Reutilization of food wastes (16): Separation of isoflavones from okara – a case study towards more sustainable process design

Polyphenols have been reported to have a wide range of health benefits. However, they are usually present in low amounts (< 1%) in complex food systems. The key challenge is to separate and concentrate those components in a cost-effective, but also environmental-friendly manner with a non-toxic solvent route. Furthermore, an overall scarcity of resources has led to the utilisation of waste streams for the recovery of valuable components. Okara is a good example as a very nutritious by-product, coming from the soymilk and tofu production. In addition to fibres (mainly insoluble), proteins and fat, okara contains isoflavones in a considerable amount. The production of isoflavones from okara would not only upgrade the soymilk production, but less valuable food resources would be required for the production of those minor, but valuable components. Therefore, the aim of this study was to develop a mild separation process for isoflavones from okara.In the first part of the study, mechanisms of extraction were investigated to gain more insight about the location of isoflavones in the food matrix, their behaviour towards the matrix, and their affinity to the chosen solvents ethanol and water. Next, purification mechanisms were investigated, amongst others processes based on affinity. Based on the gained knowledge, an extraction-adsorption process was conceptually designed and tested to separate the isoflavones in a mild and environmental-friendly way.In conclusion, different polarities of the isoflavones and their partial interaction with the matrix components complicate their separation. Nevertheless, specific knowledge about the system enabled the development of an environmental-friendly approach to separate isoflavones from okara in a combined extraction-absorption process.The full presentation and the recording of the session can only be accessed by IFA-members. Non IFA-members can ask for access against a small handling fee of 30 € at office [AT] iseki-food [dot] net