What are yeast nutrients and whether it is necessary to use them?
Yeast, like any plant, they need nitrogen and mineral salts for their development, containing phosphorus, potassium, limestone and sulfur. Undiluted in fruit juice, all these ingredients are present in sufficient quantity (the exception is blueberry juice, cowberry and honey), however, as we will see later, we usually dilute fruit juice, hence the amount of these components is significantly reduced, we also have to supplement them artificially. But undiluted fruit juice can show a lack of nitrogen-based nourishment, namely then, when it was boiled, hence fruit protein, source of this food was cut and lost as nitrogen nutrient for yeast. Scarcity, or no protein at all, can be replaced with the addition of ground malt sprouts or malt flour, taking 10 gr. on 10 liters of must. Also, the lack of protein can be replaced with mineral salts, the best of which is ammonium phosphate, ammonium carbonate, or ammonium chloride, called ammonium chloride. You can get a nutrient salt mixture commercially, in a package the contents of which are sufficient for 25 l must. Medium, called "secalum", among other salts, it also contains potassium phosphate, which has a positive effect on the development of yeast, and as some say, it has the aroma of wine. The medium mentioned is used for all musts, in particular for those which are difficult to ferment, like blueberry, cowberry, further in the production of wines from rye and honey. The "f o s f o s a l" medium is used for all other musts, and in the absence of the former, it can be successfully replaced with phosphate. If there were any difficulties in acquiring these media, then buy ammonium phosphate or one of the above-mentioned salts in a drugstore and in an amount of approx 3 gr. add to 10 liters of must. As a last resort, you can add 10% ammonia water in the amount 5 gr. on 10 liters of wine. Never overdo the wine with excess of the nutrient used, especially, when forced by circumstances, we need to add ammonia. This compound is consumed by yeasts in a small amount, it is also used in excess (above 4 gr. on 10 liters) it may adversely affect the taste of the wine.