In this experiment, high school students will investigate the role of enzymes by testing the effects of pectinase on apples. The objective is to compare the amount of juice extracted from apples treated with pectinase to those left untreated. In addition, students change the temperature of the solutions to compare enzyme activity at cold and warm temperatures.
Students begin by cutting up apples in chunks and then applying pectinase enzyme to the chunks. Then, they place the mixtures in warm and cold water, leaving one out at room temperature. An apple mixture with water instead of pectinase serves as the control group.
After the mixtures sit in the warm and cold water baths, students carefully pour the mixture into a funnel with a coffee filter. Then they measure the amount of liquid accumulating in the graduated cylinder over a period of twenty minutes.
Students will discover that apples treated with pectinase will produce more juice than the apples in water. They will also learn the warmed solutions will work faster than the cold and room temperature solutions.
How the Enzyme Works
Pectinase is an enzyme that breaks down pectin, a polysaccharide found in the cell walls of plants, particularly in fruits. Pectin gives structure to plant cells and helps bind them together. Pectinase also breaks down the the pectin holding cells together, which allows more juice to be released from the fruit.
Pectinase is commonly used in the food industry for juice extraction and clarification, as it increases yield and produces clearer juices. Essentially, pectinase speeds up the natural degradation of pectin, which would otherwise take much longer without the enzyme’s catalytic action. Recall the enzymes work on substrates. In this case, the enzyme is pectinase, and the substrate is pectin. Like most enzymes, the reaction will occur faster at warm temperatures as long as the temperature is not so hot as to cause denaturation.
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Other Resources on Enzymes
Enzymes and Substrates Coloring
A Graphical Analysis of Enzymes and Substrate Concentrations