Hiba N. Rajha

Effect of the Drying Process on the Intensification of Phenolic Compounds Recovery from Grape Pomace Using Accelerated Solvent Extraction

In light of their environmental and economic interests, food byproducts have been increasingly exploited and valorized for their richness in dietary fibers and antioxidants. Phenolic compounds are antioxidant bioactive molecules highly present in grape byproducts. Herein, the accelerated solvent extraction (ASE) of phenolic compounds from wet and dried grape pomace, at 45 °C, was conducted and the highest phenolic compounds yield (PCY) for wet (16.2 g GAE/100 g DM) and dry (7.28 g GAE/100 g DM) grape pomace extracts were obtained with 70% ethanol/water solvent at 140 °C. The PCY obtained from wet pomace was up to two times better compared to the dry byproduct and up to 15 times better compared to the same food matrices treated with conventional methods. With regard to Resveratrol, the corresponding dry pomace extract had a better free radical scavenging activity (49.12%) than the wet extract (39.8%). The drying pretreatment process seems to ameliorate the antiradical activity, especially when the extraction by ASE is performed at temperatures above 100 °C. HPLC-DAD analysis showed that the diversity of the flavonoid and the non-flavonoid compounds found in the extracts was seriously affected by the extraction temperature and the pretreatment of the raw material. This diversity seems to play a key role in the scavenging activity demonstrated by the extracts. Our results emphasize on ASE usage as a promising method for the preparation of highly concentrated and bioactive phenolic extracts that could be used in several industrial applications.

β-Cyclodextrin-Assisted Extraction of Polyphenols from Vine Shoot Cultivars

This work optimized the β-cyclodextrin (β-CD)-assisted extraction process of polyphenols from vine shoots. The efficiency of β-CD was compared to that of ethanol in terms of the quantity and antioxidant capacity (AC) of the extracted polyphenols. Response surface methodology permitted the optimization of the β-CD concentration, time, and temperature. The optimal polyphenol content (PC) [5.8 mg of gallic acid equivalent (GAE)/g of dry matter (DM)] and AC [3146 micromolar trolox equivalent per milliliter (μMTE)] were initially obtained with Syrah cultivar after an extraction of 48 h at 66.6 °C with a 37.7 mg/mL aqueous β-CD solvent. The same PC (5.8 mg of GAE/g of DM) was reached with 50% ethanol/water solvent after 1.65 h. However, a lower AC was found with ethanol (2000 μMTE) compared to β-CD. A comparison of the PC and AC of four different vine shoot cultivars was realized. Our results clearly show the capacity of β-CD to amplify polyphenol extraction from vine shoots.

Effect of pulsed electric field treatment during cold maceration and alcoholic fermentation on major red wine qualitative and quantitative parameters

This work studies the effect of pulsed electric field (PEF) treatment at moderate and high field strengths (E=0.8kV/cm & 5kV/cm) prior and during alcoholic fermentation (AF) of red grapes on improving different parameters of pre-treated extracts: pH, °Brix, colour intensity (CI), total polyphenols content (TPI) of Cabernet Sauvignon red wine. Similar trends were observed for treating grapes using moderate and high electric field strength on the enhancement of CI and TPI of the wine after AF. The application of PEF using moderate strengths at different times during cold maceration (CM) (0, 2 and 4days) was more efficient for treatment during CM. The treatment during AF showed lower extraction rate compared to treating during CM and prior to AF. Our results clearly show that the best time for applying the PEF-treatment through the red fermentation is during the CM step.

Valorization of industrial waste using energy saving procedures. Phenolic compounds purification from grape by-products by Accelerated Solvent Extraction (ASE)

The attention given by scientists these days to environment-friendly and energy saving procedures led us to work on the optimization of phenolic compounds extraction from waste industrial products using green technology methods. The growing attention towards phenolic compounds is basically due to the bioactivity of those molecules and their potential application in several industries such as pharmaceutical, nutraceutical and agriculture. In this paper we describe the extraction of phenolic compounds from grape by-products using Accelerated Solvent Extraction which was conducted and followed by a quantitative and qualitative study of the extracts in order to investigate the best extraction parameters. The extraction process using this energy saving method, showed that the optimal conditions are a 70% ethanol/water mixture (v/v) and a 140°C temperature. The quantity of the extracted phenolic compounds was determined by the Total Phenolic Index (TPI), while the qualitative study by High-Performance Liquid Chromatography (HPLC). The results showed that phenolic compounds content, quantity and diversity in each sample was dependent on the extraction temperature.

High voltage electrical discharges combined with enzymatic hydrolysis for extraction of polyphenols and fermentable sugars from orange peels

Orange peels are a biomass rich in carbohydrates and polyphenols and characterized by their low lignin content. This work focuses on finding the best combination between physical and biological treatments to enhance the extraction of fermentable sugars and polyphenols. High voltage electrical discharges (HVED) (0 to 900 kJ/kg) or enzymatic hydrolysis with Viscozyme® L (12 FBGU/g) were applied on fresh or defatted orange peels for the extraction of polyphenols and fermentable sugars. An HVED energy input of 222 kJ/kg was optimal for the extraction of reducing sugars (19 g/100 g DM) and polyphenols (0.7 g/100 g DM). However, enzymatic hydrolysis allowed a higher extraction of reducing sugars (50 g/100 g DM). HVED were then applied prior or simultaneously to enzymatic hydrolysis to maximize the extraction of biomolecules from orange peels. Thus, the results clearly showed that the HVED pretreatment of orange peels is efficient to enhance the accessibility of cellulosic biomass to enzymes. HVED (222 kJ/kg) prior to enzymatic hydrolysis (12 FBGU/g), was the most effective combination of these two processes to get an intensive extraction of biomolecules from orange peels.

Effect of the Extraction Process on the Biological Activity of Lyophilized Apricot Extracts Recovered from Apricot Pomace

The preservation of polyphenols in fruits by lyophilization has gained great interest in the recent decades. The present study aims to assess the impact of the pre-treatment extraction methods heat-assisted extraction (HAE) and infrared (IR) on lyophilized apricot pomace extracts. Then to test the conservation of polyphenols quantities as well as their bioactivities (antiradical and antibacterial) in lyophilized extract. An aqueous extract was obtained through either heat-assisted extraction or infrared pre-treatments then lyophilized to obtain a dried form. Results showed that the content of polyphenols, the antiradical and antibacterial activities in lyophilized extracts exhibited a slighter decrease in infrared sample compared to the heat-assisted extraction ones. The High-performance liquid chromatography (HPLC) analysis showed that lyophilized extracts IR and HAE preserved the same phenolic molecules (rutin, catechin and epicatechin) detected in liquid extracts (IR and HAE) with a smaller yield. Lyophilization can be used as a widely process in the food industry to conserve many bioactive molecules.

A Comparative Study of the Phenolic and Technological Maturities of Red Grapes Grown in Lebanon

Grape harvest date is determined according to the technological and phenolic maturities. These parameters were calculated for different red grape (Vitis vinifera L.) varieties (Cabernet Sauvignon, Merlot, Syrah, Cabernet Franc) over four years (2008, 2009, 2010, and 2011) (642 samples). Titratable acidity and sugar content of the grapes were used to determine the technological maturity, whereas Glories (1 and 2) and ITV (Institut Technique de la Vigne et du Vin) methods were used to monitor their phenolic maturity. The ITV method allows the monitoring of phenolic maturity by the quantification of total polyphenol index and anthocyanins, while the Glories method enables the quantitative evolution of extractable anthocyanins and tannins of the grapes. A correlation was shown between the harvest dates obtained by both ITV and Glories (R2 = 0.7 – 0.93). Phenolic maturity of grapes can, therefore, be optimized by the application of both ITV and Glories. Similarly, a correlation was observed between technological and phenolic harvest dates. The effect of climate on the phenolic content of grapes was also studied. The highest temperatures (up to 25 °C) accompanied by the lowest rainfall (null value), induced the maximal concentration of polyphenols in grapes. Thermal and water stresses were also shown to enhance the grapes’ polyphenolic production.

Infrared-Assisted Extraction and HPLC-Analysis of Prunus armeniaca L. Pomace and Detoxified-Kernel and their Antidiabetic Effects: Infrared-Assisted Phytochemical Analysis of Prunus armeniaca

INTRODUCTION Prunus armeniaca L. (P. armeniaca) is one of the medicinal plants with a high safety-profile. OBJECTIVES The aim of this work was to make an infrared-assisted extraction (IR-AE) of P. armeniaca fruit (pomace) and kernel, and analyse them using reverse phase high-performance liquid chromatography (RP-HPLC) aided method. METHODS IR-AE is a novel-technique aimed at increasing the extraction-efficiency. The antidiabetic-potentials of the P. armeniaca pomace (AP) and the detoxified P. armeniaca kernel extract (DKAP) were monitored exploring their possible hypoglycemic-mechanisms. Acute (6 h), subchronic (8 days) and long-term (8 weeks) assessment of Diabetes mellitus (DM) using glucometers and glycated hemoglobin (HbA1c) methods were applied. RESULTS Serum-insulin levels, the inhibitory effects on alpha-glucosidase, serum-catalase (CAT) and lipid peroxidation (LPO) levels were also monitored. AP was shown to be rich in polyphenolics like trans-lutein (14.1%), trans-zeaxanthin (10.5%), trans-ß-cryptoxanthin (11.6%), 13, cis-ß-carotene (6.5%), trans 9, cis-ß-carotene (18.4%), and ß-carotene (21.5%). Prunus armeniaca kernel extract before detoxification (KAP) was found to be rich in amygdaline (16.1%), which caused a high mortality rate (50.1%), while after detoxification (amygdaline, 1.4%) a lower mortality rate (9.1%) was found. AP showed significant (p ≤ 0.05, n = 7/group) antidiabetic-activity more prominent than DKAP acutely, subchronically and on longer-terms. IR-AEs displayed more efficient acute and subchronic blood glucose level (BGL) reduction than a conventional extraction method, which might be attributed to IR-AE superiority in extraction of active ingredients. AP showed more-significant and dose-dependent increase in serum-insulin, CAT-levels and body-weights more prominent than those of DKAP. Alpha-glucosidase and LPO levels were inhibited with AP-groups more-significantly. CONCLUSION In comparison to conventional-methods, IR-AE appeared to be an efficient and time-conserving novel extraction method. The antidiabetic-potentials of pomace and detoxified-kernels of P. armeniaca were probably mediated via the attenuation of glucose-provoked oxidative-stress, the inhibition of alpha-glucosidase and the marked insulin-secretagogue effect. Copyright

Emerging Technologies for the Recovery of Valuable Compounds From Grape Processing By-Products

This chapter deals with the recovery of high added-value compounds from viticulture and winemaking by-products by means of emerging extraction technologies. The denoted grape processing by-products include vine shoots, grape pomace/marc (skins, seeds), grape stems, and wine lees. The basics and action mechanisms of high voltage electrical discharges, pulsed electric fields (electroporation), ultrasounds (acoustic cavitation), microwaves, pressurized solvent, pulsed ohmic heating, infrared, and supercritical fluid extraction are presented. Their applications and efficiencies in terms of polyphenols, proteins, simple sugars, tartaric acid, essential oils (fatty acids, tocopherols), pectins, glycosidic aroma precursors, squalene, hemicellulose, and lignin extraction were discussed through recent studies published in the field.

Industrial byproducts valorization through energy saving processes. Alkaline extraction of polyphenols from vine shoots

Vine shoots are viticulture byproducts recently valorized as important sources of polyphenols. These are powerful natural antioxidants used in several industrial applications. The aim of this work is to intensify polyphenol extraction from vine shoots (Syrah variety) using energy saving techniques. In this study, we chose to work with green solvent and in absence of organic solutions. The effect of NaOH concentrations (0, 1, 10, 100 and 1000 mM) on polyphenol extraction was studied. Polyphenol concentrations (Folin-Ciocalteu) and diffusion coefficients (Ficks second law) were calculated. The radical scavenging activity (DPPH assay) of extracts was determined. Polyphenol identification and quantification were conducted by High Performance Liquid Chromatography (HPLC). The maximal polyphenol yield (5 mg GAE/g of dry matter (DM)), diffusion coefficient (9 × 10-12 m2/s), radical scavenging activity (62 %) and the maximum molecular diversity were obtained using 1000 mM NaOH solution. We hereby propose an environmentally friendly procedure to valorize industrial waste using green technology, leading to the recovery of target compounds and their recycling inside food chain.