“Maçã de Alcobaça” Portuguese apples have a Protected Geograpic Indication (PGI). The PGI encompasses the cultivars Casa Nova, Golden Delicious, Red Delicious, Gala, Fuji, Granny Smith, Jonagold, Reineta and Pink produced in the defined geographically delimited area and characterised by elevated consistency and crispness, a high percentage of sugar and high acidity, which gives them a bittersweet taste and intense aroma
For authentication analysis, reference databases based upon multivariate elemental composition have been proposed. There was concern that the databases might be invalidated by permissible changes in the fertilisation regimen. Such changes are likely, as there is a market demand for high productivity.
In this paper (open access) the authors verified that, in the case of royal gala, the PGI origin could still be verified despite variation between three common fertilisation regimens. Three different soil NPK fertilisation schemes were applied to experimental orchards within the PGI area (1 x mineral NPK proposed for integrated production, an intermediate strategy that included organic granular amendment and 2 x mineral NPK), and the elemental profiles of the apple pulps were analysed and compared.
The researchers found that some mineral elements improved their concentration in the apple pulps with fertilisation due to interactions of these elements with the fertiliser components (namely, nitrogen, potassium and phosphorus) or to potential changes in the bioavailability of the elements in the soil due to fertilisation application. This gave subtle differences in the nutritional profile of the apples. However, they found that this variation did not impede the ability of discriminating PGI from non-PGI (from North Portugal and Italy) equivalents using previously-developed models. This reinforces the edaphic characteristics of the cultivation area's prevalent role over the effect of fertilisation practices or physiological trait changes, in shaping the elemental signature of the fruits. This was found to be mostly due to the high influence of geologically linked elements (such as Rb, Pb and Y) in the discrimination of the sample provenance.
They concluded that the previously-developed classification models for “Maçã de Alcobaça” PGI authenticity analysis remained robust even if fertilisation practices are applied to fight less favourable cultivation conditions.
Photo by Matheus Cenali on Unsplash
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