SUSTAINABLE AND ORGANIC MANAGEMENT OF SELECTED FRUITS AND VEGETABLES
Title: Quantitative assessment of different phenolic compounds in Texas olive oils versus foreign oils
Submitted to: Journal of Agricultural Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 19, 2010
Publication Date: July 1, 2010
Citation: Malik, N.S., Perez, J.L. 2010. Quantitative assessment of different phenolic compounds in Texas olive oils versus foreign oils. Journal of Agricultural Science and Technology. ISSN 1939-1250,USA.
Interpretive Summary: For the first time in the history of Texas, the commercial Texas olive oil was pressed from the olives grown at Texas Olive Ranch in Carrizo Springs Texas in 2007. Since then, several thousand new olive trees are being planted throughout central and coastal Texas. For successful long term commercial viability of these farms it is important to study the quality of olive oil produced in Texas to determine if it meets the standards of foreign olive oils in the market place, and if need be, to try to find ways to improve its quality. The presence and quantity of different health benefiting polyphenols in olive oil is one important factor determining the quality of olive oil. This is because polyphenols have been shown to have many health benefiting effects. For example, they been shown to prevent certain types of cancer, reduce hypertension, reduce cardiovascular problems, and improve diabetic condition. The presence of different types of polyphenols and their quantity in olive oils depends on a number of factors such as packaging techniques, storage time, oil processing methods, harvesting and agronomic techniques, cultivars, and climatic and geographical location. Olives in Texas are harvested in late August or early September, when temperatures are quite high (>37°C ), while in most other olive growing areas the harvesting takes place in late October or early November. This distinction in harvest time, and accompanied differences in ambient temperatures, prompted us to investigate quantitative differences in total polyphenols, and in different types of polyphenols, in Texas oil versus several other oils in the market. In addition to phenolic content, we also measured free acidity and UV absorption that are generally determined for overall assessment of the grade of oil such as whether or not it can be labeled “Extra Virgin”. Results of this study show that Texas oil is of superior quality.
Texas Olive Ranch is the first one to produce olive oil and has the sole product in the Texas market place; several growers are now starting to cultivate olive at various sites in Texas. The quality of olive oil produced and pressed in Texas has never been explored. This study was conducted to investigate the quality of the first commercially produced olive oil to assess it competitiveness in the market place. Quantities of total polyphenols contents, as well as those of oleuropein, tyrosol, hydroxytyrosol, and pinoresinol were measured in Texas olive oil along with olive oils from California, Italy, Spain, Greece, Argentina, and Tunisia. The commercial Texas olive oil contained 72% higher amounts of total phenols compared to California-1 oil (which had lowest amounts) and 27% higher than Italian-2 oil (which was highest compared to all oils except Texas commercial oil). Similarly, the commercial Texas olive oil also contained higher amounts of oleuropein, hydroxytyrosol, and pinoresinol compared to the other oils tested. Thus based on the quantitative presence of health benefiting polyphenols, the first commercially produced Texas olive oil has some advantage over the other oils sold in Texas. The free acidity in the commercial Texas oil was 0.35%, based on oleic acid, and its coefficient at K270 UV absorption was <0.166. These numbers affirm that the Texas olive sold in the market is “Extra Virgin”.