Food component and processing interactions should be considered during production scale-up or troubleshooting.

You always hear about how companies are worried that their proprietary processes could be stolen. If the processes are so easy to steal, how come you can't make the same product on two different lines in the same plant?" once asked a product developer.

Experiencing such frustrations during production scale-up or trouble-shooting testifies to the fact that even small equipment differences have an impact on finished products. In turn, ingredients also influence production parameters.

Here's a look at three ingredient categories: Stabilizers, flavors and fats and how they are impacted by (and interact with) extrusion, heat, and frying processes, respectively..

Extruders are virtually stand-alone processing systems. Within an extrusion barrel, mixing and pre-wetting of raw materials first occurs. The dough is then cooked and increasingly compressed as well as subjected to increasing shear before the mass is expelled through a die, cut and expanded.

Emulsifiers are added as lubricants. For example, one rice bran extract is touted to reduce wear and tear on the equipment, decrease torque and improve definition of complex extruded shapes. Emulsifiers such as sodium stearoyl lactylate or monoglycerides also complex with starch to inhibit granule swelling and improve dough flow.

Starch characteristics and amount of water are critical to extruded product quality. If the amount of water is too low, the product won't flow or be sufficiently "plasticized" for proper expansion. However, excessive water results in limited work input and inferior, less dense product.

Stabilizers such as gum arabic or a low-viscosity CMC also work as lubricants, says Florian Ward, vice president of R&D with a supplier. Their water-binding ability results in a less friable product with improved mouthfeel, she adds. In addition, they can also save energy. See chart at right.

Preconditioning (preheating and pre-wetting) raw material components improves the flavor and texture of high-pressure extruded products. It eliminates time and energy otherwise needed to hydrate the components in the main barrel.

"Water - rather than heat - transfer controls the rate of the preconditioning process, since heat transfer is much faster," notes J.M. Bouvier with Clextral SA. "Also, the preconditioner's shaft speed (rather than throughput) significantly affects flow through the unit, which in turn affects water transfer. For example, well-mixed flow patterns at shaft speeds above 150 rpm optimize water transfer, whereas low shaft speed (below 120 rpm) can cause plug flow."

Ingredients, such as prehydrated gums and starches designed to quickly hydrate - also positively impact extruder performance, adds Ward.

Heated Issue

In the area of heat processed products, the "hot" news is FDA's acceptance of Tetra Pak's process filing which permits aseptically processed particulate foods to be manufactured for the U.S. market. (See article on page 93.) "Shelf-stable food products containing chunks of meat or vegetables in a new array of packaging options will eventually be available," says Chuck Sizer, general manager of the Tetra Pak Pilot Plant. This is big news for formula developers as well.

In heat processes, time and temperature inactivate microorganisms and enzymes [ILLUSTRATION FOR CHART OMITTED]. Heat processing impacts flavor by developing and enhancing some flavor components, but also by increasing the loss of others. This occurs by loss of volatile components through volatilization (loss to the atmosphere), flavor constituents reacting with other food components (e.g., aldehydes with amino acids), and, degradation or breakdown of flavorings. Also, "people tend to overlook the flavor development from the base material in the food system. Additionally the absorption of flavors into macromolecules (e.g., flavors entrapped in starch's amylose helix) can be a challenge," says Dan Wampler, vice president and technical director with a flavor supplier.

The new aseptic processing for foods with particulates will subject products to less prolonged high heat exposure, which should improve flavor compared to canned product.

Indirect heating methods, such as tubular or plate heat exchangers, work well and regenerate energy, but can be detrimental to product flavors - again due to longer heating and cooling times as compared to HTST (high temperature/short time) and UHT (ultra-high temperature) methods. HTST and ultrapasteurization reduce overall time of heat exposure by increasing processing temperatures.

Suppliers have developed flavorings that are touted for their heat stability. "As long as the flavors have been subjected to the appropriate thermal conditions in the food system under consideration, the flavors should perform well. This, however, is a significant challenge that cannot be generalized to any individual process," says Wampler.

To obtain the most appropriate flavor, product developers should communicate to their supplier what other food components are present. For example, will a strawberry flavor be added to a food with actual strawberries? Are there starch, gums or other carbohydrates present? And, what is the processing methodology?