Encapsulation of phenolic acids into cyclodextrins: A global statistical analysis of the effects of pH, temperature and concentrations on binding constants measured by ACE methods.

Affinity capillary electrophoresis was used for the simultaneous measurement of the pKa values and of the binding constants relative to the encapsulation of naturally occurring phenolic acids (rosmarinic and caffeic acids) with cyclodextrins. A thorough study as a function of pH and temperature was coupled to a detailed statistical analysis of the resulting experimental data. A step-by-step curve fitting process was sufficient for obtaining individual binding constant for each experimental condition, but the influence of temperature remained unclear. A quantitative and qualitative gain was then obtained by supplementing this initial analysis with global multiparameter optimization. This leads to the estimation of both entropy and enthalpy of reaction and to the full description of the binding reactions as a function of pH and temperature. The encapsulation was shown to be very sensitive to pH and temperature, with optimal complexation occurring at low pH and low temperature, gaining up to a factor of 3 by cooling from 36 to 15°C, and up to a factor of 10 by lowering the pH from 7 to 2.

Higher Yield and Polyphenol Content in Olive Pomace Extracts Using 2-Methyloxolane as Bio-Based Solvent.

Despite its severe toxicity and negative environmental impact, hexane remain the solvent of choice for the extraction of vegetable oils. This is in contrast with the constantly growing demand for sustainable and green extraction processes. In recent years a variety of alternatives to hexane have been reported, among them 2-methyloxolane (2-MeOx), which has emerged as a promising bio-based alternative. This study evaluates the possibility of replacing hexane, in the extraction of olive pomace (OP), with 2-MeOx, both dry and saturated with water (4.5%), the latter of which is called 2-MeOx 95.5%. The three solvents have been compared in terms of extraction yield and quality, as well as the lipid and polyphenol profiles of the extracts. The work concluded that both dry 2-MeOx and 2-MeOx 95.5% can replace hexane in OP extraction, resulting in higher yields and extracts richer in phenolic compounds. This study should open the road to further semi-industrial scale investigations toward more sustainable production processes.

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).

One-Step Extraction of Olive Phenols from Aqueous Solution Using ß-Cyclodextrin in the Solid State, a Simple Eco-Friendly Method Providing Photochemical Stability to the Extracts.

The extraction of phenolic compounds from olive mill wastes is important, not only to avoid environmental damages, but also because of the intrinsic value of those biophenols, well-known for their high antioxidant potential and health benefits. This study focuses on tyrosol (Tyr) and hydroxytyrosol (HT), two of the main phenolic compounds found in olive mill wastes. A new, simple, and eco-friendly extraction process for the removal of phenolic compounds from aqueous solutions using native ß-cyclodextrin (ß-CD) in the solid state has been developed. Several ß-CD/biophenol molar ratios and biophenol concentrations were investigated, in order to maintain ß-CD mostly in the solid state while optimizing the extraction yield and the loading capacity of the sorbent. The extraction efficiencies of Tyr and HT were up to 61%, with a total solid recovery higher than 90% using an initial concentration of 100 mM biophenol and 10 molar equivalents of ß-CD. The photochemical stability of the complexes thus obtained was estimated from ∆E*ab curve vs. illumination time. The results obtained showed that the phenols encapsulated into solid ß-CD are protected against photodegradation. The powder obtained could be directly developed as a safe-grade food supplement. This simple eco-friendly process could be used for extracting valuable biophenols from olive mill wastewater.

ß-Cyclodextrin Does not Alter the Bioaccessibility and the Uptake by Caco-2 Cells of Olive By-Product Phenolic Compounds.

Alperujo-a two-phase olive mill waste that is composed of olive vegetation water and solid skin, pulp, and seed fragments - is a highly valuable olive by-product due to its high content in phenolic compounds. In this study, we assessed whether ß-cyclodextrin (ß-CD), which is used to extract and protect alpejuro phenolic compounds (hydroxytyrosol-O-glucoside, tyrosol, caffeic, and p-coumaric acids) could impact on their bioaccessibility (i.e., the percentage of molecule found in the aqueous phase of the digesta) and uptake by intestinal cells, by using an in vitro digestion model and Caco-2 TC7 cells in culture, respectively. Our results showed that ß-CD did not change the bioaccessibility of the selected phenols. Hydroxytyrosol-O-glucoside and caffeic did not cross Caco-2 cell monolayers. Conversely ferulic acid, identified as the main caffeic acid intestinal metabolite, was absorbed through intestinal cell monolayers (~20%). Interestingly, ß-CD moderately but significantly improved the local absorption of tyrosol and p-coumaric acid (2.3 + 1.4% and 8.5 ± 4.2%, respectively, p < 0.05), even if their final bioavailability (expressed as bioaccessibility × absorption by Caco-2 cells) was not modified (16.2 ± 0.6% vs. 16.8 ± 0.5% for tyrosol and 32.0 ± 3.2% vs. 37.2 ± 3.2% for p-coumaric acid, from pure alperujo and alperujo complexed with ß-CD, respectively). Overall, our results show that ß-CD is an interesting extraction and storage agent for phenolic compounds that does not alter their in vitro bioavailability.

Effect of Foods and ß-Cyclodextrin on the Bioaccessibility and the Uptake by Caco-2 Cells of Hydroxytyrosol from Either a Pure Standard or Alperujo.

Hydroxytyrosol bioaccessibility and absorption by the intestinal cells were studied using an in vitro digestion model and Caco-2 TC7 monolayers cells in culture in the presence and absence of ß-cyclodextrin and foods. Hydroxytyrosol was either provided as a pure standard or in an alperujo powder. The presence of foods significantly decreased hydroxytyrosol bioaccessibility and absorption (-20 and -10%, respectively), while ß-cyclodextrin had no effect. Moreover, the presence of other compounds from alperujo in the intestinal compartment reduced hydroxytyrosol absorption by Caco-2 cells compared to pure standard (-60%). The final bioavailability of hydroxytyrosol, defined as its quantity at the basolateral side of cultured cell monolayers compared to the initial amount in the test meal, was 6.9 ± 0.4, 31.1 ± 1.1, and 40.9 ± 1.5% when hydroxytyrosol was from alperujo or a standard administered with or without food, respectively. Our results show that conversely to foods, ß-cyclodextrin does not alter hydroxytyrosol bioavailability.

The inclusion complex of rosmarinic acid into beta-cyclodextrin: A thermodynamic and structural analysis by NMR and capillary electrophoresis.

This work focuses on the characterization of the rosmarinic acid (RA)-ß-cyclodextrin (CD) complex in aqueous solution by (1)H NMR (1D- and 2D-ROESY), completed with studies by capillary electrophoresis (CE). From the (1)H NMR data, the stoichiometry of the complex was determined by a Job's plot and the binding constant was estimated from a linear regression (Scott's method). At pH 2.9, the results showed that RA binds CD with a 1:1 stoichiometry and a binding constant Kb of 445 (±53) M(-1) or 465 (±81) M(-1) depending on the CD protons (H-5 or H-3) selected for the evaluation. The Kb value was also calculated from the CD-induced chemical shifts of each RA proton in order to collect information on the structure of the complex. The pH dependence of Kb revealed that the RA carboxylic form displays the highest affinity for CD. An investigation by capillary electrophoresis fully confirmed these results. 2D ROESY analysis provided detailed structural information on the complex and showed a strong correlation between H-3 and H-5 of CD and most RA protons. In conclusion, RA, an efficient phenolic antioxidant from rosemary with a marketing authorization, spontaneously forms a relatively stable inclusion complex with CD in water.

Green ultrasound-assisted extraction of carotenoids based on the bio-refinery concept using sunflower oil as an alternative solvent.

A green, inexpensive and easy-to-use method for carotenoids extraction from fresh carrots assisted by ultrasound was designed in this work. Sunflower oil was applied as a substitute to organic solvents in this green ultrasound-assisted extraction (UAE): a process which is in line with green extraction and bio-refinery concepts. The processing procedure of this original UAE was first compared with conventional solvent extraction (CSE) using hexane as solvent. Moreover, the UAE optimal conditions for the subsequent comparison were optimized using response surface methodology (RSM) and ultra performance liquid chromatography--diode array detector--mass spectroscopy (UPLC-DAD-MS). The results showed that the UAE using sunflower as solvent has obtained its highest ß-carotene yield (334.75 mg/l) in 20 min only, while CSE using hexane as solvent obtained a similar yield (321.35 mg/l) in 60 min. The green UAE performed under optimal extraction conditions (carrot to oil ratio of 2:10, ultrasonic intensity of 22.5 W cm(-2), temperature of 40 °C and sonication time of 20 min) gave the best yield of ß-carotene.

Instant controlled pressure drop technology and ultrasound assisted extraction for sequential extraction of essential oil and antioxidants.

The instant controlled pressure drop (DIC) technology enabled both the extraction of essential oil and the expansion of the matrix itself which improved solvent extraction. The sequential use of DIC and Ultrasound Assisted Extraction (UAE) triggered complementary actions materialized by supplementary effects. We visualized these combination impacts by comparing them to standard techniques: Hydrodistillation (HD) and Solvent Extraction (SE). First, the extraction of orange peel Essential Oils (EO) was achieved by HD during 4h and DIC process (after optimization) during 2 min; EO yields was 1.97 mg/g dry material (dm) with HD compared to 16.57 mg/g d m with DIC. Second, the solid residue was recovered to extract antioxidant compounds (naringin and hesperidin) by SE and UAE. Scanning electron microscope showed that after HD the recovered solid shriveled as opposite to DIC treatment which expanded the product structure. HPLC analyses showed that the best kinetics and yields of naringin and hesperidin extraction was when DIC and UAE are combined. Indeed, after 1h of extraction, DIC treated orange peels with UAE were 0.825 ± 1.6 × 10(-2)g/g of dry material (dm) for hesperidin and 6.45 × 10(-2) ± 2.3 × 10(-4)g/g d m for naringin compared to 0.64 ± 2.7 × 10(-2)g/g of dry material (dm) and 5.7 × 10(-2) ± 1.6 × 10(-3)g/g d m, respectively with SE. By combining DIC to UAE, it was possible to enhance kinetics and yields of antioxidant extraction.

Direct enrichment of olive oil in oleuropein by ultrasound-assisted maceration at laboratory and pilot plant scale.

The possibility to improve the nutritional value of olive oil by enriching it in phenolic compounds from olive leaves (e.g., oleuropein) by ultrasonic maceration was studied. The experimental design used led to the following optimal extraction conditions: ultrasonic power of 60 W, temperature of 16°C and sonication duration of 45 min. The high total phenolic content (414.3 ± 3.2mg of oleuropein equivalent/kg of oil), oleuropein (111.0 ± 2.2mg/kg of oil) and α-tocopherol (55.0 ± 2.1g/kg of oil) concentrations obtained by optimized ultrasound-assisted extraction (UAE) proved the efficiency of this process when compared with the conventional solid-liquid extraction. Histochemical analyses showed that this efficiency is due to specific alteration of the phenol-containing leaf structures. Furthermore, the radical-scavenging activity of the processed oil (DPPH test) and its stability toward lipid autoxidation (heating test) confirmed its enrichment in antioxidants. Sensory evaluation of the enriched olive oil showed a slight increase in bitterness but an overall acceptability. Finally, the enriched olive oil was characterized by clear green color (L*, a*, b* parameters).

Extraction of kiwi seed oil: Soxhlet versus four different non-conventional techniques.

Kiwi seed oil has a nutritionally interesting fatty acid profile, but a rather low oxidative stability, which requires careful extraction procedures and adequate packaging and storage. For these reasons and with the aim to achieve process intensification with shorter extraction time, lower energy consumption and higher yields, four different non-conventional techniques were experimented. Kiwi seeds were extracted in hexane using classic Soxhlet as well as under power ultrasound (US), microwaves (MWs; closed vessel) and MW-integrated Soxhlet. Supercritical CO2 was also employed and compared to the other techniques in term of yield, extraction time, fatty acid profiles and organoleptic properties. All these non-conventional techniques are fast, effective and safe. A sensory evaluation test showed the presence of off-flavours in oil samples extracted by Soxhlet and US, an indicator of partial degradation.

Green procedure using limonene in the Dean-Stark apparatus for moisture determination in food products.

In the past 10 years, trends in analytical chemistry have turned toward the green chemistry which endeavours to develop new techniques that reduce the influence of chemicals on the environment. The challenge of the green analytical chemistry is to develop techniques that meet the request for information output while reducing the environmental impact of the analyses. For this purpose petroleum-based solvents have to be avoided. Therefore, increasing interest was given to new green solvents such as limonene and their potential as alternative solvents in analytical chemistry. In this work limonene was used instead of toluene in the Dean-Stark procedure. Moisture determination on wide range of food matrices was performed either using toluene or limonene. Both solvents gave similar water percentages in food materials, i.e. 89.3+/-0.5 and 89.5+/-0.7 for carrot, 68.0+/-0.7 and 68.6+/-1.9 for garlic, 64.1+/-0.5 and 64.0+/-0.3 for minced meat with toluene and limonene, respectively. Consequently limonene could be used as a good alternative solvent in the Dean-Stark procedure.

Towards the industrial production of antioxidants from food processing by-products with ultrasound-assisted extraction.

Apple pomace, a by-product of the cider production, has been studied as a potential source of polyphenols, compounds of great interest for the industry. Ultrasound has been used to improve extraction efficiency in terms of time needed and total polyphenol content. A preliminary study has been first investigated to optimize ethanol proportion of aqueous extractant (50%, v/v) and solid/liquid ratio (<15%, w/v). A response surface methodology has then been used to maximize total polyphenol content of extracts and investigate influence of parameters involved in extraction procedures for both total polyphenols content and composition of extracts. Optimal settings reached from a central composite design were applied for ultrasound-assisted extraction and were compared to conventional procedure: yields were increased by more than 20%. Ultrasound-assisted polyphenols extraction from apple pomace appears to be a relevant, rapid, sustainable alternative to conventional procedure, and that scale up of the process is possible.

Microwave-assisted water extraction of green tea polyphenols.

INTRODUCTION: Green tea, a popular drink with beneficial health properties, is a rich source of specific flavanols (polyphenols). There is a special interest in the water extraction of green tea polyphenols since the composition of the corresponding extracts is expected to reflect the one of green tea infusions consumed worldwide. OBJECTIVE: To develop a microwave-assisted water extraction (MWE) of green tea polyphenols. METHODOLOGY: MWE of green tea polyphenols has been investigated as an alternative to water extraction under conventional heating (CWE). The experimental conditions were selected after consideration of both temperature and extraction time. The efficiency and selectivity of the process were determined in terms of extraction time, total phenolic content, chemical composition (HPLC-MS analysis) and antioxidant activity of the extracts. RESULTS: By MWE (80 degrees C, 30 min), the flavanol content of the extract reached 97.46 (+/- 0.08) mg of catechin equivalent/g of green tea extract, vs. only 83.06 (+/- 0.08) by CWE (80 degrees C, 45 min). In particular, the concentration of the most bioactive flavanol EGCG was 77.14 (+/- 0.26) mg of catechin equivalent/g of green tea extract obtained by MWE, vs 64.18 (+/- 0.26) mg/g by CWE. CONCLUSION: MWE appears more efficient than CWE at both 80 and 100 degrees C, particularly for the extraction of flavanols and hydroxycinnamic acids. Although MWE at 100 degrees C typically affords higher yields in total phenols, MWE at 80 degrees C appears more convenient for the extraction of the green tea-specific and chemically sensitive flavanols.

New and rapid analytical procedure for water content determination: microwave accelerated Dean-Stark.

Development of new procedures in analytical chemistry is currently increasingly focussed on reducing the time, cost and energy to carry out routine analyses. The conventional Dean-Stark (CDS) distillation to determine the water content is one of the most commonly used analytical methods and uses large amounts of solvent and energy. A new microwave accelerated Dean-Stark (MADS) distillation is presented as an alternative procedure. Microwaves were applied to a mixture of toluene, Weflon stir bar and olives, and the corresponding water was collected in a Dean-Stark receiver. This procedure permits fast and efficient determination of the water content of olives. Reliability and reproducibility were evaluated using statistical analyses. Different matrices were then used with MADS and the results were compared to CDS. Water determination from olives with MADS was better than that with CDS in terms of energy saving, rapidity (10 min versus 120 min), reproducibility, and cleanliness.

Microwave-integrated extraction of total fats and oils.

An improved process of Soxhlet extraction assisted by microwave, called microwave-integrated Soxhlet (MIS) is proposed for the extraction of oils and fats from different food matrixes such as oleaginous seeds, meat and bakery products. Optimal conditions for extraction were obtained using a response surface methodology and reached from a central composite design allowing us to conclude in a previous paper that the proposed process ensures complete, efficient and accurate extraction for lipids determination from olives. In this paper, the peak areas of the main fatty acids extracted with MIS from olive seeds were considered as response variables and submitted to an analysis of variance in order to determine if there was a significant link between the extraction of fatty acids and the variables required in extraction procedures. Results have shown that MIS parameters do not affect the composition of the extracts. For the generalization of the study with several food matrixes, MIS extraction results obtained were then compared to conventional Soxhlet extraction in terms of crude extract and fatty acid composition and shown that the oils extracted by MIS were quantitatively and qualitatively similar to those obtained by conventional Soxhlet extraction. MIS labstation can be considered as a new and general alternative for the extraction of lipids by using microwave energy.

Green procedure with a green solvent for fats and oils' determination. Microwave-integrated Soxhlet using limonene followed by microwave Clevenger distillation.

Here is described a green and original alternative procedure for fats and oils' determination in oleaginous seeds. Extractions were carried out using a by-product of the citrus industry as extraction solvent, namely d-limonene, instead of hazardous petroleum solvents such as n-hexane. The described method is achieved in two steps using microwave energy: at first, extractions are attained using microwave-integrated Soxhlet, followed by the elimination of the solvent from the medium using a microwave Clevenger distillation in the second step. Oils extracted from olive seeds were compared with both conventional Soxhlet and microwave-integrated Soxhlet extraction procedures performed with n-hexane in terms of qualitative and quantitative determination. No significant difference was obtained between each extract allowing us to conclude that the proposed method is effective and valuable.

New microwave-integrated Soxhlet extraction. An advantageous tool for the extraction of lipids from food products.

A new process of Soxhlet extraction assisted by microwave was designed and developed. The process is performed in four steps, which ensures complete, rapid and accurate extraction of the samples. A second-order central composite design (CCD) has been used to investigate the performance of the new device. The results provided by analysis of variance and Pareto chart, indicated that the extraction time was the most important factor followed by the leaching time. The response surface methodology allowed us to determine optimal conditions for olive oil extraction: 13 min of extraction time, 17 min of leaching time, and 720 W of irradiation power. The proposed process is suitable for lipids determination from food. Microwave-integrated Soxhlet (MIS) extraction has been compared with a conventional technique, Soxhlet extraction, for the extraction of oil from olives (Aglandau, Vaucluse, France). The oils extracted by MIS for 32 min were quantitatively (yield) and qualitatively (fatty acid composition) similar to those obtained by conventional Soxhlet extraction for 8 h. MIS is a green technology and appears as a good alternative for the extraction of fat and oils from food products.

Comparison of the anthocyanin composition during ripening of Syrah grapes grown using organic or conventional agricultural practices.

The anthocyanin composition of Syrah grapes harvested at different stages of ripening and produced using organic or conventional agriculture was studied. Samples of grapes were collected from veraison to full maturity in each plot, and the content in nine anthocyanins was determined by high-performance liquid chromatography with diode array detection. The total content in anthocyanins during ripening of the conventionally grown grapes was significantly higher compared to that found in the organic production. The accumulation of anthocyanins reached a maximum 28 days after veraison (in agreement with high temperature) and then decreased until harvest. In all samples, grapes from the conventional agriculture presented higher proportions of delphinidin, petunidin, malvidin, and acylated malvidin glucosides compared to grapes from organic agriculture. In contrast with other comparative studies of organically and conventionally grown plants, the results demonstrated a higher content in anthocyanins in conventionally grown grapes.

Interactions of quercetin with iron and copper ions: complexation and autoxidation.

Quercetin (3,3',4',5,7-pentahydroxyflavone), one of the most abundant dietary flavonoids, has been investigated for its ability to bind Fe(II), Fe(III), Cu(I) and Cu(II) in acidic to neutral solutions. In particular, analysis by UV-visible spectroscopy allows to determine the rate constants for the formation of the 1:1 complexes. In absence of added metal ion, quercetin undergoes a slow autoxidation in neutral solution with production of low hydrogen peroxide (H(2)O(2)) concentrations. Autoxidation is accelerated by addition of the metal ions according to: Cu(I) > Cu(II)>>Fe(II) Fe(III). In fact, the iron-quercetin complexes seem less prone to autoxidation than free quercetin in agreement with the observation that EDTA addition, while totally preventing iron-quercetin binding, slightly accelerates quercetin autoxidation. By contrast, the copper-quercetin complexes appear as reactive intermediates in the copper-initiated autoxidation of quercetin. In presence of the iron ions, only low concentrations of H(2)O(2) can be detected. By contrast, in the presence of the copper ions, H(2)O(2) is rapidly accumulated. Whereas Fe(II) is rapidly autoxidized to Fe(III) in the presence or absence of quercetin, Cu(I) bound to quercetin or its oxidation products does not undergo significant autoxidation. In addition, Cu(II) is rapidly reduced by quercetin. By HPLC-MS analysis, the main autoxidation products of quercetin are shown to be the solvent adducts on the p-quinonemethide intermediate formed upon two-electron oxidation of quercetin. Finally, in strongly acidic conditions (pH 1-2), neither autoxidation nor metal complexation is observed but Fe(III) appears to be reactive enough to quickly oxidize quercetin (without dioxygen consumption). Up to ca. 7 Fe(III) ions can be reduced per quercetin molecule, which points to an extensive oxidative degradation.