Induction Period (IPR)
A model 743 Rancimat instrument from MetrOhm (Riverview, FL, USA) was employed to measure IPR at five different temperatures for CaME, PME, SME and MeC18:1 and six temperatures for MeC18:2. Depending on the FAME, measurement temperatures ranged between 50 and 140 °C (323.15 and 313.15 K). The test method used to measure IPR, EN 15751 (CEN, 2009), was conducted using the short-type test tubes on oil sample masses of 3 ± 0.1 g. Two replicate measurements were performed and the results reported as average values.
Mean absolute deviation (MAD) and root-mean-squared mean deviation (RMSD) data were calculated using the following two equations:
MAD = (Σ | IPR,i – IPi|)/n i (10)
RMSD = [(Σ(IPR,i – IPi)²/n i]½(11)
where IPR,i = experimental IPR value at temperature Ti, IPi = IP value calculated from a model equation at Ti andn i = total number of data pairs (IPR,i, IPi). The calculation of MAD and RMSD, least-squares linear regression analyses, analysis of variance (ANOVA) and statistical analysis operations were conducted in Microsoft (Redmond, WA, USA) Excel® spreadsheets.