On the composition of Iranian olive oil

Thermal Behavior Improvement of Fortified Commercial Avocado (Persea americana Mill.) Oil with Maqui (Aristotelia chilensis) Leaf Extracts

Avocado oil is considered a highly prized food due to its nutritional contribution. On the other hand, Aristotelia chilensis (Molina) Stuntz (Elaeocarpaceae), common name "maqui", is an endemic fruit in Chile, well known for its exceptional antioxidant properties. In general, maqui by-products such as leaves are considered as waste. Thus, maqui leaves extracts were used to improve the stability of vegetable oils, particularly avocado oil. Hence, avocado oil was fortified with two extracts (ethyl ether and methanol) obtained of maqui leaves and exposed to 120 °C for 386 h in an oven. The results showed a high content of monounsaturated fatty acids (69.46%, mainly oleic acid), followed by polyunsaturated fatty acids (16.41%, mainly linoleic acid) and finally saturated fatty acids (14.13%). The concentration of the total phenolic compounds in the pure oil, ethyl ether and methanol maqui leaves extracts were 45.8, 83.7, and 4100.9 ppm, respectively. In addition, the antioxidant activity was 5091.6 and 19,452.5 µmol Trolox eq/g for the ethyl ether and methanol extracts, respectively. The secondary degradation compounds showed significant differences between the fortified and non-fortified samples after 144 h and the TG/DTG analysis showed a significant increment of 7 °C in the degradation temperature (Tonset) of avocado oil fortified with the methanol extract when compared to the non-fortified oil and fortified oil with ethyl ether extract. After heating for 336 h, fortified oil with methanol extract reached the limit percentages of polar compounds, while pure oil reached it in a shorter time, i.e., 240 h. Based on the results, avocado oil can be protected with natural additives such as extracts obtained from maqui leaves, leading to an increase in its thermo-oxidative stability.

Influence of composition on the thermal behavior of oils extracted from the seeds of some Romanian grapes

BACKGROUND

The oils obtained from grape seeds are becoming a valuable way of exploiting winery waste and their properties are scrutinized for evaluating the potential usages. We examined the oils extracted with petroleum ether from grape seeds of four varieties of grapes (Cabernet Sauvignon, Feteasca Neagra, Merlot and Pinot Noir) from Romania looking at the influence of the fatty acid profile and of the antioxidants on their thermal behavior.

RESULTS

The fatty acid profiles of the oils were evaluated by ¹ H-NMR spectroscopy, and the oil antioxidant capacity was determined by cupric ion reducing antioxidant capacity (CUPRAC) method. The main fatty acid component in all the oils is linoleic acid (over 70%), which, due to its known health benefits, make the oils of commercial interest. The thermal stability of grape seed oils appears to be mainly influenced by the percentage of polyunsaturated fatty acids in their composition, less polyunsaturated fatty acids making the oils more stable. The antioxidant compounds affect only the initial stage of the decomposition by limiting the formation of hydroperoxides in the allylic positions of the fatty acid chain.

CONCLUSION

Compared to pure samples of glyceryl-unsaturated fatty acids (glyceryl-trioleate, glyceryl-trilinoleate), the grape seed oils exhibit higher thermal stability, due to the presence of antioxidant compounds and to a synergistic action of unsaturated and saturated fatty acids, smaller percentage of the polyunsaturated and higher percentage of the saturated fatty acids enhancing the stability. © 2019 Society of Chemical Industry.

Monitoring Fatty Acid and Sterol Profile of Nizip Yaglik Olive Oil Adulterated by Cotton and Sunflower Oil

In this study virgin olive oil obtained from cv. Nizip Yaglik (NY) was adulterated with different proportions (5 and 10%, v/v) of cotton (CO) and sunflower (SO) oils. Fatty acid and sterol profiles of olive oil were analyzed by using gas chromatography (GC). Also, difference of Equivalent Carbon Number 42 values (ΔECN42) of oil samples were determined by using GC and HPLC. Due to results of fatty acids analysis, the percentage of oleic acid was decreased when CO and SO were added. Palmitic acid was increased over the addition of CO, and decreased with the addition of SO. The ΔECN42 values were increased in adulterated oils. These values showed further increase in adulterated oils with SO. Beta-sitosterols decreased to 91.06 and 88.54% when mixed with 5 and 10% SO, respectively. On the other hand, decline was negligible when mixed with CO. According to principal component analyses (PCA), pure NY and adulterated oils were clearly separated in different parts of screen plot according to fatty acids, triacylglycerol (TAGs) and sterol profile. The outcomes of this first investigation provide valuable information for about the differences of fatty acids, ΔECN42 values and sterol compounds between Turkish olive oil from Nizip Yaglik cv. and its adulteration with cotton and sunflower oil. It was observed that fatty acids are not very effective in detecting adulteration of NY oil, but ΔECN values, sterols and Rmar values can be used to detect adulteration of NY olive oil.