K Nn mK - Amecamex.org.mx

FSBI – 2004
Food Science and Biotechnology in Developing Countries
Determination of Acid Value (AV)
The acid value was made as Lees´s method (9).
Pretreatment
The amaranth oil was centrifuged at 1500 rpm for 15 minutes at 20º C, was filtered using whatman
paper (number 1). All the filtrations were carried out at reduced pressure.
Degumming
Was carried out by two methods: A) Using H2SO4 at 60º Bé (7) at 0.5 % (w/v), at 20º and 30º C, was
stirred for 10 and 20 minutes, water was added at 97º C and 2 % (v/v), was filtered. B) Using the
hydration method (2): 2 % (v/v) water was added to the oil at 50º C. Stirred for 20 minutes and filtered.
In each treatment the AV was measured and precipitation residues were quantified.
Neutralization
Three methods were applied: C) the degummed oil at 60º C was mixed with 4 eq L -1 NaOH at 10 %
(v/v). 10 % (v/v) water was added at 20º and 30º C. Was stirred for 10 and 20 minutes. Was then
centrifuged at 1500 rpm (centrifugal Hermle Z 323 K) for 15 minutes at 20º C. D) Using 40 % (v/v) of
10 eq L -1 NaOH at 60º C. Was added 10 % (v/v) water at 20º and 30º C. Was stirred for 10 and 20
minutes and centrifuged at 1500 rpm (15 minutes, 20º C). E) Using 35 % (v/v) of 7 eq L -1 Na2CO3. The
solution was heated at 45º C and it was added to the degummed oil. The temperature was increased
up to 75º C, was added 50 % (v/v) hot water and was drained. After that, was added 10 % (v/v) of
solution 10 eq L -1 NaOH plus 10 % NaCl (w/v). Then, was added 50 % (v/v) hot water, it was
centrifuged at 1500 rpm for 2 minutes at 20º C and was drained. In each treatment the volume of
neutralized oil was measured and was determined the AV.
Statistical analysis
The experimental data were analyzed statistically by analysis of variance, for statistical significance
(α= 0.05) using LSD test. (Statistical Analysis System, SAS)
Results and Discussion
Degumming
The results for degumming method of the amaranth oil are shown in table 1.
Table 1. Results from degumming amaranth oil
Treatment AV (% oleic acid) Residues (g)
A 46 ± 0.636 1.70 ± 0.007
B 30.94 ± 0.028 3.42 ± 0.042
Control 35.02 -
The method A resulted in AV 46 % (initial 35.02) and residuals was 1.70 % (Table 1).This method
originated alterations, it gave a strong brown color, due to the presence of proteins and pigments that
were carbonized by the acid.
Method B had a significant effect at α=0.05 on AV, it was 30.94% and 3.42 % of residues at 10
minutes of stirring. The yield was 97 % of degummed oil. The residues can be separated easily. Lyon
and Becker (1987) used the hydration method obtaining 96 % of degummed oil (A. cruentus). The
yield is similar to the obtained by us.
Neutralization
The results for neutralization method of amaranth oil are shown in table 2.