Many researchers reported that a sigmoid kinetic curve was obtained in oil transesterification with methanol catalyzed by CaO and gave different explanations for this formation. In this paper, heterogeneously catalyzed transesterification of soybean oil with methanol using CaO has been investigated. The solid catalyst and the liquid reaction mixture under different reaction time periods were characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, and high-performance liquid chromatography (HPLC) to reveal the formation of an S-shape kinetic curve. The appearance of calcium hydroxide, calcium methoxide, calcium glyceroxide, fatty acid calcium, diglycerides, and monoglycerides and their contributions to the kinetic curve have been discussed. The low reaction rate in the induction period can be attributed to mass transfer in this three-phase system. However, the formation of surfactants, diglycerides and monoglycerides, promotes the emulsification of the reaction mixture and numerous emulsion reactors are generated. These emulsion reactors can improve the contact of the solid catalyst with the reactants and thus accelerate the reaction.
As a commercially available ingredient, the mono- and diglycerides (MDG) were widely used in a plant protein-based emulsion to provide effective, functional, emulsifying properties. The simultaneous addition of the MDG and pea protein isolate (PPI) was investigated by the methods of interfacial rheology and quantitative protein proteomics. The physicochemical quantitative analysis of the oil–water interface revealed an interfacial stability mechanism for the protein adsorption layer. For a low MDG concentration, the interfacial quantities of vicilin and albumin were increased, which could be attributed to the adsorption rate. For a high MDG concentration, both vicilin and albumin were displaced by MDG and desorbed from the interface, while legumin was more difficult to displace due to its slow adsorption and the complex structure of protein molecules. The protein molecules with the structural rearrangement interacted with MDG, exhibiting potential effects on the interfacial film structure. Combined with some nanotechnologies, the new comprehension of protein-emulsifier interactions may promote food delivery systems. The research aims to develop an in-depth analysis of interfacial proteins, and provide more innovative and tailored functionalities for the application of the plant protein emulsion.Keywords:pea protein isolate;mono- and diglycerides;competition adsorption;quantitative protein proteomics
Po1lyurethane foams (PUFs) were prepared using modified castor-oil-based polyols (MCOs). In the first stage, castor oil (CO) was converted into monoglycerides and diglycerides by alcoholysis with glycerol and pentaerythritol. Next, the polyester polyols were synthesised by condensation with the alcoholysis of CO and phthalic anhydride. The chemical and physical properties, foaming behaviour and miscibility with other components of the MCOs were studied by mechanical testing, Fourier transform infrared (FTIR) spectroscopy, gel permeation chromatography (GPC) and thermogravimetric analysis (TGA). The results showed that the components of the MCOs and the foaming behaviour of the foams prepared from the MCOs were similar to those of commercial polyester polyol PS-3152. The reaction activities esterification modified CO polyols were higher than those of alcoholysis modified CO polyols, due to the higher relative content of primary hydroxyl groups. The MCOs and CO had higher thermal stability and better miscibility with polyether polyol 4110 and the physical blowing agent cyclopentane than PS-3152. The properties and flame retardancy of PUFs prepared from MCOs were studied by mechanical testing, TGA and cone calorimetry. The results indicate that the PUFs prepared from castor-oil-based polyester polyols with a reasonable distribution of soft and hard segments had better mechanical properties and thermal conductivities than the PS-3152-based PUF5. Additionally, the MCO-modified PUFs exhibited much higher thermal stability during the pyrolysis process. The cone calorimetry results showed that adding flame retardant ammonium polyphosphate (APP) into PUFs can significantly decrease their heat release rate (HRR), total heat release (THR) and mass loss. These test results indicate that APP has a better synergistic effect with phthalic anhydride polyester polyols than long-chain fatty polyols. All of these unique properties of the MCO-modified rigid PUFs were correlated to the structures of these PUFs. This study may lead to the development of a new type of polyurethane foam using castor oil.
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