|MadSci Network: General Biology|
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
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