Improvement of oleuropein extractability by optimising steam blanching process as pre-treatment of olive leaf extraction via response surface methodology

Impact of steam, hot water blanching and UV-C irradiation as pre-treatments on extraction of oleuropein and related biophenols from olive leaves (OLs), was investigated. Moreover, particle size effect of olive leaves and steam blanching duration were selected as independent variables to optimise steam blanching process in terms of oleuropein content (OC) and antioxidant activity (AC) of ethanolic extracts, by using response surface methodology. Optimum conditions for OC and AC were 10 min steam blanching of 20–11 and 3–1 mm olive leaf fraction, respectively. Depending on the extraction procedure, at optimum conditions of steaming the results indicate that steam blanching of OL prior to extraction can significantly increase oleuropein yield from 25 to 35 times compared to non-steam blanched sample, whereas the antioxidant activity increased from 4 to 13 times. No significant UV-C effect was observed in OC and AC, while hot water blanched samples showed significantly higher oleuropein yields and antioxidant activity compared to untreated samples.     

Short communication: Determination of lactoferrin in Feta cheese whey with reversed-phase high-performance liquid chromatography

In the current paper, a method is introduced to determine lactoferrin in sweet whey using reversed-phase HPLC without any pretreatment of the samples or use of a separation technique. As a starting point, the most common HPLC protocols for acid whey, which included pretreatment of the whey along with a sodium dodecyl sulfate-PAGE step, were tested. By skipping the pretreatment and the separation steps while altering the gradient profile, different chromatographs were obtained that proved to be equally efficient to determine lactoferrin. For this novel 1-step reversed-phase HPLC method, repeatability was very high over a wide range of concentrations (1.88% intraday to 5.89% interday). The limit of detection was 35.46 μg/mL [signal:noise ratio (S/N) = 3], whereas the limit of quantification was 50.86 μg/mL (S/N = 10). Omitting the pretreatment step caused a degradation of the column’s lifetime (to approximately 2,000 samples). As a result, the lactoferrin elution time changed, but neither the accuracy nor the separation ability of the method was significantly influenced. We observed that this degradation could be easily avoided or detained by centrifuging the samples to remove fat or by extensive cleaning of the column after every 5 samples.     

Recovery of Natural Antioxidants from Olive Mill Wastewater Using Genapol-X080

The possibility of applying cloud point extraction (CPE) using Genapol X-080 as surfactant for the separation of phenolic compounds from olive mill wastewater was examined. The ability of the surfactant to recover individual and mixtures of polyphenols and tocopherols in various concentrations from aqueous solutions was tested before its application for the recovery of phenols from olive mill wastewater. Many of the examined individual polyphenols were recovered at high percentage. Especially, in the case of Luteolin, low surfactant concentrations were sufficient for quantitative removal. The recovery appeared proportional to the surfactant concentration. The complete recovery of tocopherols was also possible. Total phenol recovery by simple and successive CPE of olive mill wastewater with various concentrations (2, 5 and 20%, v/v) of Genapol X-080 was up to 89.5%.     

Diketopiperazines in wines

This study describes the identification of cyclic dipeptides known as diketopiperazines in red, white and sparkling wines from Greek market. Diketopiperazines have been isolated from bottled wines after liquid–liquid extraction and identified using gas chromatography coupled with mass spectrometry. Cyclo (Leu–Leu), cyclo (Leu–Pro), cyclo (Phe–Pro), cyclo (Leu–Phe), cyclo (Val–Phe) and cyclo (Ala–Phe) were the six diketopiperazines that were identified in bottled wines made from local and international plant varieties. The varieties tested were agiorgitiko, malagouzia, xinomauro, roditis, muscat, athiri, mandilari, vidiano, cabernet sauvignon, syrah and merlot. The cyclo (Leu–Pro) was identified in eighteen bottled wines while the cyclo (Phe–Pro), cyclo (Leu–Phe), cyclo (Leu–Leu), cyclo (Ala–Phe) and cyclo (Val–Phe) were identified in a small number of samples. The analysis of some wine samples showed that the values of cyclo (Leu–Pro) ranged from 0.1 to 1?mg/L. These cyclic dipeptides have biological properties and may contribute to the beneficial health effects of wine.