2.4. Standardization of coating solution
The coating solutions were prepared by completely gelatinizing
1, 1.5 and 2 g/100 mL starch slurry in water at 95 C for 30 min on
a heating plate while stirring with a magnetic stirrer, followed by
addition of glycerol (0.4, 0.5 and 0.6 mL) as plasticizer and further
heating and mixing for 10 min for crosslinking to occur. In a clean
Petri dish, 18 mL of the suspensions were poured and dried at 45 C
in a vacuum oven for 6 h. The films that were formed were removed
with a forceps. From the different ratios of starch: water: glycerol
tried, the solution forming the best continuous and consistent film
was chosen for preparing the final basic coating formulation (S/G).
To prepare two additional solutions viz., starch þ glycerol þ lipid (S/
G/L) and starch þ glycerol þ lipid þ antioxidant extract (S/G/L/A),
oil (2 mL) and antioxidant extract (4 mL) were added to the basic
coating solution during the last 5 min of mixing followed by
pouring and drying as described.