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Asian Journal of Agriculture and Development (AJAD) - Call for papers!

Studies on Coconut Milk Emulsion Stability

(Indonesia), Doctor of Philosophy in Food Science (University of the Philippines Los Baños)

Dissertation Abstract:

The study was conducted to determine the chemical composition and physical properties of coconut milk from nuts of varying maturity as well as some factors which affect the stability of coconut milk, and characterize the coconut protein from nuts of varying maturity.

The stability of coconut milk from fresh nuts increased with decrease in moisture, protein, sugar, and galactomannan content, and with increase in fat, nitrogen free extract (NFE), phospholipid content, and total solids. The stability effect of the components was optimum in milk from 11-month nuts of the Bali and Gading varieties and 12-month nuts of the Raja variety.

The milk stability from desiccated coconuts decreased with the increase in drying temperature due to the denaturation. However, milk stability increased with the decrease in moisture, sugar, and protein contents and with increase in total solids, NFE, and phospholipid content.

The most stable milk (1:1, w/w) was obtained from desiccated coconut dried at 50°C. The stability of the milk (1:2, w/w) treated at various temperatures (40-85°C) decreased with increase in temperature during treatment. The milk (1:1, w/w) heat treated at 85°C for 90 minutes was still stable up to 24-hour standing time due to increase in its viscosity.

Using the stepwise regression analysis, two models were established: one defining that from fresh nuts and the other defining that from desiccated nuts. Optimum stability for the coconut milk can be determined using these models.

The proportion of amino acid concentration of the coconut protein isolates from nuts of varying maturity were similar  and the concentration was optimum in the protein isolate from 12-months-old nuts.

The denaturation of the coconut proteins increased with the increase of heat treatment and nut maturity, while their solubility at various pH levels was lowest at pH 4.0 and increased in the more acidic and basic sides. The coconut proteins were composed of globulin (49.79-61.67), albumin (13.56-15.92), prolamine (1.35-1.93). and glutelin (9.61-11.31). Gel electrophoresis results showed that the higher the solubility of the coconut proteins, the greater the amount of the fractions which showed similar characteristics as shown by the control, while the major and minor components of coconut proteins were found to still contain other fractions.