(191c) Assessment of Oxidative Stability of Home-Cooked Meat Products in US By Targeted Lipidomics

Assessment of
oxidative stability of home-cooked meat products in US by targeted lipidomics

Lisaura Maldonado-Pereira¹, Matthew Schweiss,²Ilce G. Medina-Meza PhD^1,2*,

maldon60@msu.edu, schweis3@msu.edu ilce@anr.msu.edu

¹Chemical
Engineering and Material Science Department

²Biosystems
and Agricultural Engineering Department,

Keywords: Lipid
oxidation, food toxicology, lipidomics,

Abstract

Lipid oxidation is one of the most important factors limiting
the shelf life and commercial stability of meat and meat products. Meat
oxidation is related to the content of natural antioxidants and the polyunsaturation degree of fatty acids.

Monitoring and reducing lipid oxidation in food has
become a relevant topic in the meat industry due to the strict regulations of
food quality products and its effect in human health. Lipid oxidation is a significant
problem relative to off-flavour and off-odor. Warmed-over
flavor appears to be related to lipid oxidation in meat and meat products. Oxidation
can occur in either the stored triglycerides or the tissue phospholipids.
Ferric heme pigments have been implicated as the
major pro-oxidants in tissue lipid oxidation. Pigment and lipid oxidation are
interrelated, and ferric hemes are believed to
promote lipid oxidation. Oxidative
deterioration of lipids directly affects a number of quality characteristics in
meat and meat products, including flavor, color, texture, nutritive value and
safety. It has been
widely accepted that lipid oxidation in food occurs via a free radical chain
mechanism that proceeds through three distinct stages of initiation,
propagation, and termination, leading to a series of complex chemical changes.

Cooked meat undergoes rapid deterioration due to tissue
lipid oxidation. The meat pigment in the cured pink ferrous form does not
promote the rapid oxidation undergone by cooked uncured meat. For example, poultry
meat is characterized by high protein content and a low-fat content (around 20
g and 5 g fat/100 g raw meat without skin), respectively, however chicken
lipids display a high level of unsaturated fatty acids, which are usually perceived
as ‘healthy’ by consumers, especially the polyunsaturated ones. In addition, lipid
oxidation and myoglobin oxidation in meat lead to off-flavor development and
discoloration. These processes appear to be linked and the oxidation of one of
these leads to the formation of chemical species that can exacerbate oxidation
of the other.

Evaluating lipid oxidation status is a challenging task
due to a number of facts like the different compounds which are formed
depending on the time, the extent of oxidation and the mechanism involved.
Therefore, choosing just one parameter to analyze the oxidative status is
rather difficult and it is frequently more convenient to combine different
methods.

In addition, different studies have found a direct
relationship between increased quantities of lipid oxidation products and food
processing conditions (i.e. temperature, cooking time, and packaging methods). Besides
the effect of lipid oxidation in meat quality, it has been proved that there is
correlation between lipid oxidation products (derived from the oxidation
process of cholesterol) and chronic diseases, such as cancer, atherosclerosis,
and even neurological diseases such as Parkinson and Alzheimer. This suggests a
potential risk in long-term consumption of these lipid oxidation products. This
suggests the existence of a variability in lipid oxidation products consumption
per diet. Thus, the aim of this study was to evaluate the influence of pan
frying cooking method on the lipid oxidation status of the most consumed meats
and meat products in the USA diet by a lipidomic
approach. Primary and secondary oxidation products were measured on chicken, pork
chop, ground beef 80% lean, ground beef 93% lean by Peroxide Value (POV) and Thiobarbituric acid (TBARs), respectively. Additionally,
quantification of Fatty Acids Methyl Esther (FAME) was performed by Gas
Chromatography (GC) means. Raw and cooked meat products were evaluated, as well
as, other oxidative derivatives, such as Cholesterol Oxidation Products (COPs)
by GC-MS and LC/MS/MS.

Results show that pan frying has a higher effect on the
formation of primary oxidation products in pork chop with a decrease of 18% on
POV value, in comparison with raw samples (18.60 meq
O₂/kg lipid). As expected, the pan frying method has also a higher
effect on the formation of secondary oxidation products in pork chop. TBARS
shown an increase of 30% mg MDA/kg lipid between raw (553.05 mg MDA/kg lipid)
and cooked samples. (1795.03 mg MDA/kg lipid). After FAME quantification, values
for saturated fatty acids percentages (SFA%) ranges between 47.32 to 87.36 (%w/w)
in raw samples and 38.99 to 89.28 (%w/w) in cooked samples. Monounsaturated
fatty acid percentages (MUFA%) range between 6.27 to 51.02 (%w/w) in raw
samples and 10.18-55.54 (%w/w) in cooked samples. Polyunsaturated fatty acids
percentages (PUFA%) range between 1.31 to 9.35 (%w/w) in raw samples and 0.54
to 5.48 (%w/w) in cooked samples. Quantification of COPs and other derivatives
was as well performed. These results follow the proposed mechanism of chain
reaction that states the formation of primary oxidation products (peroxides)
that usually suffer further oxidation turning into secondary oxidation products
such as aldehydes, ketones, epoxides. Further studies are needed to fully
characterize oxidation products and understand its influence in both meat
quality and health related to its long-term consumption.