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.