19-08-2014, 11:45 AM
Initially, hydroxypropylation of corn and waxy amaranth starch in organic phase was carried out in an effort to get derivatives of higher molar substitution (MS), and characterized with respect to MS.
The emulsifying ability, film-forming properties, and low viscosity of gum arabic make it an industry standard for encapsulation of sensitive food ingredients. Being a tree extrudate, its supply and quality is dependent on the climatic conditions. Indian industry relies totally on imports for good quality gum arabic. Its cost factor is also not very advantageous. These reasons have prompted many manufactures to look for substitutes. Starch derivatives possessing characteristics similar to those of water-soluble natural gums have been seriously considered for several decades. This project aims at developing modified starches as gum arabic substitute for microencapsulation.
Initially, hydroxypropylation of corn and waxy amaranth starch in organic phase was carried out in an effort to get derivatives of higher molar substitution (MS), and characterized with respect to MS.
Hydroxypropyl derivatives of both starches having a MS of 0.20 were hydrolyzed with a-amylase, and the process was characterized with respect to dextrose equivalent (DE) and viscosity. The hydrolyzates of DE 16 were studied as a wall material for encapsulation of orange oil and lemon oil.
Esterified starches as gum arabic substitutes are known in patented literature. An attempt was made to check the sequence of modification, i.e. i) modification followed by hydrolysis, and ii) hydrolysis followed by modification for preparing oleates from native corn starch and maltodextrins of 12 and 18 DE, and its application for encapsulation of orange oil. Hydrolysis followed by modification proved to be a very useful. Further attempts were therefore made on modification of maltodextrin of DE 18 with octadecenyl succinic anhydride (ODSA), and n-octenyl succinic anhydride (n-OSA). The derivatives so obtained were studied for properties relevant to encapsulation of model flavouring, orange oil.
Further studies were conducted on encapsulation of orange oil and turmeric oleoresin using individual, binary and ternary blends of gum arabic /maltodextrin /modified starch. The use of pullulan as an approach to emulsifier-free emulsification of turmeric oleoresin, and its subsequent microencapsulation was also investigated. Finally, the use of encapsulated turmeric oleoresin vis-à-vis free turmeric oleoresin (with the wall materials developed in the study) as pre-extrusion colouring of sorghum flour was carried out.
The approach developed in this study is cost-effective, and eliminates the enzymatic hydrolysis of the modified starch.
Furthermore, it uses maltodextrins that are more readily available than waxy starches. The derivatives developed had better encapsulation properties than gum arabic, and were equivalent to commercially available modified starches.