The acid degumming waste of the seeds oil refining industry is currently disposed of, but, instead, it could be exploited as an important source for the preparation of many products. In this work, the waste coming from the soybean oil refining step was first recovered and treated, allowing the isolation of a fraction enriched of phospholipids (PLs). Then, the latter was transformed, via an enzymatic reaction catalysed by phospholipase D (from Streptomyces netropsis), into more valuable products: polar head modified PLs-enriched mixtures containing phosphatidylserine (PS), phosphatidylglycerol (PG), phosphatidyle-thanolamine (PE) and phosphatidylhydroxybutyrate (PB). In the following we show how biocatalysis can be exploited for the production of value-added PLs, to be used as functional food and nutraceutical ingredients, from a renewable feedstock. This alternative to the industrial usual disposal procedures should impart to the whole process a greater value in terms of carbon recycling, in agreement with the paradigms of bioeconomy for a wiser reuse of renewable resources in a circular economy perspective.

This work focused on the phospholipase D-mediated treatment of the waste residue coming from acid degumming, which constitutes the second part of the degumming step in the crude corn edible oil refining process. This industrial process produces a complex by-product (called gum), a mixture containing phospholipids (PLs) whose composition depends on the nature of the oil source. This residue is usually disposed of with the consequential costs and environmental concerns. An efficient multistep protocol of physical separations of the PL-rich fraction from waste gums has been set up, including centrifugation, precipitation and solvent partitioning. This waste stream, which is thoroughly characterized after the concentration process, constitutes a renewable feedstock for the production of value-added PLs with modified polar head-exploiting phospholipase D-mediated biotransformations, which have been successfully performed on this complex natural mixture. The valorization of these waste gums through the production of high value PLs for targeted applications paves the way to a new alternative approach for their disposal, which could be of great interest from a circular economy perspective.