Abstract
Regional niche products are increasingly sought after by consumers but also prone to food fraud. South Tyrolean cereals are mostly consumed as traditional bread which must contain a minimum of 75 % regional flour to be marketed under the “Regiokorn” seal. Four typical bread types were prepared and their Sr isotopic ratio and content together with all used ingredients was analyzed. The overall strontium pool of bread is not governed by flour alone, but by all added ingredients (flour, water, salt and yeast), making it impossible to define a clear-cut 87Sr/86Sr window for Regiokorn bread. Nevertheless, the analysis of all ingredients and the application of a mixing model allow for the prediction of a theoretical 87Sr/86Sr value. A statistical error propagation method was employed to establish 95 % confidence intervals that react dynamically to the type and ratio of ingredients. This would enable to detect fraudulent adulterations with a high likelihood.
•The 87Sr/86Sr isotopic ratio in a bread is governed by all ingredients.•87Sr/86Sr analysis can be used to trace foodstuffs based on ingredient mixtures.•The Kragten method of error propagation provides a robust 95 % confidence interval.•87Sr/86Sr analysis is useful to trace traditional bread from South Tyrol (Italy).•False negatives are possible but unlikely, false positives are extremely unlikely.