Hi Heathk –
Yes I know how to do it. It’s not difficult but I’m going to warn you that it’s very tedious.
The first thing I’d recommend doing is making a chart with the name of the ingredient, weight of the ingredient used (keep everything in the same units – I use grams), grams protein, % moisture, dry matter ingredient weight, % protein, % fat, weighted % protein and weighted % fat.
1) Fill in the first column with all the ingredients you’ll be using.
2) Fill in the second column with the amount of each ingredient used. For example, if I’m using 1 lb. ground beef I’d put 448 g.
3) Go to the USDA Nutrient Database. It’s much more effcient than Self Nutrition Data – you can enter the amount of the ingredient you’re using and it will automatically calculate nutrient values for you and it gives moisture values. Get the grams of protein from this site and enter it for each ingredient in this column.
4) Enter grams of fat for each ingredient in this column.
5) The grams of water per 100 g. given on the USDA Nutrient Database will be equal to the percent moisture. Enter the pecent moisture in this column.
6) Subtract percent moisture from 100% to get percent dry matter. Multiply percent dry matter (as a decimal) by the grams of the ingredient to get the dry matter weight. Enter that in this column.
7) Divide g. protein by dry matter weight to get percent protein. Enter that in this column.
8) Divide g. fat by dry matter weight to get percent fat and enter in this column.
9) Calculate weighted protein value for each ingredient by multiplying column 6 by column 7.
10) Calculate weighted fat by multiplying column 6 by column 8.
11) To get the % protein on a dry matter basis for the entire recipe add the weighted protein values for each ingredient and divide the sum by the sum of the dry matter weights of each ingredient.
12) To get the % fat on a dry matter basis for the whole recipe repeat step 12 using the sum of the weighted fat instead of the sum of the weighted protein.
