Towards zero waste food production: utilization of grape seeds

Abstract

In recent decades, wine production has been expanding, with emerging wine regions and new small and medium-sized wineries. Winemaking produces large amounts of grape seeds, often discarded as waste, which are rich in oil, dietary fibers, tocopherols, and polyphenols. If used, the seeds are usually utilized as a source of oil, while the cake remaining after oil extraction is the additional waste with limited usage. Thus, we are working to establish the procedures for the complete utilization of grape seeds with zero byproducts. Pinot Noir variety from a small winery, Zmajevac, Serbia, was used. The main benefit of the oil, obtained by cold pressing, is the high content of unsaturated fatty acids, i.e., linoleic (70%) and oleic acid (19%), with a total oil content of 15 % and an 11 % yield after cold pressing. To facilitate handling, potential addition to food products, and its protection, grape seed oil was encapsulated into calcium alginate-based gel capsules. Encapsulation techniques, electrostatic extrusion, and atomization were used to produce finely powdered encapsulates with encapsulation efficiencies of close to 90 %. The potential use of these capsules is in the substitution of saturated fats in food products where the capsules, apart from protecting oil, could prevent its leakage from food matrices. The results showed that the oil cake could be a promising source of dietary fibers. It contained up to 38 % of insoluble dietary fibers and around 2% of soluble ones (w/w). The high content of insoluble dietary fibers is a basis for further modifications to increase the content of soluble fibers and modulate the nutritional properties of the oil cake. Thus, we tested the enzymatic and hydrothermal processes as modification procedures. The results showed that the enzymatic treatment was more promising regarding the control of soluble/insoluble fibers ratio. Also, the enzymatic process should be more cost- effective regarding capacity and energy consumption.