Effect Of Different Rearing Conditions On Microstructure And Stable Isotopes Of Silk Fibers

Stable isotope technique provides a potential method for the traceability of silk fabrics due to its advantages of fast detection and accurate results.Even in a small regional-scale level,there are significant differences in stable isotope values even among cocoons of the same origin due to different climatic conditions.Therefore,it is necessary to investigate the effect of rearing conditions on the stable isotope ratios in cocoons.In this paper,we analyzed the changes of microstructure and stable isotope ratios of silkworm under different rearing conditions based on stable isotope technology,which can provide a scientific basis for the origin traceability of silk fabrics.Stable isotope techniques and Fourier infrared spectroscopy were used to characterize cocoons and silk fiber to investigate the changes in microstructure and stable isotope ratios of silk under different feeding conditions.Based on the above background,mulberry silkworms were artificially cultured under natural conditions in spring,summer and autumn,and cocooning temperature,humidity and starvation time were controlled.Stable isotope analysis was carried out on cocoons produced by mulberry silkworms under different conditions,and the cocoons were drawn by hand reeling machine,and then the microstructure of silk was characterized by Fourier infrared spectroscopy and stable isotope mass spectrometry.The main experimental results are as follows:1.The carbon stable isotope ratios in summer cocoons were lower than spring and autumn cocoons.The nitrogen stable isotope ratios in autumn cocoons were higher than spring and summer cocoons,which suggesting that there is an obvious seasonal effect on carbon and nitrogen stable isotopes in cocoons.There were also differences in carbon and nitrogen stable isotope ratios in mulberry leaves in spring,summer and autumn,suggesting that the differences in carbon and nitrogen stable isotope ratios in cocoons between seasons may be due to the mulberry leaves.There were also minor differences in carbon and nitrogen stable isotope ratios between cocoons of different quality,suggesting that the size of individual cocoons should be taken into account when using cocoons as traceability landmarks.2.The carbon and nitrogen stable isotope ratios in cocoons from 4 different mulberry leaf-fed silkworms also showed regional differences,suggesting that carbon and nitrogen stable isotopes in mulberry leaves are transferred in the silkworm ecosystem and leave specific isotopic ’fingerprints’ in the cocoons.In addition,there are large differences in the carbon and nitrogen stable isotope ratios in different varieties of mulberry leaves,which can also have an effect on carbon and nitrogen stable isotope ratios in cocoons.3.Under high temperature cocooning conditions,the carbon stable isotopes in cocoons are lower than normal and low temperature conditions,and the nitrogen stable isotope ratios are higher than normal and low temperature conditions,indicating a significant temperature effect on the carbon and nitrogen stable isotope ratios in cocoons.The heavy carbon and nitrogen elements in cocoons are depleted under starvation conditions.