Having 30 years experience in food manufacturing, all USDA inspected factories, its good you are doing your research before you jump in. Applesauce would be under the jurisdiction of the FDA. I would suggest you form a corporation and get liability insurance. Check out the link for some guidance.

Here is a link that might be useful: regulations

garyt33, sorry, I failed to mention in my initial post that I live in Japan, so our applesauce would be sold only in Japan. That said, we intend to conform to any legalities that are specific to Japan, including whatever is equivalent to the FDA. And I'm aware that any product intended for export to the US would have to meet FDA standards. That's not even on our radar at the moment, but thank you for the link. At this point I am more interested in the actual production of applesauce and what factors affect especially the taste when you start making very large batches.

One factor that will have a significant impact on taste and perhaps texture is how you plan to preserve it.

I assume you will be using some type of canning and pasteurizing.

It will need to either be sufficiently acidic or brought to a relatively high temperature and pressure. Oxidation during the processing may also be a concern with respect to color and perhaps flavor.

You said you are more interested in the actual production than in the legalities, but those things may be very highly related.

The regulations may require specific production practices. It could be frustrating to come up with a plan for production only to learn that it cannot legally be followed. I'd personally want at least a outline of the regulations before making any investment, and by investment I don't just mean money.

Aside from those comments, I'd think that the varieties of apples that you use will have as big an effect as anything on the taste of the sauce.

"It will need to either be sufficiently acidic or brought to a relatively high temperature and pressure. Oxidation during the processing may also be a concern with respect to color and perhaps flavor. "

Well that's an easy one! Lemon juice. It will preserve color, is the most powerful acidifier used in canning. It also changes taste the least.
I think a whole market of flavored applesauce products is wide open. Raspberry, maple, currant. The choices of product are unlimited. Companies that supply cider mills probably have huge apple sauce making machines. So it's a matter of finding the companies that make these machines. I just googled commercial machines and found a company in China that makes production line machines for apple sauce or jam. The Jiangsu Kuwai Machinery Co., Ltd. Took 30 seconds...

Here is a link that might be useful: Apple sauce production line equipment

Murky, Drew 51--thank you for your input. We've already run our production process through the regulating authority so I think we're good to go on that front. I am concerned about oxidization and I imagine that the degree to which we can control it will depend in part on the type of machinery we will use. We're in an apple growing region and many growers make their own juice so we think we can find a machine locally. Although our apples are acidic enough, for color preservation I'm leaning more and more towards lemon juice because I want to keep everything as natural as possible and because what I've been reading agrees with what Drew51 says. Cost-wise, I imagine that lemon juice is probably more expensive than Vitamin C/ascorbic acid, but I haven't compared costs yet. Any ideas?

You might also want to ask your question on the Harvest Forum where the serious canners congregate.

Here is a link that might be useful: Harvest Forum

Ooops, guess I didn't look far enough into all the forum subtitles-- thanks for pointing me in the right direction. I'll post there. Thank you to all who took the time to respond here.