Starches Lab Report

EFFECT OF STARCHES ON PUDDINGS ANDVISCOSITY OF PIE FILLINGS AND PASTES

I. EFFECT OF STARCHES ON PUDDINGS AND VISCOSITY OF PIE FILLINGS AND PASTES

Autumn FunderburgKitchen 4

Section 101Wednesday 2-5 P.M.T.A.: Amanda Culley

March 19, 2015

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II. Purpose

Starch is a complex carbohydrate consisting of amylose and amylopectin

molecules that are organized as granules (Brannan, 57). Amylose is a linear chain of

glucose molecules while amylopectin is a branched chain. Amylose forms the amorphous

regions of the starch granule and amylopectin forms the crystalline region of the starch

granule. Amylopectin tends to be more abundant in starches compared to amylose and the

amount of amylose and amylopectin varies from starch to starch. Cereal starches, root

starches, and tree starches are the classifications of food starches. Starch is a thickening

agent that is used in many products such as soups, sauces, gravies, salad dressings, and

desserts (Brannan, 57). This lab focuses on cornstarch, rice flour, tapioca, potato starch,

and arrowroot. The experiment demonstrates the effect of various starches on different

variations of vanilla puddings and lemon pie fillings. Demonstrated also is the effect of

various starches on viscosity of starch pastes as well as a variation using sugar and acid.

III. Methodology

Procedure A demonstrated variations of vanilla cornstarch puddings. The first

variation was homemade vanilla pudding. To start, 3 tablespoons of cornstarch and 3/8

cup of granulated sugar were mixed in a saucepan. Blended into the mixture were 2 cups

of whole milk and 1/8 teaspoon of salt. The mixture was cooked over medium-low heat

and stirred continuously to prevent scorching of the milk. The mixture was heated to a

full boiled and then boiled for 1 minute longer. Next, 1 teaspoon of vanilla extract was

added. The pudding was poured into custard cups. One was covered with aluminum foil

and one was left uncovered and both were chilled. The appearance, flavor, and texture

were evaluated. The second variation was cooked vanilla pudding mix. The pudding was

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prepared as directed on the package and poured into custard cups. One was covered with

aluminum foil and one was left uncovered and both were chilled. The appearance, flavor,

and texture were evaluated. The third variation was instant vanilla pudding mix. One

package of instant vanilla pudding was prepared as directed on the package and poured

into custard cups. One was covered with aluminum foil and one was left uncovered and

both were chilled. The appearance, flavor, and texture were evaluated. The fourth and last

variation was canned vanilla pudding. One can of vanilla pudding was opened and poured

into custard cups. One was covered with aluminum foil and one was left uncovered and

both were chilled. The appearance, flavor, and texture were evaluated.

Procedure B demonstrated the effect of various starches on lemon pie filling.

Kitchen 4 used the rice flour starch variation. To start, 2 tablespoons of rice flour, ½ cup

granulated sugar, and a dash of salt were added to a saucepan. Blended in was ¼ cup of

cold water. For 3 minutes, ¾ cup of water was boiled in another saucepan and then added

to the starch mixture. The mixture was cooked over medium heat until it was thick and

translucent. It was stirred constantly until it reached a full boil. It was then removed from

heat. Some of the hot mixture was poured into a bowl containing 1 beaten egg. The

starch-egg mixture was added back to the remainder of the hot mixture and stirred well.

The mixture was cooked over medium heat and stirred constantly until thick. The mixture

was removed from heat and 1 tablespoon of butter, 2 tablespoons of grated lemon rind,

and 2 ½ tablespoons of lemon juice were added and mixed well. The pie filling was

poured into custard cups and cooled. The appearance, flavor, and texture were evaluated.

Procedure C demonstrated the effect of various starches on the viscosity of starch

pastes. Kitchen 4 used the rice flour starch variation. To start, 2 tablespoons of rice flour

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were blended with ¼ cup of cold water to form a smooth paste. After ¾ cup of water was

boiled, it was added to the paste mixture and stirred well. The paste was poured into a

saucepan and cooked over medium heat and stirred continuously. The paste was heated

until it thickened and reached a full boil. The starch paste was set to cool to 50°C. A

Brookfield test was performed. The paste was poured into a custard cup.

Procedure D demonstrated the effect of acid and sugar on the viscosity of starch

pastes. To start, 6 tablespoons of sugar and 2 tablespoons of cornstarch were mixed.

Next, 4 tablespoons of lemon juice were mixed with ¼ cup of cold water. After, the entire

mixture was combined with ¾ cup boiling water. The pH of the paste was measured.

IV. Results

The homemade vanilla pudding, procedure A1, was off-white in color with a

glossy sheen, had a vanilla flavor, and was a sticky, smooth texture that was a gel. The

cooked vanilla pudding, procedure A2, was light yellow in color with a glossy sheen, had

very little vanilla flavor, and had a smooth texture that was partial gel. The instant vanilla

pudding, procedure A3, was light yellow in color, had a slight vanilla flavor, and had a

smooth texture that was a partial gel. The canned vanilla pudding was very light yellow

in color, had a strong vanilla flavor, and had a smooth, sticky texture that was gel.

Table 1

Procedure APudding Variation Appearance Flavor TextureCanned Very light yellow,

glossyStrong vanilla

flavor Smooth, sticky, gel-like

Cook ‘N’ Serve Light yellow, glossy Little vanilla flavor, bland Smooth, partial gel

Homemade Off-white, glossy Vanilla flavor Sticky, smooth gelInstant Light yellow Slight vanilla flavor Smooth, partial gel

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The lemon pie filling using the rice flour variation was light yellow in color with

a glossy sheen, had a strong lemon flavor, and had a smooth, sticky texture that was gel.

The lemon pie filling using the cornstarch variation was yellow in color with a glossy

sheen, had a lemon flavor, and had a gritty, gel texture. The lemon pie filling using the

tapioca variation was yellow in color with a glossy sheen, had a strong lemon flavor, and

had a gritty, gel texture. The lemon pie filling using the potato variation was yellow in

color with a glossy sheen, had a light lemon flavor, and had a smooth gel texture. The

lemon pie filling using the arrowroot variation was dark yellow in color, had a lemon

flavor, and a sticky, gritty texture.

Table 2

Procedure BStarch Variety Appearance Flavor TextureRice Flour Light yellow, glossy Strong lemon flavor Smooth, sticky, gel-like

Corn Starch Yellow, glossy Lemon flavor Gritty, gel-like

Tapioca Yellow, glossy Strong lemon flavor Gritty, gel-like

Potato Yellow, glossy Light lemon flavor Smooth, gel-like

Arrowroot Dark yellow Lemon flavor Sticky, gritty

Kitchen 1 used 2 tablespoons of cornstarch, ¼ cup of cold water, and ¾ cup of

boiling water in the starch paste variation. The viscosity of the paste at 50°C was

determined to be 12.2 million cP and a gel. The viscosity of the paste at room

temperature (23°C) was determined to be 9 million cP. Kitchen 2 used 2 tablespoons of

potato starch, ¼ cup of cold water, and ¾ cup of boiling water in the starch paste

variation. The viscosity of the paste at 50°C was determined to be 48.2 million cP and a

gel. The viscosity of the paste at room temperature (23°C) was determined to be 94.6

million cP. Kitchen 3 used 2 tablespoons of tapioca, ¼ cup of cold water, and ¾ cup of

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boiling water in the starch paste variation. The viscosity of the paste at 50°C was

determined to be 10 million cP and a gel. The viscosity of the paste at room temperature

(23°C) was determined to be 25,000 cP. Kitchen 4 used 2 tablespoons of rice flour, ¼

cup of cold water, and ¾ cup of boiling water in the starch paste variation. The viscosity

of the paste at 50°C was not determined, but the paste did gel. The viscosity of the paste

at room temperature (23°C) was determined to be 8 million cP. Kitchen 5 used 2

tablespoons of arrowroot, ¼ cup of cold water, and ¾ cup of boiling water in the starch

paste variation. The viscosity of the paste at 50°C was not determined, but it did not form

a gel. The viscosity of the paste at room temperature (23°C) was determined to be 580

million cP. Kitchen 6 used 2 tablespoons of cornstarch, ¼ cup of cold water, and ¾ cup

of boiling water in the starch paste variation. The viscosity of the paste at 50°C was

determined to be 25,000 cP and a gel. The viscosity of the paste at room temperature

(23°C) was determined to be 31,000 cP. Kitchen 7 used 2 tablespoons of potato starch, ¼

cup of cold water, and ¾ cup of boiling water in the starch paste variation. The viscosity

of the paste at 50°C was determined to be 48.2 million cP and a gel. The viscosity at

room temperature (23°C) was determined to be 94.6 million cP. Kitchen 8 used 2

tablespoons of tapioca, ¼ cup of cold water, and ¾ cup of boiling water in the starch

paste variation. The viscosity of the paste at 50°C was determined to be 10 million cP

and a gel. The viscosity of the paste at room temperature (23°C) was not determined.

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Table 3

Procedure C

Starch Type Viscosity (50C) Gel? Viscosity (Room Temp)

Rice Flour N/A Yes 8 million

Cornstarch 12.2 million Yes 9 million

Cornstarch 25,000 Yes 31,000

Tapioca 108 million Yes N/A

Tapioca 10 million Yes 25,000

Potato 48.2 million Yes 94.6 million

Arrowroot N/A No 580 million

Procedure D demonstrated the effects of acid and sugar on the viscosity of starch

pastes. Kitchen 1 used 2 tablespoons of cornstarch, 6 tablespoons of sugar, and 1 cup of

water in the starch paste variation. The viscosity of the paste was determined to be 4

million cP at 50°C with little to no gelling. The viscosity at room temperature (23°C)

was determined to be 3 million cP. Kitchen 2 used 2 tablespoons of cornstarch, and 1 cup

of water in the starch paste variation. The viscosity of the paste was determined to be 25

million cP at 50°C with little to no gelling. At room temperature (23°C), the viscosity

was not determined. Kitchen 3 used 2 tablespoons of cornstarch, 4 tablespoons of lemon

juice, and ¾ cup of water in the starch paste variation. The viscosity of the paste was

determined to be 35 million cP at 50°C with gelling. The viscosity of the paste at room

temperature (23°C) was determined to be 35 million cP. Kitchen 4 used 6 tablespoons of

sugar, 2 tablespoons of cornstarch, 4 tablespoons of lemon juice, and ¾ cup of water in

the starch paste variation. The viscosity of the paste at 50°C was not determined, but

there was partial gelling of the paste. The viscosity of the paste at room temperature

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(23°C) was determined to be 13 million cP. Kitchen 5 used 2 tablespoons of cornstarch,

and 1 cup of water in the starch paste variation. The viscosity of the paste at 50°C was

not determined, but there was gelling of the paste. The viscosity of the paste at room

temperature (23°C) was determined to be 18,600 cP. Kitchen 6 used 6 tablespoons of

sugar, and additional 2 tablespoons of cornstarch, and 1 cup of water in the starch paste

variation. The viscosity of the paste at 50°C was determined to be 4 million cP with little

to no gelling of the paste. The viscosity of the paste at room temperature (23°C) was

determined to be 3 million cP. Kitchen 7 used 2 tablespoons of cornstarch, 4 tablespoons

of lemon juice, and ¾ cup of water in the starch paste variation. The viscosity of the paste

at 50°C was determined to be 6 million cP with gelling of the paste. The viscosity of the

paste at room temperature (23°C) was determined to be 20 million cP. Kitchen 8 used 6

tablespoons of sugar, 2 tablespoons of cornstarch, 4 tablespoons of lemon juice, and ¾

cup of water in the starch paste variation. The viscosity of the paste at 50°C was not

determined but there was partial gelling of the paste. The viscosity of the paste at room

temperature (23°C) was 13 million cP.

Table 4

Procedure DVariation Viscosity (50C) Gel? Viscosity (Room

Temp)A 25 million Little/none 18,600

B 4 million Little/none 3 million

C 35 million Yes 35 million

D N/A Partial 13 million

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V. Discussion

The canned pudding took the least time to prepare of all the pudding variations.

The homemade pudding variation took the most time to prepare. The changes that took

place in the pudding mixtures to indicate that gelatinization had occurred included

swelling of water into the starch granules and thickening of the puddings. The gels then

had a glossy sheen and were firm.

Agitation was important for this pudding while heating to keep the milk from

scorching. However, when cooling, it was important for the pudding to be left without

agitation so as to not disrupt the hydrogen bonds in the pudding (Starch PowerPoint, slide

26). The homemade pudding variation was the only one to be more off-white in color.

This can be attributed to the fact that there is no artificial dyes present as with instant,

canned, and cooked puddings. The process of heating and cooling this pudding was

different as well, compared to canned, cooked, and instant puddings.

The starch ingredient present in the instant pudding, the cook‘n’serve pudding and

the canned pudding was modified food starch. This starch is pre-gelatinized and cooked

with water to gelatinize. For instant and cooked puddings, the starch is then dehydrated

after becoming swollen resulting in a desirable thickness when water is added (Starch

PowerPoint, slide 35). This would also be ideal for commercial canned puddings,

however the starch is rehydrated and then canned. Cornstarch forms a translucent,

satisfactory gel and is ideal for instant puddings (McWilliams, table 9.6). Modified

cornstarch, in this case, is used to thicken the pudding much faster than a more

conventional non-modified starch. This includes a lower gelatinization temperature (Aini,

2010). This would explain why the pudding was able to partially gel so quickly for the

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instant and cooked puddings. Oxidized cornstarch is used in the food industry for

products that require low viscosity and neutral taste (Aini, 2010). The instant pudding

had a very faint vanilla flavor and was light yellow in color. The cook‘n’serve pudding

had a very bland flavor and was light yellow in color. The canned pudding had a light

yellow color and a strong vanilla flavor. The stronger flavor in canned pudding can be

attributed to the fact that it has more time to react with the sugar and artificial flavors.

Retrogradation was enhanced in all pudding variations. Refrigerating the

puddings speeds up the cooling process of the puddings and the tightening of the starch

network that forms during gelatinization is able to perform more quickly.

Procedure B determined the effect of starch variety on lemon pie filling. All of the

variations were a glossy, yellow gel except for the arrowroot variation. The arrowroot

lemon pie filling variation was dark yellow in color and was not gelled. This may be a

factor of egg yolk protein coagulation. Egg yolk added to a gelatinized starch mixture

needs to be heat sufficiently for proper coagulation or the cooled thickened mixture does

not gel (Starch PowerPoint, slide 27).

In the case of the pie fillings, the amylose molecules oriented themselves in

crystalline regions in retrogradation (Starch PowerPoint, slide 29). All the lemon pie

fillings experienced retrogradation except for the potato variation. It was the only filling

that did not have a gritty texture when sampled; it was a smooth gel. The rice flour

variation, cornstarch variation, tapioca variation, and arrowroot variation all had texture

that was detected on the tongue.

Procedure C determined the effect of starch variations on starch pastes. Viscosity

is the measure of a fluid or gel’s resistance to flow. To determine a fluid’s viscosity, first

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find the spindle number used. In most cases in this experiment it was spindle number 7.

There are then four speeds (2, 4, 10, and 20) that help to determine a factor. In most cases

in this experiment the speed that was used was 20. Each spindle number and speed

number determine different factors. The dial reading multiplied by the factor number

equals the viscosity in centipoises (cps). Viscosity of starch paste will increase during

cooling when the re-association of amylose molecules develops new gel structure (Aini,

2010). Cold viscosity is the viscosity that is maintained at 50°C for 15 minutes (Aini,

2010). Setback viscosity is the increase in viscosity when the starch paste is cooled (Aini,

2010).

The viscosity of the starch paste that used the cornstarch variation when cooled to

50°C was determined to be 25,000 cP (.013 x 2M = 25,000) for one kitchen and 12.2

million cP (6.1 x 2M = 12.2M) for another kitchen. The viscosity of the starch paste that

used the cornstarch variation when cooled to room temperature (23°C) was determined to

be 31,000 cP (.015 x 2M = 31,000) for one kitchen and 9 million cP (4.5 x 2M = 9M) for

another kitchen For both variations the viscosity decreased. This determines that

cornstarch pastes are thicker when hot and thinner when cooled. The cold viscosity of the

starch paste that used the rice flour variation when cooled to 50°C was not determined.

This was an experimenter error; the directions were misunderstood and the Brookfield

Viscometer was having issues finding a reading. Although the viscosity of the rice flour

starch paste variation was not determined, the product still gelled and the setback

viscosity when cooled to room temperature (23°C) was determined to be 8 million cP (4

x 2M = 8M). The cold viscosity of the starch paste that used the potato starch variation

when cooled to 50°C was determined to be 48.2 million cP (24.1 x 2M = 48.2M). The

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setback viscosity when cooled to room temperature (23°C) was determined to be 94.6

million cP (47.3 x 2M = 94.6M). The product gelled. The cold viscosity should be higher

in this case because the hotter potato starch is, the thinner it should be. As the starch paste

cooled, the force decreased meaning that the cooler it got, the less viscous the product

became. The cold viscosity of the starch paste that used the tapioca starch variation when

cooled to 50°C was determined to be 108 million cP (54 x 2M = 108M) for one kitchen

and 10 million cP (5 x 2M = 10M) for another kitchen. The setback viscosity when

cooled to room temperature (23°C) was not determined for one kitchen and was 25,000

cP (.013 x 2M = 25,000) for another kitchen. One kitchen most likely misunderstood

directions and only did one viscometer reading for the starch paste. The second kitchen

had a proper reading in which the tapioca starch paste became more viscous as the

product cooled to room temperature. The cold viscosity of the starch paste that used the

arrowroot starch variation when cooled to 50°C was not determined. The setback

viscosity when cooled to room temperature (23°C) was determined to be 580 million cP

(290 x 2M = 580M). The product did not gel. This explains the very large viscosity

reading meaning the product was not viscous.

As with procedure C, viscosity was measured when acid and sugar were added to

the pastes. The same formula was used to determine viscosity readings in both

procedures C and D. To determine a fluid’s viscosity, first find the spindle number used.

In most cases in this experiment it was spindle number 7. There are then four speeds (2,

4, 10, and 20) that help to determine a factor. In most cases in this experiment the speed

that was used was 20. Each spindle number and speed number determine different

factors. The dial reading multiplied by the factor number equals the viscosity in

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centipoises (cps). Cold viscosity is the viscosity that is maintained at 50°C for 15 minutes

(Aini, 2010). Setback viscosity is the increase in viscosity when the starch paste is cooled

(Aini, 2010). Pasting temperatures greatly increase at higher sugar concentrations,

however, the sugar added decreases the viscosity of the paste due to the sugar’s ability to

tie up water (Brannan, 57). Acid added to a starch paste decreases viscosity of the paste

by hydrolyzing the starch to form smaller dextrin molecules (Brannan, 57).

The cold viscosity of variation A at 50°C was determined to be 25 million cP

(12.5 x 2M = 25M). The setback viscosity of variation A at room temperature (23°C) was

determined to be 18, 600 cP (.009 x 2M = 18,600). There was little to no gelling in this

variation. Variation A became more viscous after the product had cooled to room

temperature. The cold viscosity of variation B at 50°C was determined to be 4 million cP

(2 x 2M = 4M). The setback viscosity at room temperature (23°C) was determined to be

3 million cP (1.5 x 2M = 3M). There was little to no gelling. Viscosity should have

decreased with the addition of 6 tablespoons of sugar in this variation, however, viscosity

increased. Sugar decreases viscosity because the sugar has the ability to tie up water.

The cold viscosity of variation C at 50°C was determined to be 35 million cP (17.5 x 2M

= 35M). The setback viscosity at room temperature (23°C) was determined to be 35

million cP (17.5 x 2M = 35M). The product gelled. The viscosity of this variation neither

increased nor decreased. With the addition of acid, 4 tablespoons of lemon juice, the

viscosity should decrease because the starch is hydrolyzed to form smaller molecules.

The cold viscosity of variation D at 50°C was not determined. The setback viscosity at

room temperature (23°C) was determined to be 13 million cP (6.5 x 2M = 13M). There

was partial gelling. If the cold viscosity had been determined, it should have been more

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viscous than the setback viscosity. With the addition of 6 tablespoons of sugar and 4

tablespoons of lemon juice, the sugar would tie of the water and the acid would hydrolyze

the starch.

VI. Summary and Conclusions

To conclude, starches are an important component in foods. Both amylose and

amylopectin molecules make up starch. The main cereals that are used as sources of

starch include corn, wheat, rice, oat, barley, and rye (McWilliams, 173). Starches are

used as thickeners in soups, sauces, gravies, salad dressings, and desserts (Brannan, 57).

Unmodified starches, any grain, root, or tuber starch, are available for commercial food

products (McWilliams, 175). Modified starches are developed with unique characteristics

that are useful in instant foods, such as instant pudding, gravy, and cake mixes. Modified

starch allows products to thicken faster and have a lower viscosity and a neutral taste.

With many starch options, the starch needs to be well suited to the specific requirements

of the item being formulated in commercial foods (McWilliams, 181). These

requirements can include low-calorie options, mouthfeel, and freeze-thaw stability.

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VII. References

Aini, N., & Purwiyatno, H. (2010). Gelatinization properties of white maize starch from

three varieties of corn subject to oxidized and acetylated-oxidized modification.

International Food Research Journal. 17(4). 961-968.

Brannan, Robert. Nutrition 2220 Lab Manual. 2014. Print.

McWilliams, Margaret. (2001). Foods: Experimental Perspectives (4th ed.).

Upper Saddle River, NJ: Prentice Hall, Inc.

Sun, Q., Xing, Y., Qiu, C. & Xiong, L. (n.d). The Pasting and Gel Textural Properties of

Corn Starch in Glucose, Fructose and Maltose Syrup Plos One, 9(4).

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