Preparation of dairy products for scanning electron microscopy: etching of epoxy resin-embedded material

Summary Sections (1–5 μm thick) of epoxy resin-embedded cheese curd, yogurt, whipped cream and cream cheese were etched by treatment with warm alcoholic NaOH. Thin specimens were produced which could be metal coated and examined by scanning electron microscopy using accelerating voltages of at least 30 kV without producing charging problems. The images observed were easy to interpret and could be used to produce quantitative results. Although native milk fat globules did not survive the etching process, homogenized milk fat was not adversely affected. Critical point drying of etched sections produced results superior to those obtained by air drying.