With the beginning of autumn the olive harvest began, the mills began their activity and the first thread of oil came out of the separator, with its intense colour and an almost material density.
On the supermarket shelf, clear glass bottles with oil must are stacked, evoking the craftsmanship of the product: “Unfiltered olive oil”, “raw”, “natural” are some of the words on display.
The colour and density of the oil should not influence the purchase choice: it would, in fact, be more appropriate to focus on containers that reflect light, protecting the quality of the product. However, especially in this season, the consumer, allured to the fresh olive oils, wrongly identifies an unfiltered product as being a more genuine oil than the filtered one, thinking it capable of a better organoleptic and nutritional quality.
Differences between filtered and unfiltered olive oil
The veiled appearance of the must oil is determined by the presence of tiny particles of olive and water droplets left in suspension. The visual impact is an initial winning factor, but with time the impurities and residual humidity settle on the bottom of the bottle and trigger sensory decay reactions.
Removing these impurities before bottling allows better and longer lasting conservation.
The two main systems for eliminating impurities are filtering and natural settling. In the first case, the oil is passed through cardboard filters or inert fossil flours; these hold water droplets and other solid particles, making it shiny in appearance.
In the second case, the oil is left to rest in storage tanks for an adeguate period of time, so that the particles initially in suspension settle on the bottom due to the force of gravity; afterwards the residue is eliminated.
Both these methods do not reduce or modify the chemical-sensory characteristics of the product, but actually allow a longer conservation time.