Carrefour Piedras, Piedras 383 has a decent sized selection of cake mixes, sweet crackers, rice noodles, etc. It was better for the gluten-free traveller than the gf/df one, but this supermarket had better selection than most I went in to.
Supermercado Ruta 17, 3370 Av Victoria Aguirre has an extremely limited selection of gf/df biscuits made by Dimax Alimentos...I wouldn't exactly call them tasty, but in a pinch, they were edible. For a night out, try the Wok and Grill, Av Misiones 125, for a change of palate. They have gluten-free soya sauce.
I disappointingly didn't find my regular selection, or any selection of gluten-free products at the Carrefour on Av Gral Las Heras, Mendocinas. This was the only supermarket I had time to look in.
Junin de los Andes:
This is a small town with one main street that you pass through on the Seven Lakes drive between San Martin and Bariloche. About half way down the street, on the East side, there's a grocery store. Here, I found boxes of brownie, cake, and pancake mix by a company called Exent. These are gf/df and delicious. I especially enjoyed the ease of making pancakes in the morning with only an egg and some water!
Quinoa Dietetica, Albaraccin 711, is a store dedicated to gluten-free foods. There are non-perishables like cookies, crackers, and pastas, as well as a freezer full of fresh/frozen empanadas, pizzas, and bread. Unfortunately, there are hardly any lactose-free products, and what they do have is all non-perishable.
La Anonima on Albarracin 601 had a small area of gluten-free products with sadly only one type of Santa Maria cookies. Maybe they just hadn't had a shipment in a while?
La Anonima on San Martin also had a good supply of gluten-free/dairy-free crackers, granola bars and pasta.
La Anonima, Av del Libertador Gral San Martin 902, had Santa Maria products, which are boxed cookies of different flavours (chocolate, vanilla, chocolate/vanilla, lemon, scones, jelly...) that all taste the same but are pretty good. They did not have any rice/corn pasta substitutes when I was there.
The small grocery store by the bus station, on the SW corner of Julio Argentino Roca & San Juan Bosco, had a bag of rice pasta that wasn't the best (got pretty soggy) and there wasn't any other gf/df products in the store, but I was thankful to find something.
This tiny town is not the place to go to find groceries. Everything is also expensive because it's shipped in. Bring provisions from El Calafate. BUT there is a fantastic little place called La Cervezeria at 564 San Martin with gluten-free pizza, pasta and tostadas (and the biggest glasses of wine you've ever seen!).
La Anonima, Av San Martin 1506, has a full selection of gluten-free/dairy-free products such as Santa Maria cookies and crackers, pasta substitutes and granola bars (pictured right). This was a great place to stock up. The other Anonima at Gdor. Felix Paz 190 had some types of Santa Maria cookies but no granola bars when I was there.
I was delighted to find boxes of chocolate Gullon cookies at a little supermarket on the SW corner of Av General Flores & Washington Barbot. These are some of the best gf/df cookies I've ever eaten!
We weren't there long and I didn't find any gf/df products at the grocery stores I checked in the old city.
I had read that Chile has less laws on packaging and it's more difficult to find food substitutes, but I was amazed by the selection of products at the Supermercado Eltit on Av O'Higgins between Ansorena and Fresia. Coming from Argentina, it was exciting to find foods such as peanut butter, taco seasoning, and delicious gf/df products by Noglut. They had animal crackers and chocolate cookies that were such a treat! These are also the best rice crackers I've ever had.
We weren't in Talca long and I didn't find any products at their stores.
The supermarket at Huerfanos & Amunategui had a disappointing selection of products considering its size. They had a few gf cookies that weren't df. A much better grocery store was the Express at San Martin & Gnrl Mackenna (close to Plaza des Armas). They have a large imported selection, a great variety of gf/df cookies such as the Gullons I mentioned earlier and some coconut cookies that were also good. (They also have a fantastic selection of wine!).