Prof. M. Mukhopadyay and her student of Department of Chemical Engineering has devised a novel process for the sterilizing and enhancement of the shelf-life of biological material using sequential pressurization-depressurization treatment with supercritical fluids. Biological materials require sterilization or preservation to overcome the problem caused by presence of naturally occurring microbes and enzymes that eventually cause degradation and limit the safety and shelf-life of the biological material. The existing sterilization techniques such as pasteurization, use of ultra high temperature, ultra high pressure has impact on shelf-life. However, they are not desirable as they result in loss of natural flavour, aroma, colour, freshness and texture felt in the mouth.

The process devised combines one or more sequences of pressurization-depressurisation using supercritical fluids. The process involves subjecting the biological material to sequences of pressurisation-depressurisation at a specified pressure and treatment time, based on the nature of the biological material, to achieve sterilization with desirable characteristics; the process parameters are adjusted based on the material. This method of extraction allows shelf-life enhancement for at least 90 days using no chemical preservatives.