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Effect of baking and fermentation on the stable carbon and nitrogen isotope ratios of grain‐based food
Author(s) -
Bostic Joshua N.,
Palafox Sherilyn J.,
Rottmueller Marina E.,
Jahren A. Hope
Publication year - 2015
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/rcm.7178
Subject(s) - chemistry , ingredient , fermentation , food science , sugar , yeast , stable isotope ratio , isotope ratio mass spectrometry , raw material , isotope , isotope analysis , isotopic signature , mass spectrometry , chromatography , biochemistry , organic chemistry , ecology , physics , quantum mechanics , biology
Rationale Isotope ratio mass spectrometry (IRMS) is used extensively to reconstruct general attributes of prehistoric and modern diets in both humans and animals. In order to apply these methods to the accurate determination of specific intakes of foods/nutrients of interest, the isotopic signature of individually consumed foods must be constrained. For example, 86% of the calories consumed in the USA are derived from processed and prepared foods, but the relationship between the stable isotope composition of raw ingredients and the resulting products has not been characterized. Methods To examine the effect of common cooking techniques on the stable isotope composition of grain‐based food items, we prepared yeast buns and sugar cookies from standardized recipes and measured bulk δ 13 C and δ 15 N values of samples collected throughout a 75 min fermentation process (buns) and before and after baking at 190°C (buns and cookies). Simple isotope mixing models were used to determine if the isotopic signatures of 13 multi‐ingredient foods could be estimated from the isotopic signatures of their constituent raw ingredients. Results No variations in δ 13 C or δ 15 N values were detected between pre‐ and post‐baked yeast buns (pre: –24.78‰/2.61‰, post: –24.75‰/2.74‰), beet‐sugar cookies (pre: –24.48‰/3.84‰, post: –24.47‰/3.57‰), and cane‐sugar cookies (pre: –19.07‰/2.97‰, post: –19.02‰/3.21‰), or throughout a 75 min fermentation process in yeast buns. Using isotopic mass balance equations, the δ 13 C/δ 15 N values of multi‐ingredient foods were estimated from the isotopic composition of constituent raw ingredients to within 0.14 ± 0.13‰/0.24 ± 0.17‰ for gravimetrically measured recipes and 0.40 ± 0.38‰/0.58 ± 0.53‰ for volumetrically measured recipes. Conclusions Two common food preparation techniques, baking and fermentation, do not substantially affect the carbon or nitrogen isotopic signature of grain‐based foods. Mass‐balance equations can be used to accurately estimate the isotopic signature of multi‐ingredient food items for which quantitative ingredient information is available. Copyright © 2015 John Wiley & Sons, Ltd.