Analysis of Tuscan Olive Oil: study of the 2017 season
What was the outcome of the 2017 oil production season?
The beginning of the season was rightly perturbed by forecasts of reduced production which came true. In particular, in a few central Italian region, productivity was very low, whereas at a national level, production was below average, despite being slightly up compared to the previous oil production season. What about quality?
Scarce production quantities this year are attributable to low temperatures during late spring, when trees begin to blossom, followed by scarce rainfall already in May, compromising fruit setting.
The harvest began early, given that already in late September olives presented an advanced state of colour change. However, this is not always an indication of effective ripening, especially after a hot and dry summer, when changes in drupe colour often occur in response to water or heat stress.
This is why those who began harvesting in the first few days of October meant that scarcely ripened olives with low oil accumulation were delivered to mills, resulting in rather dry pastes, typically more difficult to process, and ultimately, in low yields.
Luckily Autumn rain re-balanced fruit hydration and in November medium/high yields were recorded.
Olive Oil quality
In contrast, in terms of quality this was an excellent year, but oil analysis should be preceded by a discussion on climate.
Rainfall was scarce or altogether absent in July and August (in some regions in June too). This is always good news for oil quality, although this year weather was excessively dry, resulting in water shortage problems in various regions.
No rain = no flies
It has to be said that the absence of rainfall meant that the olive oil industry’s biggest enemy did not make an appearance, thus minimising all the problems linked to the timing of treatments, fruit drop or the speed of harvesting/processing.
In view of these conditions, in analytical terms we expected and confirmed very low acidity levels.
Scarce rainfall and the absence of flies results in healthy fruits which are protected against hydrolytic rancidity.
Absence of rainfall = high polyphenols
As we found in previous years, one of the positive consequences of a “dry” summer is higher polyphenol content, as confirmed in oil from the most recent harvest.
In view of experience acquired during the study conducted in 2014, we expected an average polyphenol value of between 500 and 600 mg/Kg.
With reference to acidity, it is clear how low rainfall results in low values. However, understanding the correlation between scarce precipitation and high polyphenol levels is not so simple.
As anti-oxidising substances, polyphenols may form as part of a plant self-protection mechanism, or perhaps lower water levels in fruit may limit the migration of these water-soluble compounds from oil to water.
As confirmation of observations regarding the effects of precipitation during previous years and based on forecasts made at the beginning of the season, the resulting outcomes went according to predictions. Indeed most samples yielded high or very high quality results.
Analysis of Olive Oil
Like previous years, CDR OxiTester was used to analyse a few dozen new oil samples from various areas of Tuscany. Results were similar to those for oils from other Italian regions.
Very low acidity was found in all analysed samples, with an average of 0.11% (oleic acid), without a doubt the lowest value from the last few years.
As previously mentioned, it has been a record year for polyphenols/biophenols, with a very high average (560 mg/Kg), and with the highest values close to 900 mg/Kg. Obviously organoleptic values confirmed the product’s excellent quality.
Peroxide values are generally very low for fresh oils; despite slightly exceeding historic averages this year, they still remained well within extra virgin limits.
This may be a direct consequence of high temperatures during early October, when harvesting had already begun.
High temperatures, especially during the day, accelerate oxidation processes in harvested fruits, which may be affected by increased acidity and peroxide levels, if not crushed immediately after being picked.
Results of chemical analysis
The table here below contains results of oil analyses ordered according to biophenol levels.
In conclusion, climate is a determining factor, holding the balance of this production activity.
Quality, yield and productivity are all closely linked to this aspect. Those who decide to invest in this sector must take into account current climatic changes under way, mindful of the fact that seasons characterised by particular weather may become increasingly frequent, and of the influence they may have on oil quality and production.