Utilization of Hempseed Press Cake: Optimization of Protein Isolation and Ice Cream Formulation

Abstract: Hempseeds, a by-product from hemp fiber production, have a very good nutritional profile, both for essential fatty acids and amino acids, increasing the interest to use hempseeds as a food source. The aims of this project were to optimize the extraction of proteins from hempseed press cake, characterize the functions of the proteins and determine if an ice cream formulation can be created. The extraction of proteins was based on a method for alkali extraction with isoelectric precipitation. Three different optimizations were investigated, different alkali pH treatments, different extraction times for the alkali extraction and a test to scale up to semi-pilot scale. The results showed that the most optimal treatment was when the alkali pH was kept constant at 10.5 with 1 h extraction time. This yielded in a protein rich sediment with 90% protein content on dry basis and a 60% yield. It was also shown that the process could be scaled up to semi-pilot scale. The characterization was made by examining the proteins emulsifying properties, thermal behavior by differential scanning calorimetry (DSC) and viscosity behavior by a rapid visco analyzer (RVA). The results showed that the proteins have an ability to work as an emulsifier, it also has a thermal transition at approximately 80°C. Whereas the RVA showed no heat induced viscosity change. The ice cream formulations were created with different protein to fat to water (PFW) ratios and compared to an ice cream reference. The ice cream with the properties most similar to the ice cream reference had a PFW ratio of 1:4.5:12 with equal amounts of rapeseed oil and coconut oil as a fat source and fresh sediment as protein source. This concludes that it was possible to create an ice cream formulation based on hempseed proteins.