Detecting Quickly Chemical Additives In Food Using Raman Spectroscopy

Frequent food safety incidents had been occur, which affected the health and safety of Chinese consumers in recently years. Therefore, a real and rapid detection technique should be used to supervise and regulate the food quality and safety for the huge-demand and short consuming market. Laser Raman spectroscopy is a rapid detection technology having some merit such as simple operation low cost and quick detection. In this paper, Raman spectroscopy technology as a rapid and real-time detection method was used to analyze qualitatively and quantitatively the allura red and patent blue V in hard candy, as well as saccharin sodium in spirit. The main research contents are as follows:(1) Portable raman spectrometer was used to detect the allura red in hard candy. After attributed and analyzed the raman peaks of allura red by density functional theory method and normal raman spectroscopy, six characteristic raman peaks were confirmed which were 1 222, 1 272, 1 330, 1408, 1 500 and 1 580 cm-1, respectively. Then the standard curve was established under the characteristic raman peaks with 1 500 cm-1. The results indicated that the curve possessed a good linear relationship between 0.1~1.0 g/kg, the determination coefficient was 0.995, average recovery of allura red ranged from 95.99% to 102.92%, and the relative standard deviation(RSD) was between 3.19%~5.59%. The limits of detection(LOD) of allura red reached to 0.1 g/kg, which conformed to the national standard. These results would provide scientific reference for raman spectroscopy rapid detection,especially detected the allura red in hard candy.(2) In this paper, surface enhanced raman spectroscopy(SERS) was employed to quickly detect illegally additive(sodium saccharin sweeteners) in spirit. Gold colloid was used to enhance raman signal of molecule. Several parameters such as the volume ratio of gold colloid, detection sample and sodium chloride solution, time of mixing, p H value of working buffer were optimized. The results illustrated that the strength of raman signal was maximum when the volume ratio of gold colloid, detection sample and sodium chloride solution, time of mixing, p H value of working buffer were 1:1:0.5, 5 min and 4,respectively. Contrasting the test values of sodium saccharin sweeteners and the simulation values by Density Functional Theory, and three characteristic peaks of sodium saccharin sweeteners such as 1148, 1164 and 1296 cm-1were found. These characteristic peaks could be as a basis for qualitatively and quantitatively analyzing sodium saccharin sweeteners in spirit. The standard curve of saccharin sodium concentration in spirit was established based on the strength of 1164 cm-1. The results indicated that the curve possessed a good linear relationship within the range of 0.8 and 20 mg/L, and the determination coefficient was0.9933. Average recovery of saccharin sodium in spirit was 98.57% ~ 102.5%, and the relative standard deviation(RSD) was 2.44% ~ 8.6%. The minimum detectable concentration of sodium saccharin sweeteners in spirit reached to 0.8 mg/L and thedetection time of a sample was within 10 min. The study indicated that SERS method could rapidly and accurately identify saccharin sodium sweeteners in spirit. This study can offer method support for the development of real-time and rapid detection device in liquor.(3) Surface enhanced raman spectroscopy was employed to rapidly detect patent blue V which was a banned additive in hard candy. Silver colloid was used to enhance raman signal of molecule. Initially, the raman peaks of patent blue V molecular was calculated by density functional theory, and then compared with the experimental raman spectral peaks to confirm the characteristic peaks. The results showed that the 1156,1184, 1210 and 1612 cm-1 peaks were selected as the characteristic peaks to analyze the patent blue V in hard candy qualitatively and quantitatively. The standard curve of patent blue V(hard candy was used as matrix) exhibited a good linear, the limit of detection was1.43 mg/kg, linearity range ranged from 1.43 to 24 mg/kg, coefficient of determination higher than 0.9906.The relative standard deviation(RSD) that was established by the peak intensity of 1210 cm-1 ranged from 3.17% to 5.33%, and the average recovery rate from84.62% to 103.05%. In summary, the developed surface enhanced raman spectrum method can accurately, rapidly and sensitively detect patent blue V in hard candy, which will provide a basis detection technology for detection and supervision of illegal additive patent blue V in import candy.