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Higiene e segurança alimentar em vegetais para consumo humano: comparação entre produtos de agricultura biológica e convencional
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O consumo de vegetais crus fornece nutrientes essenciais e muitos benefícios para uma dieta saudável. No entanto, podem também causar doenças intestinais, com um importante impacto na saúde humana. Além disso, devido aos perigos químicos associados a esses alimentos, nomeadamente pesticidas e metais pesados, tem havido um aumento do consumo de alimentos de origem biológica em todo o mundo. Considerando a escassez de estudos nesta temática, inclusive em Portugal, pretendeu-se com este trabalho contribuir para o maior conhecimento sobre a segurança microbiológica e parasitológica entre alimentos de cultivo biológico e convencional. Foi avaliada a presença de coliformes termotolerantes e de Escherichia coli e a presença de protozoários e nemátodes em vegetais comercializados em mercados e feiras da Área Metropolitana de Lisboa. As variedades de vegetais avaliadas foram agrião, alface, cebolinho, couve-galega e espinafre, sendo amostradas 10 unidades de cada uma, sendo avaliadas 100 amostras, 50 de origem biológica e 50 de origem convencional. Foram detectados valores de coliformes termotolerantes superiores ao limite máximo de quantificação da técnica utilizada em 21% das amostras, o equivalente a 14% (7/50) das amostras de origem biológica e 28% (14/50) de origem convencional. A contaminação por E. coli foi detectada em 56% das amostras, nomeadamente em 34% (17/50) das amostras de origem biológica e 78% (39/50) de origem convencional. Verificaram-se associações estatisticamente significativas no caso da presença de E. coli em vegetais de origem convencional e quanto à presença de valores elevados de coliformes termotolerantes e de contaminação fecal em amostras de cultivo convencional. Também foi observada uma associação entre a presença de E. coli e a proveniência das amostras, para os dois tipos de cultivo. Quanto às análises parasitológicas, 45% das amostras (45/100) apresentaram contaminação por pelo menos um género de protozoário ou nemátode, tendo sido identificados 5 géneros: Entamoeba, Amoeba, Balantidium, Paramecium e Colpoda. Verificaram-se associações estatisticamente significativas quanto à presença de contaminação (protozoários e/ou nemátodes) no caso da proveniência das amostras, para os dois tipos de cultivo. A proveniência das amostras também foi significativa quanto à prevalência de parasitas intestinais, para os dois tipos de cultivo. Também foi encontrada associação entre amostras contaminadas por protozoários e/ou nemátodes e ausência de contaminação fecal quanto ao cultivo biológico. Os resultados deste trabalho sugerem que a contaminação microbiana e parasitológica nos alimentos de origem biológica foi inferior à dos alimentos convencionais. Contudo, são necessários mais estudos para melhor avaliação dos critérios de qualidade sanitária destes alimentos. Do que se sabe, este é um dos primeiros estudos em Portugal a relatar a presença de protozoários intestinais em vegetais para o consumo humano. Estes resultados contribuem de forma inequívoca para o conhecimento da segurança alimentar relacionada com o consumo de produtos hortícolas vendidos em mercados e feiras de agricultura biológica e convencional na Área Metropolitana de Lisboa.
The consumption of raw vegetables provides essential nutrients and many benefits to a healthy diet. However, they can also cause intestinal diseases, with a significant impact on human health. In addition, due to the chemical hazards associated with these foods, namely pesticides and heavy metals, there has been an increase in the consumption of organic produce almost everywhere in the world. Considering the scarcity of studies in this subject, including in Portugal, this work was intended to contribute to a better knowledge about microbiological and parasitological safety between organic and conventional produce. The presence of thermotolerant coliforms, Escherichia coli and the presence of protozoa and nematodes in vegetables sold in open-aired markets of the Metropolitan Area of Lisbon were evaluated. Five varieties of vegetables were sampled: watercress, lettuce, chives, kale and spinach, 10 samples of each. In total, a hundred samples, 50 from organic and 50 from conventional origin were evaluated. Thermotolerant coliform values were detected above the maximum detection limit of the technique in 21% of the samples, equivalent to 14% (7/50) of biological samples and 28% (14/50) from conventional samples. E. coli contamination was detected in 56% of the samples, namely 34% (17/50) from organic and 78% (39/50) from conventional origin. There were statistically significant associations between the presence of E. coli and conventional produce and between the presence of high values of thermotolerant coliforms and fecal contamination from conventional produce. Also it is reported an association between the presence of E. coli and the provenance of the samples, for both types of produce. Also 45% of the samples (45/100) showed contamination by at least one genus of protozoa or nematode. Five genera were identified: Entamoeba, Amoeba, Balantidium, Paramecium and Colpoda. There were statistically significant associations regarding the presence of contamination (protozoa and/or nematodes) and the provenance of the samples, for both types of produce. The source of the samples was also significant related to the presence of intestinal protozoa, for both types of produce. It was also found an association between samples contaminated by protozoa and/or nematodes and the absence of fecal contamination in the biological produce. From this work, it can be assumed that microbiological and parasitological contamination in organic produce was lower than conventional produce. However, further studies are needed to better assess the quality criteria of organic produce. From what is known, this is one of the first studies in Portugal that report the presence of intestinal protozoa on vegetables for human consumption. These results contribute undeniably to the knowledge of food safety related to the consumption of vegetables sold in markets from organic and conventional produce in the Metropolitan Area of Lisbon.
The consumption of raw vegetables provides essential nutrients and many benefits to a healthy diet. However, they can also cause intestinal diseases, with a significant impact on human health. In addition, due to the chemical hazards associated with these foods, namely pesticides and heavy metals, there has been an increase in the consumption of organic produce almost everywhere in the world. Considering the scarcity of studies in this subject, including in Portugal, this work was intended to contribute to a better knowledge about microbiological and parasitological safety between organic and conventional produce. The presence of thermotolerant coliforms, Escherichia coli and the presence of protozoa and nematodes in vegetables sold in open-aired markets of the Metropolitan Area of Lisbon were evaluated. Five varieties of vegetables were sampled: watercress, lettuce, chives, kale and spinach, 10 samples of each. In total, a hundred samples, 50 from organic and 50 from conventional origin were evaluated. Thermotolerant coliform values were detected above the maximum detection limit of the technique in 21% of the samples, equivalent to 14% (7/50) of biological samples and 28% (14/50) from conventional samples. E. coli contamination was detected in 56% of the samples, namely 34% (17/50) from organic and 78% (39/50) from conventional origin. There were statistically significant associations between the presence of E. coli and conventional produce and between the presence of high values of thermotolerant coliforms and fecal contamination from conventional produce. Also it is reported an association between the presence of E. coli and the provenance of the samples, for both types of produce. Also 45% of the samples (45/100) showed contamination by at least one genus of protozoa or nematode. Five genera were identified: Entamoeba, Amoeba, Balantidium, Paramecium and Colpoda. There were statistically significant associations regarding the presence of contamination (protozoa and/or nematodes) and the provenance of the samples, for both types of produce. The source of the samples was also significant related to the presence of intestinal protozoa, for both types of produce. It was also found an association between samples contaminated by protozoa and/or nematodes and the absence of fecal contamination in the biological produce. From this work, it can be assumed that microbiological and parasitological contamination in organic produce was lower than conventional produce. However, further studies are needed to better assess the quality criteria of organic produce. From what is known, this is one of the first studies in Portugal that report the presence of intestinal protozoa on vegetables for human consumption. These results contribute undeniably to the knowledge of food safety related to the consumption of vegetables sold in markets from organic and conventional produce in the Metropolitan Area of Lisbon.
Descrição
Tese de mestrado, Biologia Humana e Ambiente, Universidade de Lisboa, Faculdade de Ciências, 2016
Palavras-chave
Vegetais Segurança alimentar Qualidade microbiológica Qualidade parasitológica Lisboa Teses de mestrado - 2016