When an apple turns brown, it's just oxidation (being exposed to oxygen).

Rust is another example of oxidation, but slow oxidation. The apple, being more susceptible to oxygen goes brown a little faster. But it's natural and okay.

The apple and/or apple juice turning brown is a good illustration of why fresh juice should be drunk within 20 minutes of juicing. After 20 minutes, most of the enzymes and many of the vitamins begin to naturally go away or are at least, substantially reduced due to the oxidation.

While other vegetables or fruits may not go brown like the apples or apple juice, a similar thing is happening even if no visible signs.

You don't need to add lemon juice or soak the apples in lemon water before juicing though. As long as you cut the apple just before juicing, then that's fine. If you still want to add some lemon juice to the apple to help minimize the oxidation, then that's fine — it just seems like extra work to me!

The reason why the lemon juice and/or lemon water prevents the apple from going brown before you juice the vegetable is due to the fact lemon juice contains vitamin C — a known anti–oxidant. The vitamin C, therefore, helps to slow the rate of oxidation. The same can be done when making guacamole (an avocado type of sauce). Since avocados also begin to go rancid really fast once cut open and exposed to oxygen, adding some lemon juice to the guacamole helps prevent the avocados from spoiling due to oxidation. The lemon juice really makes a difference.

Although lemon juice or lemon water can help prevent oxidation before juicing, the reality is, the lemon water is only protecting the surface of the apple slice. Once you juice, you are exposing every cell of the apple to oxygen including those parts that are not protected by the anti–oxidant properties of the vitamin C. Thus the reason why you still see the apple juice turning brown slightly once juiced.

The apple juice turning brown all has to do with oxidation — being exposed to oxygen. A seed's shell or wall, a nut's shell or wall, a vegetable peel or fruit peel — these are all Mother Nature's way of protecting the nut, seed, fruit or vegetable from light, heat and/or oxygen. If you bruise an apple, then the apple will go brown even though the apple peel has not been cut or sliced open. The apple still goes brown once bruised because the cell walls have been broken, even though we cannot see it with our eyes, allowing oxygen to creep into the fruit leading to oxidation.

Off the topic a little, but still relating to oxidation — many people buy oils for their health and this is great because we all need essential fatty acids. But all of the oils need to be cold processed (to minimize exposure to heat), packaged in opaque bottle (to protect from the light) and must have minimal oxygen exposure. Once opened, these oils can go rancid and must therefore be kept in the fridge. Yet, Mother Nature has protected all seeds and nuts from going rancid naturally. So while many people have oils, if you really want the freshness of oils, then it's worth considering eating seeds and nuts especially since not only do you get the oils, but all of the minerals too.

Jesse's fingers are currently on holiday and taking a break. He will be accepting new questions after a rest.

1. How Can I Store Vegetables?
2. Hypolycemia — blurred vision and tiredness while juicing.
3. Which Juices Would Be Good For Depression?
4. My Husband Got A Stomach Ache From His Juice?
5. What can I juice or do to help with my excessive sweating (hyperhidrosis)?
6. Juicing and Detoxification
7. What Do You Recommend for high blood pressure and high cholesterol?
8. Do you have some tips for IBS, constipation and gallstones?
9. Does pickling remove the benefits?
10. Did not realize that pears and beets are high in sugar!
11. Can I juice beets everyday?
12. Can I drink more than 1/2 pint (1 cup) of juice per day?
13. Can I juice carrot greens?
14. Do you have any tips for Cystic Fibrosis, asthma and respiratory illnesses?
15. What can help with my hemorrhoids, fissures and inflammation?
16. I Got Ill, For A Short Time, While Juicing
17. How Can I Help Reverse Acne For My Son?
18. Juicing and Weight Loss
19. Juicing while pregnant and breastfeeding (nursing).
20. Juicing Gave Me An Upset Stomach
21. Juice Combination For Liver, Kidneys, Bile and Overall Health
22. Is it okay to store juice and drink it later?
23. Juicing Combination Review
24. Putting Vegetables On Ice Before Juicing
25. How important is a slow speed juicer compared to fast speed?