3-
Commercial popcorn kernels contain about 13-15% by mass of water for
optimum popping ability. When popcorn is heated sufficiently, the water within the
kernels is covered to water vapor, which expands with increasing temperature until it
bursts out of the pericarp.
Post lab 5
1-How does the percentage of water in each sample compare to the expected amount of
water for optimum popping ability?
2-Based on your results, do you think the percentage of water has any effect on the ability
of the popcorn to pop? Explain.
If a stale sample of popcorn were to be analyzed, would you expect the % water to be
higher or lower than a sample that is not stale? Explain why
If the popcorn was stale, the percentage of water in the sample was lower than in
a non-stale sample. This is all since it is stale, which means it is dry. When the sample is
dry, it contains very little water, lowering the water percentage.
Yes, it has effect on the ability of the popcorn to pop. The kernels pop slightly
faster as the water content rises. Water expands when the kernel heats up, putting
pressure on the hard starch surface. The outer layer eventually loses way, allowing the
popcorn to burst. The soft starch within the popcorn inflates and bursts when it explodes,
turning the kernel inside out.
4-
5-The usual instructions for popping in the microwave oven tell us to stop the heating when
the popping slows down to 1-2 minutes between pops. At this time, we often find there
are unpopped kernels remaining. Explain why we cannot separate these duds and reheat
them to get them pop.
we can't separate these duds and reheat them to obtain the pop, because they've
already lost their water. We'll need water to reheat the duds, so they'll pop. When popcorn
kernels have been toasted, they lose their water content, making it difficult to reheat them
and make them pop again.
If you weighed the popped kernels while they were still warm, how would that affect your
calculated mass of water, and your percent of water? Be specific (would they be too heigh
or too low) and explain your line of reasoning in a well- organized paragraph.
If we weighed the popped kernels while they were still warm it will give us false
mass because it must always be at room temperature, weighing the popped kernels while
they are still warm will give us false mass. If you put it on the balance pan while it's still
warm, the air circulation will pull the pan up, making the mass look lighter than it is. (If the
balance's mass continues to rise, the item is still warmer than room temperature.)
