Nutrition calculations for recipes - Things to consider
Dr David F Bartley
Reliable advice and information in this area appears to be in very short supply. Many food professionals are not aware of all of the various considerations. 25 years in this industry, hearing the stories and activities of professionals throughout the industry and our own vast experience has prompted me to write this paper.
The considerations I want to look at are:
- The McCance & Widdowson data, as published, are not suitable
- Many suppliers specifications are outdated, wrong or incomplete
- The loss and or gain of moisture must be considered
- The inclusion of alcohol may affect the way products are calculated
- The limitations & strengths of laboratory analysis
- The limitations & strengths of calculated results
- The intended end use of the information
The McCance & Widdowson data, as published, is not suitable
Since December 2014, the legislation has stated that all figures for nutrition labelling must be calculated in line with the new EU1169/2011 requirements.
The well-known McCance & Widdowson data are considered to be the industry-standard ingredient information used throughout the UK, and have been widely available for 75 years.
But the figures offered in the McCance & Widdowson publication have not been suitable for labelling purposes since 1978, unless they are re-calculated to bring them in line with the Labelling Regulations. This is because they are expressed in line with the requirements of dieticians.
For example, the McCance carbohydrate figures have been modified to take account what happens in the stomach. Thus, the carbohydrate figure for white sugar is stated in the book as 105%. Most of the other carbohydrate values are not correct. Those that can be relied upon are the ingredients for which all carbohydrate is monosaccharide.
A lot of the protein values are also unsuitable, because of varying nitrogen factors.
And there is therefore an impact of both of these factors on the overall energy values.
Figures for labelling must be calculated in line with the new EU1169/2011 requirements. So the NutriCalc version of this data file has been re-calculated to make it suitable for labelling.
Any person wishing to make manual calculations from data provided by either McCance and Widdowson or data taken from other national databases must make adjustments in order to be in line with the EU1169/2011 requirements.
Many ingredients do not appear in national databases, in which case it is usually necessary to use a supplier’s specification. It is extremely important, especially where an ingredient is a major part of a recipe, to have good quality data for it.
Increasingly, suppliers are very happy to supply a specification sheet to their customers which includes a nutrition component. And it will be obligatory from December 2016.
How good are specifications?
Some are an excellent source of information. I am particularly impressed with information provided by Barry Callebaut, Puratos and several other reputable companies.
Some specs however are inaccurate and/or incomplete. If any values are missing, it should not be assumed that these values are 0. It is sometimes possible to fill in blanks from a knowledge of the ingredient type, e.g. if sugars are not declared, but all carbohydrate comes from apple and sugar, then the sugars will equal the carbohydrate.
Unfortunately, energy calculations are quite frequently wrong. We recommend getting NutriCalc to work out energy values when the ingredient information is being entered into the software, rather than taking the figures on the spec.
An experienced eye cast over the ingredient declaration will help to assess whether the nutrition information looks about right because I have seen glaring mistakes, for example where the product is stated to contain no carbohydrate even when it can be seen to contain flour!
If the information has come from a non-EU country, the information may not be appropriate to use because it is produced according to the requirements of that country.
One thing worth checking with specs from the USA or Canada is that they will give the carbohydrate is presented as ‘Total’ whereas in the EU we use ‘Available’. So to convert ‘Total’ to ‘Available, subtract the dietary fibre (or fiber!).
Please talk to me or a member of my team if you are unsure what to do about this.
Many people ask us why, when water has no nutrition value, they need to add this into their recipe. The reason is very simple, the addition or loss of water in any product will either dilute or concentrate the food and for this reason alone it is very important as it can make a very big overall difference.
Of course, some moisture will usually be lost if the product is cooked.
Within NutriCalc, there are three main ways to account for cooking loss:
- Select the overall % cook loss
- Enter the batch and yield weights of the product
- Enter the final moisture content (ideal for biscuit, cracker and sweet manufacturers)
If you have separate components to your product with different cook losses, you may either calculate the overall loss and enter that or save the components as sub recipes each with their own cook loss.
Of course with rice and pasta, cooking actually increases the moisture level. It is possible to create a sub-recipe for cooked pastas and rices.
The inclusion of alcohol in a product is also an important consideration for food manufacturers. The use of alcohol ‘as is’ in products where no cooking takes place after the addition of the alcohol, all is well. If the product is cooked after the addition of a small amount (proportionally) of alcohol, all is also well. However, where there is a large amount of alcohol used in a product which is all boiled off (cooked out), consideration must be given to the overall energy values and must be re-calculated to take this into account.
The strengths and limitations of laboratory analysis
As a previous manager of accredited laboratories within the food industry, I am fully aware of both the strengths and limitations of analysis as a way to determine accurate data for food products.
Lab analysis is applicable to most products, although for products such as low-carbohydrate ‘Atkins’-diet style meals, the lab carbohydrate value will not be precise enough.
Analysis is really the only suitable method for establishing accurate data for deep-fried and fermented products such as salami, as well as those products that lose material (not moisture) with cooking or standing. (Having said that however, these products are by definition very variable and would therefore require a good range of samples for testing to get reliable results).
Sampling is the weakest part of an analysis: if the sample is not representative of the product the lab cannot get good results.
Although generally accurate, lab methods have limitations of precision (plus or minus factors). Since carbohydrate is obtained by subtracting several nutrient values from 100%, the precision of the carbohydrate result will be poorer than the others.
I would normally prefer to obtain high carbohydrate values by calculation.
The limitations & strengths of calculated results
To obtain accurate nutrition information for a recipe, it is necessary to use good data, avoid human error and account for any cooking process.
It is therefore not possible to get calculated results if data are not available for a significant ingredient.
Just as not all products are suitable for analysis, some products are unsuitable for calculation. These are:
- Fermented products such as salami, sauerkraut and yoghurt
- Deep-fried products
- A product that has something removed after or during cooking (such as skimming fat or removing skins etc.)
- Products that lose material (not moisture) during the cooking process (such as grilled chops)
- Pickled products where vinegar is drained (chutneys etc. are fine)
Calculation is quick and economical and allows recipes to be designed, tested and tweaked at the development stage.
The intended use of the Nutrition Information
All of the opinions and advice contained in this paper are based on the assumption that the nutrition information will be used for product labels.
For Restaurants, Caterers and Retail outlets selling unwrapped foods, there is much more scope. Again, please speak to me or a member of my team if you are uncertain about where you stand on this.