COMMENTS ON THE ADOPTION OF ABSOLUTE ERYTHRODIOL+UVAOL INSTEAD OF % ERYTHRODIOL+UVAOL FEBRUARY 2017 By Efi Christopoulou, expert chemist of the EC and the IOC The parameter erythrodiol+uvaol is a parameter for the detection of pomace oil in an olive oil (virgin or not). Recently, the expert chemists are examining the replacement of the % erythrodiol+uvaol by the absolute erythrodiol+uvaol. Besides the examination of the method for the determination of this parameter, I consider that the limit to be adopted is also a very crucial issue. The method has been thoroughly examined (since it is common for both % or absolute erythrodiol+uvaol) and there is not much more to be done, beyond achieving the good discrimination of erythrodiol+uvaol and its calculation with the best possible accuracy. A. Equivalence of the various values of absolute E+U to the limit of % E+U Table 1. Equivalence of the values of the absolute E+U to the limit of E+U (%) on the various total sterols content TOTAL STEROLS (mg/kg) E+U (%) E+U (mg/kg) 1000 4,50 47,1 1500 4,50 70,7 2000 4,50 94,2 2500 4,50 117,8 3000 4,50 141,4 abs( E U) % E % U * sterols 100 (% E % U) 1
% erythrodiol+uvaol Conclusions The parameter % E+U means that the E+U content of olive oils varies depending on their total sterols content. The use of the limit E+U=4,5% results in the acceptance of: A max value of E+U=47,1mg/kg in olive oils with 1000mg/kg total sterols A max value of E+U=141,4 mg/kg in olive oils with 3000mg/kg total sterols So, it is strict for low total sterols olive oils and wide for high total sterols olive oils. B. Equivalence of the values of % E+U to the various limits of absolute E+U Table 2. Equivalence of the values of the % E+U to the various limits of absolute E+U on the various total sterols content limit of abs E+U 50mg/kg 70mg/kg 90mg/kg TOTAL STEROLS (mg/kg) % erythrodiol+uvaol 1000 4,8 6,5 8,3 1500 3,2 4,5 5,7 2000 2,4 3,4 4,3 2500 2,0 2,7 3,5 3000 1,6 2,3 2,9 Figure 2. % E+U content using various limits for absolute E+U content 9,0 8,0 7,0 6,0 8,3 6,5 5,7 limit abs E+U=50mg/kg limit abs E+U=70mg/kg limit abs E+U=90mg/kg 5,0 4,0 3,0 2,0 1,0 4,8 4,5 3,2 4,3 3,4 2,4 3,5 2,7 2,0 2,9 2,3 1,6 0,0 500 1000 1500 2000 2500 3000 3500 total sterols (mg/kg) 2
Conclusions The adoption of the absolute E+U instead of % E+U will result in a significant modification of the official (until now) erythrodiol+uvaol limits. The use of the limit E+U=70mg/kg results in the acceptance of A max value of E+U=6,5% in olive oils with 1000mg/kg total sterols A max value of E+U=2,3% in olive oils with 3000mg/kg total sterols. The adoption of abs E+U seems to be in favor of olive oils with low total sterols content. The researches have proved that oils with low total sterols content are those produced from the small size olives. These olives are used almost exclusively for the production of olive oil and produce high quality extra virgin olive oil, depending of course on the applied production practices. It is remarkable that the grade of maturity of small size olives has influence in the total sterols content of olive oils. The more unripe olives (which usually means excellent organolepric characteristics), the lower the total sterols content of the produced olive oils. Consequently, it would be fair that these oils should be covered by the erythrodiol+uvaol limit and not to be characterised as adulterated with pomace, because they exhibit a level of E+U higher than 4,5% due to the low total sterols content. C. Application of the various limits of absolute E+U to Greek virgin olive oils The following tables provide statistical data of Greek olive oils (virgin olive oils and crude olive pomace oils) carried out in the Chem Labs of the Ministry of Development, on the official and not official parameters used for the detection of pomace oil. The samples were authentic since the sampling took place directly from olive oil-mills and from factories producing crude olive pomace oil. Table 3. Statistical data on Greek virgin olive oils (n=710) MEAN STDEV MIN MAX MEDIAN total sterols (mg/kg) 1695 411 1018 2996 1596 erythrodiol+uvaol% 2,62 1,12 0,36 7,14 2,38 erythrodiol+uvaol (mg/kg) 44,0 18,3 6,7 116,4 39,9 waxes (mg/kg) 161 74 23 577 149 aliphatic alcohols (mg/kg) 233 84 61 593 221 alcoholic index 0,66 0,57 0,02 3,84 0,52 3
percentage of the samples Table 4. Statistical data on Greek crude olive-pomace oils (n=90) MEAN MIN MAX RANGE MEDIAN Erythrodiol + uvaol % 19,38 9,06 34,46 25,4 18,80 Erythrodiol + uvaol (mg/kg) 882,2 383,1 1625,1 1242,0 828,3 Waxes (mg/kg) 3152,3 1306,5 8220,0 6913,5 1630,0 Aliphatic alcohols (mg/kg) 2948,5 1389,0 8942,7 7553,7 2746,8 Alcoholic index 163,90 20,27 928,09 907,82 54,39 Figures 3 and 4 illustrate the distribution of 710 samples of virgin olive oils regarding the parameters total sterols content, erythrodiol + uvaol % and absolute erythrodiol+uvaol content. The column with red color presents the percentage of the samples which is out of limits. Figure 3. Distribution of Greek virgin olive oils regarding total sterols content (n=710) 45,0 40,0 35,0 30,0 25,0 20,0 15,0 10,0 5,0 0,0 38,7 40,3 14,8 6,2 1000-1500 1501-2000 2000-2500 >2500 total sterols (mg/kg) 4
As we can see, 6,2% and 10,0% of the examined samples exhibit the limits of 4,5% and 70ppm regarding the erythrodiol + uvaol % and absolute erythrodiol+ uvaol content respectively. Most of the deviated samples regarding %E+U were olive oils with low total sterols content and excellent organoleptic characteristics, produced from small size olives. Most of the deviated samples regarding abs E+U were olive oils with higher than 1500mg/kg total sterols content, produced from medium or large size olives. Summarizing the above, we made the following table which shows the percentage of samples which exhibits deviations from the limits of each parameter. Table 5. Percentage of samples deviated from the limits of each parameter Total number of examined samples = 710 parameter limit deviated samples (% of total samples) Erythrodiol + uvaol % 4,5 6,2 % Erythrodiol + uvaol (mg/kg) 50 29,0% 60 15,9% 5
70 10,0 % The adoption of absolute E+U with limit 70mg/kg will have as consequence a significant number of Greek virgin olive oils to be characterized as not authentic. D. Effectiveness of the above parameters in the detection of the presence of pomace oil in a virgin olive oil. Using the statistics of this study, we examined the effectiveness of the above parameters in the detection of the presence of pomace oil in a virgin olive oil and the results were the following : Table 6. Detecting the presence of olive-pomace oil in a virgin olive oil Erythrodiol +uvaol % Erythrodiol+uva ol (mg/kg) Mixtures of samples % detectable pomace oil Virgin olive oil (min) Virgin olive oil (median) Virgin olive oil (mean) Pomace (min) >21% 17% Pomace (median) 6% 7,5 % Pomace (min) >21% 8,5% Pomace (median) 5% 4% Pomace (min) >21% 7,5% Pomace (median) 5% 3% Limit of the parameter : 4,5 % 70mg/kg Based on the above, the following conclusion could be drawn : The use of absolute E+U (limit 70 mg/kg) is preferable than the use of E+U % (limit 4,5%). Certainly, these conclusions are based on the statistical data of Greek olive oils. It would be useful to have data of olive oils from other countries, in order to check the reliability of the limits and the possible deviations from the limits of the oils of each country. 6
% increase or descrease E. Variations on the values of total sterols and E+U during refining The following table provides certain data of lampante virgin olive oils and refined olive oils from a chemical refinery. Table 7. Data on lampante and refined olive oils (n=10) LAMPANTE VIRGIN OLIVE OILS REFINED OLIVE OILS (chemical refining) a/a free acidity (% of oleic acid) total sterols (mg/kg) erythrodiol +uvaol (%) erythrodiol + uvaol (mg/kg) total sterols (mg/kg) erythrodiol +uvaol (%) erythrodiol + uvaol (mg/kg) 1 4,5 1750 3,1 56,0 1100 4,6 53,0 2 5,2 1550 3,8 61,2 1050 5,6 62,3 3 6,1 1650 2,2 37,1 1080 3,6 40,3 4 6,9 1800 2,4 44,3 1100 4,1 47,4 5 7,6 1500 3,2 49,6 950 4,8 47,9 6 8,2 1700 3,5 61,7 1080 5,4 61,6 7 9,8 1850 3,5 67,1 1150 5,5 66,9 8 9,8 1900 3,3 64,8 1150 5,5 66,9 9 10,7 1750 3,4 61,6 1050 5,6 62,3 10 11,0 1850 3,2 61,2 1080 5,8 66,5 MEAN 8,0 1730 3,2 56,5 1079 5,1 57,5 STDEV 2,3 132 0,5 9,7 57 0,7 9,6 MIN 4,5 1500 2,2 37,1 950 3,6 40,3 MAX 11,0 1900 3,8 67,1 1150 5,8 66,9 MEDIAN 7,9 1750 3,3 61,2 1080 5,5 62,0 100 80 60 40 20 0-20 -40-60 Figure 6. Variations on the values of certain parameters during refining MEAN MIN MAX 61 47-37 -32-42 total sterols (mg/kg) erythrodiol +uvaol (%) erythrodiol + uvaol (mg/kg) parameter 81 2-5 9 7
Table 8. Variations on the values of total sterols and E+U during refining (n=10) a/a free acidity of lampante total sterols (mg/kg) % increase or decrease erythrodiol +uvaol (%) erythrodiol + uvaol (mg/kg) 1 4,5-37,1 48,4-5,3 2 5,2-32,3 47,4 1,7 3 6,1-34,5 63,5 8,6 4 6,9-38,9 72,1 7,1 5 7,6-36,7 50,0-3,4 6 8,2-36,5 54,3 0,0 7 9,8-37,8 57,1-0,2 8 9,8-39,5 66,7 3,2 9 10,7-40,0 64,7 1,1 10 11,0-41,6 81,3 8,7 MEAN -37,5 60,5 2,2 STDEV 2,7 11,1 4,8 MIN -41,6 47,4-5,3 MAX -32,3 81,3 8,7 MEDIAN -37,5 60,3 1,4 Based on the above, the following observations could be made: Significant decrease of total sterols content occurs during refining, ranges from 32% to 42%, depending on the free acidity value of the lampante oil which is subjected to refining. Dramatic increase of erythodiol+uvaol (%) occurs during refining, ranges from 47% to 81%, resulting in the deviation of a lot of produced refined olive oils from the erythodiol+uvaol (%) limit. This was expected, since the total sterols are reduced. It is clear, that the marketing of these oils is difficult, as they are. The only solution to this problem is the addition to these oils of virgin olive oils with high content of total sterols. The variations on the absolute E+U during refining is not so significant, ranges from -5% (decrease) to 9% (increase). It proves that during refining, a significant loss of total sterols occurs, while the amount of E+U remains almost constant. 8
GENERAL CONCLUSIONS All above observations lead to the same conclusion drawn in part D Effectiveness of the above parameters in the detection of the presence of pomace oil in a virgin olive oil, which is: Since the oils with low total sterols exhibit high E+U % and the oils with high total sterols exhibit low E+U %, it is concluded that the actual E+U content does not depends on the total sterols content. The use of absolute E+U (limit 70 mg/kg) is preferable than the use of E+U % (limit 4,5%) For all categories of olive oils (virgin olive oils, refined olive oils and olive oils). For the detection of presence of pomace oil in olive oil However, the reliability of the limits should be checked by all olive oil producing countries, in order to adopt a parameter which will be effective in the detection of fraud of olive oil with pomace oil and applicable on olive oils of all countries. 9