Stable Isotope And Mineral Fingerprint Characteristics Of Mutton In Inner Mongolia

Inner Mongolia is one of the major mutton production areas in China due to its grassland resource advantages.The quality of mutton is affected by external factors such as feeding patterns,regions and species,there is a lack of systematic evaluation on stable isotope and mineral characteristics of mutton in Inner Mongolia,especially the source authenticity and traceability system are not enough.In order to explore the identification effect of carbon and nitrogen stable isotopes and mineral elements on different feeding patterns of Inner Mongolia mutton,87 samples of grassland pasturing sheep meat,17samples of barn feeding sheep meat and 24 samples of pasturing goat meat were collected from 11 banners/counties in four typical pastoral areas and agro-pastoral areas in northeast,east-center,west and westernmost parts of Inner Mongolia.The?¹³C and?¹⁵N values in the longissimus dorsi muscle of mutton were determined by Isotope Ratio Mass Spectrometry(IRMS),and 14 mineral elements were determined by Inductively Coupled Plasma Mass Spectrometry(ICP-MS).Descriptive statistics and cluster analysis were carried out on different feeding patterns,regions and species,trying to establish a discrimination model between pasturing and barn feeding sheep meat.The results showed that there were significant differences in the stable isotopic composition of carbon and nitrogen in sheep meat between pasturing and barn feeding,and they are clustered separately.The mean?¹³C and?¹⁵N of pasturing sheep meat were(-21.59±3.52)‰and(7.35±2.67)‰,respectively.The mean?¹³C and?¹⁵N values of sheep meat in barn feeding sheep meat were(-14.57±1.02)‰and(4.38±1.01)‰,respectively.A single index carbon stable isotope can effectively distinguish different feeding patterns,and the overall discrimination accuracy of?¹³C and?¹⁵N values on sheep meat feeding patterns was 99%.The linear discriminant analysis of?¹³C and?¹⁵N values in sheep meat from four cities showed that the correct rate of original overall discriminant was 70.2%,and there was an obvious trend of separation among cities and banners/counties,respectively.Principal component analysis(PCA)of minerals showed that sheep meat from pasturing and barn feeding were obviously separated,and the regional clustering was consistent with the clustering mode of feeding patterns.Further PCA analysis showed that sheep meat in pasturing cities were obviously separated,and there was also a trend of separation among banners/counties,and there was also a trend of clustering between two counties in barn feeding area,which implied that minerals fingerprints of mutton can be applied to establish geographical origin authentication model.There were differences in carbon and nitrogen stable isotopes and mineral fingerprint characteristics between goats and sheep in Alxa League,and the separation trend of PCA analysis results of species by the combination of two traceability indicators is more obvious.Carbon and nitrogen isotope and mineral elements combine was superior to single traceability index in distinguishing sheep feeding pattern and origin,and the separation of PCA cluster was more obvious and the distance was longer.The three characteristic traceability indicators screened out can still effectively classify feeding patterns.The accuracy of external verification of Soft Independent Modeling of Class Analogy(SIMCA)was 100%.Overall,the results confirm the potential of carbon and nitrogen isotopes and multi-element analysis to identify Inner Mongolia mutton.