polyphenols in olive oil; part 1: the olive

Filippo Camerini [email protected]

ThePolyphenolsintheoil.

Part1:theolive;whensizematters.

Olive oil is commonly considered one of healthiest fats and antioxidants play a major role in this kind of properties. Further, many panelists and tasters are progressively driving consumers (especially in new expanding market and in the US) to prefer oils with pungent sensorial profiles. This brought journalists and practitioners (more than nutritionists and consumers) to identify the general quality of olive oil with its content in polyphenols. Although this being far from true, in some marketplaces, PPHs count is progressively getting more relevance and many operators seek for advices to produce olive oil with high PPHs content. Probably due to the fact that PPHs value involves a number of different compounds, possibly behaving differently with ripening, researchers have not achieved common management guidelines to maximise PPHs value. In fact, most answers provided to growers are generic and vague. As an olive and oil consultant, I found myself in the need to better understand PPHs so to be able to provide appropriate advices. I began with reconsidering general assumptions and personal observations in relation to basic factors. The PPH content in olive oil depends on the original matter (olives) and the methods of processing. The potential content of PPHs depends on the plant genotype (or genotypes) and its interaction with the growing environment (including management techniques). The final content of PPHs in oil depends on how the potential content of PPHs is preserved in processing. This text reports my considerations relating to the first of these issues.

The potential content of PPHs depends on the plant genotype (or genotypes) and its interaction with the

growing environment (including management techniques).

As for the genotype, a comparison of monovariety oils from trees from the same grove (same area and

management) allowed many researchers to categorize cultivars according to high, medium and low PPHs

values. This grouping is normally confirmed through years (and in different research stations) and therefore

we can assume this “positioning” as not linked to the growing characteristics (environment or

management).

Althought, interesting inconsistencies regularly appear in some particular cases:

‐when extreme alternate bearing occurs, higher values of PPHs are reported in “on” years.

‐ In wet seasons or irrigated groves, PPHs are normally lower.

‐ After severe pruning of olive trees PPHs values are lower than expected (this somehow contradicts the

general assumption about higher PPH values depending on the amount of direct sunlight green olives are

exposed to).

Considerations about best harvesting time and ripening point will be considered as part of processing and

analysed in a following paper.

I then considered PPHs physiology and among other things, their distribution inside the olive. The highest

concentration is located in the most external layers, just under the olive skin. I think this is a key

information to understand how to deal with these compounds.

Filippo Camerini [email protected]

Due to the fact that surface area to volume ratio increases with the decrease of size, larger objects have

small surface area compared to the volume so they have a small surface area to volume ratio.

In facts, to get the same quantity of oil (volume), in smaller olives more surface area (PPHs) will be

processed than bigger olives.

This perfectly suits previous assumptions and observations. Hence, considering olives from the same

cultivar within a specific area the size of olives might fluctuate. This has some consequences.

Trees tend to bear olives smaller than usual in case of:

Trees bear olives bigger than usual when they are less in number. This might occur in case of:

‐ over cropping (or alternate bearing “on‐years”), ‐ “Off” years;

‐ non irrigated groves;

‐ First years after restructuring tree shape or severe pruning;

‐abundance of fruity branches (light pruning).

‐Production of table olives and use of table olives variety;

In all these cases high values of PPHs were reported.

In all these cases low values of PPHs were reported. Further oil from table olive cultivars (big fruit) normally has low amount in PPHs.

To appreciate how much this might interfere with the potential PPHs content, it is interesting to consider how the surface area to volume ratio decrease in cultivar bearing bigger olives By approximation olives can be considered as perfect spheres and considering average diameter moving from 1 to 3 cm the impact on surface area to volume ratio is obvious.

Sure, the awareness of this connection between olive size and PPHs content in oil is not enough to control

oil profile but provides indications to explain fluctuations through years and helps foresee the quality of

future oil.

Following sections will consider harvest time and processing impact on PPHs.

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surface area to volume ratio

polyphenols in olive oil; part 1: the olive

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