educed incubation temperature to 40 °C did not affect the digestion efficacy but decreased variability for digestates of M. gigas tissue (Table 2). Digestion efficacy for the clam species Ruditapes philippinarum was 91.2 ± 0.5% at 1.2 μm pore size (Table 2). In absolute terms, when treated with 10% KOH at 40 °C and subsequent neutralisation with citric acid, 0.021 ± 0.002 g of R. philippinarum was not digested in compared to 0.079 ± 0.037 g of M. gigas.
The KOH protocol is the most economic digestion method at £0.55/sample (as of December 2017) out of the four methods tested (Table SI.2). In addition, together with H2O2, this digestion method took <120 min of researcher time over three and two days respectively (Table SI.2). Each digestion method scored once in health hazard category 1, except for Proteinase K, which scored twice (Table SI.2). Overall, trypsin did score once, the H2O2 method twice and the other methods five to 13 times in the health hazard class.