Regarding ammonia (chemical formula NH3), I’m glad you brought the subject up. There’s a reason why we don’t use ammonia for sanitation in the winery and one acronym says it all: DAP. More on that in just a little bit, however.
Myself, I keep a little ammonia squirt bottle under the kitchen sink to remove persistent grease stains from my stovetop. Just squirt it on, wait a few seconds and wipe clean with my little scrubby sponge. Presto change-o, no more grease-o! I Love it for the occasional dirty-job use in kitchen, but not for my winery. Why, you ask? Let me explain.
One of the most popular and widely-used yeast nutrients for home and large-scale winemakers alike is DAP, aka: diammonium phosphate (chemical formula (NH4)2HPO4). When added to juice or must, the ammonia part of DAP disassociates (becomes free in solution) and is available to the fermentation as a source of nitrogen for your soon-to-be happy yeast beasties. Nitrogen (N) is a critical component for yeast metabolism and for the completion of a healthy fermentation. Grape juice and must naturally contain nitrogen, but often, if it is lacking, we supplement with other nitrogen-containing yeast nutrient blends, which are specially formulated for winemaking. Perhaps the cheapest sources of nitrogen is the aforementioned diammonium phosphate, usually sold in powder form. Feeding the right amount is important too; if you have residual nitrogen in your wine after it goes dry, you will just be feeding the leftovers to spoilage microbes. This is why, if you can afford it, it’s key to measure the “yeast assimilable nitrogen” (YAN) of your juice or must before adjusting. If you have a wine lab nearby and don’t mind paying for the privilege (depending on the lab, $35–75), get your baseline YAN (can range anywhere from about 50 to 300) and then only add nitrogen so that the initial total is about 300 ppm. This is enough to get a healthy fermentation but not too much so that you’ll have beaucoup leftover. As an aside, more-complex nutrient blends containing critical amino acids like argenine and proline as well as other yeast-supporting ingredients like yeast hulls are probably a better choice than DAP alone as they provide more balanced yeast nutrition.
So what does this all mean for your idea about using ammonia in the cellar to clean equipment? Well, if you’re rinsing ammonia (which contains lots of nitrogen) down the drain in your winery, it means you’ll be feeding the microbes (bacteria, fungi, yeast etc) that live in your drains, on your floors, and even in the nooks and crannies in your equipment (like underneath the lip of your plastic buckets, for instance, where fresh rinse water sometimes doesn’t quite go).
I don’t know about you, but I like to keep the population of “bad guys” to a minimum in my winery, not add to it. In winemaking, when everything depends on a healthy fermentation during harvest, and then protection from undesirable microbes the rest of the year, it pays to have as clean of a cellar as possible with a minimal microbial population. Targeted ammonia application, when you do it at all, should be done to juice or must only. Otherwise you are not just feeding the yeast, you could also be feeding a beast!
