Hydrogels constitute a highly promising material class for drug delivery systems and actuation. Upon appropriate tuning they may even exhibit a volume phase transition upon physiological stimuli like changes in pH-value or temperature. This promises controlled drug delivery for diseases with fluctuating metabolic requirements like inflammatory diseases. We present a thermal actuator composed of a blend of biopolymers with a tunable transition temperature in the range from 36°C to 43°C. Heating of the gels induces nearly reversible contraction while the onset temperature of contraction can be controlled. We can attribute specific protein structures to be involved in the contraction process by circular dichroism measurements. To do so, we established a method for dissolving the hydrogel in water while retaining its protein structure. We also show the nearly reversible behavior of the hydrogel by exposing it to a periodic heating-cooling cycle. Furthermore, the contribution of the network pore size to the contraction process is shown.