Thunnalin Winuprasith. Stability of emulsion prepared using mangosteen shell fiber as an emulsifier and the application in food products. Master's Degree(Food and Nutrition for Development). Mahidol University. : Mahidol University, 2009.
Stability of emulsion prepared using mangosteen shell fiber as an emulsifier and the application in food products
Abstract:
Dried, ground mangosteen shell is a by-product of the pharmaceutical industry
that is usually discarded as waste. In this study, mangosteen shell fiber (MSF) was
prepared from mangosteen shell by alcohol extraction and used as an emulsifier. The
ability of MSF to form and stabilize 65% oil-in-water emulsions was examined. The
concentration of MSF was varied from 0.5%-2.0% by weight. Emulsions with a
mono-modal particle size distribution and relatively small mean droplet diameters
(16.1 μm) could be produced at MSF concentration > 1 %. However, optical
microscopy showed that there was always a small population of large droplets present
in emulsions after homogenization, creating some creaming instability. No creaming
was observed in emulsions stabilized by 2.0 % MSF during 3 days storage. A high
viscosity emulsion was formed that can retard droplet movement. At 0.5 % of MSF,
the emulsions had poorer storage stability. This means that emulsions produced at this
concentration could be more susceptible to flocculation or coalescence. The results
show that increasing MSF concentration significantly increased (p<0.05) the values of
viscosity, creaming and storage stability. The mean droplet diameter significantly
decreased (p<0.05) with increasing MSF concentration in each sample. Application of
MSF in food products was tested in thousand islands salad dressing and chocolate ice
cream. Salad dressing and ice cream were formulated by using MSF to replace
lecithin and glycerol monostearate at 0.5, 1.0, 1.5 and 2.0%, respectively by weight.
For salad dressing, the optimum level was found to be 0.5 %. The product was
accepted by the panelists with the overall acceptability score between like slightly and
like moderately. Little effect was observed on increasing firmness and decreasing
droplet size, whereas a marked effect was observed on color and smoothness. Phase
separation occurred after 6 weeks of storage. For ice cream, the optimum level was
found to be 1.0 %. The product was accepted by the panelists with the overall
acceptability score between like slightly and like moderately. The products with a
higher MSF concentration showed a higher viscosity, and also higher fat
destabilization and hardness whereas the overrun value, melting rate and air cell size
decreased. The quality and acceptability of formulated ice cream deteriorated with
increasing storage time up to 2 months. This study demonstrates that MSF may have
the potential for some applications as an emulsifier in food emulsion.