THE EFFECT OF PROCESSING ON STARCH

VI. THE EFFECT OF PROCESSING ON STARCH

There are many facets to a process that must be understood prior to formulating a food product. We have touched on some processes and their relationship to starch selection. We now need to relate what effects different processes may contribute, both positive and negative. The following issues have been identified as critical to the production of a suc- cessful food product.

A. Temperature Control

Temperature control does not mean just the temperature for gelatinization. The rate for heating the system and, just as importantly, the rate of cooling must be considered. Both of these are essential for providing a fixed set of conditions that can be monitored and repeated. Knowing the rates for both conditions will also help to identify the necessary equipment for scaling the system for commercialization.

B. Shear

Earlier shear was described for its degrading effect upon starch. Knowing about equipment and its shear potential is very helpful to a food technologist. Knowing when and where shear can and cannot be introduced is critical also. Many of the modified starches designed for food processing can withstand some shear. A few are specifically engineered to with- stand very high shear systems. In all cases though, starch is much more shear stable at ambient or cool temperatures as compared to elevated temperatures. Studies have shown that below 135 °F starch solutions can be processed with little shear damage. Starch in solution prior to gelatinization is very shear stable ( Table 10 ).

C. Packaging

One mistake common to many products prepared with starch relates to packaging. Too many times the same product is packaged in a variety of containers. This in most cases is not a reliable practice. Many starch-stabilized food products cannot be packaged over

a large volume range of filled quantities. An example would be hot fudge topping. Utilizing

a single correctly modified starch to achieve viscosity, texture, and stability is possible for product packaged in containers from 1 pint (0.5 L) to 5 gallons (20 L). However, attempts to package this same product in 55 gallon drums (110 L) will most likely be

Table 10 Shear Intensity Based on Equipment

Equipment

Intensity of shear

Dixie Mixer

Low

Lightnin’ Mix

Moderate

Likwifier

Moderate to high

Colloid mill

High

Homogenizer

Very high

Piston pump

Low to moderate

Gear pump

Moderate

Moyno Pump

Moderate

Centrifuge

Moderate to high

Kettle cooker

Low

Steam infusion cooker

Low to moderate

Swept surface cooker

Moderate to high

Plate heat exchanger

High

Flash cooler

High

Jet cooker

Very high

Spray-drying

Moderate to high

modified starches or a starch/gum blend. In both cases starch levels had to be adjusted, and some characteristic difference was noted in the finished topping.

D. Storage

All too often the storage of product is overlooked when initiating product development. The storage conditions used for the is food product just as important as the container. In addition to conditions, the time of storage is critical. Some foods can be stored much longer than others under the same conditions. Changes usually occur in texture during storage. Some products thin; others thicken. Others could become lumpy, grainy, or even- tually separate. Warehouse, cooler, or freezer conditions are essential to be specified. Also, the food product should be pretested in as many storage conditions as possible; one never knows what the consumer or transportation department will do.