Welcome back to Food-for-Thought Wednesday! We will continue discussing ascorbic acid today because I received a request last week for more in-depth information.
Let’s start by taking step back and defining the difference between ascorbic acid and Vitamin C
Synthetic Ascorbic acid: Also known as D-ascorbic acid. This molecule does not occur in nature and may be synthesized artificially. It has identical molecular structure and antioxidant properties to L-ascorbic acid yet has far less vitamin C activity (although not quite zero). 
Vitamin C complex as found in fruits and vegetables: Includes natural L-ascorbic acid along with a comprehensive matrix of many nutrients and natural compounds such as bioflavonoids, co-enzymes and unique cofactors.
Here’s how D-ascorbic acid is made 
It starts with corn syrup that may be from GE corn and goes through these chemical steps:
Steps 1 thru 9 (Starch Hydrolysis): Corn starch is broken down into simple sugar (D-Glucose) by the action of heat and enzymes.
Step 10 (Hydrogenation): D-Glucose is converted into D-Sorbitol.
Step 11 (Fermentation): D-Sorbitol is converted into L-Sorbose.
Step 12 (Acetonation): Yes that’s right, they use acetone! L-Sorbose is combined with an acid at low temperatures.
Step 13 (Oxidation): The product is then oxidized with a catalyst, acidified, washed and dried forming L-Gluconic Acid.
Step 14 (Hydrolysis): L-Gluconic Acid is treated with hydrochloric acid forming crude ascorbic acid.
Step 15 (Recrystallization): The crude ascorbic acid is filtered, purified and milled into a fine crystalline powder.
This is very different than the vitamin C complex found in food. However, the Food & Drug Administration has permitted ascorbic acid to be identified as Vitamin C. This is why beverages, foods, and supplements which are fortified with ascorbic acid can say they contain this vitamin. Technically they do contain it, since according to the FDA, they’re allowed to call it that. However, based on what we know, it doesn’t really – it contains some anti-oxidant properties, but not the full benefit of vitamin C. (For some reason, the phrase “liar, liar pants on fire” comes to mind.)
Doesn’t sound too appealing, but a study was done which compared the activity of synthetic and natural ascorbic acid, and did not find a difference:
However the main issues for me are that the synthetic ascorbic acid is likely made from GE corn and does not provide the full benefit of natural vitamin C complex. Therefore seems like the benefits are minimal.
Why is ascorbic acid used instead of natural Vitamin C? The C vitamin is a naturally occurring nutrient found in countless fruits and vegetables. However the problem is that when it is heated to above 70C , vitamin C denatures and becomes useless for nutrition. This poses a problem when it comes to beverages like orange juice. Pasteurization (heating up to 100C for up to 30 minutes to kill off pathogens) is required for virtually every beverage sold today in the United States, so the natural vitamin C is destroyed in pasteurized orange juice. Synthetic ascorbic acid can therefore replace the natural form which is destroyed by heat, so that glass of pasteurized orange juice may not actually contain natural Vitamin C. Rather, you are consuming synthetic ascorbic acid which was added to replace the original.
In conclusion, the best way to get vitamin C is from whole foods or a whole food supplement – the synthetic ascorbic acid route is not ideal. The best food sources for vitamin C are papaya, red bell peppers, broccoli, kale, strawberries, kiwi, cauliflower, brussels sprouts, sweet potato, and cantaloupe. 
I hope this information was helpful. Thanks for stopping by and have a great day!
 http://www.realvitaminc.com/ascorbic-acid.html – this is a commercial interest but their description of how ascorbic acid is made is objective and consistent with other sources of this information.