Loaded with essential nutrients for health, apples lead the list of top ten superfoods. According to fruit nutrition facts, they serve as a rich source for antioxidants (vitamin C and more), fibers (especially pectin), and carbohydrates. More importantly, apples have a low glycemic index, contain less cholesterol, and are low in calories. For consumption part, apples are delicious, less messy to eat, and you can carry whole apples easily for anytime snacking. But when cut into slices, they turn brown very soon. Here, we shall focus on the causes for apple flesh turning brown after peeling, and tips to keep them from turning brown after cutting them.
What Causes Apples to Turn Brown after Slicing?
In addition to sugar, water, dietary fiber, vitamin C, and many other nutrients, apples contain several enzymes. It is the tyrosinase and alike phenolic oxidase enzymes present in chloroplast cells, which are responsible for brown coloration of apples after cutting. After peeling and exposing apple flesh to air, these enzymes react with atmospheric air, and catalyze the conversion of phenolic compounds into o-quinones. These substances cause apple slices to turn brown. Likewise, bruises in the apple skin are browned due to the action of phenolic oxidase enzymes.
The key tips for keeping apples from turning brown are concentrated on reducing conversion of phenolic compounds. In addition to oxidation reaction triggered by enzymes, there are several factors that affect browning of apples. Say for example, some types of apples are browned more quickly than others. As per a study report, the red delicious apple variety is more susceptible to browning than the golden delicious type. In comparison to these, granny smith has a tendency to withstand browning for a longer period. Besides variety, the provided growth conditions and maturity of apple fruit are equally responsible for apple flesh to turn brown. The more ripe they are, the quicker apples turn brown, and vice-versa.
How to Keep Apples from Turning Brown after Slicing?
The first thing that you need to do is select different types of apples that are less prone to browning. You can conduct a brief research on apple types and purchase them according to your requirements.
As far as the query 'how to prevent apples from turning brown' goes, using lemon juice is the best alternative. This mild acid counteracts oxidation reaction, and reduces the browning effect easily. And the plus point for using lemon juice is, it is purely natural and you don't have to rely on chemical preservatives for keeping cut apples fresh. Similarly, you can use pineapple juice and ginger ale for the same purpose.
Tossing the cut pieces in sugary water or saline water also helps. This option is not healthy, as excess sugar or salt consumption is not recommended for health. Also, people with high blood sugar and those who are predisposed to diabetics should avoid this option.
Speaking more on keeping cut apples from browning, you can place cut halves in water, ensuring that the cut side is immersed in water. By doing so, you are preventing the contact of apple flesh and air. As a consequence, there will be no oxidation of phenolic compounds, and the apple halves will not turn brown. However, some water-soluble nutrients may be leached out in water.
Last but not the least, you have a choice of heating up the apple slices to slow down chemical reaction. But, the unfortunate part is changing the texture of the apples. Apart from these options, wrapping the cut apples with plastic or blanching them in boiling water can also reduce the browning.