Re: How does fruit rot (what happens) and what gases are produced when it does?

Hi Lindsay,

You performed some interesting experiments, and I will attempt to provide 
you with further explanations of your results. The first thing to remember 
is that fruits and vegetables are living organisms. Thus, they are subject 
to physical, chemical, and microbiological spoilage from harvest until 
consumption. Your experiments involved chemical and microbiological 
spoilage but physical damage could have been a contributing factor. Fruit 
will continue to respire after harvest. These biochemical changes result in 
a breakdown of carbohydrates with the production of carbon dioxide and 
methane. Enzymes (i.e pectinases which breakdown the cementing material 
between cells) in the fruit also result in softening. Molds, yeasts, and 
bacteria associated with the surface or inside of the fruit can also cause 
spoilage. All of these changes can occur alone or in combination with each 
other. In your experiments in closed containers,some biochemical changes 
would occur until the oxygen was used up. Some carbon dioxide and methane 
would be produced. Under anaerobic conditions (absence of oxygen), 
microorganisms can breakdown sugars to prodcue ethanol and more carbon 
dioxide.This process is referred to as fermentation. Did you smell alcohol 
when you opened the containers? If you used apples as one of your fruits, 
you may also have noticed a vinegar like odor (acetic acid). I hope this 
helps to clarify the results from your experiments.

Alfred. A. Bushway
Professor of Food Science