My wife and I have been making numerous small batches of ice cream in the past few months, as we are intending to start making some for sale in our local market (west coast of Scotland). Initially we made Vanilla ice cream that we really liked, in terms of flavour. But we knew we had to improve how it sits in the freezer, and so I went on an ice cream making course, and was told to add gum powders for stabilising the ice cream in the freezer. So I bought Guar Gum powder, and Locust Bean powder, and Xanthum Gum powder, and created an even mix of these 3. (They each have their strengths and weaknesses, so the advice is to mix them.)
We have been adding one teaspoon (5ml / 2 gm) of this mixed gum powder to our basic 1.5 litre batches. Seems fine, but not when it comes to making Vanilla. We could not get rid of an unwanted "powdery" flavour. So we finally made two batches yesterday, identical to each other except one had the gum powders and the other did not.
Result? It was very clear to us that the gum powder mix is the culprit. The batch without the powder did not have the unwanted odd taste, and was the flavour of Vanilla Ice Cream we had been aiming for.
I notice that Haagen-Daz do not add these powders to their Vanilla ice cream.
By the way, to help the scooping softness, we added 25 ml of veg. glycerine to the batch. It definitely helps keep the ice cream a bit softer once it has got down to really cold temp in the freezer, but doesn't appear to add any unwanted flavour at all.
The machine we are using is a Cattabriga MTM K20, which is great in that it uses between 1.5 litres and 2.5 litres of ice cream mix, and turns it into ice cream in about 6 minutes. As it is a horizontal batch freezer, you can't add inclusions in the making. Other than that we have found it to be a great machine to work with.