Suggestions for adjusting sourness of a BM Rhubarb Strawberry Centennial Blonde

[carloswlkr]

I brewed a batch of BM's Centennial Blonde and after a week in the primary, racked half of it (about 2.3 gallons) onto 4 lbs of strawberries and 2 of rhubarb, both washed, rinsed in sanitizer then frozen and thawed. The beer is [almost] ready to keg and carbonate, but it is quite sour from the rhubarb. I've read several suggestions in other threads for back sweetening with lactose or maltodextrine, and also suggestions to adjust the PH with chalk or baking soda to neutralize the acidity. What would you suggest to tone down the sourness a bit without imparting off flavors? (I'm not a fan of using Splenda.) If I went with chalk, gypsum or baking soda, any suggestions for how much to use in 2.2 or 2.3 gallons? I don't have a ph reading. If I went with maltodextrine (I have plenty on hand), how much should I use?

Thanks!