Is ripening fruit a self-contained system, or is the rate of these changes affected by the environment? We designed the experiment below to see if different atmospheres, produced by different packaging, affected the rate of ripening. You will vary the atmosphere surrounding unripe bananas and observe the effect on the ripening process.Now set up the bananas in their environmentsas follows:
1.Put two green bananas in a paper bag and fold the top over to seal out the air.
2.Put one green banana and the very ripe banana in the other paper bag and fold over the top.
3. Puttwo green bananas in a plastic bag and seal it.
4. Wrap one green banana tightly in a plastic bag.
5. Leave one green banana exposed to the air.
Leave the fruit alone for four or five days to ripen. Ripening fruit “breathes”.This means that it takes up oxygen and gives off CO2. Oxygen is extremely important and necessary for the chemical reactions involved in ripening. Inaddition, ripening fruit gives off another gas,called ethylene . Not only is ethylene a product of ripening fruit，it also promotes the further ripening of the fruit.
Paper bags tend to keep the ethylene in, but they allow oxygen and ethylene to pass through slowly. Plastic bags do not allow the free flow of oxygen or ethylene. In this experiment, the green banana in the paper bag with the ripe banana should ripen most quickly. The green bananas in the paper bag should ripen faster than the bananas in the plastic bag. The banana left exposed to air has an unlimited supply of oxygen, so it will turn brown most quickly. You will notice that the side of this banana that rests on the counter will ripen more quickly than the other sides, because it has the closest contact with its own ethylene. The banana that is tightly wrapped in plastic has no oxygen supply and should ripen most slowly. Now can you see why bananas are sealed in plastic in many supermarkets?
I find the two underlined sentences are contradictory with each other? As a reader, I cannot learn from the passage which kind of banana will ripen most quickly.
Am I right in my comprehension?