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Five protein fractions (albumins, globulins, prolamines, glutelins-1, and glutelins-2) from defatted coconut flour were fractionated and then characterized by SDS−PAGE, gel filtration, differential scanning calorimetry (DSC), and amino acid analysis. The albumins and globulins were the predominant protein fractions. Native coconut proteins consisted of four major polypeptides with molecular weights ranging from about 22 to greater than 100 kDa. However, in a reduced state, there were about seven major bands with molecular weights of between 14 and 52 kDa. SDS−PAGE of protein fractions indicates that the total protein, globulins, and glutelins-1 are composed of polypeptides linked via one or more disulfide bonds. DSC analysis showed that albumins had an endothermic peak of 94 °C, while globulins had peaks at 92, 98, and 112 °C. Amino acid analysis demonstrated that the coconut proteins had a relatively high level of glutamic acid, arginine, and aspartic acid. Keywords: Coconut protein; albumins; globulins; prolamines; glutelins; differential scanning calorimetry

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Biopolymers from soy protein isolate (SPI) crosslinked with glutaraldehyde (GA) were prepared. Surface hydrophobicities of SPI-GA biopolymers and SPI were 4.4 and 11.5, respectively. The solubility profile of SPI was slightly higher than that of SPI-GA biopolymers. Foaming capacities of SPI-GA biopolymers (23 mL) were higher than that of SPI (19 mL), but similar to egg white (22 mL). Foaming stabilities of SPI-GA biopolymers (120 min) were significantly higher than those of SPI (40 min) and egg white (98 min). The emulsifying properties of SPI-GA biopolymers were lower than those of SPI and bovine serum albumin (P > 0.05). Tensile strength (TS) and elongation at break (ETB) of SPI-GA biopolymer films were significantly higher than those of glycerol-plasticized soy protein films. TS and ETB of SPI-GA biopolymer films increased with increasing GA concentrations. GA treatment intensified yellowness of SPI-GA biopolymer films. SPI-GA biopolymers may have potential use for biodegradable packaging materials.