04-Gomez:gomez 9-06-2011 16:39 Pagina 22 L AVORO ORIGINALE A.M. G ÓMEZ -C ARAVACA 1, 2 , Qualitative phenolic profile (HPLC- L. C ERRETANI 1, DAD-MS) from olive oil mill waste A. S EGURA -C ARRETERO 2, waters at different states of storage and A. F ERNÁNDEZ -G UTIÉRREZ 2, G. L ERCKER 1, evaluation of hydrolysis process as a T. G ALLINA TOSCHI 1 pretreatment to recover their antioxidants PROGRESS IN NUTRITION Summary VOL . 13 , N. 1, 22-30, 2011 Olive oil mill waste water (OOMWW) represents a waste that it is gene - rated during the extraction process of olive oil from olives and it is an im - TITOLO portant environmental problem because of the huge volume generated in Profilo fenolico qualitativo the mills. Nevertheless, it is highlighted in literature the high concentra - (HPLC-DAD-MS) di acque tion of antioxidants, especially phenolic compounds, in the OOMWW. reflue di vegetazione Principally, the qualitative phenolic profiles of OOMWW differ depen - dell’industria olearia a diversi ding on the technological process of production of olive oil and the time stadi di conservazione e of storage. The aim of this work was to compare qualitatively the pheno - valutazione dell’idrolisi quale lic profile of OOMWW by HPLC-DAD-MS. Glucosilated secoiridoids pretrattamento per il recupero as oleuropein and ligstroside, their aglycon derivatives and simple phenols degli antiossidanti were the principal compounds found in these matrixes. Furthermore, dif - ferent hydrolysis reactions have been studied for the phenolic fraction in the oleuropein standard as well as in the OOMWW samples. These steps KEY WORDS Olive, olive oil mill waste waters, have been evaluated as pretreatment for the selection and a possible sub - antioxidants, phenols sequent recovery of most interesting phenolic compounds as hydroxytyro - sol that has been proved to possess an important antioxidant activity PAROLE CHIAVE Oliva, acque reflue, antiossidanti, Riassunto fenoli Le acque reflue di vegetazione (AV) dell’industria olearia rappresentano un rifiuto generato dal processo di estrazione dell’olio dalle olive e pertan - to sono un problema ambientale per l’elevato volume generato presso gli impianti di produzione. Tuttavia, è nota dalla letteratura, l’elevata concen - 1 Department of Analytical trazione nelle AV di composti antiossidanti a struttura fenolica. I profili Chemistry, Faculty of Sciences, fenolici qualitativi delle AV differiscono principalmente in funzione delle University of Granada, condizioni di produzione e delle modalità e tempi di conservazione. Que - C/Fuentenueva s/n, E-18071 sto lavoro ha l’obiettivo di confrontare qualitativamente i profili fenolici Granada, Spain delle AV mediante analisi HPLC-DAD-MS. Nelle acque reflue di vege - 2 Department of Food Science, tazione appena prodotte sono state ritrovate principalmente secoiridoidi University of Bologna, Piazza glicosilati (oleuropeina e ligstroside) nonché le loro forme derivate aglico - Goidanich 60, I-47521 Cesena (FC), Italy niche e basse concentrazioni di fenoli semplici. Allo stesso tempo sullo standard puro di oleuropeina e sugli stessi campioni di AV sono state in - Indirizzo per la corrispondenza: dagate diverse modalità di idrolisi della frazione fenolica. Tale operazione Dr. A.M. Gómez-Caravaca è stata valutata come pretrattamento per la selezione e l’eventuale succes - Tel. +390547338117 E-mail: [email protected] or sivo recupero dei composti fenolici di maggiore interesse come [email protected] l’idrossitirosolo al quale è riconosciuta una elevata attività antiossidante. 22 04-Gomez:gomez 9-06-2011 16:39 Pagina 23 PROGRESS IN NUTRITION 1/2011 Introduction tioxidant activity makes them in - hydrolysis reactions were studied teresting for the food, pharmaceu - using oleuropein as standard and Olive oil mill waste water tical and cosmetic industry. Be - better results were apply to the (OOMWW) represents the main cause of that, to reutilize them, OOMWW phenolic samples. environmental problem in the oli - their extraction from OOMWW The aim of this treatment was to ve oil production process. 100 kg is a very important objective that evaluate the hydrolysis and to use of olives are necessary to produce also helps to diminish the volume it as a pretreatment for the selec - just 10-20 kg of olive oil, but it re - of olive oil industry by-products. tion and a possible subsequent re - sults in a huge amount of Many phenolic compounds have covery of most interesting pheno - OOMWW (40-100 kg been identified in OOMWW, al - lic compounds as hydroxytyrosol OOMWW) (1) that depends on though the phenolic fraction is very (HYTY) that has been proved to the olive cultivar, ripening index, different from that of olive fruit. possess an important antioxidant time of storage and quantity of OOMWW presents a high con - activity. water added during the olive oil centration of secoiridoids derivati - extraction process. ves, such as hydroxytyrosol, and the The treatment of OOMWW is dialdehydic form of decarboxy - Material and methods extremely difficult due to its large methyl oleuropein aglycone (1). volume and the high concentra - The profile of OOMWW is cha - Samples tion of organic matter (BOD va - racterized by a great complexity (9). ries between 15000 and 50000 A wide variety of methods have Three different OOMWWs that mg/L and COD can reach values been suggested for the treatment vary on the state of storage and the of around 250 g/L). Its principal of OOMWW, such as compo - ripeness of the olives were studied: components are polysaccharides, sting (10), anaerobic digestion OOMWW just produced from sugars, polyphenols, polyalcohols, (11), aerobic treatment (12), mi - fresh olives (AV1), OOMWW proteins,organic acids, and oil (2). xing with municipal wastewater just produced from very ripe olives Moreover, OOMWW contains (13), direct land application (irri - (AV2) and OOMWW from very considerable amounts of suspen - gation) (14), chemical oxidation in ripe olives and storage during three ded solids that may reach up to combination with biological treat - months (AV3). 190 g/L. Despite that, one of the ment (15) or adsorption (2), and major factors of the environmental even the utilization of fungi spe - Extraction of polar phenolic fraction problems caused by the cies (16). However, these metho - OOMWW is the high concentra - dologies had given rise to decom - Phenolic compounds were extrac - tion of polyphenols, because they position or destruction of the phe - ted from OOMWW by a liquid- present phytotoxicity (3, 4), toxi - nolic compounds contained on it liquid extraction method. 10 mL city against aquatic organisms (5), and not to their exploitation. of sample were centrifuged at or suppression of soil microorga - In this work the phenolic profile of 3500 rpm during 10 min. After nisms (6) and are difficult to de - three different OOMWWs concer - that, they were washed twice with compose (7,8). Although polyphe - ning their state of storage were stu - 15 mL of hexane in order to re - nols constitute an important envi - died by HPLC-DAD-MS (TOF, move lipids. The extraction was ronmental problem, their high an - time of flight). After that, different carried out with 20 mL of ethyl 23 04-Gomez:gomez 9-06-2011 16:39 Pagina 24 VOLUME 13 acetate for three times. Finally, the HPLC-DAD-MS(TOF) equip - USA). Parameters for analysis we - ethyl acetate fraction was evapora - ped with a reverse phase C18 Lu - re set using negative ion mode ted under vacuum and then the naTM column according to Ro - with spectra acquired over a mass dry residue was redissolved in 1 tondi et al. (17). Phenolic com - range from m/z 50–1000. The op - mL MeOH/H 2O (50/50). pounds were tentatively identified timum values of the ESI-MS based on their UV-vis and mass parameters were: capillary voltage, Acid and basic hydrolysis spectra obtained by HPLC- +4.5 kV; drying gas temperature, DAD-MS(TOF). 190°C; drying gas flow, 9 L/min; Four different kind of hydrolyses The HPLC system was coupled to and nebulizing gas pressure, 2 bar. were studied: strong and weak acid a Bruker Daltonik microTOF External calibration was perfor - hydrolyses, basic hydrolysis and mass spectrometer (Bruker Dalto - med using a sodium formiate so - enzymatic hydrolysis. nik, Bremen, Germany) using an lution injected at the beginning of Three modalities of strong acid orthogonal electrospray interface the run and all the spectra were hydrolyses were performed: 0.5 M (ESI) (model G1607A from Agi - calibrated prior to the polyphenol HCl/H 2SO4 2 h stirring at 80ºC; lent Technologies, Palo Alto, CA, identification. 1 M HCl/H 2SO4 2 h stirring and 1 M HCl/H 2SO4 22 min ultra - Figura 1 - Decrease of oleuropein after hydrolysis Vs time of hydrolysis. sounds. a) hydrolysis with HCl, b) hydrolysis with citric acid. The weak acid hydrolysis was car - ried out using a saturated solution of citric acid in MeOH/H 2O du - ring 6 h at 80ºC. The basic hydrolysis was carried out in the following way: 2 M NaOH/KOH during 4h stirring, after that it was acidified with HCl until pH=1. Finally, the sam - ple was extracted with diethyl ether/ethyl acetate. To perform the enzymatic hydroly - sis 1 mg oleuropein (Ol) in sodium acetate buffer 0.1 M, pH=5.5 and 5 mg β-glucosidase (from almonds) ≥ 6 units/mg were heated at 37ºC in a water bath during 1 h. Chromatographic procedure Determination of the phenolic fraction was performed using an 24 04-Gomez:gomez 9-06-2011 16:39 Pagina 25 PROGRESS IN NUTRITION 1/2011 The accurate mass data for the Figura 2 - Changes in the concentration of oleuropein and hydroxytyrosol du - molecular ions were processed ring the HCl hydrolysis at different times. using the software Data Analysis 3.4 (Bruker Daltonik), which pro - vided a list of possible elemental formulas by using the Generate Molecular Formula TM editor.