Severity indices, which combine variables such as temperature and reaction time, are often employed to evaluate the extent to which feedstock is processed by hydrothermal treatment. However, few studies have examined how heating rate affects the yield and characteristics of hydrothermal products. Given the enormous quantity of food waste generated annually and its potential conversion into future energy resources via hydrothermal treatment, this study focused on food constituents, particularly cellulose, using a batch reactor with a practical volumetric capacity of 280 mL. To achieve rapid yet controllable heating at rates as high as approximately 100 °C/min, induction heating was applied to the pressure vessel. The weight, total organic carbon (TOC), total nitrogen (TN), and pH of the hydrothermal treatment products were measured. Analysis of variance (ANOVA) was used to evaluate the significance of heating rate effects on these parameters. Furthermore, chemical components in the aqueous phase and heavy bio-oil were analyzed using gas chromatography–mass spectrometry (GCMS) to assess how varying heating rates influence the decomposition of the feedstock.
