Cheese Yield (Van Slyke Formula)
Estimates how many kilograms of cheese come out of 100 kg of milk using the Van Slyke formula: 93% of the milk fat is added to the casein content, 0.1 point is discounted as loss to the whey, the sum is multiplied by 1.09 to include the salt and ash retained in the curd, and all of it is divided by (1 minus the cheese moisture). The result is the theoretical yield, the reference against which the real plant loss is measured: a gap above half a point between the theoretical figure and the vat balance is almost always fat escaping into the whey or curd cut at the wrong moment. Note that moisture sits in the denominator and dominates the result — the same milk yields 11.2 kg in a soft cheese at 45% moisture and only 9.5 kg in a hard cheese at 35%, and that difference is water, not solids, so a high yield on its own does not mean a better process. The classic Van Slyke form was adopted, with the 0.93 fat retention coefficient and the 1.09 factor; dairies usually recalibrate both numbers for their own process, and for milk standardised by ultrafiltration the formula underestimates the yield. Enter the milk fat, the milk casein and the target cheese moisture.
Result
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Van Slyke cheese yield: the benchmark for your vat
A vat of 1,000 kg of milk turned out 96 kg of cheese. Good or bad? On its own the figure tells nothing: it hangs on the fat of the day, on the casein of that herd, and on the moisture of the style being made. Which is why every dairy that tracks losses keeps a theoretical yield beside the vat balance. The gap between the two reveals fat escaping into the whey, fines going down the drain, or curd cut at the wrong firmness.
The formula is Y = [(0.93 × F + C − 0.1) × 1.09] ÷ (1 − M/100), with Y in kilograms of cheese per 100 kg of milk. The 0.93 stands for the fraction of milk fat retained in the curd; the other 7% leaves with the whey. C means casein, never total protein. The 0.1 point discounted covers fine casein lost to the whey. The 1.09 adds the salt, ash and lactose held in the curd. Moisture sits in the denominator, where it rules the outcome: from the same milk at 3.5% fat and 2.5% casein, a soft cheese at 45% moisture yields 11.21 kg while a hard one at 35% yields 9.48 kg. That gap is water, so a high yield alone proves nothing. At the default 37% moisture the answer reads 9.784 kg.
The figure is theoretical: it counts no mechanical loss in the press, no fines through the screen, no curd on the vat wall, no salt picked up in brine. The formula assumes classic rennet coagulation, with casein almost entirely retained and whey protein almost entirely lost. For ultrafiltered milk, or for cheese made with whey protein incorporated, it underestimates the yield, at times by more than a point. In direct-acid styles such as cottage and quark the 1.09 factor breaks down, since calcium and phosphate leave with the acid whey. The typing slip that ruins the answer is moisture entered as a fraction: 0.37 in place of 37 returns 6.187 kg, a number that looks ordinary and reads wrong.
Frequently asked questions
Where does 9.784 kg come from with the default values?
I only have total milk protein. Can I use it in place of casein?
The vat came in below the theoretical yield. Where do I look first?
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