Abstract:

In this study, the physico-chemical properties of fresh citrus pectin (FCP) and dried citrus pectin (DCP) were
analyzed and compared. FCP and DCP were prepared from fresh and dried citrus peel by traditional acid method with metal
chelators (sodium hexametaphosphate). Then, their physico-chemical properties parameters were determined including
moisture, ash content, acid insoluble ash content, protein content, and pectin quality evaluation indexes such as galacturonic
acid content, esterification degree, gelation degree, relative average molecular weight and apparent viscosity. The results
showed that both pectins had no significant difference in physico-chemical properties. Galacturonic acids content,
esterification degree, gelation degree and relative average molecular weight of FCP were 77.29%, 67.5%, 179.8 and 158.8 kD,
respectively, and those of DCP were 74.98%, 66.7%, 153 and 109.1 kD, respectively. Apparent viscosity of FCP was higher
than that of DCP. An obvious difference between both in quality was observed. Especially, FCP had a higher gelation degree as
an important indicator of pectin quality than DCP. This was probably due to the higher molecular weight of FCP. However, the
esterification degree and galacturonic acid content of both pectins met the requirements of the national standard for pectin quality.
Therefore, dried citrus peel is more suitable for commercial pectin production for storage and season reasons.

Key words: fresh citrus peel, dried citrus peel, pectin, physico-chemical properties