Apple Browning

Browning Lab Investigation The effect of different Factors on the activity of enzyme

INTRODUCTION Apples have a group of enzymes called polyphenol oxidases. When apples are cut, polyphenol oxidase catalyses the reaction between polyphenols, which are naturally present in apple tissues, and oxygen. This oxidation reaction leads to the formation of black-brown complexes called melanin, causing browning of apples

Questions How many different types of apples do you know? Did you ever have you apple go brown before you finished eating it? Do you know why apples are good for you?

An apple a day keeps the doctor away? Apples contain antioxidants which may help lower the chances of developing diabetes and asthma. Research has shown that eating food high in fiber such as apples can lower the build up of cholesterol in arteries and lower your risk for pancreatic cancer and Parkinson’s disease. Eating an apple helps stimulate the production of saliva in your mouth which helps reduce tooth decay by lowering the amount of bacteria.

An apple a day keeps the doctor away? A medium sized apple has about 80 calories! This makes it a healthier alternative to other snacks! Apples don’t have any fat, sodium or cholesterol!

Why do apples brown? Apples contain an enzyme that reacts with oxygen when the apple is cut. Enzymes are made up of proteins that can either break things down or connect molecules together. When the apple is cut or dropped, these enzymes are exposed to the air and react causing the brown spots. Different apples brown at different rates because they have varying concentrations of the enzymes.

Why do apples brown? There are ways to stop the browning of apples! Certain solutions can stop or kill the enzyme which will prevent the browning. The browning usually occurs if the pH of the fruit is between 5.0 and 7.0, so adding an acidic solution will help prevent the browning. Heating the apple slices will kill the enzymes, which will prevent browning. They can’t react if they are dead!

Materials Apples (1 can be divided between 2 groups) Knife Plates (1 per group) Lemon juice Sugar solution Boiling water worksheets

The Activity! Get with your group Submerge the wedges for three minutes Place on a paper towel (skin side down) Record the relative amount of discoloration of each apple wedge.

Did you know? An apple’s flavour comes from cells found on the skin? So for the best flavour, don’t peel your apple! The vitamins also are just below the peeling and they are pretty important for you too! Apples soften/ripen up to 10 times faster at room temperature than if they are in the refrigerator

Did you know? The world’s largest apple peel was 172 feet, 4 inches long! It was peeled by Kathy Madison in 1976. The science of apple growing is called pomology Did you ever wonder why apples float? It is because 25% of their volume is air!