Effects of production conditions and some additives in olive oil extraction on quality characteristics of the oil

In the olive oil industry, the technological preferences of the production facility affect the quality of the final product due to the biochemical activities that take place in the olives being processed during the process. It is well known that phenolic compounds are directly related to the nutritional benefits and organoleptic properties of extra virgin olive oil. The transition of hydrophilic phenols to extra virgin olive oil is related to the initial phenolic glycoside content of the olive fruit and the activity of hydrolytic and oxidative enzymes on these glycosides during the oil extraction process. The endogenous β-glucosidase enzyme that hydrolyzes phenolic glycosides and oxidoreductases such as polyphenol oxidase (PPO) and peroxidase (POD) are the main biochemical factors affecting the phenolic content of extra virgin olive oil. In the study in question, the phenolic profile of the oil produced was evaluated by inhibiting the activity of PPO and POD enzymes during olive oil extraction. In the study, firstly, the optimum crushing rate was determined and oxalic acid (OA), L-cysteine (L-cys), ascorbic acid (AA) and magnesium chloride (MgCl2) were added during the malaxation stage at the rates determined by the response surface methodology (YYM, response surface methodology RSM) method. The effects on some physical and chemical properties of the olive oil obtained as a result of these substances added to the olive paste were examined by comparing them with the traditional application. In addition, the nutritional and sensory quality of olive oil was also investigated. 20 samples were obtained by adding inhibitory additives at the rates determined during the malaxation stage to the olives crushed at the optimum crushing rate (1000 rpm). With the addition of these substances, an increase was observed in the oil yield and free fatty acid values (excluding 1% L-cys + 1% MgCl2 and 0.5% OA + 0.5% L-cis + 0.5% AA + 0.5% MgCl2) of the samples. While peroxide values, K232 and K270 values were mostly decreased, oxidative stability values were mostly increased. The decrease in oxidative stability with the increase in the peroxide and K232 values was evident in the sample using 2% MgCl2. It was determined that the total phenolic substance and DPPH values of olive oils increased. While increases were observed in the antioxidant activity value determined by the β-carotene bleaching method, when 2% MgCl2 and 2% AA were used, increases were determined compared to the use of other additives used only. In terms of the total phenolic content of olive pastes, the highest values were found in the sample to which 2% AA was added, and the lowest result was found in the control sample. While inhibitory additives caused an increase in DPPH values in olive pastes, a decrease in β-carotene bleaching value was detected. Among treatments, POD, PPO and β-glucosidase enzyme activity ranged between 5.26-100 U/gr, 33.08-100 U/gr and 138.78-218.11 U/gr, respectively.