Utilization of coconut protein in tofu-like products

Abstract

Coconut production and processing are the predominant economic activities in rural communities in many tropical regions of Asia and the South Pacific. However, utilization of coconut protein is limited to household scale because of the low protein content of coconuts and poor extractability of good quality proteins. Therefore, the objectives of this study were to optimize protein extraction and recovery from coconuts, to develop tofu-like products from coconut protein, and to characterize physicochemical properties of coconut protein ingredients and products. Grated coconut meat was blended with distilled water (2:1 w/w) and squeezed to yield coconut milk. Defatted coconut milk was also prepared by centrifuging the milk. The optimum extractability of coconut protein was obtained with 0.5-1 M NaCi solution, at pH 1 0-1 1 and a temperature of 35-55'C. Utilizing coconut milk and defafted coconut milk, tofu-like products were developed. Coconut milk, either whole or defafted, was heated at 980C to produce soft curds. After heat coagulation, the curds were pressed in cheesecloth overnight to drain the whey. Addition of calcium sulfate (0.06 M) to the coconut milk and/or adjustment of pH to 5 increased the hardness of tofu- like products. The molecular forces involved in the formation of tofu-like products (coconut protein coagulation) were mainly electrostatic and hydrophobic interactions. The fluorescence tests for the titration of coconut proteins indicated that the higher heating temperature increased the hydrophobicity of coconut protein, which mainly led coconut protein to coagulation and curd formation. Tofu-like products have unique textural properties with no adhesiveness. The firmest tofu-like product made from defafted coconut milk (2.75 kg/c M2 ) has textural properties very similar to commercial tofu. Laboratory experiments were conducted utilizing the coconut protein concentrate prepared by ultrafiltration membrane technique, and a series of scale-up production tests were carried out to determine the commercial applicability of the processes. The results of these studies indicate that tofu-like products could be produced directly from coconut milk, utilizing the improved coconut protein extraction and coagulation methods, which could broaden food uses of coconuts and their products.