Quality and safety of oils and fats obtained as co-products
or by-products of the food chain and destined to animal
production
Creators: name: Pignoli, Giovanni <1976>
Publisher: name: Alma Mater Studiorum - Università di Bologna
Year: 2008
Subjects: AGR/15 Scienze e tecnologie alimentari

description: The aim of the first part of this thesis was to evaluate the effect of trans fatty acid-
(TFA), contaminant, polycyclic aromatic hydrocarbon (PAH)- and oxidation productenriched
diets on the content of TFA and conjugated linoleic acid (CLA) isomers in
meat and liver of both poultry and rabbit. The enriched feedings were prepared with
preselected fatty co-and by-products that contained low and high levels of TFA (low,
palm fatty acid distillate; high, hydrogenated palm fatty acid distillate), environmental
contaminants (dioxins and PCBs) (two different fish oils), PAH (olive oil acid oils and
pomace olive oil from chemical refining, for low and high levels) and oxidation
products (sunflower-olive oil blend before and after frying), so as to obtain single
feedings with three enrichment degrees (high, medium and low) of the compound of
interest. This experimental set-up is a part of a large, collaborative European project
(http://www.ub.edu/feedfat/), where other chemical and health parameters are assessed.
Lipids were extracted, methylated with diazomethane, then transmethylated with 2N
KOH/methanol and analyzed by GC and silver-ion TLC-GC. TFA and CLA were
determined in the fats, the feedings, meat and liver of both poultry and rabbit. In
general, the level of TFA and CLA in meat and liver mainly varied according to those
originally found in the feeding fats. It must be pointed out, though, that TFA and CLA
accumulation was different for the two animal species, as well as for the two types of
tissues. The TFA composition of meat and liver changes according to the composition
of the oils added to the feeds with some differences between species. Chicken meat with
skin shows higher TFA content (2.6–5.4 fold) than rabbit meat, except for the “PAH” trial. Chicken liver shows higher TFA content (1.2–2.1 fold) than rabbit liver, except for
the “TRANS” and “PAH” trials. In both chicken and rabbit meats, the TFA content was
higher for the “TRANS” trial, followed by the “DIOXIN” trial. Slight differences were
found on the “OXIDATION” and “PAH” trends in both types of meats. In both chicken
and rabbit livers, the TFA content was higher for the “TRANS” trial, followed by those
of the “PAH”, “DIOXIN” and “OXIDATION” trials. This trend, however, was not
identical to that of feeds, where the TFA content varied as follows: “TRANS” &gt;
“DIOXIN” &gt;“PAH” &gt; “OXIDATION”. In chicken and rabbit meat samples, C18:1 TFA
were the most abundant, followed by C18:2 TFA and C18:3 TFA, except for the
“DIOXIN” trial where C18:3 TFA &gt; C18:2 TFA. In chicken and rabbit liver samples of
the “TRANS” and “OXIDATION” trials, C18:1 TFA were the most abundant, followed
by C18:2 TFA and C18:3 TFA, whereas C18:3 TFA &gt; C18:2 in the “DIOXIN” trial.
Slight differences were found on the “PAH” trend in livers from both species.
The second part of the thesis dealt with the study of lipid oxidation in washed turkey
muscle added with different antioxidants. The evaluation on the oxidative stability of
muscle foods found that oxidation could be measured by headspace solid phase
microestraction (SPME) of hexanal and propanal. To make this method effective, an
antioxidant system was added to stored muscle to stop the oxidative processes. An
increase in ionic strength of the sample was also implemented to increase the
concentration of aldehydes in the headspace. This method was found to be more
sensitive than the commonly used thiobarbituric acid reactive substances (TBARs)
method. However, after antioxidants were added and oxidation was stopped, the
concentration of aldehydes decreased. It was found that the decrease in aldehyde concentration was due to the binding of the aldehydes to muscle proteins, thus
decreasing the volatility and making them less detectable.