Ohmic Heating as a By-Product Valorization Platform to Extract Oil from Carp (Cyprinus carpio) Viscera

This study proposed a new application for ohmic heating (OH), i.e., extracting oil from carp viscera, a seafood processing by-product. The effects of temperature (75 degrees C, 85 degrees C, 95 degrees C) and electric field strength (EFS) (7, 9, 22 V/cm) on the system performance and the physicochemical characteristics of the extracted oil were studied and compared with conventional heating (CH). Besides, environmental impacts were assessed based on green extraction principles. Results showed that heating rate values were higher for OH than CH (4.5-51.1 degrees C/min vs. 1.0 degrees C/min). Also, the specific energy consumption (SEC) of OH was lower than that of CH by 94.46%. Furthermore, replacing CH with OH reduced the extraction time from 72 to 30 min. Compared with CH, OH improved the color values and decreased the peroxide, free fatty acids (FFA), and thiobarbituric acid (TBA) values by 13.63%, 44.25%, and 93.15%, respectively. An EFS of 22 V/cm and a temperature of 95 degrees C resulted in the highest system performance (0.97), productivity (1.03 L/h), and oil yield (26.66%). Moreover, increasing temperature and EFS improved productivity. Similarly, temperature and EFS affected the viscosity and density of extracted oils. Gas chromatography-mass spectrometry (GC-MS) identified fourteen major fatty acids in the extracted oil samples. These include dodecanoic acid, n-hexadecanoic acid, and oleic acid. The approach proposed in this study valorized the carp viscera, yielded a value-added product, and improved process greenness by 50.08-69.07%. Such an approach can contribute to achieving sustainable development goals (SDGs), considering reduced energy consumption, enhanced process greenness, and increased resource efficiency through waste valorization.