock, etc.) and the specific ingredient or substance added to the casing. An array of different ingredients can be impregnated or coated in or on the casings themselves.

Natural smoke condensate (also known as liquid smoke) impregnation is one of the most common types of casing treatment. However, other ingredients such as flavorings and spices are also readily used in casing treatments.

Smoke condensates comprise one of the most useful applications for pre-coated/treated casings due to the high demands of today’s ham manufacturing processes. Beginning in the 1970s, fibrous casings impregnated with natural smoke condensates started being utilized commercially for the manufacture of various processed meat products.

By impregnating the manufactured fibrous casing with a liquid solution of smoke condensate, the length of thermal processing time can be significantly reduced while improved external color and flavor uniformity can be achieved. A pretreated casing, having a uniform concentration of smoke condensate applied throughout the casing, helps result in less smoke-related variation and problems due to smokehouse or operator induced inconsistencies.

These improvements can be found not only within a batch but also from batch to batch. Depending on the specific application (cured, uncured, whole muscle, comminuted, etc.) and the desired final appearance, a variety of smoke condensates can be utilized. However, special consideration must be taken during thermal processing to ensure optimum application parameters are met which are similar to those required for drenching, showering or atomizing smoke condensate applications. Achieving and maintaining optimum product surface conditions during critical smoke absorption and color development stages are vital for success.

Smoked impregnated nettings can offer the benefit of having the ability of holding a higher amount of smoke condensate for measurably higher transfer amounts which can result in improved color and flavor characteristics. In severe situations, an undesirable rind formation can result due to a higher than normal amount of surface protein cross linking from low pH smoke condensates. Netting applications can also create other negative effects such as over drying and peelability problems due to the faster drying rate properties of the netting material. This is most often addressed by proper adjustment of smokehouse cycles and/or inclusion of a release agent.

Multi-layer casings composed of fibrous material laminated with moisture impermeable plastic such as nylon or polyethylene have been developed and are gaining widespread industry usage. These casings offer the ability to combine the benefits of a smoke impregnated fibrous material with a moisture impermeable environment. Smoke condensates with a higher acidity and greater concentrations of phenol and carbonyl compounds can allow for greater color uniformity with improved transfer and depositing of smoke flavors/aromas.

Further, the moisture impermeability of the casings, creating a cook-in-bag product environment, offers significant improvements for food safety as well as shelf life as the product is not exposed to a post-processing environment.

A variety of flavoring applications can also be included in casing treatments similar to those previously described. However, application is generally more straightforward as there is typically less need for stringent product surface conditioning and other processing controls. Flavors ranging from oil-fried to a vast number of herbs, aromatics or other flavorings can be added via coating or impregnating which can offer an immediate product line expansion.

Spices coated on the inside of cloth, fibrous or plastic casings are available in a number of mixtures, seasoning profiles and grind sizes. They offer a unique and attractive product appearance with new and distinctive flavor profiles. Adhered to the casing walls by starch or sugar molecules, spice particles are released and transferred to the product surface upon moisture absorption and heating during thermal processing which dissolves and breaks the particle-to-casing bond.

Pre-coated/treated casings are a technology that can offer a number of advantages to processors including increased product throughput, improved finished product quality and uniformity, expansion of an existing product line, and even improved shelf-life and food safety. With a multitude of options for casing and ingredient choices, this technology has allowed for a growing number of different