My understanding is, that one method of determining the contents of saccharides in food is (or was) to empirically determine the other macro components, i.e. fats, proteins, water and ash. The saccharides were later calculated to add up to 100%. If other methods are used, I assume, the addition should be approximately 100% again. How much deviation from that value is reasonable to ecpect ? 10% ? 20 % ? Or more ?
In modern food analysis, more advanced techniques like chromatography or enzymatic methods are often used to directly measure carbohydrates. However, if you're using the traditional "difference" method, you're essentially working with a balance, where the sum of all components (fats, proteins, water, and ash) should ideally be close to 100%, and the difference can be attributed to carbohydrates.
Expected deviation:
In theory, the sum of the components should add up to exactly 100%. However, in practice, some small deviations are expected due to:
Measurement inaccuracies – There may be slight variations in lab equipment, technique, and sample handling.
Presence of minor components – Foods may contain small amounts of other substances that aren’t directly measured (e.g., fibers, vitamins, minerals, or trace elements).
Moisture content – Moisture content can vary based on the sample's storage, preparation, and environmental conditions.
Reasonable deviation:
A deviation of up to 2-3% from 100% is typically acceptable for most routine food analysis. A deviation larger than that, especially around 10% or more, may indicate issues with the analysis, such as:
Improper sample preparation (e.g., incomplete drying of the sample before measurement),
Poor accuracy in measuring one or more components, or
Overlooking other components that might not be accounted for in the analysis (e.g., fiber content or other non-nutrient substances).
If you observe a deviation of 10% or more, it might suggest a more significant issue with the methodology or measurement process, and further investigation would be warranted.
@Nicolas Poirer, is 10% too much even if you use modern chromatographic methods etc and not the "difference method" for saccharides ?
Is the fiber declared sometimes as saccharides ? I got the impression, that sometimes it is and sometimes it isn't, but maybe I am missinterpering something ?
Fiber may or may not be included as part of the carbohydrate content depending on the source or methodology being used. In many cases, it is reported under total carbohydrates, but in some cases, it is listed separately.
In certain contexts, especially in more detailed scientific studies, fiber may be reported separately from saccharides. The fiber content is considered more as a distinct component that doesn’t get broken down into simpler sugars. This distinction can lead to a report where fiber is listed separately from the total carbohydrates, especially if the food product is high in fiber.
If some other minor components in the food matrix (like specific fibers or other trace elements) aren’t accounted for, it might result in a discrepancy, but again, this should be minimal in modern methods.
10% is generally too high, even with modern techniques. If you see such a deviation, it might be a sign to review the methodology or check if there's an issue with the sample preparation or analysis process.
The error margin is typically much smaller, usually within 5% or less for most food matrices.
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