I’m growing some San Marzano tomatoes this year and am about to make some tomato sauce I can use on pizza.
Sugar is usually added to tomato sauces to cut the acidity. Is there a keto-friendly ingredient that will do the same? Or is it simply unnecessary?
I usually don’t use sugar at all in tomato sauce, I would only use at most a teaspoon for a 500g can of tomatoes if the acidity was really off and I never needed more to get it right. I also don’t think I’ve ever tasted a sauce that I wouldn’t eat if I didn’t add sugar to it. Maybe my tomatoes are less acidic than most, maybe I like the acidity, maybe it’s the amount of onion I add to the sauce, I don’t know, but I could certainly get by without sugar at all.
That said, I honestly still add sugar to my sauce even after I went keto if I feel it needs it. I don’t make tomato sauce nearly as much since I don’t eat pasta anymore, but even if I did I wouldn’t be too concerned. One teaspoon is how much? 5g? And I’m eating at most 1/3 of that, probably less. A full teaspoon is also the high mark of what I’ll use. The point isn’t to taste the sugar, it’s just to blunt the edge of the acidity ever so slightly if it’s a tad too sharp but usually I don’t need any at all.
I have heard that you could use a pinch of baking soda (not baking powder) if your sauce is too sour. I have never tried that myself so I can’t vouch for it.
A suggestion or two…
You could try roasting the tomatoes. That will bring out some flavors, some use the word caramelizing, and also help you thicken things up more quickly than simmering for many hours.
Caramelizing onions could also add some sweetness if you like onions in your sauce.
Garlic is good, too, so long as you don’t burn it. It’ll get bitter if it’s burned.
It sounds like you’re growing your tomatoes this year so if you can leave them on the vine long enough to get even just a little over-ripe, I am told by more than one person that the flavors will be less tart. (I’ve had disagreements about that by people who like to tell me otherwise and spout off research studies to say so. My taste buds don’t agree. But hey, we all know that research studies are infallible… 
)
I find tomato paste very sweet, so I end up adding a big dollop to tomato-based sauces to thicken and sweeten them. Frankly, I use it in lieu of ketchup. I once knew a girl who ate it like pudding.
I don’t add anything in place of sugar. Tomatoes on their own seem really sweet to me.
OP, I feel the same way, home grown tomatoes never need sugar. Something grown 1000 miles from you and picked in its green state, might need some sweetening. But the type of tomato and then being homegrown, I’d say no sugar needed.
I also agree that roasting the tomatoes first and adding in caramelizing onions should make any sauce plenty sweet.
Let us know what you end up trying out and the results.
I’ve decided to split a small, salted batch into 3, one with sugar, one with erythritol, and one plain.
My ultimate plan is to spice up my sauce with garlic, onion, oregano, etc. Sweetening it up may not matter in the end, but I’ll do it to get the base right.
I did my test and decided to leave my sauce unsweetened.
The samples with sugar and erythritol did not improve the flavor of the sauce. I preferred the flavor of the plain. The sauce did not seem to me to be overly acidic so I’ll just be adding garlic, onion, and herbs.