Physico-Chemical Properties, Fatty Acids Profile, and Economic Properties of Raspberry (Rubus idaeus L.) Seed Oil, Extracted in Various Ways

In Europe, the green course is becoming increasingly relevant, and there are more and more suggestions for its improvement. The valorization of food waste attracts increasing attention and is one important current research area. The aim of this study was to examine oils from 16 raspberry variety seeds and to compare their yields and fatty acid contents. The next task was to extract oil from the raspberry variety 'Polka' by four different methods and to compare the yield, colors, fatty acids content and composition, and kinematic and dynamic viscosity. The last task was to analyze the economic profitability of oil extraction by different methods. This study demonstrates the potential of different varieties of raspberry by-products and shows the influence of different oil extraction methods on the fatty acid composition of the oil and the economic potential of such products. The analysis revealed that the predominating fatty acid in the raspberry variety 'Polka' seed oil was linoleic acid (44.0-44.8%), followed by α-linolenic acid (37.9-38.1%) and oleic acid (10.2-10.6%). Of the 16 raspberry cultivars tested, 'Polka' seed oil had the least linoleic (ω-6) (44.79%) and the most α-linolenic (ω-3) fatty acids and the best ratio of ω-6 to ω-3 fatty acids-1.2:1. Raspberry variety 'Polka' seed oil contains a lot of carotenoids; their total amount depending on the extraction method varies from 0.81 mg/100 g (extracted with subcritical CO2) to 3.25 mg/100 g (extracted with supercritical CO2). The oil yield can be increased by grinding the seeds into a finer fraction. The most expensive method of oil production is supercritical CO2 extraction, and the cheapest method with the fastest payback of equipment is the cold-pressing method. The results of the research have revealed the influence of different oil recovery methods on the yield of oil, the composition of the fatty acid, colors, and viscosity. The results are very important for producers wishing to commercialize raspberry seed oil.