No activity was detected when testing the phosphate OSI-744 mouse buffer without enzymes. equation(1) AR=AA0 The peroxidase test proceeded according to manufacturer’s

instructions (Merck, 2008), using a 1.0 mL sample, 4.0 mL of distilled water and five drops of reagent POD-1. The reaction time was 180 s at 23 °C. Phosphatase test required a 2.0 mL sample and four drops of reagent ALP-3 (originally, it would require a 5.0 mL sample with ten drops of ALP-3). The reaction time was 20 min at 37 °C (Merck, 2005). For both tests, the test strip was kept inside a semi-microcell, which was partly immersed in a water bath with temperature control. For the phosphatase test, the semi-microcell was previously filled with 15 drops of reagent ALP-1. After the reaction time, the test strip was inserted in the reflectometer, which gives the activity in U/L. Measuring ranges were 5–200 U/L for peroxidase and 1.0–10.0 U/L for phosphatase activity. To obtain thermal inactivation data of the enzymic indicators, several discontinuous thermal treatment tests were performed. A sample

of the Ixazomib mw indicator (2.0 mL of POD, 2.0 mL of LPO or 3.0 mL of ALP) was placed in a polyethylene pouch (2.5 cm × 30 cm, thickness: 0.06 mm) with an exposed-junction type-K thermocouple placed at the center of the liquid. Polyethylene was used instead of glass because of its small thickness and, consequently, low thermal resistance. Temperature data was collected every second using a calibrated portable digital thermometer (TH-060, Instrutherm, São Paulo, Brazil). Instead of assuming isothermal conditions, Arachidonate 15-lipoxygenase the time-temperature history was obtained for each test and taken into account in the calculations, as proposed by Matsui, Gut, Oliveira, and Tadini (2008). Thermal treatment was accomplished by immersion of the pouch in a hot water bath (controlled

temperature) for a determined time, followed by immersion in an ice water bath until temperature was below 10 °C. Samples were kept in the ice bath for up to 90 min before activity measurement. Fig. 1 shows a scheme of the thermal treatment and presents some examples of obtained time-temperature histories. Because of the volume required for the activity assay (1.0 mL for POD/LPO and 2.0 mL for ALP), it was not possible to determine the activity in duplicate or triplicate for each sample after thermal treatment. Some time-temperature conditions were repeated; however, since each run has an individual and precise time-temperature history, they were not treated as replicates. Several combinations of hot water temperature and immersion time were tested in order to obtain values of residual activity in the range 5 ≤ AR ≤ 95%. Immersion times were between 15 s and 10 min. For indicator POD, tested temperatures were 60.0, 65.0, 70.0, 75.0, 80.0, 85.0, 90.0 and 95.0 °C. Tested temperatures for LPO were 60.0, 62.5, 65.0, 67.5, 70.0, 72.5, 75.0, 77.5 and 80.0 °C.