Desamerização por salmoura natural de azeitonas, cultivar Cobrançosa, produzidas em condições de rega deficitária
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2022-02-24
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A oliveira é uma cultura bem-adaptada às condições climáticas que caracterizam a bacia mediterrânica, ainda que nas últimas décadas se tenha vindo a assistir à intensificação dos olivais tradicionais para intensivos e super-intensivos, que para obterem maiores produções, necessitam de maior disponibilidade de água para satisfazer as necessidades hídricas. De forma a garantir o sucesso da rega, tanto no olival como noutras culturas, é importante estudar os diferentes períodos do ciclo vegetativo, perceber em que momentos do ciclo são exigidas maiores quantidades de água, e em que momentos a cultura está menos suscetível aos efeitos do stress hídrico. Com este trabalho, pretendeu-se estudar a influência de duas estratégias de rega na perda de amargor, na composição química e da microbiota durante o processo de salmoura natural da azeitona, cultivar “Cobrançosa”, na região de Trás-os-Montes. As estratégias de rega estudadas foram bem regado (FI), fornecendo-se uma quantidade de água equivalente a suprimir a evapotranspiração da oliveira, e a rega deficitária controlada (RDI100) que recebeu a mesma quantidade de água que o tratamento FI excepto na fase do endurecimento do caroço, em que a rega sofreu uma redução de 15% em relação ao FI. Estudou-se ainda a influência do corte na azeitona (azeitona retalhada) nos parâmetros acima mecionados. A rega deficitária apesar de favorecer a textura, a concentração de pigmentos, a atividade antioxidante, e a menor concentração de polifenóis totais, não permitiu a perda mais rápida de oleuropeína das azeitonas, principal composto responsável pelo amargor. A produção de azeitonas retalhadas parece ser interessante para tornar o processo de fermentação mais rápido, pois favorece a mais rápida solubilização de constituintes da azeitona. Não foram registadas diferenças estatisticamente significativas do efeito da rega na densidade populacional de leveduras e de bactérias. Das diversas colónias isoladas durante o presente trabalho, destacam-se 8 estirpes de leveduras (Metchnikowia fructicola, Metchnikowia pulcherrima, Metschnikowia sp., Aureobasidium pullulans, Wickerhamomyces anomalus, Meyerozyma gulliermondii, Rhodotorula mucilanginosa e Yarrowia lipolytica) e 8 estirpes de bactérias (Bacillus velezensis, Bacillus subtilis, Lysinibacillus fusiformis, Bacillus pumilus, Bacillus safensis, Bacillus thuringiensis, Bacillus aryabhattai e Pantoea agglomerans). Não foram detetadas bactérias pertencentes à família Enterobactereaceae, nem ao género Pseudomonas e nem ao grupo das bactérias do ácido láctico (BAL).
The olive tree is a plant well know fot the capacity to adapt to the climatic conditions that characterize the Mediterranean basin. However, in recent decades there has been and intensification of tradition olive groves that, to obtain greater productions, require grater water supply to meet their needs. To ensure the success of the irrigation, that affects the production, it is important to study the vegetative cycle of the crop and to understand when, in the cycle, the crop is less susceptible to the effects of water stress. With this work, it was intended to study the influence of two irrigation strategies in the loss of bitterness and on the chemical and microbial composition during the natural brine process of “Cobrançosa” cultivar olives, in Trás-os-Montes. The irrigation strategies studied were full irrigation (FI), providing the water equivalent to suppress the evapotranspiration of the olive tree and control deficit irrigation (RDI100) which received the same amount of water as the FI treatment except in the hardening of the stone phase, in which the irrigation was reduced to 15% in comparison to the FI treatment. It was also studied the influence of the cut on the olive in the above-mentioned parameters. Deficient watering, despite favoring texture, pigment concentration, antioxidant activity and lower total polyphenol concentration, did not benefit a faster loss of oleuropein, the main compound responsible for bitterness, from the olives. The production of shredded olives seems to be interesting to fasten the fermentation process, because by increasing the permeability of the skin, it favors the faster loss of olives constituents. There were no statistically significant differences in the effect of watering in yeast and bacterial population densities. From the different colonies isolated during this work, 8 yeast strains standed out (Metchnikowia fructicola, Metchnikowia pulcherrima, Metschnikowia sp., Aureobasidium pullulans, Wickerhamomyces anomalus, Meyerozyma gulliermondii, Rhodotorula mucilanginosa e Yarrowia lipolytica) and 8 bacterial strains (Bacillus velezensis, Bacillus subtilis, Lysinibacillus fusiformis, Bacillus pumilus, Bacillus safensis, Bacillus thuringiensis, Bacillus aryabhattai e Pantoea agglomerans). Bacteria belonging to the Eterobactereaceae family, the genus Pseudomonas of the lactic acid bacteria froup (BAL) were not detected.
The olive tree is a plant well know fot the capacity to adapt to the climatic conditions that characterize the Mediterranean basin. However, in recent decades there has been and intensification of tradition olive groves that, to obtain greater productions, require grater water supply to meet their needs. To ensure the success of the irrigation, that affects the production, it is important to study the vegetative cycle of the crop and to understand when, in the cycle, the crop is less susceptible to the effects of water stress. With this work, it was intended to study the influence of two irrigation strategies in the loss of bitterness and on the chemical and microbial composition during the natural brine process of “Cobrançosa” cultivar olives, in Trás-os-Montes. The irrigation strategies studied were full irrigation (FI), providing the water equivalent to suppress the evapotranspiration of the olive tree and control deficit irrigation (RDI100) which received the same amount of water as the FI treatment except in the hardening of the stone phase, in which the irrigation was reduced to 15% in comparison to the FI treatment. It was also studied the influence of the cut on the olive in the above-mentioned parameters. Deficient watering, despite favoring texture, pigment concentration, antioxidant activity and lower total polyphenol concentration, did not benefit a faster loss of oleuropein, the main compound responsible for bitterness, from the olives. The production of shredded olives seems to be interesting to fasten the fermentation process, because by increasing the permeability of the skin, it favors the faster loss of olives constituents. There were no statistically significant differences in the effect of watering in yeast and bacterial population densities. From the different colonies isolated during this work, 8 yeast strains standed out (Metchnikowia fructicola, Metchnikowia pulcherrima, Metschnikowia sp., Aureobasidium pullulans, Wickerhamomyces anomalus, Meyerozyma gulliermondii, Rhodotorula mucilanginosa e Yarrowia lipolytica) and 8 bacterial strains (Bacillus velezensis, Bacillus subtilis, Lysinibacillus fusiformis, Bacillus pumilus, Bacillus safensis, Bacillus thuringiensis, Bacillus aryabhattai e Pantoea agglomerans). Bacteria belonging to the Eterobactereaceae family, the genus Pseudomonas of the lactic acid bacteria froup (BAL) were not detected.
Descrição
Trabalho elaborado como dissertação original, para o efeito de obtenção de grau de Mestre em Engenharia Agronómica
Palavras-chave
Oliveira , necessidade de rega