Effect of storage methods on quality of lac - a natural resin.

摘要

A study was carried out to assess the changes in physico-chemical parameters of lac resin during storage for one year. All three forms of lac viz. sticklac. seedlac and shellac were stored following different methods as practiced by lac traders and industries, and some quality parameters of the products were evaluated during storage. Qualitative losses included decrease in flow, heat polymerization time (life) and rate of filtration; and increase in colour index and hot alcohol insolubles of lac resin during storage. In case of sticklac, maximum increase in hot alcohol insolubles (24% in ari and 69% in phunki sticklac) was noticed in samples stored in plastic bags and minimum increase (4.87% in immature lac and 37% in used-up broodlac) was observed in samples stored on cement floor. Very little difference in the value of flow was observed between different methods of storage. Better life and colour were observed in products stored on earthen floor. Seedlac stored on cemented floor best retained the properties i.e. minimum increase in hot alcohol insolubles (6.17%) and minimum decrease in flow (35.89%) and life (13.43%) after one year of storage. Storage in metal container resulted in 87.65% increase in hot alcohol insolubles, 61.54% decrease in flow and 19.4% decrease in life. Flow and life of cold stored shellac samples were found slightly higher (2 to 5%) than the samples stored by other methods after one year of storage.