Starch Based Fat SubstitutesThere are many different fat substitutes on the market. They are often used as binders to maintain juiciness and tenderness in low fat meat products.

There are many starch based fat substitutes used in the food industry. The reasons for this are:

o Starches readily bind water o Low Cost o Familiar ingredient technology o Positive acceptance by consumer

Table 1: Selected Fat Substitutes

The following table describes the properties of starch based fat substitutes.

Table 2: Description of Starch Based Fat SubstitutesProperty Characteristic

Gel Strengthrepresents gelling abilityRigidity Modulus

Gelatinization TemperatureWater Solubility water and fat binding abilityParticle Size

slicing characteristicsApparent Viscosity

Flavour / Aroma flavour enhancementWater Absorption

ability to improve cooking yieldsWater Holding CapacitypH/ Electrical Conductivity ability to be utilized in foodColour colour

Determination of the properties of the different starch based fat substitutes is useful for proper product design. Below are a series of graphs showing the properties of several commercially designed products. Use the graph to answer the questions provided. Refer to table 1 for identification of selected fat substitutes.

The peak G values indicate the formation of stable, stiff and elastic matrix structures of typical heat induced protein gels.

Shear rate is a measure of how fast a batch of sample is being spun under a viscometer which is measuring the apparent viscosity of the sample. Newtonian fluids is discriptive of a shear rate that does not affect the viscosity of the liquid. Most foods however demonstrate non-Newtonian behavior. For example, the apparent viscosity decreases with increasing shear rate. This is commonly called shear thinning. The accompanying graph shows how the fat-substitutes undergo shear thinning. This character can be problematic if the food has to undergo a lot of mixing or travel through many pipes and channels, hence being subjected to increasing amounts of shear stress. For example, with proteins, apparent viscosity is a function of protein type (molecular size, shape, surface charge, type, concentration), pH, temperature and shear rate.

Starch GranulesFocus on morphology and degradation

Hydrolysis of starches is important in the production of foods where reducing sugars are needed. Some examples include corn syrups, beer and bread. Recall that reducing sugars effect non-enzymatic browning, alter texture and change the sweetness and water activity of foods. In the case of brewing and bread making the sugars are utilized by microoganism for growth and fermentation.

Below are two photographs of starch granules acquired using the scanning electron microscope (SEM)

Potato Starch - Notice the smooth surface - no pores

Corn Starch - Notice the pores on the corn starch. These openings may be the site of initial enzyme attack. Essentially they allow enzymes direct access to the center of the granule interior.

Ref: Fannon, J.E., R. J. Hauber and J. N. BeMiller. Surface pores of starch

granules. Cereal Chemistry 69(3):284-288.

Table 1 Amylases and Their Functional Characteristics

Name Type Function Resulting Properties of the Starch

a - Amylase Endo-enzyme

Hydrolyses (cleaves) the a-1,4- glucan linkages in a random manner.

Rapid decrease in viscosity. Generation of reducing groups.

B - Amylase Exo-enzyme

Removal of maltose units from the non-reducing end of starch by hydrolyzing alternate 1,4- glycoside linkages except those three units away from the branch point.

Production on maltose increases the sweetness on a solution.