Exploring a safer alternative to eosin in soft tissue staining

Hematoxylin-eosin (H&E) stain has stood the test of time as the standard stain for histologic examination of human tissues. Haematoxylin is a natural dye, on the contrary, its counterstain eosin is a synthetic dye which belongs to the xanthene group. Synthetic dyes are hazardous to human and animal health. With the increasing awareness of a green earth, it is advisable to use environment-friendly and biodegradable materials. Therefore, an attempt was made to develop as biofriendly substitute in the form of food colour as a counterstain for haematoxylin.

To assess the staining ability of food colouring agents in routine staining and to compare its staining efficacy with Eosin.

Two food colours were obtained and stain was prepared by using 70% ethyl alcohol as counterstain for haematoxylin. Different tissue structures such as epithelium, keratin, collagen fibers, muscles, salivary glands, adipocytes, blood vessels, RBCs were observed and evaluated.

Group A -10 slides stained with green food colour, Group B - 10 slides stained with tomato red food colour and Group C - 10 slides stained with conventional H and E. The stained sections were assessed and graded for nuclear staining, cytoplasmic staining, clarity, uniformity and crispness of staining.

The non-parametric Kruskal-Wallis and Mann-Whitney U tests were performed for statistical analysis.

There was no statistically significant difference between the three study groups with respect to all the parameters except crispness of staining. The crispness of Tomato Red and H and E was better compared to green food colour.

Food colouring agents can be used as a safe, biofriendly and inexpensive substitute to eosin in conventional soft tissue staining.