Describe the principle assumptions of Richard$$s sterilization method. With the aid of the table below calculate the holding time in minutes at $121\backslash$deg C needed to achieve a risk of contamination after treatment of one$-$in$-$ten thousand in the small reactor $($with $80$ mm impeller diameter$).$ The initial microbial load has been determined to be of $106$ microorganisms per ml$.$ Assume that it takes $10$ minutes to heat the contents of the reactor from $100\backslash$deg C to $121\backslash$deg C and $13$ minutes for the cooling cycle