掺假咖啡的形态鉴别研究

Identification of morphology of adulterated coffee

目的建立掺假咖啡的形态鉴别方法。方法通过电子显微镜镜检对巴西莓果粉、炒大麦粉末、黑玉米粉末掺假咖啡进行鉴别。结果咖啡颗粒显微镜镜检大多呈棕色不规则砂粒、砂晶状,镜下串联成直链和支链,10%咖啡水溶液镜下大多呈棕色不规则砂晶状,表面密布卷曲纹;巴西莓果粉及其水溶液镜下常见深浅不一紫红色、紫色表面平滑晶块晶片,还有极少表面呈紫红色、棕红色蜂窝状纹路碎块;炒大麦粉末镜下大多呈灰色、灰黑色、棕黑色无定型不规则碎粒状、块状,其水溶液镜下呈边缘较柔和或散碎无定型银灰色、银黑色、灰黑色碎块或糊化团;黑玉米粉末及其水溶液镜下大多呈银灰色、银黑色不规则块状物,边缘或柔和或散碎。咖啡粉末显微透光性强于大麦、黑玉米等禾谷类淀粉颗粒。结论通过本形态鉴别方法,可分辨出巴西莓果粉、大麦、玉米等掺假的咖啡。

Objective To establish a morphological identification method of adulterated coffee. Methods The acai berry fruit powder, roast barley powder and black corn powder adulterated coffee were identified by electronic microscope. Results Coffee particles were mostly brown irregular sand, sand crystalline, and connecting in series under microscope. The 10% coffee solution mostly showed brown irregular sand crystalline, with densely curly lines on surface. Acai berry fruit powder and its solution commonly appeared two-tone purple, purple crystal surface smooth piece of wafer, and rarely surface with purple red and brown red honeycomb fragments under microscope. Roast barley powder microscopically mostly showed gray, grey black and dark brown, and the amorphous irregular granular or lump. Edge of its solution microscopically showed soft and/or scattered broken and amorphous colored pieces or pasting group with silver gray, silver black and gray black. Black corn powder and its solution mostly showed silver and silver black irregular lumps, edge or soft or broken under microscope. The microscopic transmission of light of coffee powder was also stronger than barley, black corn and other cereal starch granules. Conclusion With the method of morphological identification, adulterated coffee blended with acai berry fruit powder, barley and black corn can be distinguished.