Does milk matter to achieve the perfect latte?

Barista here, and yes you are 100% correct milk does matter when making the perfect latte. When you look at the latte, the milk makes up at least half of the beverage. Not only does it enhance and add to taste, it is a very visual medium through latte art.

The key to great milk in a latte lies primarily in preparation, you need to heat and handle your milk correctly.

Now to answer your question about specific milk options. First rule - BUY ORGANIC. Fresh milk from healthy cows is always going to be the superior choice. If you live in a rich agricultural area where fresh milk is available, it is a compulsory choice when making a great latte.

Second rule - more fat less heat. A simple rule, if you are dealing with thick and delicious fresh cream milk, you will need baseline heat. 150 Farenheit. Once you use the low fat milk options, you will need to increase the heat ever so slightly. Never over 175. You want silky and glossy, and adjusting heat to milk fat is an important part of the process.

At the end of the day, a latte will be delicious with any type of milk if prepared correctly. Just treat the milk with care, and buy organic where available, and you will enjoy a delicious cafe latte.

If you want Fuller body for the drink use milk with more fat, if not use less fat. If you are making foam art check out this explanation.

Note: all milk will taste sweeter as its temperature rises because the lactose will become more soluble, making its sweetness more perceptible.

As for the type of milk:

You can froth pretty much any type of milk, including soy milk, rice milk, etc... In general, milk with a lower fat content is easier to deal with because it won't burn as easily, and cold milk typically responds more easily to steam. Although milk with too little fat may not steam or foam at all! So use whatever milk you want; do what thou wilt. (Espresso Guy)

If you are asking whether there will be a difference between factory-dairy hormone imbued milk picked up in a gas station, as compared to that from some grass-fed roaming home-farm cow, it seems likely to me. That said, for that kind of answer, making such a claim would rely on a leap of faith to overcome the likelier impact of psychosomatic flavors and guilt-reduced taste. (i.e. It feels better to buy local, organic so it tastes better.)

First of all soy tastes different to cow milk. So your resulting drinks will taste different. But this is a personal preference.

Secondly various milks will froth up differently. Most soys I've tried don't froth up very well. They end up too bubbly and I was never able to achieve the micro foam I can with regular full cream cow milk. So your latte simply won't look as good. This also effects your latte art. Properly foamed milk will have - for a short time - the air actually textured through the milk. If you make your coffee in a transparent glass you will see the bubbles start to separate. If you try to pour art with the foam and milk already separated, you just get blobs of foam on top.