Milk Solid Non Fat (MSNF)

To do this you need to find the MSNF in your milk and cream and sum them. This will give the MSNF in your mix.

To find the MSNF in cream you need to know the fat content. If you search this forum you will find out how to do this. There is also a calculator on the subscription On Line calculator that will do this for you. Assuming your milk contains 9% MSNF then the contribution from milk will be 20 x 0.09 about 2%. So you add the 2 % to what you calculate from the cream. 

I can tell you in advance that this will give you a very low MSNF value. A mix like this will have a weak body and should not be stored for long since ice crystal growth and iciness would be expected.

Use of the formula will give you a target MSNF valueyou will need to add skimmed milk powder to increase your MSNFto aim for. This should improve your ice cream quality.

To use the formula 

you need to find how much fat the cream contributes to your mix. Say the cream contains 30% fat. Then the fat from cream will be 30 x 0.3 = 9%. You know the sugar it is 18%. next you need to find the solids in your liquid egg and fruit purree. Then these are added and subtracted from 100. Finally you divide by 7.

I guessand it is a guessthat you will get a value of around 9% or more.

If you mix has a MSNF of say 6% you should increase it to 9%. These values are only for illustration.

Hope this helps.

There are other similar formulae.

What these formulae do is to provide a maximum value for MSNF that gives a lactose in free moisture value that will not result in the crystallisation of lactose and the development of 'sandy' ice cream during storage and distribution. Sandiness refers to a gritty feeling from the lactose crystals in the mouth.

The formula is an alternative to working out the actual lactose concentration in the ice cream mix. MSNF can absorb about 6 times their weight of water. So knowing thisand the concentration of lactose in your mix you could work out  the free water and the concentration of lactose in the free water. You could then compare this with the solubility data for lactose in water at various temperatures.

This relationship is very useful when working with artisan mixes that do not use stabilisers.

In practice you can exceed the MSNF by a considerable margin if you use stabilisers. This has been known since the work of  Nickerson in 1960.

Yes you need to include other ingredients in the formula. Add their dry weights.