Relationships between the effects of plant additives on linoleic acid oxidation and microbial growth in minced pork
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Kuupäev
2024
Kättesaadavus
Ajakirja pealkiri
Ajakirja ISSN
Köite pealkiri
Kirjastaja
Estonian University of Life Sciences
Abstrakt
Peroxidation of polyunsaturated fatty acids (PUFA), especially unconjugated linoleic (9,12-
octadecadienoic) acid and microbial degradation of various constituents are the main integrated processes of
spoilage of muscle foods. Peroxidation of linoleic acid in meat occurs through the combination of enzymatic and
free radical mechanisms, the most important oxidation enzymes being lipoxygenase (LOX) and cytochrome
oxidase P450 (CYP450). The aim of this study was to describe the relationship between these two processes in
minced pork in the presence of nine plant-derived additives. Powders of freeze-dried apple (Malus domestica),
also without seeds, blackcurrant (Ribes nigrum), rhubarb (Rheum rhaponticum), tomato (Lycopersicon
esculentum), chokeberry (Aronia melanocarpa), garlic (Allium sativum), and rowan berries (Sorbus aucuparia)
were mixed with fresh minced pork (2% w/w) and stored at 6 °C during 8 or 14 days. Samples were taken at days
1, 4, 6, 8 and additionally at days 11 and 14 for rhubarb. Enumeration of aerobic mesophilic microorganisms,
yeasts and moulds, and presumptive Pseudomonas spp. was performed according to the ISO standards. The main
primary oxidation products of linoleic acid (oxylipins) were quantified by LC-MS performed on a 1290 Infinity
system liquid chromatograph coupled to 6450 Q-ToF mass spectrometer (Agilent Technologies, Germany).
Concentration of malondialdehyde (MDA) as a main secondary oxidation product of linoleic acid was estimated
using 2-thiobarbituric acid reactive substances (TBARS) method on an Agilent 1100 series LC-UV/Vis
chromatograph. All additives inhibited the growth of tested microorganisms compared to meat, but to different
extents. Blackcurrant (BC) powder had both high antioxidant and antimicrobial activity. The antioxidant activity
of BC is mainly due to the free radical scavenging and LOX inhibiting effect of polyphenols of the anthocyanin
group, there are various hypotheses about the mechanisms of the BC`s strong antimicrobial effect. Chokeberry
(CB), with higher anthocyanins content, showed lowest MDA value, but had lower antimicrobial activity than
BC. Rowan berries, which contained less anthocyanins than CB or BC, also had lower antioxidant capacity, but
moderate antimicrobial activity. Garlic and rhubarb had by far the lowest antioxidant activity, showing the highest
values of both MDA and total oxylipins already at days 4 and 6, respectively. However, these additives were most
effective in inhibiting microbial growth that could be caused by MDA and oxylipins. According to the literature,
MDA is also synthesized by the corresponding bacterial enzymes. As an efficient cross-linker of macromolecules
such as DNA, MDA is particularly toxic to microorganisms. Removal of seeds significantly reduced the
antibacterial and antifungal activity of apples, while maintaining high antioxidant capacity. Apparently, seedspecific
substances such as furocoumarins or phloretin, which have no antioxidant effect, are responsible for the
antimicrobial effect of apples. Seedless tomato significantly inhibited linoleic acid oxidation, while like seedless
apple, was relatively powerless against microorganisms. Considering both antioxidant and antimicrobial effects,
it is difficult to achieve reasonable extension of the shelf life of minced pork when combined with a single plant.
Kirjeldus
Märksõnad
antimicrobials, antioxidants, oxylipins, plant-derived, pork, abstracts