[erockrph]

Not to take things off on a tangent too far but...

- Most brewers make their acid additions to the mash water, but just because brewers may not usually adjust pH of a finished beer, that doesn't make it wrong to do so. Adding a touch of baking soda to a stout that tastes muddy, or a touch of lactic acid to a lager that tastes a bit flabby will likely improve the beer, sometimes greatly so. You can't go by the numbers, you have to go by your palate.

- Winemakers adjust acidity of their wine all the time. There's no reason it can't work for beer as well.

- Rose hips contain more malic acid than ascorbic acid (5-10 times more malic acid than apples). That would likely be a much bigger factor than their ascorbic acid content.

- Not all acids have the same flavor impact where tartness is concerned. Acids like citric and malic are quite tart (think lemons and sour patch kids, respectively). Other acids, such as lactic, produce a softer acidity. I have no clue where ascorbic fits in here, because it is rarely used as a flavorant. Again, I'd be willing to wager that the malic acid content of the hips would have a significantly greater flavor impact.

- Fruits are pretty commonly added to beer. If the added acidity was a problem, then there'd be no fruit beer.

I understand your reasoning, but I think you're making too many assumptions and extrapolations to make an accurate prediction on the end result. There's just no way to tell if it will be too tart without tasting it. And if it is, I doubt that the ascorbic acid would be the primary cause.

[JJeffers09]

Ascorbic acid is only bitter, no depth of flavor just makes beverages taste bitter.  The only example I can think of is like bottled lime juice vs fresh lime juice.  Bottled is cloyingly sweet from the added sugar to balance the antioxidant benefits from the additional artificial ascorbic acid in the lime juice, lost in production and reintroduced which is common practice.  It tastes bitter, cloyingly sweet, and almost all lime aroma is lost.  Fresh lime juice that is sweet, sour, tangy, and bitter with loads of lime aroma.  There is no question bottled lime juice makes TERRIBLE pico de gallo, lol.

Where did you find that rose hips have 5-10x as much malic acid as apples?  That would be anywhere from 3.5g-7.6g of malic acid per 100g of rosehips.  Which would be bitter, and tart.  Rosehips are used in sours, so I guess taking a Tripel and making it sour or tart is the direction the OP is taking, Let us know how it comes out!