Natural Olive Oil Preservative as Effective as Synthetic Ones

Researchers found that oleoresin had competitive antioxidant properties without the same health risks associated with the synthetic antioxidants

By Daniel Dawson
Dec. 4, 2017 08:40 UTC

A new study has found that adding tomato peel extracts to refined olive oil increases the pro­duc­t’s shelf life.

Researchers from the University of Sfax and Ayachi Group Industry in Tunisia com­pared the sta­bi­liz­ing effects of adding ole­o­resin and syn­thetic antiox­i­dants to the oils.

Extracts from tomato indus­trial byprod­ucts can be used as an effec­tive sta­bi­lizer against the oxi­da­tion reac­tions dur­ing long stor­age.- Noureddine Allouche, Researcher

When olive oil is refined some of its nat­ural antiox­i­dants are par­tially elim­i­nated and there­fore must be sup­ple­mented in order to pre­vent the oil from spoil­ing. Olive oil must be refined when the qual­ity is too low to be safely con­sumed. According to the International Olive Council, more than 50 per­cent of olive oil pro­duced in the Mediterranean region is refined.

The group of researchers found that ole­o­resin had com­pet­i­tive antiox­i­dant prop­er­ties with­out the health risks asso­ci­ated with the syn­thetic antiox­i­dants.

Oleoresin is a lycopene-rich extract from tomato peels. Up until a cer­tain point, the com­pound pro­tects olive oil against oxi­da­tion, a process which spoils the oil. The study found that 250 μg/g (micro­grams of ole­o­resin per gram of oil) is the opti­mal ratio.

The pro­tec­tive effect of tomato peel ole­o­resin (TPO) against the pri­mary oxi­da­tion of these refined oils was sig­nif­i­cantly cor­re­lated to their lycopene con­tents,” Noureddine Allouche, one of the researchers involved with the study wrote in the report. Hence, it can be con­cluded that lycopene rich-TPO is endowed with a com­pet­i­tive free rad­i­cal scav­eng­ing capac­ity with that of syn­thetic antiox­i­dants.”

The syn­thetic antiox­i­dants buty­lated hydrox­yanisole (BHA) and buty­lated hydrox­y­toluene (BHT) were com­pared with TPO in the study. Both of these syn­thetic antiox­i­dants have been labeled as human car­cino­gens. BHA is banned in sev­eral European Union (EU) coun­tries, Japan and California, while reg­u­la­tors from the United States and sev­eral European coun­tries allow small amounts BHT in food prod­ucts.

TPO is a nat­u­rally occur­ring antiox­i­dant that cap­tures free rad­i­cals and helps to pre­vent lipid oxi­da­tion in olive oil, while it is being trans­ported and stored.

However, in con­cen­tra­tions of more than 1000 μg/g, the extract’s effec­tive­ness begins to wane after week 11.

TPO and other nat­ural antiox­i­dants have dis­played proox­ida­tive prop­er­ties at high con­cen­tra­tions and under high oxy­gen ten­sion in foods and emul­sions.

The study also found that TPO’s effec­tive­ness at all con­cen­tra­tions decreases, but does not entirely fade after week 19.

TPO com­po­nents and mainly carotenoids, e.g. lycopene, were expected to act as pow­er­ful antiox­i­dants pre­vent­ing the oxida­tive reac­tions occur­ring within [refined olive oils].” Allouche wrote. However, for long stor­age peri­ods, carotenoids may have acted as proox­i­dant agents.”

In spite of this, the study con­cluded that using TPO as a preser­v­a­tive is still prefer­able to the syn­thetic antiox­i­dant alter­na­tives.

TPO extracts from tomato indus­trial byprod­ucts can be used as an effec­tive dietary sta­bi­lizer of [refined olive oil] instead of the syn­thetic preser­v­a­tives, against the oxi­da­tion reac­tions dur­ing long stor­age,” Allouche wrote.

The study, which was funded by the EU, comes at a time of ris­ing pop­u­lar­ity for ole­o­resins on the con­ti­nent. According to the Dutch Center for the Promotion of Imports (CBI), demand for ole­o­resin has increased in many EU and European Free Trade Association coun­tries.

One of the rea­sons for the increase cited by the CBI is the sub­sti­tu­tion of nat­ural ingre­di­ents for syn­thetic ones that is tak­ing place across Europe.

Increasingly health con­scious con­sumers are also look­ing for nat­u­rally pre­served food in the United States, which is already the sec­ond largest importer of olive oil.

More American con­sumers are jump­ing on the free-from’ and seek­ing out more nat­ural or less processed foods,” Judie Bizzozero, a man­ag­ing edi­tor at the Natural Products Insider Magazine, said.

Interestingly, 71 per­cent of free-from’ con­sumers are look­ing for preser­v­a­tive-free claims on food and bev­er­age label, which opens the door for inno­va­tion in the area of nat­ural antiox­i­dants as food preser­v­a­tives.”


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