Lignans in Olive Stones Discarded From the Oil Industry. Comparison of Three Extraction Methods Followed by HPLC-Dad-MS/MS and Antioxidant Capacity Determination

Abstract

Lignans are secondary metabolites with diverse chemical structure, and are frequent in food grains. A lignan rich diet have a positive health impact over chronic diseases and protection against certain types of cancer. To enhance the intake of lignans the addition of this compound in processed food could be a solution, so the best approach is to find a source of lignans, especially one that is discarded as waste. In the olive oil production there is a large volume of phytotoxic waste generated, among these is the olive stone (OS), that it is generally burned for fuel. It has been reported the presence of lignans in olive stones extracted with methanol reflux.Three extraction methods for lignans and polyphenolic compounds were assessed: solid-liquid ultrasound assisted extraction with basic hydrolysis, methanolic extraction with Soxhlet, and CO 2 supercritical fluid extraction with methanol as a modifier. The determination of lignan content in OS samples were evaluated by HPLC with a core shell C18 column and the detection was in tandem with DAD and MS/MS. The extracts were also evaluated in their antioxidant capacity with ABTS, CUPRAC and ORAC assays and total polyphenol concentration.The aim of this work is to evaluate different methods to extract lignans from OS discarded from the olive oil industry. The main lignan identified in OS extract was pinoresinol. The SFE method to extract pinoresinol was more efficient than Soxhlet and ultrasound assisted solid liquid extractions, producing a higher amount of pinoresinol in the extract in less time and with less amount of co-extracted interferents. The extract produced with Soxhlet had a higher antioxidant capacity.

The use of ultrasound in the South Cone region. Advances in organic and inorganic synthesis and in analytical methods

“…sonicated (UP) in three 1 min pulses at 65 Hz to homogenize, to macerate for 30 min, a second round of us treatment. Shortened the extraction time [140] Phenolic compounds (Cafeic acid, vanillic acid, quercetin 3-β- d-glucoside, p-coumaric acid, vanillin, trans -ferulic acid, myricetin, benzoic acid, quercetin and kaempferol) Quinoa (Chenopodium quinoa Will) seeds UAE ES: Ethyl Acetate (1:10 ratio) 0.8 g powdered quinoa sample, 8.0 mL of solvent, sonicated (USB) 40 kHz, 40 W L −1 (200 W) for 10 min at 39 °C Diminished up to 12-fold the extraction time [141] Polyphenols Chilean bee pollen UAE ES: Methanol 1 g pollen sample, 7.5 mL of solvent, sonicated for 30 min at 50 Hz. Smaller amounts of sample for the extraction Reduced the volume of solvents Shortened the extraction times [142] Polyphenols Avocado peel UAE and MAE ES: Ethanol/Water 1 g of avocado peel powder, 25 mL of solvent, sonicated (USB) 40 kHz and 90 W for 15 min and 95.1 s of microwave ------ [143] Fatty acid composition, total phenolic content and antioxidant capacity Seed oils from Pica oasis D-UAE/I-UAE ES: n-hexane 3 g of each ground powder, 50 mL of solvent in ice-bath monitoring the temperature at 25 °C, sonicated (UP) 30 kHz and 100 W for 90 min.…”

“…Undoubtedly, the most explored topic throughout the South Cone region is the extraction of polyphenols assisted by ultrasound. Table 1 shows 29 works from Chile [140] , [141] , [142] , [143] , [144] , [145] , [146] , Uruguay [147] , [148] , Southern Brazil [149] , [150] , [151] , [152] , [153] , [154] , [155] , [156] , [157] , [158] , [159] and Argentina [160] , [161] , [162] , [163] , [164] , [165] , [166] , [167] , [168] , [169] reported during the last 10 years The most important aspects highlighted were that ultrasound helped and improved extraction procedures, reduced operational time, enhanced extraction yields and made it greener in comparison to traditional extraction methods, according to others publication [170] . Nevertheless, the use of ultrasound did not always improve the performance of an analytical procedure or showed an important benefit in an extraction process [140] , [160] , [171] , [172] , [173] .…”

Towards the Integral Valorization of Olive Pomace‐Derived Biomasses through Biorefinery Strategies

“…Phenolic compounds have been characterized in olive pomace [49,125], pa ˆte ´ [53,87], exhausted olive pomace [56], olive stone [126], and residual pulp [67]. Currently, there is no general procedure for the extraction of phenolic compounds.…”

“…Maceration (4 % w/v, 24 h, 4 °C) 80 % methanol Nuezhenide (3.3 mg g -1 c) ) [129] Soxhlet extraction (50 % w/v, 12-24 h) Hexane (12 h); methanol (24 h) Pinoresinol (2.1 mg g -1 a) ) [126] Probe-UAE (10 % w/v, 30 min, 65 Hz) 80 % methanol + 1 N NaOH Pinoresinol (4.0 mg g -1 a) ) SFE (10 % w/v, 80 °C, 40 MPa) CO 2 Pinoresinol (1.0 mg g -1 a) )…”

Dietary Lignans: Definition, Description and Research Trends in Databases Development

“…Nowadays, attention is paid to less common species and agro-industrial side streams [89,90,91], in order to continually explore new sources of lignans.…”