Evaluation of the effects of certain plant extracts obtained by supercritical fluid carbon dioxide extraction on biogenic amine formation

Biogenic amines are biologically active organic compounds with low molecular weight that are formed as a result of the metabolic activities of plants, animals, and microorganisms. In foods, especially in meat products, they are formed through the decarboxylation of amino acids interacting with microorganisms or through the amination and transamination of aldehydes and ketones. These amines are reported in the literature to cause cancer, hypertension, and allergic reactions in humans. Various techniques such as ultraviolet, gamma irradiation, and optimization of storage conditions are suggested to prevent and eliminate the formation of biogenic amines in foodstuffs. Additionally, some active compounds present in the environment have significant effects on reducing biogenic amines. This thesis aims to evaluate the effects of plant extracts obtained using supercritical fluid carbon dioxide (SFE-CO2) extraction, an innovative and environmentally friendly method for extracting plant active substances, on biogenic amines formed in meat products. In line with this aim, thyme (Origanum onites), black pepper (Piper nigrum), red pepper (Capsicum annuum L.), and cumin (Cuminum cyminum), which are predicted to affect biogenic amines, were procured. Extracts of these plants were obtained using the SFE-CO2 extraction method optimized with the response surface method. The active components in the samples were determined using High-Performance Liquid Chromatography (HPLC). To induce the formation of biogenic amines in vitro, a decarboxylase liquid containing tyrosine, lysine, histidine, and ornithine was prepared and inoculated with bacteria (Enterococcus faecalis, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Staphylococcus aureus). The types (dopamine (DOP), putrescine (PUT), cadaverine (CAD), tryptamine (TYP), phenylethylamine (PHEM), spermidine (SPM), spermine (SPR), histamine (HIS), and tyramine (TYR)) and levels of biogenic amines formed in each decarboxylase liquid were analyzed using the HPLC method. Different types and levels of plant extracts were applied to inhibit the biogenic amines formed, and the efficacy of the extracts on both the microorganisms and the formed biogenic amines was evaluated. The most effective type and level of extract were then applied to real samples. For this purpose, plant extracts were added to minced meat samples along with microorganisms, and the changes in biogenic amines in the meat samples were examined at different temperatures and durations. In addition to biogenic amine analyses, microbial, chemical, physical, and sensory analyses were also conducted on the samples. The most effective active compounds in the plant extracts were found to be cuminaldehyde for cumin, capsaicin for red pepper, piperine for black pepper, and carvacrol for oregano. Analyses conducted on the production of biogenic amines in decarboxylase liquids revealed that E. coli had the highest biogenic amine production capacity. Despite the different effects of the extracts on biogenic amines formed in the decarboxylase liquid, oregano extract at a 0.5% level was found to be the most effective. Based on the data obtained from the decarboxylase liquid, E. coli was used to form biogenic amines in real meat samples, and different levels of oregano extract were used to inhibit this microorganism and the formed biogenic amines. According to the findings, a 0.5% concentration of oregano extract significantly reduced the total biogenic amine content from 106.38 mg to 34.84 mg and caused significant reductions in biogenic amines such as PUT, CAD, HIS, and TYR. Regarding the effects of the added oregano extract on the physicochemical and sensory properties of the meat, in samples without E. coli and with 0.5% oregano extract, the free fatty acid (FFA) levels decreased from 3.08% to 2.26%, and from 3.58% to 2.52% in samples with E. coli. Similarly, total volatile basic nitrogen (TVB-N) levels decreased from 25.76 mg N/100 g to 15.74 mg N/100 g, and from 27.82 mg N/100 g to 18.56 mg N/100 g under the same conditions. For TBARS values, the same conditions resulted in decreases from 1.03 mg MDA/kg to 0.74 mg MDA/kg and from 1.18 mg MDA/kg to 0.84 mg MDA/kg. The highest water-holding capacity (WHC) level (31.14%) was observed in samples without E. coli and with 0.5% oregano extract. The total aerobic bacteria count (TAB) generally decreased as the concentration of oregano extract increased, with the TAB count reducing from 9.63 to 7.28 log CFU/g when 0.5% oregano extract was added to samples containing E. coli. Similarly, these values for psychrotrophic bacteria and coliform bacteria were found to be 8.14 to 6.48 log CFU/g and 4.25 to 3.29 log CFU/g, respectively. In sensory tests evaluating product quality characteristics, 0.25% oregano extract was found to be the most suitable concentration for sensory acceptance in terms of improving quality parameters over different storage periods, enhancing taste, aroma, and overall acceptance. The obtained results indicate that oregano extract, depending on its concentration, has the ability to prevent and inhibit the growth of pathogenic microorganisms, reduce the formation of biogenic amines, and positively affect the quality criteria of meat.