Macadamia Oil Extraction With Alcoholic Solvents: Yield and Composition of Macadamia Oil and Production of Protein Concentrates From Defatted Meal

The aim of this study is to evaluate the performance of ethanol and isopropanol in the extraction of macadamia oil and the production of protein concentrates from the defatted meal. Partially defatted macadamia cake is submitted to batch extractions in one stage of contact at 60, 75, and 90 °C, while the sequential extraction trials considering four stages are performed at 75 °C. Oil extraction yield is influenced by the solvent type, temperature, and pre‐treatment of the material. Absolute isopropanol at 90 °C enables to extract 66% of the oil while in the sequential configuration, oil yield up to 96% is attained after four stages. The retention of the solution adhered to the fiber (liquid holdup, LH) is affected by the type of solvent and characteristics of the raw material, being obtained LH values higher than 2. The oil extraction conditions affect negatively on the nitrogen solubility index of the defatted meal. The solvents in absolute degree impact less on the solubility of the proteins, enabling the production of macadamia protein concentrates (protein content of 70%) with functional properties suitable for using in the food industry. Practical Applications: This study is useful to oilseed processors and researchers because it addresses the issue of using macadamia cake as raw material to oil extraction with alcoholic solvents, ethanol, and isopropanol, which are less flammable and toxic than hexane. In addition, it is evaluated the effect of process variables on the oil yield, liquid holdup, and characteristics of the extraction products (oil and defatted meal). The results of this work could help to develop macadamia oil extraction process safe for the workers of oil industry and consumers and, simultaneously, to enable the use of by‐products (defatted meal) in the protein concentrates production. Macadamia oil extraction, from partially defatted macadamia cake, is carried out using ethanol and isopropanol (absolute and hydrated) as solvents. The products of macadamia oil extraction are characterized, thus the extracted oils show typical fatty acid composition and the defatted meal presented higher protein content than raw material. Therefore, from these defatted meals are produced macadamia protein concentrates, which show good functional properties to be used as food ingredients.