关键词: 茧丝, 多酚, 单因素, Folin酚法, 响应面优化法

Abstract: Cocoon silk contains approximately 2 wt% of polyphenols, and the residue of these polyphenols is closely related to some factors, such as producing area, variety, season, processing methods and so on. Therefore, we can know the identity of raw silk products by detecting the polyphenols residue in the silk. Currently, there is no reliable and accurate method for determining the polyphenol content in cocoon silk. In this study, a quantitative method for detecting the content of polyphenols in cocoon and silk using the Folin phenol colorimetric method through Response Surface Methodology (RSM) was established. The effects of the dosage of Folin phenol reagent, the dosage of Na2CO3 solution, reaction time, and detection wavelength on the determination of polyphenol content in cocoon and silk were investigated. On the basis of single factor experiments, the detection conditions of cocoon and silk polyphenols were further optimized through Box Behnken design. It is shown that the detection wavelength, reaction time and amount of Na2CO3 solution have significant influence on the quantification results, while the amount of Folin phenol solution within the range of 1.0 mL to 1.4 mL has insignificant influence on the result. According to the result of Box Behnken design trial, the optimal detection conditions for cocoon and silk polyphenols are: 1.1 mL of Folin phenol solution, 0.65 mL of Na2CO3 solution, 32 minutes of reaction time, and detection wavelength of 760 nm. This method has good repeatability and reproducibility, and high detection stability within 40 minutes. The proposed method is accurate, reliable and low-cost, and can be applied for the detection of the content of polyphenols in silk cocoons, raw silks and related silk products.

Key words:  , cocoon and silk, content of polyphenols, quantity, Folin-Ciocalteu method, Response Surface Methodology (RSM)