An assay for analysing carbohydrates, lipids, triglycerides and/or proteins or breakdown products thereof; or for simulating the digestion of an edible/potable substance, the method comprising: (a) subjecting the carbohydrate, lipid, triglyceride, protein or breakdown product thereof, or edible/potable substance to a salivary phase consisting of synthetic saliva comprising an aqueous mixture of one or more salivary enzyme(s), and one or more suitable salivary diluent components at a pH in the range of from 5 to 9, preferably from 6.8 to 7.8; (b) subjecting the product of (a) to a gastric phase consisting of synthetic gastric juice comprising an aqueous mixture of gastric lipase, pepsin and one or more suitable gastric diluent components, at a pH from 1.5 to 3.5, wherein the gastric lipase is present at a level of from 8.5 to 250 μg/ml of synthetic gastric juice and the pepsin is present at a level of from 85 to 5000 μg/ml of synthetic gastric juice and wherein the synthetic gastric juice is added to the gastric phase at a rate of 0.1 - 2.5 ml/min; and (c) subjecting the product of (b) to a pancreatic phase consisting of synthetic pancreatic juice comprising pancreatin and one or more suitable pancreatic diluent(s) at a pH from 7 to 9, preferably 7.9 to 8.2, and porcine bile, wherein: i) when the pancreatin is dialysed pancreatin, it is provided at a concentration of 5 to 40 mg/ml of pancreatic diluent and is added to the pancreatic phase at a rate of 0.1 - 2.5 ml/min; or ii) when the pancreatin is non-dialysed pancreatin, it is provided at a concentration of 50 to 90 mg/ml of pancreatic diluent, and is added to the pancreatic phase at a rate of 0.1 - 2.5 ml/min. (a) subjecting the carbohydrate, lipid, triglyceride, protein or breakdown product thereof, or edible/potable substance to a salivary phase consisting of synthetic saliva comprising an aqueous mixture of one or more salivary enzyme(s), and one or more suitable salivary diluent components at a pH in the range of from 5 to 9, preferably from 6.8 to 7.8; (b) subjecting the product of (a) to a gastric phase consisting of synthetic gastric juice comprising an aqueous mixture of gastric lipase, pepsin and one or more suitable gastric diluent components, at a pH from 1.5 to 3.5, wherein the gastric lipase is present at a level of from 8.5 to 250 μg/ml of synthetic gastric juice and the pepsin is present at a level of from 85 to 5000 μg/ml of synthetic gastric juice and wherein the synthetic gastric juice is added to the gastric phase at a rate of 0.1 - 2.5 ml/min; and (c) subjecting the product of (b) to a pancreatic phase consisting of synthetic pancreatic juice comprising pancreatin and one or more suitable pancreatic diluent(s) at a pH from 7 to 9, preferably 7.9 to 8.2, and porcine bile, wherein: i) when the pancreatin is dialysed pancreatin, it is provided at a concentration of 5 to 40 mg/ml of pancreatic diluent and is added to the pancreatic phase at a rate of 0.1 - 2.5 ml/min; or ii) when the pancreatin is non-dialysed pancreatin, it is provided at a concentration of 50 to 90 mg/ml of pancreatic diluent, and is added to the pancreatic phase at a rate of 0.1 - 2.5 ml/min. i) when the pancreatin is dialysed pancreatin, it is provided at a concentration of 5 to 40 mg/ml of pancreatic diluent and is added to the pancreatic phase at a rate of 0.1 - 2.5 ml/min; or ii) when the pancreatin is non-dialysed pancreatin, it is provided at a concentration of 50 to 90 mg/ml of pancreatic diluent, and is added to the pancreatic phase at a rate of 0.1 - 2.5 ml/min.