Preservatives in Food

3.6 based on 47 ratings

Updated on Aug 22, 2013

We use chemicals such pesticides, fumigants and algaecides in the field to deal with pests, fungus and mold. After harvest, we use chemicals to firm our fruit, waxes to prevent water loss, antibiotics to prevent infection, and preservatives to prevent food from going stale. Some of these chemicals benefit the consumers by minimizing pathogens such as Salmonella, E. coli 0157:H7 and Hepatitis A. Other chemicals keep prices low by extending the shelf life of products. Still others make our produce more cosmetically desirable. For example, waxes on applies deepen the color tone while preventing water loss and shriveled skin.

Organic vegetables and fruits are grown without pesticides, fumigants, algaecides and other chemical agents. Prepared organic foods such as spaghetti sauce do not include preservatives, antibiotics or brightening agents. Many people think that organic foods taste better and are healthier. They are understandably wary about eating produce that has been tampered with.

This project is about learning how preservativesin food extend the shelf life of goods. The goals are to encourage students to understand the value of both organic foods and preservatives.


How do preservatives in food affect the shelf life of food and other goods?


  • Camera
  • Plastic food containers
  • Paper plates
  • Organic and non-organic bread
  • Organic and non-organic milk
  • Several kinds of organic and non-organic produce. Strawberries are ideal if they are available, but celery, cucumbers, other berries; red or green peppers are excellent as well. Be sure to purchase an organic and non-organic variant of each fruit of vegetable.


  1. Identify a working area that will remain un-disturbed for a week. If you are going to be comparing organic and non-organic milks, select an area in a shed or basement because the smell can be pretty “skunky.”
  2. Put two or three organic strawberries on a plate. Repeat with non-organic strawberries. Label the plate as to whether it is organic or non-organic.
  3. Repeat step 2 with the other fruits and vegetables you selected.
  4. Label two plastic food containers “organic” and “conventional.” Measure 0.5 cup organic milk and put it on one container. Do the same with the non-organic milk.
  5. Repeat step #4 with the organic and non-organic bread.
  6. Take photos of each food item.
  7. Observe your foods and write up your observations every day for a week. Take photos of every food item. Looking a shelf life alone, which food would be more economical for stores and consumers?
Cy Ashley Webb is a science writer. In addition to having worked as a bench scientist and patent agent, she judges science fairs in the San Francisco bay area. She loves working with kids and inspiring them to explore the world through science.

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