Starch staining

6/20/97

Does anyone know of a stain, either for light microscopy or SEM, that could

differentiate a gelled starch binder from a cellulose fiber matrix? If not a

stain, any other good methods? The magnification would be 50X-300X, and the

sample is dry.

Thanks --

Dave Stadden

DRStadden@Armstrong.com

717-396-5109

Try Schiff's reagent (I get mine from Fisher, but I am sure many places

can supply it). Then, do a control where you digest with

alpha-amylyase followed by reaction with Schiff's. Any place on the

specimen that was starch or glycogen would be magenta with just Schiff's

and colorless (or faint pink) following digestion.

Please contact me directly for a full protocol.

Good luck.

Don

______________________________________________________________________

Donald L. Lovett e-mail: lovett@tcnj.edu

Assoc. Professor, Dept. of Biology voice: (609) 771-2876

The College of New Jersey fax: (609) 771-2674

Trenton, NJ 08650-4700

David,

A dilute solution of iodine-potassium iodide will stain starch. See

"Analysis of Paper" by B.L. Browing for more information.

John Catino

Union Camp

jcatino@ix.netcom.com

I copy this from a book of Olga Flint, Food Microscopy:

If you stain with aqueous iodine viewed brightfield and between crossed

polars:

Raw, amylose-containig starches -> blue, birefringent

Raw, amylopectin starches-> Reddish, birefringent

Chemically modified starches-> yellow or brown, birefringent

Pre-gelatinized, i.e., precooked starch powders-> Reddish, swollen

particles, which may contain blue-stained granules (not birefringent)

Dextrins-> Blue-purple or reddish particles which quickly disperse

Proteins in cryosections and powders-> yellow

I hope this can help.

Rui Costa

ruicosta@esb.ucp.pt