Cold-particle suspension has been used for years in meat and poultry plants, but today's technology is significantly advanced.

While research projects have defined start and finish dates, development work can extend for years. Cold-particle suspension injection is a case in point. USDA standards of identity for meat and poultry allow processors to add specified trimmings and other ingredients into whole muscle cuts without changing the product's name. Besides boosting yields, injection can enhance flavor and functional aspects: boneless, skinless chicken breast makes for a dry and tasteless meal, but injecting the skin back into it restores flavor. Of course, if a processor deviates from the government rules-adds shoulder muscle, say, to a hind portion of a pig-a fanciful name such as Spam instead of ham is necessary.

A number of suspension systems began appearing in meat processing in the mid 1980s. Most eventually were withdrawn from the market. Fat buildup in the injectors resulted in frequent maintenance shutdowns and lost production. One of the early innovators was Ivo Cozzini. His Chicago-based namesake company has revised and refined the technology to overcome specific application hurdles and to adapt it for a changing processing environment. Today, the system can be found in plants throughout the world. Greg Grady, director of technical services, oversees most of the installations and product applications at Cozzini Inc. Food Engineering recently spoke with Grady as he was preparing for a three-week trip to clients in Russia, China and beyond.

FE: What are the components in a cold particle suspension system?

Grady: The preparation stage involves a brine tank and emulsifier. The operator hits a button to bring brine solution to the tank, trimmings are added to create a batch of up to a 1,000 lbs. and a positive displacement pump moves the homogeneous solution to the emulsion mill. A series of plates and knives reduce particle size, and an impeller in the emulsifier generates enough force to return the solution to the brine tank, creating a loop. Time or an increase in temperature is used to calculate when proper particle-size reduction has occurred. The process takes 3-5 minutes.

If fresh trimmings are used, the suspension goes through a scraped surface heat exchanger to reduce temperature to the 26

FE: What is included in the suspension?

Grady: It really depends on what kind of product a processor is trying to make and whether it is a premium or a commodity product. Anybody can turn up the juice, but the most money is saved in the gold-standard meats. If you follow the right procedures, you can supplement meat selling for $3 a lb. with items costing 80 cents a lb. and end up with a product that is better slicing, better tasting and with greater yield.

Typically, the suspension is one quarter meat and three-quarters brine. Cold temperature sodium is added to water to create the brine and to activate the proteins. Milk proteins, starches and carrageenan may be added. There are three types of carrageenan: lambda, kappa and iota. It sounds like a bad sorority house. Whether it's carrageenan or starch, it's critical to avoid cold-swelling ingredients that bind water and increase viscosity.

Trimmings need to have good water-binding characteristics, have a pH above 5.4 and be of a type consistent with the rules in USDA policy memo 041-B. Collagens such as skin, tendons and mechanically separated meats have excellent water-holding properties and provide excellent mouthfeel. Rework and denatured material also can be added. For cured products like corned beef, up to 200 ppm of nitrites traditionally have been added to give the meat a pink appearance. Testing confirms nitrites are evenly dispersed in the suspension.

The suspension has a milkshake-like consistency and is held as cold as the salt will allow to prevent activation of meat proteins. At 26