Impact of the malaxation temperature on the phenolic profile of cv. Cobrançosa olive oils and assessment of the related health claim

Abstract

Phenolic compounds contribute to the bioactive properties of olive oil. However, olive oils can only support a health claim concerning the protection against oxidative stress depending on the polyphenolic concentration, requiring effective measures during extraction to preserve/enhance their concentrations. The effect of the malaxation temperature (22, 28 and 34°C) on the phenolic profile was studied for industrially extracted cv. Cobrançosa oils. Higher malaxation temperatures decreased the contents of the majority of the chromatographically detected compounds (P < 0.05, one-way ANOVA), enabling oils' differentiation. This decreasing trend was observed for hydroxytyrosol and tyrosol bound forms, determinant for the health claim, which were also negatively affected by temperature, despite revealing that all the industrially extracted oils tested supported the health claim. The observed constant free to bound forms ratio showed that the temperature range tested had a minor effect on bound-forms hydrolysis, being both free and bound forms equally affected by temperature.

Optimizing the Malaxation Conditions to Produce an Arbequina EVOO with High Content of Bioactive Compounds

“…Indeed, β values of the total secoiridoids were −8.00 and −18.25 when the temperature was increased to 25 and 30 °C, respectively, and −8.15 when malaxation was extended from 30 to 45 min ( Table 3 ). Studies show that secoiridoids are the phenolic group most affected by oxidative degradation [ 27 ] and temperature [ 6 ]. A depletion of secoiridoids with malaxation time and temperature has been attributed to the action of oxidoreductases [ 4 , 14 , 33 ].…”

“…Results in the literature are contradictory. Marx, Casal et al [ 6 ] observed an increase in flavones with temperature, but no trend for phenolic alcohols and acids, whereas other studies found no changes in the flavone content [ 14 , 33 ]. Boselli et al [ 31 ] reported that phenolic acids and alcohols were not significantly affected by malaxation temperature and time.…”

“…Thus, malaxation of the olive paste may be viewed not only as an extraction process to achieve satisfactory yields but also as a crucial production step whose modification may enhance both the quality and quantitative chemical composition of the EVOO [ 1 ]. The influence of malaxation time [ 3 , 4 , 5 ] and temperature [ 5 , 6 , 7 , 8 ] on the overall quality of EVOO has been widely investigated but with divergent results.…”

Impact of incorporating olive leaves during the industrial extraction of cv. Arbequina oils on the physicochemical–sensory quality and health claim fulfillment

“…The phenolic profile of the olive oil samples was established following the guidelines of the International Olive Council (IOC) [30], with minor modifications as previously described [9]. Methanolic extracts (80% v/v), from duplicate extractions of each sample, were injected in a HPLC-DAD system (Jasco, Japan) comprising a data transmitter (LC-NetII/ADC), two integrated pumps (PU-4180), an auto-sampler (AS-4050), a column oven (ECOM Eco2000, Czech Republic), and the DAD (MD-4010).…”

“…Several strategies have been proposed to enhance the phenolics contents of olive oils, namely the optimization of the extraction conditions (e.g., malaxation/extraction time-temperature conditions during malaxation [8][9][10]). Another trend focused on the use of natural sources such as olive oil by-products, namely olive leaves [11].…”