# How to scale up modernist Potato Puree?

The recipe for Potato Puree in "Modernist Cooking at Home" calls for precooking the potatoes in water at 65 degrees Celsius for 35 minutes. The bag should hold 500 g potatoes and 1 liter water. Since the recipe says to scale the water at 200% this means that if I am to use 1 kg of potates I need 4 liter of water.

However, trying to do this for only 35 minutes did not give a satisfactory result. Looking back, this is not surprising since the added size of the bag means it needs more time in the sous vide.

What is the right way to scale up the recepie? Should I use two bags? If that is the case, the scaling factor of the water makes little sense. How about 750 grams of potatoes, or 1.5 kg of potatoes?

• I have not read this book, but I note that 1 liter of water is 200% of 500 g of potatos; could that be what is meant? Aug 31, 2013 at 15:19
• @SAJ14SAJ I believe the interpretation of the scaling factor is correct, but the question still remains on what is the best way to scale this recepie in relation to time and the number of bags etc. Aug 31, 2013 at 15:29
• Well you could always do the recipe twice, independently, at the same time. That kind of shows the scaling interpretation may be a little odd. Aug 31, 2013 at 17:00
• @SAJ14SAJ Yes, I could do that, and then it seems reasonable to use 2:1 amount of water to potatoes described in the recipe. I guess the question is about the what should be done with 750 grams and so on. I was hoping someone had some experience on precooking potatoes for potato puree in this way and tips on timing etc. I guess in a more general setting one could say: "How do I scale Starch Gelatinization in potatoes with a sous vide?". Aug 31, 2013 at 17:19
• See Jefromi's answer below; it is almost certainly as I was guessing using the same technique as baker's percentage, but with potato rather than flour as the baseline 100% ingredient. So 750 g of potato would go to 1.5 l (1500 g) of water. In most sous-vide recipes there is enough slush that the number of bags should not make that much difference. You can always divide into 2 if it is more convenient. Aug 31, 2013 at 17:22