BACKGROUND The oil palm tree produces 90% of wastes and the limited usage of these wastes causes a major disposal problem in the mills. Nevertheless, these by‐products have a large amount of nutritional components. Thus, the present study aimed to determine the physicochemical and functional properties of protein hydrolysates (PH) from oil palm leaves (OPL) extracted using different concentrations of Alcalase (0–10%) at 2 h of hydrolysis time. RESULTS Fourier transform infrared spectral analyses showed that the enzymatic hydrolysis altered functional groups of OPL where a secondary amine was present in the PH. Changes were also observed in the thermal stability where the enthalpy heat obtained for PH (933.93–1142.57 J g−1) was much lower than OPL (7854.11 J g−1). The results showed that the PH extracted by 8% Alcalase exhibited absolute zeta potential, as well as a high emulsifying activity index (70.64 m2 g−1 of protein) and emulsion stability index (60.58 min). Furthermore, this PH showed higher solubility (96.32%) and emulsifying properties compared to other PHs. It is also comparable with commercial plant proteins, indicating that 8% Alcalase is an optimum concentration for hydrolysis. CONCLUSION In summary, the physicochemical and functional properties of PH extracted from OPL showed good functional properties, suggesting that it can be used as an alternative plant protein in food industries. © 2021 Society of Chemical Industry.

Although the fried products are delicious with a tenderizing effect on the crust due to the presence of fat, over-consumption of fried products causes health problems, especially coronary diseases. The tendency of proteins in film formation and thermal gelation to reduce the absorption of oil in fried products is emphasized. The purpose of this study was to determine the reduction of oil in deep-fried squid by the incorporation of protein hydrolysate and to discuss its effect. Yellowstripe scad protein hydrolysate was produced using Alcalase® enzyme. Fat content was determined using the Soxhlet method, subsequently substituted into a formulation for oil uptake calculation. The viscosity of batter was determined using a rheometer. The viscosity of the batter and batter pick-up was found to be directly proportional, showing a significantly reduced pattern from 0 to 20%. Incorporating 10% of fish protein hydrolysate successfully decreased oil absorption by 17.35±0.73% with a good water retention rate of 38.46%. The addition of the Yellowstripe scad fish protein hydrolysate modified the size and shape of the pore. Sensory acceptance portrayed no significant difference among the three samples (0%, 5% and 10% of incorporation), indicating that panellists were able to accept samples incorporated with fish protein hydrolysate. The findings of this study showed that Yellowstripe scad protein hydrolysate can minimize the uptake of oil in fried seafood products and thus could increase the economic value of the Yellowstripe scad fish.

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Oil palm is currently the world's leading vegetable oil crop, with Indonesia and Malaysia as the two largest producers and exporters of palm oil in the world. In order to meet the demand for palm oil, the mills generate huge quantities of by-products causing an alarming concern on environmental impact. Hence, the effort to transform "waste to gold" is very crucial. This review focused on the extraction methods for holocellulose and lignin, as well as processing methods to produce value-added components such as nanoparticles, fermentable sugar, bioethanol, biochemicals, biofuel and phenolic compounds because the oil palm biomass (OPB) generated contain high amounts of nutritional or bioactive components. Processes such as chemical extractions, enzymatic hydrolysis, microorganism fermentation, organic solvent extractions and green extraction technology using deep eutectic solvents, protic ionic liquid, and supercritical fluid, were used to transform OPB into value-added bio-products for various industries especially food, agricultural, and pharmaceutical industries. Chemical extraction was crucial to extract cellulose and hemicellulose from the lignocellulosic material of OPB prior to other processing methods to produce a variety of valuable components. Sequential mild chemical extraction, cellulase cocktail hydrolysis, supercritical carbon dioxide extraction and ethanol extraction successfully extracted OPB value-added components with improved physical and chemical properties.

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