How to calculate a recipe not included in the database
If the composition of a composite or mixed dish is not known, it can be estimated by calculation from a standard recipe and applying appropriate nutrient retention factors and, in some cases, adjusting for changes in moisture content due to cooking loss or gain during cooking. The following guidelines are suggested.
● Identify the ingredients of the recipe from the most appropriate foods available in the food composition database table.
● Quantify the ingredients in mass (g).
● Calculate the nutrient values for the specific amount of each ingredient.
● Add up the nutrient values of the individual ingredients.
● Calculate the nutrient composition for 100 g of the recipe.
● Apply suitable retention factors to the mineral and vitamin nutrient values if the recipe food is cooked. Note that if individual ingredients are in a cooked form this step is not necessary.
● Compare the moisture content of the calculated recipe with a similar cooked composite dish. If the moisture content differs by more than 1%, adjust the moisture content of the recipe food. All of the nutrients of the recipe food must be adjusted (concentrated or diluted) according to either the decrease or increase in moisture content.
● Assign to a suitable food group and list.
This is only an estimation of the make-up of a com-posite or mixed dish of unknown composition. Refer to Table 11.7 for an example of the calculation of the composition of a dish from a recipe. However, if this dish is a very important part of the diet of an indi-vidual or group and the information is crucial in assessing the adequacy of the diet, analysis should be considered.
Food composition tables and databases are mainly used in nutritional epidemiology to estimate the composition of foods consumed by individuals. All subjects have difficulties in estimating the exact portion sizes of food consumed. This issue is further complicated by the difference between the weight of a product as purchased and that of the actual item consumed (e.g., in meat after cooking there is at least a 25% cooking loss, without bone and with or without visible fat). Standardized portion sizes for individual foods within countries may help, but a set of standard food models (small, medium, and large) for use in dietary assessment may be of more value.