Starch, soluble has been used:

• as a reference standard in amyloglucosidase activity assay[1]
• as a substrate for amylase activity in digestive system homogenates of fish[2]
• as a component of feed solution in simulated human intestinal redox model[3]

Starch synthesised by plants is a polymer of amylose and amylopectin. Amylose is a linear polymer of glucose whereas amylopectin is a highly branched polymer. Starch is a renewable and biodegradable polymer and is widely used in starch nanoparticles (SNP) development.[4] Starch has flexible structural properties and is modified and functionalized for pharmaceutical applications.[5] Starch comprises of rapidly digestible starch (RDS), slowly digestible starch (SDS) and resistant starch (RS). Resistant starch improves metabolic profile, gut bacteria and has anti-diabetic functionality.[6] Resistant starch has low glycemic index and helps in weight management. It may be effective in treating metabolic diseases and colon cancer.[7]

It is best practice to initially prepare a paste using 2 g of starch with a small amount of cold water and add to 100 mL of boiling water with stirring.
There should be no noticeable change in opalescence.