I got a hankering for chips and dip the other night. Salsa wouldn't cut it, I wanted cheese. The kind of creamy gooey cheese you get on convenience store nachos. The kind I'd been reading about how you can make it at home in Modernist Cuisine. So I took a look at the recipes from the 'constructed cheese' parametric table, and cobbled together a formula based on what I had in the pantry.
Sodium Carbonate 1.98g
Citric Acid 7.85g
Non Fat Milk Powder 4g
Cheese 200g (85g med cheddar, the remainder low moisture mozzarella)
Green Chiles, roasted and diced. to taste
1) Bring the water and salts to a simmer. 2)Stir in the cheese, and simmer for 2 minutes. 3) add chiles and adj seasoning.
I ended up with mixed results. I used the liquid to cheese ratio for fondue from the table, and it seemed to be pretty thin. I added around 100g more mozzarella. It got to a nice thickness for dipping, when it cooled a little.
The main problem was the citrate component. I did't know if the sodium citrate called for in the book was mono- di- or tri-sodium citrate, and I didn't have any sodium citrate laying around. So I did the math, and added the chemicals for 8 grams of mono-sodium citrate. When I weighed the chemicals, I made the assumption that the citric acid I had was monohydrate (according to wikipedia citric acid is either anhydrous or a monohydrate depending on how it's processed). This assumption and the decision to use mono-sodium citrate was because posters on the eGullet forums have reported that in their MC cheese attempts, they ended up with a cheese that was too basic. So I erred on the side of acid.
The dip was aggressively tangy. Almost overpowering. I didn't measure the ph, but based on taste, I'd say around 3 to 4.
The second issue was the texture. It didn't get smooth, and stayed pretty rough, even after hitting it with the immersion blender. Before that, there were little traces of curd. There was no fat separation, and the liquid it self looked nice and creamy. I think the cause of this fault is either, the ph being too low, use of dry milk instead of whey powder, type of cheese, or too short cooking time. I'm guessing it's the ph.
It didn't need any table salt for seasoning. The emulsifying salts was salty enough.
Later, I did some dairy science reading to figure out what went wrong, and I confirmed that the problem was it was too acidic, and that it's tri-sodium citrate mainly used. Mono- and di- sodium citrate are used sometimes to decrease the pH of the mix.
I also found out how the emulsifying salts work. First, it raises the pH. Secondly, the sodium ions swap with the calcium ions in the protein matrix. Third, the citrate ions sequester the calcium ions. The pH change combined with the ion exchange and sequestration, allows the proteins to hydrate and de-aggregate , allowing you to make smooth cheese with heat and sheer.