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Authors
Abstract(s)
A deterioração dos alimentos contribui para o elevado desperdício alimentar
globalmente, pois altera o valor nutricional e as propriedades organoléticas dos
alimentos. A ocorrência de oxidação e contaminação microbiana são dois dos fatores que
contribuem para que a deterioração alimentar ocorra. A presença de microrganismos
gera várias alterações nos alimentos, sendo exemplos a produção de ácido lático,
produção de odores desagradáveis e alteração da pigmentação, enquanto a oxidação leva
à deterioração da cor, odor, sabor e textura. Assim, de modo a impedir a ocorrência de
deterioração alimentar, existem vários métodos de conservação disponíveis (exemplos:
refrigeração, fumagem e conservantes químicos). Os conservantes químicos podem ser
naturais (exemplos: vinagre e extrato de alecrim) ou artificiais (exemplo: nitrato de
sódio), no entanto já foi demonstrado que alguns conservantes artificiais têm efeitos
prejudiciais à saúde. Devido à atual demanda dos consumidores por alimentos
saudáveis, com maiores tempos de prateleira e livres de conservantes artificiais, estão a
ser desenvolvidos vários estudos em busca de novos conservantes naturais e os óleos
essenciais são possíveis alternativas. Estes são líquidos lipofílicos extraídos de várias
partes de plantas (exemplos: sementes e frutas), conhecidos por apresentarem
bioatividade. Assim, o objetivo desta dissertação foi avaliar as interações entre os óleos
essenciais de Cymbopogon martinii (palmarosa), Citrus aurantium ssp. bergamia
(bergamota), Cistus ladanifer (esteva) e Foeniculum vulgare (funcho) ao nível das
atividades antioxidantes e antimicrobianas. Para fazer estas avaliações, foram realizados
o ensaio do sequestro do radical livre DPPH, o ensaio da descoloração do ß-caroteno, o
ensaio da difusão em disco e o ensaio da microdiluição utilizando a resazurina como
indicador de crescimento e usaram-se as seguintes estirpes bacterianas: Listeria
monocytogenes LMG 16779, Enterococcus faecalis ATCC 29212, Staphylococcus aureus
ATCC 25923, Escherichia coli ATCC 25922, Salmonella Typhimurium ATCC 13311 e
Pseudomonas aeruginosa ATCC 27853. Como resultados obtiveram-se interações de
sinergismo nas combinações de óleos essenciais de bergamota e esteva, de palmarosa,
bergamota e esteva e de bergamota, esteva e funcho, relativamente ao ensaio da difusão
em disco para a bactéria Pseudomonas aeruginosa ATCC 27853, e na combinação dos
óleos essenciais de palmarosa, bergamota e esteva, relativamente ao ensaio da
microdiluição utilizando a resazurina como indicador de crescimento para a bactéria
Listeria monocytogenes LMG 16779. Estas interações sugerem que a combinação dos
óleos essenciais de bergamota e esteva potencia a ação dos óleos essenciais de palmarosa e de funcho na bactéria Pseudomonas aeruginosa ATCC 27853 e a ação do óleo essencial
de palmarosa na bactéria Listeria monocytogenes LMG 16779.
Food deterioration contributes to the global food waste because it changes the organoleptic properties and nutritional value of food products. Oxidation and microbial contamination are two factors responsible for food deterioration. Microorganisms generate several changes in food products, including lactic acid production, unpleasant odor production and changes in the pigmentation, while oxidation generates deterioration of color, odor, flavor and texture. Thus, to avoid food deterioration, many preservation techniques are available (examples: refrigeration, smoking and chemical preservatives). There are several natural (examples: vinegar and rosemary extract) and artificial (examples: sodium nitrate) chemical preservatives, however it has been demonstrated that some artificial preservatives cause adverse health effects. Due to consumer demand for healthy foods, with extended shelf life and free from artificial chemical preservatives, research is being conducted with the aim of finding new natural preservatives and essential oils are possible alternatives. Essential oils are lipophilic liquids, extracted from several plant parts (examples: seeds and fruits), known for their bioactivity. Hence, the aim of this dissertation was to assess the effect of the interactions between the essential oils Cymbopogon martinii (palmarosa), Citrus aurantium ssp. bergamia (bergamot), Cistus ladanifer (rockrose) and Foeniculum vulgare (fennel) on the antioxidant and antimicrobial activities. In order to assess these activities, the DPPH radical scavenging assay, the ß-carotene bleaching assay, the disc diffusion assay and the resazurin microtiter assay were carried out and the following bacterial strains were used: Listeria monocytogenes LMG 16779, Enterococcus faecalis ATCC 29212, Staphylococcus aureus ATCC 25923, Escherichia coli ATCC 25922, Salmonella Typhimurium ATCC 13311 and Pseudomonas aeruginosa ATCC 27853. The results revealed synergistic interactions for the essential oil combinations of bergamot and rockrose, palmarosa, bergamot and rockrose and bergamot, rockrose and fennel, in the disc diffusion assay for the Pseudomonas aeruginosa ATCC 27853 bacteria and the essential oil combination of palmarosa, bergamot and rockrose in the resazurin microtiter assay for the Listeria monocytogenes LMG 16779 bacteria. These interactions suggest that the combination of the essential oils bergamot and rockrose might potentiate the action of the palmarosa and fennel essential oils in the Pseudomonas aeruginosa ATCC 27853 bacteria and the action of palmarosa essential oil in the Listeria monocytogenes LMG 16779 bacteria.
Food deterioration contributes to the global food waste because it changes the organoleptic properties and nutritional value of food products. Oxidation and microbial contamination are two factors responsible for food deterioration. Microorganisms generate several changes in food products, including lactic acid production, unpleasant odor production and changes in the pigmentation, while oxidation generates deterioration of color, odor, flavor and texture. Thus, to avoid food deterioration, many preservation techniques are available (examples: refrigeration, smoking and chemical preservatives). There are several natural (examples: vinegar and rosemary extract) and artificial (examples: sodium nitrate) chemical preservatives, however it has been demonstrated that some artificial preservatives cause adverse health effects. Due to consumer demand for healthy foods, with extended shelf life and free from artificial chemical preservatives, research is being conducted with the aim of finding new natural preservatives and essential oils are possible alternatives. Essential oils are lipophilic liquids, extracted from several plant parts (examples: seeds and fruits), known for their bioactivity. Hence, the aim of this dissertation was to assess the effect of the interactions between the essential oils Cymbopogon martinii (palmarosa), Citrus aurantium ssp. bergamia (bergamot), Cistus ladanifer (rockrose) and Foeniculum vulgare (fennel) on the antioxidant and antimicrobial activities. In order to assess these activities, the DPPH radical scavenging assay, the ß-carotene bleaching assay, the disc diffusion assay and the resazurin microtiter assay were carried out and the following bacterial strains were used: Listeria monocytogenes LMG 16779, Enterococcus faecalis ATCC 29212, Staphylococcus aureus ATCC 25923, Escherichia coli ATCC 25922, Salmonella Typhimurium ATCC 13311 and Pseudomonas aeruginosa ATCC 27853. The results revealed synergistic interactions for the essential oil combinations of bergamot and rockrose, palmarosa, bergamot and rockrose and bergamot, rockrose and fennel, in the disc diffusion assay for the Pseudomonas aeruginosa ATCC 27853 bacteria and the essential oil combination of palmarosa, bergamot and rockrose in the resazurin microtiter assay for the Listeria monocytogenes LMG 16779 bacteria. These interactions suggest that the combination of the essential oils bergamot and rockrose might potentiate the action of the palmarosa and fennel essential oils in the Pseudomonas aeruginosa ATCC 27853 bacteria and the action of palmarosa essential oil in the Listeria monocytogenes LMG 16779 bacteria.
Description
Keywords
Atividade Antimicrobiana Atividade Antioxidante Óleos Essenciais Sinergismo