Extraction, benefits and valorization of olive polyphenols

Synergistic protective effects of 3,4-dihydroxyphenylglycol and hydroxytyrosol in male rats against induced heat stress-induced reproduction damage

Testicular heat stress disrupts spermiogenesis and damages testicular tissue. The study aims to assess 3,4-dihydroxyphenylglycol (DHPG) and hydroxytyrosol (HT) from olive oil as antioxidants to reduce heat-induced testicular damage. Seven groups of 35 male rats were used. Group I got normal saline. Group 2 had HS (43 °C for 20 min/day) and normal saline for 60 days. Groups 3-7 had HS and DHPG/HT doses (0.5 mg/kg DHPG, 1 mg/kg DHPG, 5 mg/kg HT, 0.5 mg/kg DHPG + 5 mg/kg HT, and 1 mg/kg DHPG + 5 mg/kg HT). The evaluation included tests on testicular tissue, sperm quality, oxidative status, gene activity, and fertility after 60 days. After DHPG and HT treatment, sperm motility, viability, and plasma membrane functionality, as well as levels of total antioxidant capacity (TAC), glutathione peroxidase (GPx), superoxide dismutase (SOD), and catalase (CAT), and Bcl-2 gene expression, and in vivo fertility indexes increased. Meanwhile, abnormal morphology and DNA damage decreased, along with levels of glutathione (GSH), nitric oxide (NO), and malondialdehyde (MDA), and Bax, caspase-3, and caspase-9 gene expression, compared to the HS group. The study found that DHPG and HT have a more substantial synergistic effect when used together, improving reproductive health.

The Effects of Encapsulation on the In Vitro Anti-Clostridial Activity of Olive Mill Wastewater Polyphenolic Extracts: A Promising Strategy to Limit Microbial Growth in Food Systems

Despite the technologies applied to food production, microbial contamination and chemical deterioration are still matters of great concern. In order to limit these phenomena, new natural approaches should be applied. In this context, the present study aimed to assess the antioxidant and anti-Clostridial effects of two different polyphenolic extracts derived from olive mill vegetation water, one liquid (LE) and one encapsulated (EE). The extracts have been preliminary characterized using Liquid Chromatography Quadrupole Time-Of Flight spectrometry. The Oxygen Radical Absorbance Capacity method was used to determine the antioxidant capacity, registering a higher value for EE compared to that for LE (3256 ± 85 and 2446 ± 13 µgTE/g, respectively). The antibacterial activity against C. perfringens, C. botulinum and C. difficile was studied by the agar well diffusion method, MIC and MBC determination and a time-kill test. The results confirm that EE and LE are able to limit microbial growth, albeit with minor effects when the phenolic compounds are encapsulated. Further studies are needed to evaluate the possible application of these extracts in food systems.

Preventing Microbial Growth in Game Meat by Applying Polyphenolic Extracts from Olive Mill Vegetation Water

We studied the efficacy of different formulations of polyphenol extracts (mainly containing hydroxytyrosol and tyrosol) from olive mill vegetation water on the microflora on the surfaces of game meat cuts with high or low initial bacterial loads. Meat with a high microbial load (>5 Log cfu/g; mean value = 6.83 ± 0.45 standard deviation) was immersed for 10 or 60 sec into 25% and 10% solutions of microencapsulated freeze-dried and non-encapsulated polyphenolic extracts. Aerobic colony, Enterobacteriaceae, Pseudomonas spp., and lactic acid bacteria counts were determined on treated samples compared to controls after 7 days of storage (in vacuum-packed conditions at +3 °C). Significant differences were registered only for aerobic colony count for a 10% liquid extract treatment (0.64 log reduction). In contrast, the dipping or immersion of game meat with low initial microbial loads (<5 Log cfu/g; mean value = 3.58 ± 0.72 standard deviation) in 10% solutions of the polyphenol extracts effectuated significant reductions in all bacteria counts (p < 0.002) at 7 and 14 days of storage for different extracts, independently from the application methods. The use of the extracts to inhibit bacterial growth in game meat should only be considered if a good hygienic baseline is guaranteed.

Up-Cycling of Olea europaea L. Ancient Cultivars Side Products: Study of a Combined Cosmetic-Food Supplement Treatment Based on Leaves and Olive Mill Wastewater Extracts

In recent years, a reversal of the global economic framework has been taking place: from the linear model, there has been a gradual transition to a circular model where by-products from the agri-food industry are taken and transformed into value products (upcycling) rather than being disposed of. Olive tree pruning represents an important biomass currently used for combustion; however, the leaf part of the olive tree is rich in phenolic substances, including hydroxytyrosol. Mill wastewater is also discarded, but it still contains high amounts of hydroxytyrosol. In this study, cosmetic and food supplement formulations were prepared using biophenols extracted from leaves and wastewater and were tested in a placebo-controlled study on healthy volunteers using a combined cosmetic and food supplement treatment. A significant improvement in skin health indicators (collagen density, elasticity, etc.) and a 17% improvement against Photo-induced Irritative Stimulus was observed.

Intensification of Biophenols Extraction Yield from Olive Pomace Using Innovative Green Technologies

Olive pomace is the main by-product generated by the olive oil production process. Although toxic to the environment, olive pomace is an important source of natural antioxidants due to its high content of phenolic compounds. The aim of the current study is to maximize the extraction yields of the main phenolic compounds present in olive pomace using innovative green technologies. For this purpose, the present work is divided into two parts. The first part is based on a solubility study of targeted phenolic compounds in various ethanol/water ratios at two different temperatures (20 °C and 50 °C). A computational prediction using COSMO-RS software was applied for the calculation of eventual solubility, which was subsequently confirmed by practical experiments. The determination of the optimal extraction conditions of solvent ratio (EtOH/H2O) (60:40 v/v) and temperature (50 °C) led to the second part of the work, which concerns the intensification of extraction yields. Furthermore, various green extractions using innovative technologies, including accelerated solvent extraction (ASE), ultrasound with its both system (probe (UAE-P) and bath (UAE-B)), bead milling (BM) and microwave (MAE), were carried out and then compared to conventional maceration (CM). Results showed that ASE was the most effective method for extracting phenolic compounds from dried olive pomace powder (5.3 milligrams of tyrosol equivalent (TE) per gram of dried olive pomace powder (DOP)) compared to CM (3.8 mg TE/g DOP).

Development of a Chemically Modified Sensor Based on a Pentapeptide and Its Application for Sensitive Detection of Verbascoside in Extra Virgin Olive Oil

In addition to their antioxidant and antimicrobial action in functional foods, beverages, and in some dermato-cosmetic products, olive phenolic compounds are also recognized for their role in the prevention of diabetes and inflammation, treatment of heart disease and, consequently, of the numerous chronic diseases mediated by the free radicals. In recent years, attention has increased, in particular, regarding one of the most important compound in extra virgin olive oil (EVOO) having glycosidic structure, namely verbocoside, due to the existence in the literature of numerous studies demonstrating its remarkable contribution to the prophylaxis and treatment of various disorders of the human body. The purpose of this study was the qualitative and quantitative determination of verbascoside in commercial EVOOs from different regions by means of a newly developed sensor based on a screen-printed carbon electrode (SPCE) modified with graphene oxide (GPHOX), on the surface of which a pentapeptide was immobilized by means of glutaraldehyde as cross-linking agent. The modified electrode surface was investigated using both Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) methods. This newly developed sensor has shown a high sensibility compared to the unmodified electrode, a low detection limit (LOD) of up to 9.38 × 10^-8 M, and a wide linearity range between 0.1 µM and 10.55 µM. The applicability of the modified sensor was confirmed by detecting verbascoside in ten different EVOOs samples using the cyclic voltammetry (CV) method, with very good results. The validation of the electroanalytical method was performed by using the standard addition method with very good recoveries in the range of 97.48-103.77%.

Valorization of olive processing by-products via drying technologies: a case study on the recovery of bioactive phenolic compounds from olive leaves, pomace, and wastewater

Olive by-products are rich sources of phenolic compounds and their valorization is a favorable approach in line with sustainable development goals of the United Nations (UN) organization to promote well-being and production of healthier products; also, to deal with the environmental and economic subjects resulting in more profitability in the olive oil industry. The production of value-added ingredients from these by-products is not extensively exploited on the industrial scale. Drying is a critical pretreatment before extraction that can have a direct impact on the recovery and yield of the available bioactive compounds in olive by-products. In order to produce more stable and high quality phenolic products, encapsulation using spray and freeze drying is used. In this study, the effect of the drying process before and after extraction of bioactive compounds from olive by-products as a valuable source of phenolic compounds is reviewed. In addition, fortification using these ingredients and their incorporation in food formulations is also investigated.

Exploitation of virgin olive oil by-products (Olea europaea L.): phenolic and volatile compounds transformations phenomena in fresh two-phase olive pomace ('alperujo') under different storage conditions

BACKGROUND

Much effort has recently been spent for re-using virgin olive oil by-products as nutraceutical ingredients for human diet thanks to their richness in bioactive phenols, but their management is not easy for producers. We aimed to provide useful information for a better management of fresh olive pomace before drying, by studying the phenolic and volatile compounds transformations phenomena of fresh olive pomace stored under different conditions planned to simulate controlled and uncontrolled temperature conditions in olive oil mills.

RESULTS

The evolution of the phenolic and volatile compounds was studied by high-performance liquid chromatography-diode array detector mass spectrometry (HPLC-DAD-MS) and headspace solid-phase microextraction gas chromatography-mass spectrometry (HS-SPME-GC-MS). The phenolic profile varied rapidly during storage: the verbascoside content decreased about 70% after 17 days even at 4 °C, while the content of simple phenols such as hydroxytyrosol and caffeic acid increased over time. The low temperature was able to slow down these phenomena. A total of 94 volatile organic compounds (VOCs) were detected in the fresh olive pomace, with a prevalence of lipoxygenase (LOX) VOCs (78%), mainly aldehydes (19 490.9 μg kg^-1 ) despite the higher number of alcohols. A decrease in LOX volatiles and a quick development of the ones linked to off-flavors (carboxylic acids, alcohols, acetates) were observed, in particular after 4 days of storage at room temperature. Only storage at 4 °C allowed these phenomena to be slowed down.

CONCLUSION

To preserve the natural phenolic phytocomplex of fresh olive pomace before drying and to avoid off-flavors development, storage in open containers must be avoided and a short storage in cold rooms (7-10 days) is to be preferred. © 2021 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

The antiinflammatory and antifibrotic effect of olive phenols and Lactiplantibacillus plantarum IMC513 in dextran sodium sulfate-induced chronic colitis

OBJECTIVES

After a chronic intestinal injury, several intestinal cells switch their phenotype to activated myofibroblasts, which in turn release an abnormal amount of extracellular matrix proteins, leading to the onset of the fibrotic process. To date, no resolutive pharmacological treatments are available, and the identification of new therapeutic approaches represents a crucial goal to achieve. The onset, maintenance, and progression of inflammatory bowel disease are related to abnormal intestinal immune responses to environmental factors, including diet and intestinal microflora components. This study aimed to evaluate the potential antiinflammatory and antifibrotic effect of a biologically debittered olive cream and its probiotic oral administration in an experimental model of dextran sodium sulfate (DSS)-induced chronic colitis.

METHODS

Chronic colitis was induced in mice by three cycles of oral administration of 2.5% DSS (5 d of DSS followed by 7 d of tap water). Mice were randomly divided into five groups: 10 control mice fed with standard diet (SD), 20 mice receiving SD and DSS (SD+DSS), 20 mice receiving an enriched diet (ED) with olive cream and DSS (ED+DSS), 20 mice receiving SD plus probiotics (PB; Lactiplantibacillus plantarum IMC513) and DSS (SD+PB+DSS), and 20 mice receiving ED plus PB and DSS (ED+ PB+DSS). Clinical features and large bowel macroscopic, histologic, and immunohistochemical findings were evaluated.

RESULTS

The simultaneous administration of ED and PB induced a significant reduction in macroscopic and microscopic colitis scores compared with the other DSS-treated groups. In addition, ED and PB led to a significant decrease in the expression of inflammatory cytokines and profibrotic molecules.

CONCLUSIONS

The concomitant oral administration of a diet enriched with biologically debittered olive cream and a specific probiotic strain (Lactiplantibacillus plantarum IMC513) can exert synergistic antiinflammatory and antifibrotic action in DSS-induced chronic colitis. Further studies are needed to define the cellular and molecular mechanisms modulated by olive cream compounds and by Lactiplantibacillus plantarum IMC513.

Synthesis of Tyrosol and Hydroxytyrosol Glycofuranosides and Their Biochemical and Biological Activities in Cell-Free and Cellular Assays

Tyrosol (T) and hydroxytyrosol (HOT) and their glycosides are promising candidates for applications in functional food products or in complementary therapy. A series of phenylethanoid glycofuranosides (PEGFs) were synthesized to compare some of their biochemical and biological activities with T and HOT. The optimization of glycosylation promoted by environmentally benign basic zinc carbonate was performed to prepare HOT α-L-arabino-, β-D-apio-, and β-D-ribofuranosides. T and HOT β-D-fructofuranosides, prepared by enzymatic transfructosylation of T and HOT, were also included in the comparative study. The antioxidant capacity and DNA-protective potential of T, HOT, and PEGFs on plasmid DNA were determined using cell-free assays. The DNA-damaging potential of the studied compounds for human hepatoma HepG2 cells and their DNA-protective potential on HepG2 cells against hydrogen peroxide were evaluated using the comet assay. Experiments revealed a spectrum of different activities of the studied compounds. HOT and HOT β-D-fructofuranoside appear to be the best-performing scavengers and protectants of plasmid DNA and HepG2 cells. T and T β-D-fructofuranoside display almost zero or low scavenging/antioxidant activity and protective effects on plasmid DNA or HepG2 cells. The results imply that especially HOT β-D-fructofuranoside and β-D-apiofuranoside could be considered as prospective molecules for the subsequent design of supplements with potential in food and health protection.

Olive Mill Wastewater as Renewable Raw Materials to Generate High Added-Value Ingredients for Agro-Food Industries

Olive oil production represents an agro-industrial activity of vital economic importance for many Mediterranean countries. However, it is associated with the generation of a huge amount of by-products, both in solid and liquid forms, mainly constituted by olive mill wastewater, olive pomace, wood, leaves, and stones. Although for many years olive by-products have only been considered as a relevant environmental issue, in the last decades, numerous studies have deeply described their antioxidant, anti-inflammatory, immunomodulatory, analgesic, antimicrobial, antihypertensive, anticancer, anti-hyperglycemic activities. Therefore, the increasing interest in natural bioactive compounds represents a new challenge for olive mills. Studies have focused on optimizing methods to extract phenols from olive oil by-products for pharmaceutical or cosmetic applications and attempts have been made to describe microorganisms and metabolic activity involved in the treatment of such complex and variable by-products. However, few studies have investigated olive oil by-products in order to produce added-value ingredients and/or preservatives for food industries. This review provides an overview of the prospective of liquid olive oil by-products as a source of high nutritional value compounds to produce new functional additives or ingredients and to explore potential and future research opportunities.

Strategies for fortified sustainable food: the case of watermelon-based candy

The aim of this research was to design a new product, in particular a watermelon-based jelly candy, without generating waste. The study was divided in two steps: (i) optimization of candy formulation in terms of amount of rind, pulp and juice; (ii) fortification of the jelly candy with different concentrations of orange by-products (albedo and flavedo flours). The fortified jelly samples were assessed for sensory quality and chemical properties, before and after digestion. The new candy product was greatly appreciated. The addition of albedo and flavedo flours significantly improved the chemical composition compared to jelly candy without by-products, before and after digestion. A whole quality index was also calculated to determine the best combination of by-products to be added. Fortification with albedo 1.2% and flavedo ranged between 0.6 and 1.2% allowed recording the most interesting jelly candy.

Biogas Potential of the Side Streams Obtained in a Novel Phenolic Extraction System from Olive Mill Solid Waste

The olive oil production is an important industrial sector in many Mediterranean areas, but it is currently struggled by the necessity of a proper valorisation of the olive mill solid waste or alperujo. The alperujo is the main by-product generated during the two-phase olive oil extraction, accounting for up to 80% of the initial olive mass. The alperujo is a source of valuable compounds, such as the pomace olive oil or highly interesting phenolic compounds. In the present research, a novel biorefinery approach has been used for phenolic compounds recovery. However, the extraction of these valuables compounds generates different exhausted phases with high organic matter content that are required to be managed. This study consists of the evaluation of the anaerobic biodegradability of the different fractions obtained in a novel biorefinery approach for the integral valorisation of alperujo. The results show that the different phases obtained during the biorefinery of the alperujo can be effectively subjected to anaerobic digestion and no inhibition processes were detected. The highest methane yield coefficients were obtained for the phases obtained after a two-months storages, i.e., suspended solids and liquid phase free of suspended solids, which generated 366 ± 7 mL CH₄/g VS and 358 ± 6 mL CH₄/g VS, respectively. The phenol extraction process reduced the methane yield coefficient around 25% due to the retention of biodegradable compounds during the extraction process. Regardless of this drop, the anaerobic digestion is a suitable technology for the stabilization of the different generated residual phases, whereas the high market price of the extracted phenols can largely compensate the slight decrease in the methane generation.

Industrial-Scale Study of the Chemical Composition of Olive Oil Process-Derived Matrices

The effect of the industrial process and collecting period on produced olive oil and by-products was evaluated. Obtained results showed significant variations for the majority of quality indices before and after vertical centrifugation between all samples from the three collecting periods. All samples were rich in monounsaturated fatty acid: Oleic acid (C18:1) with a maximum of 69.95%. The total polyphenols and individual phenolic compounds varied significantly through the extraction process, with a significant variation between olive oil and by-products. Notably, the percentage of secoiridoids and their derivatives was significant in paste and olive oil, highlighting the activity of many enzymes released during the different extraction steps. Regarding antioxidant capacity, the most remarkable result was detected in olive oil and olive mill wastewater samples.

Distribution of bioactives in entire mill chain from the drupe to the oil and wastes

Industrial olive oil production generates large amounts of by-products, mainly pomaces and wastewaters. The latter, in particular, represents serious environmental problems requiring special treatments prior to disposal. While olive pomace finds use as alternative energy source, wastewaters still remain a task since it is not reusable, representing an additional cost on olive oil for its treatments. This study is a "comprehensive" overview on the distribution of bioactives in entire mill chain from the drupe to the oil and wastes. Identification was achieved through liquid chromatography coupled with mass spectrometry, spectrofotometric and fluorimetric detection. Phenols resulted the most abundant class of substances, with the highest hydroxytyrosol amounts in wastewater (214 mg/kg). Pomace contained a total of 304 mg/kg in terms of bioactives, thus representing a potential food supplement ingredient for functional foods with high nutritional values.

Hydroxytyrosyl Oleate: Improved Extraction Procedure from Olive Oil and By-Products, and In Vitro Antioxidant and Skin Regenerative Properties

Recently, we identified hydroxytyrosyl oleate (HtyOle) in the by-products of olive oil, pomace and olive mill waste water (OMWW). Herein, we report that HtyOle is more accurately quantified by extracting the phenolic fraction from both matrices by using aqueous methanol (80%). By applying this method, HtyOle was also detected in extra virgin olive oil (EVOO). Since olive oil is used in the preparation of many cosmetic formulations, we explored the antioxidant capacity of HtyOle in human keratinocytes. Formation of reactive oxygen species (ROS) and malondialdehyde (MDA), as well as activity of Glutathione-S-transferase (GST) and superoxide dismutase (SOD) were decreased by HtyOle. In addition to that, microRNAs (miRs) involved in both redox status balance and skin regeneration potential were also tested. The following miRs, hsa-miR-21 and hsa-miR-29a, were increased while has-miR-34a was not affected by HtyOle.

Long-Term Evaluation of Mesophilic Semi-Continuous Anaerobic Digestion of Olive Mill Solid Waste Pretreated with Steam-Explosion

Steam-explosion is a promising technology for recovering phenolic compounds from olive mill solid waste (OMSW) due to its high impact on the structure of the fibre. Moreover, the recovery of the phenols, which are well-known microbial inhibitors, could improve the subsequent biomethanization of the dephenolized OMSW to produce energy. However, there is a considerable lack of knowledge about how the remaining phenolic compounds could affect a long-term biomethanization process of steam-exploded OMSW. This work evaluated a semi-continuous mesophilic anaerobic digestion of dephenolized steam-exploited OMSW during a long operational period (275 days), assessing different organic loading rates (OLRs). The process was stable at an OLR of 1 gVS/(L·d), with a specific production rate of 163 ± 28 mL CH4/(gVS·d). However, the increment of the OLR up to 2 gVS/(L·d) resulted in total exhaust of the methane production. The increment in the propionic acid concentration up to 1486 mg/L could be the main responsible factor for the inhibition. Regardless of the OLR, the concentration of phenolic compounds was always lower than the inhibition limits. Therefore, steam-exploited OMSW could be a suitable substrate for anaerobic digestion at a suitable OLR.

Evaluation of Phytochemical and Antioxidant Properties of 15 Italian Olea europaea L. Cultivar Leaves

Olive leaf extracts are of special interest due to their proven therapeutic effects. However, they are still considered a by-product of the table olive and the oil industries. In order to learn possible ways of exploiting this waste for health purposes, we investigated the phytochemical profiles and antioxidant activities in the leaves of 15 Italian Olea europaea L. cultivars grown in the same pedoclimatic conditions. The phenolic profiles and amounts of their seven representative compounds were analyzed using HPLC ESI/MS-TOF. The antioxidant activities were determined using three different antioxidant assays (DPPH, ORAC, and superoxide anion scavenging assay). Wide ranges of total phenolic content (11.39-48.62 g GAE kg^-1 dry weight) and antioxidant activities (DPPH values: 8.67-29.89 µmol TE mg^-1 dry weight, ORAC values: 0.81-4.25 µmol TE mg^-1 dry weight, superoxide anion scavenging activity values: 27.66-48.92 µmol TE mg^-1 dry weight) were found in the cultivars. In particular, the cultivars Itrana, Apollo, and Maurino, showed a high amount of total phenols and antioxidant activity, and therefore represent a suitable natural source of biological compounds for use in terms of health benefits.

Performance evaluation of mesophilic semi-continuous anaerobic digestion of high-temperature thermally pre-treated olive mill solid waste

The aim of the present work was to evaluate the effects of a thermal pre-treatment of olive mill solid waste (OMSW) and phenol extraction process on the semi-continuous anaerobic digestion of this pre-treated waste during a prolonged operational period (275 days) in order to assess the organic loading rates (OLR) of 1 ad 2 g Volatile Solids (VS)/(L·d). The anaerobic digestion of thermally pre-treated and de-phenolized OMSW was stable at an OLR of 1 g VS/(L·d), which permitted a specific production rate of 172 ± 60 mL CH₄/(g VS·d). However, the system was not able to operate at an OLR of 2 g VS/(L·d), which resulted in the total failure of the process. Regardless of the applied OLR, the phenolic compounds were effectively degraded and the inhibition thresholds were not reached. The inhibition of the anaerobic digestion process at an OLR of 2 g VS/(L·d) was probably due to the overloading of the system, indicated by the accumulation of organic matter and volatile fatty acids. The operation of the anaerobic digester under stable conditions allowed for high profitability for the proposed bio-refinery concept, which would still be profitable at a phenol extract price above 51.8 €/kg, which is 90% lower than the current price of 520 €/kg.

Molecular Docking Studies of Coumarins Isolated from Extracts and Essential Oils of Zosima absinthifolia Link as Potential Inhibitors for Alzheimer's Disease

Coumarins and essential oils are the major components of the Apiaceae family and the Zosima genus. The present study reports anticholinesterase and antioxidant activities of extracts and essential oils from aerial parts, roots, flowers, fruits and coumarins—bergapten (1); imperatorin (2), pimpinellin (3) and umbelliferone (4)—isolated of the roots from Zosima absinthifolia. The investigation by light and scanning electron microscopy of the structures of secretory canals found different chemical compositions in the various types of secretory canals which present in the aerial parts, fruits and flowers. The canals, present in the aerial parts, are characterized by terpene hydrocarbons, while the secretory canals of roots, flowers and fruits include esters. Novel data of a comparative study on essential oils constituents of aerial parts, roots, flowers and fruits of Z. absinthfolia has been presented. The roots and fruits extract showed a high content of total phenolics and antioxidant activity. The GC-FID and GC-MS analysis revealed that the main components of the aerial parts, roots, flowers and fruits extracts were octanol (8.8%), octyl octanoate (7.6%), octyl acetate (7.3%); trans-pinocarvyl acetate (26.7%), β-pinene (8.9%); octyl acetate (19.9%), trans-p-menth-2-en-1-ol (4.6%); octyl acetate (81.6%), and (Z)-4-octenyl acetate (5.1%). The dichloromethane fraction of fruit and flower essential oil was characterized by the highest phenolics level and antioxidant activity. The dichloromethane fraction of fruit had the best inhibition against butyrylcholinesterase enzyme (82.27 ± 1.97%) which was higher then acetylcholinesterase inhibition (61.09 ± 4.46%) of umbelliferone. This study shows that the flowers and fruit of Z. absinthifolia can be a new potential resource of natural antioxidant and anticholinesterase compounds.

Patè Olive Cake: Possible Exploitation of a By-Product for Food Applications

Patè Olive Cake (POC) is a new by-product derived from recently introduced new decanters in the olive oil production process. POC, is essentially composed of water, olive pulp and olive skin, and is rich in several valuable bioactive compounds. Moreover, it still contains about 8-12% residual olive oil. We characterized the main bioactive compounds in POC from black olives (cv. Leccino and Cellina di Nardò) and also verified the biotechnological aptitude of selected yeast and lactic acid bacteria from different sources, in transforming POC into a new fermented product. The strategy of sequential inoculum of Saccharomyces cerevisiae and Leuconostoc mesenteroides was successful in driving the fermentation process. In fermented POC total levels of phenols were slightly reduced when compared with a non-fermented sample nevertheless the content of the antioxidant hydroxytyrosol showed increased results. The total levels of triterpenic acids, carotenoids, and tocochromanols results were almost unchanged among the samples. Sensory notes were significantly improved after fermentation due to the increase of superior alcohols, esters, and acids. The results reported indicate a possible valorisation of this by-product for the preparation of food products enriched in valuable healthy compounds.

Identification of hydroxytyrosyl oleate, a derivative of hydroxytyrosol with anti-inflammatory properties, in olive oil by-products

Hydroxytyrosyl esters with short, medium and long acyl chains were evaluated for their ability to reduce nitric oxide (NO) production by lipopolysaccharide-stimulated RAW264.7 macrophages. Among the compounds tested, C18 esters, namely hydroxytyrosyl stearate (HtySte) and hydroxytyrosyl oleate (HtyOle), were found to decrease NO production in a concentration-dependent manner, while the other compounds, including the parent hydroxytyrosol, were ineffective in the tested concentration range (0.5-5 μM). Further study of the potential immune-modulating properties of HtyOle revealed a significant and concentration-dependent suppression of prostaglandin E₂ production. At a transcriptional level, HtyOle inhibited the expression of inducible NO synthase, cyclooxygenase-2 and interleukin-1β. Moreover, HtyOle was identified for the first time in olive oil by-products by means of high performance liquid chromatography coupled with mass spectrometry. By contrast, HtyOle was not found in intact olives. Our results suggest that HtyOle is formed during oil processing and represents a significant form in which hydroxytyrosol occurs.

Unravelling the Distribution of Secondary Metabolites in Olea europaea L.: Exhaustive Characterization of Eight Olive-Tree Derived Matrices by Complementary Platforms (LC-ESI/APCI-MS and GC-APCI-MS)

In order to understand the distribution of the main secondary metabolites found in Olea europaea L., eight different samples (olive leaf, stem, seed, fruit skin and pulp, as well as virgin olive oil, olive oil obtained from stoned and dehydrated fruits and olive seed oil) coming from a Picudo cv. olive tree were analyzed. All the experimental conditions were selected so as to assure the maximum coverage of the metabolome of the samples under study within a single run. The use of LC and GC with high resolution MS (through different ionization sources, ESI and APCI) and the annotation strategies within MetaboScape 3.0 software allowed the identification of around 150 compounds in the profiles, showing great complementarity between the evaluated methodologies. The identified metabolites belonged to different chemical classes: triterpenic acids and dialcohols, tocopherols, sterols, free fatty acids, and several sub-types of phenolic compounds. The suitability of each platform and polarity (negative and positive) to determine each family of metabolites was evaluated in-depth, finding, for instance, that LC-ESI-MS (+) was the most efficient choice to ionize phenolic acids, secoiridoids, flavonoids and lignans and LC-APCI-MS was very appropriate for pentacyclic triterpenic acids (MS (−)) and sterols and tocopherols (MS (+)). Afterwards, a semi-quantitative comparison of the selected matrices was carried out, establishing their typical features (e.g., fruit skin was pointed out as the matrix with the highest relative amounts of phenolic acids, triterpenic compounds and hydroxylated fatty acids, and seed oil was distinctive for its high relative levels of acetoxypinoresinol and tocopherols).

Olive leaf extracts for shelf life extension of salmon burgers

In this work, the effect of the addition of olive leaf extracts on the quality of vacuum-packed salmon burgers stored at 4 ℃ during 16 days has been studied. Olive leaf extract and its hydrolysate were initially characterized and then incorporated to salmon burgers. A shelf life study was conducted in three different batches (control, olive leaf extract, and hydrolyzed olive leaf extract burgers). Among the chemical indices determined, total volatile base nitrogen values were lower in hydrolyzed olive leaf extract and olive leaf extract burgers than in control samples. Lipid oxidation was lower in salmon burger with olive leaf extract. Salmon mince treated with hydrolyzed olive leaf extract showed lower microbial counts during the whole study, which extended the shelf life of the fish product. Therefore, the potential of olive leaf extracts to preserve salmon burgers during cold storage has been demonstrated.

An effective HPLC-based approach for the evaluation of the content of total phenolic compounds transferred from olives to virgin olive oil during the olive milling process

BACKGROUND

Several studies demonstrate a strong interest in learning more about phenolic transfer during oil extraction, with the main goal of increasing the phenolic concentration in olive oils. We aimed to propose and apply a new methodological approach for evaluating phenolic transfer from olives into oil during milling, based on the quantification of phenolic content in whole lyophilized fruits and the corresponding oils and considering the oil extraction yields.

RESULTS

We investigated the phenols transferred into the oil during olive milling in continuous extraction systems in Tuscany. In 2012, oils were extracted from cultivar Frantoio by a two-phase extraction system; in 2016, oils were extracted from cultivars Leccio del Corno and Arbequina by a three-phase extraction system. Results highlighted very low percentages of extracted phenols: up to 0.40% by the two-phase system and up to 0.19% by the three-phase system (0.08% for cultivar Arbequina and 0.19% for cultivar Leccio del Corno).

CONCLUSION

The usefulness of a simple and effective methodological approach for evaluating the extracted phenols was highlighted. Values of extracted phenols were up to 25 times lower than previous literature data. The proposed approach is applicable in all types of milling processes. © 2017 Society of Chemical Industry.

Effect of edible pectin-fish gelatin films containing the olive antioxidants hydroxytyrosol and 3,4-dihydroxyphenylglycol on beef meat during refrigerated storage

The objective of this research was to evaluate the effect of the addition of two antioxidants naturally present in olives, hydroxytyrosol (HT) and 3,4-dihydroxyphenylglycol (DHPG), to a pectin-fish gelatin edible film on the preservation of raw beef meat during refrigerated storage. A new composite film that included beeswax was also prepared, resulting in a reduction in the film's oxygen permeability. Results showed that the meat samples wrapped with film containing antioxidants reduced the formation of oxidation products in the form of thiobarbituric acid reaction substances (TBARS) compared with control film without antioxidants. HT added at 0.5% to the film with beeswax suppressed the lipid oxidation of beef meat during 7 days of storage at 4 °C, possibly by the combined effect of acting as an oxygen barrier and the specific antioxidant activity. The interference of plasticizer agents (glycerol and sorbitol) incorporated to the film on the TBARS method was showed for the first time.

A Two-Step Process for the Synthesis of Hydroxytyrosol

A new process for the synthesis of hydroxytyrosol (3,4-dihydroxyphenylethanol), the most powerful natural antioxidant currently known, by means of a two-step approach is reported. Catechol is first reacted with 2,2-dimethoxyacetaldehyde in basic aqueous medium to produce the corresponding mandelic derivative with >90 % conversion of the limiting reactant and about 70 % selectivity to the desired para-hydroxyalkylated compound. Thereafter, the intermediate is hydrogenated to hydroxytyrosol by using a Pd/C catalyst, with total conversion of the mandelic derivative and 68 % selectivity. This two-step process is the first example of a synthetic pathway for hydroxytyrosol that does not involve the use of halogenated components or reduction methodologies that produce stoichiometric waste. It also avoids the complex procedure currently used for hydroxytyrosol purification when it is extracted from wastewater of olive oil production.

Recovery and stability over time of phenolic fractions by an industrial filtration system of olive mill wastewaters: a three-year study

BACKGROUND

The recovery of phenolic compounds from olive milling is recognized as strategic for producers. The aim of this work was to evaluate the quality and stability of retentates obtained from olive mill wastewaters treated with a membrane filtration system constituted by a micro-, ultra- and nanofiltration, followed by a final reverse osmosis, over three crop seasons. Efficiency was evaluated in terms of phenolic amount in the retentates and of organic load in the final discarded waters. Phenolic compounds were quantified using tyrosol as external standard.

RESULTS

Our study highlighted a reproducibility of the process over years and a low organic load in permeates from reverse osmosis. Hydroxytyrosol was very stable in the liquid products at 18-28 °C over 24 months of storage. The retentates from reverse osmosis showed the highest phenolic content (78.6 mg g^-1 dry matter in 2015), associated with a potassium content of 22 g kg^-1 .

CONCLUSIONS

The liquid concentrated retentates showed an unexpected stability over time of their bioactive phenolic compounds, particularly of hydroxytyrosol. These samples recovered from olive mill wastewaters can be good sources of natural antioxidants and potassium to guarantee the correct intake and to formulate new food ingredients or food products. © 2017 Society of Chemical Industry.

Phenols recovery after steam explosion of Olive Mill Solid Waste and its influence on a subsequent biomethanization process

A promising source of high added value compounds is the Olive Mill Solid Waste (OMSW). The aim of this research was to evaluate the viability of a biorefinery approach to valorize OMSW through the combination of steam explosion, phenols extraction, and anaerobic digestion. Steam explosion treatment increased the total phenol content in the steam exploited OMSW, which was twice than that the total phenol content in raw OMSW, although some undesirable compounds were also formed. Phenol extraction allowed the recovery of 2098mg hydroxytyrosol per kg of OMSW. Anaerobic digestion allowed the partial stabilization of the different substrates, although it was not improved by the steam explosion treatment. The economic suitability of the proposed biorefinery approach is favorable up to a phenol extract price 90.7% lower than the referenced actual price of 520€/kg.

Biomethanization of olive mill solid waste after phenols recovery through low-temperature thermal pre-treatment

Due to the high polluting potential of Olive Mill Solid Waste (OMSW), it is necessary to develop an economical and environmental-friendly sustainable management method. OMSW anaerobic digestion has been shown to be an interesting management alternative, although it should be optimized to improve its economic viability. In the present study, low-temperature thermal pre-treatment of OMSW is proposed to allow the extraction of high added-value compounds, such as phenols, and to enhance the subsequent biomethanization of the substrate. OMSW low-temperature thermal pre-treatment facilitated the separation of a solid phase, where most of organic compounds remained, and a liquid phase, where most of phenolic compounds were concentrated. Hydroxytyrosol presented the highest concentration of the measured individual phenols in the liquid phase, i.e. 1034±22mg/L. Anaerobic digestion of OMSW and the different pre-treated phases and mixtures operated under stable conditions, except the biomethanization of the liquid phase, which was mainly inhibited by the high phenols content. Low-temperature thermal pre-treatment allows obtaining an improvement on biodegradability and methane production up to 37% and 34%, respectively. The proposed economic assessment showed that the combination of low-temperature pre-treatment, phenols recovery and the subsequent biomethanization of the substrates was the most attractive treatment option. This management option could reach economic benefit of €0.845/kg OMSW, i.e. twenty times higher than only energy recovery.

Complexation of hydroxytyrosol and 3,4-dihydroxyphenylglycol with pectin and their potential use for colon targeting

Hydroxytyrosol (HT) and 3,4-dihydroxyphenylglycol (DHPG) are two phenolic antioxidants naturally found in olive fruit with anti-inflammatory properties. This study explored the interaction of pectin with HT and DHPG via their encapsulation into pectinate beads. Purification by size exclusion chromatography, changes in the fluorescence spectrum of the HT and pectin, and MALDI TOF-TOF analysis suggested the existence of the phenol-pectin complexes. The entrapment efficiency, swelling properties, and in vitro release of HT and DHPG of the beads were studied. The results show that the beads can entrap the water soluble compounds HT and DHPG in sufficient amounts to reach the colon. The beads consisted of an important amount of pectin-bound HT or DHPG after two hours at gastric pH. This study highlights the potential use of HT-and DHPG-loaded pectinate gel beads for the colon-targeted delivery of these bioactive compounds to help prevent or relieve chronic inflammatory bowel disease.

Quick assessment of the economic value of olive mill waste water

BACKGROUND

Olive biophenols are emerging as a valued class of natural products finding practical application in the food, pharmaceutical, beverage, cosmetic and nutraceutical industries due to their powerful biological activity which includes antioxidant and antimicrobial properties. Olive mill waste water (OMWW), a by-product in olive oil manufacturing, is rich in biophenols such as hydroxytyrosol and tyrosol. The amount of biophenols depends on the cultivar, the geographical area of cultivation, and the seasonal conditions. The goal of this study was to develop a straightforward method to assess the economic value of OMWW via quantification of hydroxytyrosol and tyrosol.

RESULTS

The amount of hydroxytyrosol and tyrosol phenolic compounds in the OMWW from four different cultivars grown in four different regions of Sicily was analyzed using liquid-liquid and solid-liquid analytical protocols developed ad hoc. Results showed significant differences amongst the different cultivars and their geographical origin. In all samples, the concentration of hydroxytyrosol was generally from 2 to 10 times higher than that of tyrosol. In general, the liquid-liquid extraction protocol gave higher amounts of extracted biophenols. The cultivar Cerasuola had the highest amount of both hydroxytyrosol and tyrosol. The cultivar Nocellara Etnea had the lowest content of both biophenols.

CONCLUSIONS

A quick method to assess the economic value of olive mill waste water via quantification of hydroxytyrosol and tyrosol in olive phenolic enriched extracts is now available.