A few interesting recent research results
admin | November 22, 2012Olives did not make up a significant area of land in Southern Spain the 20th century. In the mid 18th century the land dedicated to olives was around 1/20th of what it is today. Groves as we know them today were rare. Olive trees were scattered amongst other crops particularly cereals which made up over 50% of the arable area, and were managed more as a forestry enterprise with very few inputs and little management. Olive trees were grown as they provided a wide range of products – pomace and leaves for fuel and livestock feed, oil for lighting and for soap production. Olive wood was used for fuel at twice the rate as forest wood in 1750, and the percentage of olive wood to forestry wood used for fuel increased up until the early 1900’s. Clearly the diversity of outputs was well suited for small subsistence landholders.
However, in 1750 only 8% of the oil produced was eaten, the rest was used for lighting and animal production. 90% of fat intake in Baena (a major olive growing region in Southern Spain) was animal fat, with olive oil making up the remainder. It was only around 1900 when the consumption of olive oil first surpassed that of animal fats,
The final decades of the 20th century saw olive growing increase significantly. Area to olives in Andalucia increased by 300,000 ha and oil production tripled to current levels. The authors attribute this to increased supply due to industrialisation of agriculture, modernisation of mills (both resulting in significantly higher oil yields per ha), and the introduction of EU subsidies. On the demand side, appreciation of the health benefits of olive oil has stimulated worldwide demand. Finally, olives were not seen as a single crop in the Andalucian landscape on any scale until well into the 20th century.
InfanteAmate(2012)The Ecology and History of the Mediterranean Olive Grove: The Spanish Great Expansion, 1750 2000. Rural History. 23: 161-184 doi:10.1017/S0956793312000052
Comment: Very interesting as this paper presents evidence that suggests that the use of olive oil as a major part of the Med diet may be a relatively recent phenomenon. No doubt the olive tree was an important crop as it provided a number of resources for small scale subsistence farmers. As one of my friends commented. Perhaps in 1750 when people died of TB, diptheria, plague or even minor infections, the concept of eating something healthy to prolong life may have been a bit weird.
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Normally I comment after presenting research results but this time I’ll comment first by saying that this was 20 minutes of my life that I will never get back. This paper compared 2 phase, 3 phase and a traditional press with respect to total polyphenol content and polyphenol type in the oil, waste-water and pomace. The researchers also measured antioxidant activity so they could comment on the healthfulness of the oils produced by the three systems. There was extensive analysis of the types of polyphenols using high performance liquid chromatography.
However when I later read the methods carefully, the researchers had used three different batches of olives, with each batch being a different variety grown in different places, with a different batch being processed using each of the different extraction methods. e.g. Variety X from place A was processed by press, Variety Y from place B was processed by 2 phase and Variety Z from place C was processed by 3 phase. How could they possibly think that they could compare systems when the effect of processing system is totally confounded with the effect of the olive source? I won’t even summarise with what they came up with (although the results seemed in line with expectations).
An example of the danger of just reading the abstract.
Klen and Vodopivec (2012) The fate of olive fruit phenols during commercial olive oil processing: Traditional press versus continuous two- and three-phase centrifuge. LWT – Food Science and Technology 49, 267-274 doi:10.1016/j.lwt.2012.03.029
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Enclosing the vertical centrifuge in a container filled with argon with an oxygen level of 3% reduced dissolved oxygen in the oil by 6.8 mg/L (71%), peroxide values by 3.8 (44%), and K232 by 0.46 (27%) compared with decantation under air. FFA and polyphenol level were unchanged.
Masella et al. (2012) DOI: 10.1002/ejlt. 201100400
Comment: Others have found that vertical decanting is the primary cause of dissolved oxygen in EVOO. The large effects reported here support this. However how this could be put into practice is unclear.
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Olives were stored in plastic bags under high CO2 modified atmosphere and at 5C for up to 21 days prior to being processed. The first sampling day was at day 7. Free fatty acidity increased as expected with storage time, but the increase was lower under the modified atmosphere and at 5C compared with when the olives were stored in a normal atmosphere at room temperature. Over the most realistic storage time used in this study (7 days), total polyphenols and radical scavenging activity fell except when the olives were stored in the modified atmosphere at the lower temperature. The bitterness index increased with storage time.
Ben Yahia et al. (2012) Quality, stability and radical scavenging activity of olive oils after Chétoui olives (Olea europaea L.) storage under modified atmospheres. Food Science and Technology International 18: 353-365. DOI: 10.1177/1082013211428102
Comment: Only a small amount of olives were stored (1.5kg). It would be interesting to see if the same results were observed in a more realistic situation of having bins of olives whereby heat builds up due to fermentation, and that the olives are generally starved of oxygen in these bins due to carbon dioxide production. The realistic storage time comment was in the context of, most producers try to keep the time between harvest and processing to a minimum. However, due to unusual circumstances (e.g. equipment breakdown), sometimes olives have to be stored for a short time. Ok, not 7 days, but this was the first time point of analysis in this study.
Love reading this research. My comment is actually regarding this post. The comments were closed. http://www.aromadictionary.com/EVOO_blog/?p=147. Simple question. I love the info but I’m a science geek, can you provide the link to the original research? Thanks so much for your time!
Hi Richard,
Re: Masella et al. (2012) DOI: 10.1002/ejlt. 201100400
You commented,
Others have found that vertical decanting is the primary cause of dissolved oxygen in EVOO. The large effects reported here support this. However how this could be put into practice is unclear.
Now, I have never actually set foot in an olive mill, and am not the most mechanically-inclined individual in the world, so WTF do I know, but from what they say in the ‘Methods’ it sounds entirely doable to my ignorant read: “The machine is a conventional vertical separator for olive oil processing and it does not provide any system to avoid the contact between the treated product and the surrounding air. Thus, a full contact between the atmospheric oxygen and olive oil was reasonably assumed in the [conventional] treatment.” In turn, the same design feature meant that they were able to just slap a giant plastic container AROUND the apparatus and pump it continuously with Ar, leading to substantial O2 exclusion. That sounds dead simple to me, except perhaps if the centrifuge were of necessity located in a corner where there’s no room for the “bell jar” and it’s extremely hard to move. Moreover, I know (and have seen, on YouTube) that there are systems out there (Apollo in CA has one) that are hermetically sealed to excludeO2, which is nice, but (a) presumably quite expensive when starting up, and (b) impossible or nearly so to retrofit into an existing system and thus VERY expensive as a replacement (rather than marginal) cost, whereas this could simply (it seems) be slapped onto existing equipment for a small additional cost. What do you think?
Hi Michael
While it is possible to hermetically seal a piece of equipment in an industrial situation (which an olive mill is), people who I have talked to, have questioned the practicality of doing so. The fancier a machine is, the harder it is to clean and maintain. It is also worth noting that it takes a lot of inert gas to displace air, as mixing occurs and in effect you are diluting air rather than displacing it fully. I know of a couple of producers have done some home made retrofitting of inert gassing to the outlet of the decanter. While not totally excluding air, it would reduced dissolved O2, and they have been happy with the results.
Maybe some other readers would like to weigh in with their experiences.