A STARCH SELECTION

V. A STARCH SELECTION

Too many times a food technologist or formulation scientist initiates a formulation profile without analyzing the ingredients. In addition the same person will rely on past recipes or formulations to establish their baseline. This can be a critical error. Not to say that the use of existing formulas is not a good idea but too many times we do not consider all the parameters before beginning our research. By simply asking a few questions pertaining to what you want and requesting input from suppliers about their respective ingredients, research could save you a lot of time and expense. Unfortunately, many suppliers are not aware of how their ingredients might interact with other ingredients under a variety of conditions. What they have studied may not be relevant to your system. The following questions should be asked when selecting a starch. For additional information see Table 9 .

A. What Is the Desired Function of the Starch Being Added

Considering the food product, is the starch expected to provide only one function or act as a multiple function ingredient? The answer to this question could help identify whether one starch or a blend of starches is required. If it is a blend that is required, then the ratio between starches becomes critical as related to the physical properties ultimately desired. Answering just this one question directs many of the choices regarding starch selection.

B. What Is the Method of Processing Being Considered?

This question is designed to identify whether you are going to cook the starch-containing food or not. If it is a dry mix or a noncooking preparation, we have possibly identified the need to consider instant starches, perhaps not exclusively, but we should consider them. If cooking is required, from a cost and functional standpoint a cook-up starch would

be first choice. For foods that are dry mixes, we will have to consider what happens when the consumer interacts with the product before we can make a selection.

C. What Is the Food System pH?

The acidity of the food is extremely important. Because foods can be hot filled at pH ⬍4.6, knowing the finished food pH is important. Acids possess different pK values and

therefore food technologists should consider the total acidity of the food system. Using titration for total acidity is more accurate. The pH considered neutral for starch is not 7. Those foods having a measurable pH of at least 4.6 or higher are considered neutral. Typically a pH value above 7.5 is self-regulating due to off-flavors being generated. Neu- tral foods expected to retain long shelf-life require sterilization. The sterilization process requires temperatures above atmospheric and thus dictates starch selection. Foods having extreme or high acidity, less than pH 3.5, possess the potential to hydrolyze starch. There- fore starch selection will be determined by degree of crosslinking and textural properties.

Table 9 Questions to Ask Before Selecting a Starch 1. What is the desired function for the added starch?

a. thickener e. binder b. stabilizer

f. bulking agent c. texturizer

g. d. emulsifier

2. What is the processing method? a. cooking (liquid)

c. dry mix b. noncook (liquid)

d. 3. What is the pH of the food system?

a. ⬎4.5 c. ⬍3.5 b. ⬍4.5

d. 4. What is the percent soluble solids (ingredients that hydrate water)?

a. ⬎45% d. ⬍20% b.⬍45%

e. c. ⬎55%

5. What is the shelf-life expectancy? a. ⬍30 days

c. ⬎1 year b. 1–6 months

d. 6. How will the finished product be stored?

a. ambient temperature b. frozen

c. 7. What is the desired product texture?

a. smooth c. grainy b. nonsmooth

d. 8. What is the desired eating quality (mouth-feel)?

a. creamy d. jelly b. fudge

e. c. pasty

9. What is the desired surface appearance? a. sheen

d. translucent b. opaque

e. c. dull

10. How and when will you measure or determine viscosity? a. Visco-Amylo-Graph

e. Fluidity (funnel) b. Brookfield

f. Rapid-Visco-Analyzer c. Bostwick

g. d. FMC brabender

11. Is high or excessive shear introduced? a. homogenization

d. direct steam injection b. milling

e. pumping ⬎25 ft hot c. vacuum

f.

Table 9 Continued 12. Will the process involve one or more of the following?

a. hot filling e. blast or quick freezing b. ambient filling

f. reheating (reconstitution) c. refrigeration

g. steam tables d. slow freezing

h. 13. If fat is used, what type?

a. liquid d. lard b. solid

e. c. shortening

14. Are salts utilized? a. what type? b. percent? c. blends?

d. 15. Are other hydrocolloids used?

a. what type? b. blends?

c. 16. Is the final product a dry mix? 17. If yes to No. 16, does the process involve the following?

a. blending c. extruding b. agglomerating

d. 18. Is moisture content of the added starch critical? 19. If a dry mix, what is the anticipated packaging?

a. paper d. heat sealed b. wax coated

e. c. poly-lined

20. If not a dry mix, what is the anticipated packaging? a. glass

e. paper b. can

f. plastic c. pouch

g. tote d. drums

h. 21. Is the added starch to be used in more than one product? If yes, consider similar events for

the other products and identify the critical functions contributed by the starch. 22. How important is ingredient economics?

a. very c. quality dependent b. not very

d.

The food systems that range between pH 3.5 and 4.6 offer several starches for selection. The texture, process, and other handling parameters will determine the starch of choice.

D. Does the Process Contribute High Shear?

Knowing the answer to this question aids the technologist to determine how to maintain granule integrity. If this is not important, an instant starch may be acceptable. However, if water management is critical, granule stabilization is also. Shear is similar to heat and acidity; it can destroy starch granules. Simple milling can fracture granules; consider what high shear homogenization or vacuum could do to starch under stress conditions.

E. What Percent Soluble Material Will Be Present?

Ingredients that hydrate water limit the available water for granule swelling and generating viscosity. They do so not so much by taking on the water, but by reducing the water directly available. Starch requires minimum levels of water to be fully functional. When other soluble material is present and elevates the total soluble solids to greater than 45%, the starch has a tendency to limit hydration under atmospheric conditions. At soluble solids less than 20%, starch typically is incapable of adequately managing the water that it could if the solids were greater than 20% but less than 45%. Therefore, to do so the technologist must increase the percentage of added starch.

F. Is One of the Following Used: Fats, Salts or Gums?

As with soluble solids two of these ingredients hydrate water and can significantly alter the hydration and functional potential of any incorporated starch. Gums, like starches, contribute to viscosity and texture. They can also influence mouth-feel or eating quality. Because they compete for water, they can cause latent starch hydration, or not allow it to hydrate at all. This then could contribute to a starchy flavor (off-taste). Salts, too, hydrate water, but more importantly they can be thermally active. In other words they may retain or store heat, thus potentially causing starch over cook, as well as alter flavors. Lipids or fats obviously do not hydrate the water, but can alter the hydration rate of added starches. This can be accomplished by coating the starch with fat or using the fat to coat other ingredients. Therefore knowing the type of fat is important. If it is a hard fat, knowing the melting point is important. All of these are critical for preparing a dry mix. Incorrect ingredient addition can not only change hydration rates, but also contribute to final product characteristics.

G. Is the Final Product Subjected to Postprocessing?

Having the knowledge of what is going to happen to the finished food is critical. If the consumer is going to bake, microwave, or subject it to steam heating for prolonged periods, the technologist’s choice of starch and processing will be very important. The technologist should ensure the product going to the consumer is capable of meeting the requirements demanded. Therefore, process specifications from the consumer are necessary prior to formulating.

H. How Will the Product Be Stored?

Storage of the food product is sometimes as important as the preparation. Knowledge of Storage of the food product is sometimes as important as the preparation. Knowledge of