Lucky dip of interesting olive oil research (part 2)
admin | November 4, 2010As they say, “results may vary”
———————-
Irrigation effects
Irrigation regimes including deficit irrigation on Cornicabra in central Spain were compared with rain-fed controls. Irrigation (b/w 56 and 206mm per season) tended to produce oil with slightly lower fruitiness and bitterness. Polyphenol levels declined substantially with amount of applied water, which was reflected in lower oxidative stability and oil bitterness. Pulp to pit ratios increased with moderate irrigation. Oleic acid and tocopherol levels were largely unaffected by irrigation.
Gomez-Rico et al. (2007) Influence of different irrigation strategies in a traditional Cornicabra cv. olive orchard on virgin olive oil composition and quality. Food Chemistry, 100, 568-578.
http://bit.ly/bbEX1Y
———————-
Lots of the healthy plant sterol campesterol = non extra virgin
Campesterol levels of 334 olive oils made from the variety Cornicabra ranged from 3.4% to 4.5% with a middle value of 4%. Therefore, depending on crop year, between 25 and 85% of oils exceeded the upper IOC limit for extra virgin olive oil. The authors concluded that this variety is naturally high in campesterol. (Note that high campesterol is used as a marker for adulteration with sunflower oil however many varieties have naturally high levels of this sterol – RG)
Rivera del Alamo et al. (2004) Sterol and alcohol composition of Cornicabra virgin olive oil: the campesterol content exceeds the upper limit of 4% established by EU regulations. Food Chemistry, 84, 533-537.
http://bit.ly/cbY9R4
———————-
Effect of irrigation and talc during processing
Irrigation produced fruit with significantly lower pigments (both the green chlorophylls and the yellow carotenoids) which also don’t transfer as well from the paste into the oil during extraction. The use of talc during malaxation resulted in more pigmentation of the oils, but the effect compared to irrigation was small.
Criado et al. (2007) Effect of the technological extraction and agronomical factors on the pigment transfer during olive oil extraction. J. Agric. Food Chem. 55, 5681-5688.
http://pubs.acs.org/doi/abs/10.1021/jf070303d
———————-
Using salt to improve extraction
Adding salt (0.6% and 1.2%) to paste prior to malaxation resulted in greater extraction of oil similar to when (the more expensive) talc was used. The oils extracted with the aid of salt contained slightly more pigments and were also slightly more bitter. (The authors do not discuss the significant negative environmental impact of salt remaining in the pomace – RG)
Cruz et al. (2007). Salt improves physical extraction of olive oil. European Food Research and Technology 225, 359–365.
http://www.springerlink.com/content/2606726183051183/
———————-
Does organic growing produce better olive oil?
Organic and conventional olive oils grown 1.5 km apart and made using identical processing methods were compared over three growing seasons. There were no consistent differences in the concentrations of polyphenols, tocopherol, key flavour compounds, or the intensity of aroma notes between organic and non-organic oils.
Ninfali et al. (2008) A 3-year study on quality, nutritional and organoleptic evaluation of organic and conventional Extra-virgin olive oils. Journal of the American Oil Chemists Society, 85: 151-158.
http://www.springerlink.com/content/r25u245128858030/
———————-
Natural way of reducing bitterness in olive oil
Immersing olives in hot water at 50-60C for 3 minutes prior to milling resulted in greater oil extraction. increased colour and reduced bitterness. Other measured oil quality parameters remained largely unaffected.
Cruz et al. (2007) Heat treatment improves olive oil extraction. Journal of the American Oil Chemists Society, 84: 1063-1068.
http://www.springerlink.com/content/68230130tq24732w/
[…] Read this article: Slick Extra Virgin » Lucky dip of interesting olive oil research … […]