Fractionation Effect Of Stable Isotopes In Beef During Its Processing

Stable isotope fingerprint analysis technique is one of the most effective techniques for traceability of beef origin.However,the current research focuses on raw materials;how different processing methods and processing times affect the stable isotope fingerprints of beef,and whether stable isotope fingerprints can be used for the beef geographical origin traceability of semi-finished products and processed products is still unclear.This study collected three different sources of beef,which were treated by three processing methods of boiling,roasting and frying at different time.The boiling and roasting time is 5 min,10 min,15 min,20 min,25 min and 30 min respectively,and the frying time is 1 min,2 min,3 min,4 min and 5min respectively.The?¹³C,?¹⁵N,?¹⁸O,?²H values in defatted beef,crude fat and residue were determined by Element-Analyzer-Isotope Ratio Mass Spectrometry?EA-IRMS?.With the aim of exploring the changes of stable isotopes in different tissues and by-products of beef,we used a combination of one-way ANOVA,multiple comparisons,discriminant analysis and other multivariate statistical analysis methods to study the fractionation effect of stable isotope of beef in different processing processes and to confirm the stability and effectiveness of stable isotopes in the geographical traceability of beef processing products.Subsequently,it can provide theoretical support for the traceability of the beef industry chain.The main conclusions were as follows:1.The stable C isotope of defatted beef has no significant fractionation effect during the boiling process whereas the stable N,H and O isotopes have a certain fractionation effect.The?¹⁵N value reached 0.27‰after 25min and the fractional values of?²H and?¹⁸O ranged from 2‰⁵‰and-5‰^-2‰,respectively during the boiling time.The stable C isotope in the boiled residue did not change significantly,while the stable N,H and O isotopes showed a significant decrease trend;the stable C and O isotopes of crude fat shows no significant fractionation effect while the hydrogen isotope is significantly reduced.2.Stable C,N,H and O isotopes in defatted beef have no significant fractionation effect during the roasting process;stable C isotope of crude fat displays no significant fractionation effect,but H and O isotopes show significant fractionation effect.3.The stable C,N,H and O isotopes of the defatted beef have no significant fractionation effect during the frying process;the C,H and O isotopes of the crude fat are affected by the vegetable oil;the stable isotopes in different frying time show no significant difference,thus,processing time has no effect on it.4.When there are significant differences in stable isotopes among beef raw materials in different regions,the stable isotope fingerprints of processed beef in different regions are also significantly different.The isotope fractionation effect occurring during processing is not enough to affect the differences between regions,therefore,multiple stable isotope combinations can be used to identify of the origin of beef processed semi-finished products and finished products.