Cordero-Bueso G.,Instituto Madrileno Of Investigacion |
Arroyo T.,Instituto Madrileno Of Investigacion |
Serrano A.,Instituto Madrileno Of Investigacion |
Valero E.,Pablo De Olavide University
International Journal of Food Microbiology | Year: 2011
Some oenological practices, such as the massive utilisation of commercial yeast and the consequent colonisation of wineries, can contribute to reducing the native yeast biodiversity. In this context, the vineyard could be a reservoir of autochthonous yeasts of oenological interest. Thus, the evaluation of the influence of different agricultural parameters on the biodiversity of yeast population in the vineyard is necessary. This work shows the results of the influence of some floor management strategies of the vineyard in the natural yeast population associated with the grape-berries. With this objective, a three year sampling plan was designed in the Shiraz vineyards of the Madrid region using three floor management strategies: bare soil by tillage, bare soil maintained with herbicides and soil maintained with cover crop. The results of this study have shown that bare soil by tillage could be a sustainable alternative for managing the soil, due to the reduced use of agrochemicals and the resulting high yeasts biodiversity. Nevertheless, the presence of herbicides in the vineyard has a minor impact on the diversity of grape associated yeast communities, and this could have increased the yeast populations. Hence, from the fermentative yeasts' (like Saccharomyces) point of view, in hot and arid environments where soils may be affected by the tillage management, the best option could be the maintenance of the bare soil with the use of herbicides. © 2011 Elsevier B.V.
Palancar Olmo M.,Instituto Madrileno Of Investigacion |
Vergara Garcia G.,Instituto Madrileno Of Investigacion |
Angeles Perez M.,Instituto Madrileno Of Investigacion
Acta Horticulturae | Year: 2012
Virgin olive oil is one of the edible fats most highly appreciated because it can be consumed without any refining process and thus retains its natural flavour and aroma. Nevertheless, its consumption has also increased due to its nutritional and healthy characteristics thanks to its balanced fatty acid composition, and because of the fact that virgin olive oil provides a rich source of natural antioxidants, as tocopherols and phenolic compounds. However, the levels of the major and minor compounds of the virgin olive oil depend on different factors, the cultivar and the ripening index of the fruit being some of the most important ones. The aim of this work was to study the influence of the stage of the fruit ripening on the nutritional quality of virgin olive oils produced in Madrid, in order to establish an optimum harvesting time for the main cultivars cultivated in this region: 'Cornicabra' and 'Manzanilla'. Olives of 'Cornicabra' and 'Manzanilla' cultivars were harvested in two consecutive crops (2005-2006 and 2006-2007), and picked at three ripening stages. Ripening index of the fruits was determined. Olive oils were extracted using Abencor system and fatty acid composition and polyphenol and tocopherol contents were determined in the oils. Fatty acid composition suffered slight changes in relation to the ripening stage. Just palmitic acid content decreased significantly with the ripening process in both cultivars in study, and the oleic acid level increased in 'Cornicabra' oils. Both 'Cornicabra' and 'Manzanilla' oils showed high levels of oleic acid, with average values of 76 and 80% respectively. Polyphenol content significantly decreased with the ripening process. Loss was more marked in 'Manzanilla' oils, which levels fell from 369 ppm in the first harvesting period to 261 ppm in the last one. Oils from 'Cornicabra', a high phenol content cultivar, decreased from 473 to 458 ppm. Tocopherol content (vitamin E) followed a similar trend to that of phenol compounds, decreasing its levels with the ripening process. 'Cornicabra' oils showed values that ranged from 421 to 253 ppm at the last harvesting period, while 'Manzanilla' oils varied from 359 to 192 ppm. This study reveals the importance of both cultivar and harvesting time for the nutritional quality of virgin olive oils. These facts have to be taken into account in order to decide the optimum harvesting time, which not necessarily has to be established to obtain a high percentage of oil content, and not necessarily needs to be the same for all the cultivars that coexist in a region.