Based on the linespread test, which starch was most viscous?- Starch E. The larger the linespread values the more the starch paste spread and the thinner it is. Starch E spread the least.
Based on the percent sag test, which starch dispersion most likely had the firmest gel?
- Starch E had the lowest % sag meaning it had the firmest gel.
Based on amylose (%), which starch-water dispersion would you expect to have the firmest gel?
- Starch B would be assumed to have the firmest gel as it has the highest amylose. Of course the assume is all things were equal except for the five experiments.
Based on iodine absorption, which starch would you expect to have the most viscous starch-water dispersion?
- Starch E would have been expected to be the most viscous starch-water dispersion. The less iodine absorption the less amylose. One would expect the less amylose the more amylopectin and more viscous.
Based on the linespread, which starch was most likely a waxy cornstarch?
- if only one cornstarch was a waxy cornstarch, the dispersion would have been Starch E. This is the most viscous starch dispersion.
Based on the percent sag, which starch most likely was a high amylose starch?
- Starch E would have likely been high amylose starch as it should have given a firmer gel than normal cornstarch.
Based on the percent sag, which starch most likely had the lowest pH of the water-acid dispersion?
- The low pH of the water-acid dispersion would have been less viscous and would have a less firm gel. The 99% sag gel, starch A, would fit this description; however, it would also likely have complete starch dextrinization. The amylose polymers would not crossbond to trap water in pockets.
Based on the percent sag, which of the following most likely had corn oil added to the dispersion versus the same percentage butter?
- Both of these would likely have a higher percent sag than a regular cornstarch dispersion. Of the two, the butter would likely have the highest % sag as it is more likely to have free fatty acids or mono- and diglycerides.
Based on percent sag, which starch dispersion was likely cooked to 90C the fastest (at a speed 5 that of optimum)?
- Generally, the faster it cooks the thinner it will be. For example, heating slower in a double boiler will make a thicker starch paste than over direct heat. Because the starch granule doesn't swell as well and amylose doesn't "dissolve" off I would expect Starch A to be the answer. however, that is a little unrealistic likely as it means no gelation.
Based on endpoint temperature alone, which starch would you say with greatest assurance had lost its characteristic of birefringence?
- Based on birefringence, I would say that Starch A is most likely to be the most gelatinized. Loss of birefringence is the loss of the maltese cross in the granule when looked at through a polarizing microscope.
On the basis of amylose (%) in the cornstarch, which treatment would likely give the firmest gel?
- Certainly the higher the amylose content the more likely that starch would have the firmest gel. Starch B meets this criteria.
On the basic of endpoint temperature of the cornstarch paste/gel, which paste likely had the greatest amount of sugar added? Assume all starch pastes were taken to the same degree of viscosity or swelling of the granule.
- That one still has gelatinization at the endpoint temperature of 95.0 likely has sugar added. When sugar is added you can heat more to overcome the polarity hygroscopicity of the sugar. Starch A meets this critieria.
On the basis of the linespread test, which of the treatments likely had the greatest amount of acid added? Assume that all were taken to 85C.
- The linespread with the highest values indicates the most spread. Starch B spread the most and so the starch polymers were likely hydrolyzed by the acid.
On the basis of gel strength, which of the treatments likely had the most starch added? Assume a typical 5% cornstarch-water dispersion.
- Certainly, the firmest starch, the least % sag, Starch E had the most starch added. The higher the concentration, generally the firmer the gel, and the more viscous the starch paste.
Briefly compare and discuss the results of variables A, B, and C from data presented in the table.
- No they aren't. For example, compare the amylose and iodine absorption, C is contradictory as to expectations. The same holds true for linespread test.
