Khaled Belkacemi

Effect of pre-harvest chitosan sprays on post-harvest infection by Botrytis cinerea and quality of strawberry fruit

The effect of pre-harvest sprays of chitosan on post-harvest decay and quality of strawberries stored at 3 and 13°C was investigated. Strawberry plants were sprayed with 2, 4 an d6gl 1 , chitosan solutions as the fruit were turning red. A second spray was performed after 10 days. Fruit were picked 5 and 10 days after each spray. Harvested fruit from chitosan sprayed plants were challenged with Botrytis cinerea. Chitosan sprays significantly reduced post-harvest fungal rot and maintained the keeping quality of the fruit compared with control. The incidence of decay decreased with increased chitosan concentration and increased with storage period and temperature. The second spray of chitosan extended the protective effect against decay of fruit from subsequent picks. Fruit from chitosan sprayed plants were firmer and ripened at a slower rate as indicated by anthocyanin content and titratable acidity than berries from non-treated plants. Chitosan sprays were not phytotoxic at all the concentrations tested. Chitosan sprays at 6 gl 1 concentration performed twice, 10 days apart, protected the fruit from decay and kept the fruit quality at an acceptable level throughout the storage period of 4 weeks in fruit stored at 3°C. The protective effect of chitosan sprays was more pronounced for fruit from pick 1 than pick 2. Kinetic data on decay and ripening characteristics provided quantitative evidence that chitosan compensates for higher storage temperature and protects against deterioration of lower quality fruit from the second harvest.

Catalytic oxidation of aqueous phenolic solutions catalyst deactivation and kinetics

Abstract The catalytic oxidation of aqueous phenol over MnO 2 /CeO 2 mixed oxide catalyst was shown to be accompanied with undesirable formation of heavy polymers on the catalyst surface leading thereby to its deactivation. This deactivation was proved experimentally through comprehensive quantitative and qualitative experimental measurements such as elemental analysis of deactivated cata-lyst, X-ray photoelectron spectroscopy, and temperature-programmed oxidation coupled with mass spectrometry. Using the Langmuir–Hinshelwood–Hougen–Watson approach, a deactivation-reaction network kinetic model was developed to predict the fate of the various carbon lumps involved in phenol wet oxidation. It was postulated that deactivation was the resultant of blockage of active sites by fouling species issued from polymerization of parent reactant (phenol) and its daughter intermediate dissolved partially oxidized products. The kinetic model was verified by comparing the experimental results with those foreseen in the simulation for different experimental conditions.

Ethanol Production from AFEX -Treated Forages and Agricultural Residues

Lignocellulosic materials derived from forages, namely timothy grass, alfalfa, reed canary grass, and agricultural residues, such as corn stalks and barley straw, were pretreated using ammonia fiber explosion (AFEX) process. The pretreated materials were directly saccharified by cellulolytic enzymes. Sixty to 80% of theoretical yield of sugars were obtained from the pretreated biomasses. Subsequent ethanolic fermentation of the hydrolysates byPachysolen tannophilus ATCC 32691 resulted in 40-60% of theoretical yield after 24 h, based on the sugars present in the hydrolysates. The uptake of sugars was not complete, indicating a possible inhibitory effect onP. tannophilus during the fermentation of these substrates.

Adsorptive removal of dihydrogenphosphate ion from aqueous solutions using mono, di- and tri-ammonium-functionalized SBA-15

Adsorption of monovalent phosphate anions from aqueous solutions on mono, di- and tri-ammonium-functionalized mesoporous SBA-15 silica was investigated. The adsorbent was prepared via a post-synthesis grafting method, using 3-aminopropyltrimethoxysilane (N-silane), [1-(2-aminoethyl)-3-aminopropyl]trimethoxysilane (NN-silane) and 1-[3-(trimethoxysilyl)-propyl]-diethylenetriamine (NNN-silane), followed by acidification in HCl solution to convert the attached surface amino groups to positively charged ammonium moieties. The loading of amino moieties on the SBA-15 surface was varied from 5% to 40% as organoalkoxysilane/silica molar ratio. The adsorption experiments were conducted batchwise at room temperature. Results showed that adsorption capacity increased with increasing the concentration of functional groups on the SBA-15 adsorbent whatever the nature of the functional group. In the case of monoammonium functional groups, the adsorption capacity increased from 0.64 to 1.07 mmol H(2)PO(4)(-)/g when the molar ratio organoalkoxysilane/silica was varied from 5% to 40%, respectively. Similar tendency was observed in the case of diammonium and triammonium organic functional groups. Also, for the same organoalkoxysilane/silica molar ratio, the adsorption capacity increased markedly with the increase of the number of protonated amines in the functional groups. Therefore, maximum adsorption capacities of 1.07, 1.70 and 2.46 mmol H(2)PO(4)(-)/g adsorbent were obtained using mono-, di- and tri-ammonium-functionalized SBA-15, respectively.

Catalytic wet air oxidation with a deactivating catalyst analysis of fixed and sparged three-phase reactors

Abstract A comparative analysis is made for a trickle-bed reactor, a packed-bubble column, a three-phase fluidized bed and a slurry-bubble column with an active and moderately deactivating catalyst for the wet oxidation at high pressure and temperature of organic-containing aqueous wastes. Compared to other mature industrial sectors where multiphase reactors are prevalent, the design of three-phase catalytic reactors for wet air oxidation processes is still at an emerging stage. This paper discusses, from a multiphase reactor engineering perspective, the design of such contactors by setting an exhaustive modeling framework of catalytic wet oxidation in which the molecular, particle and reactor scales are integrated. The simulation results indicate that when wet oxidation is liquid-reactant limited, packed-bubble columns outperform trickle beds, whereas slurry-bubble columns are the most vulnerable to “coke” deactivation.

Effect of Protein on Flux and Selectivity in Pervaporation of Ethanol from a Dilute Solution

The separation of ethanol from a 2% w/w ethanol–water mixture by pervaporation through a thin polydimethyl-siloxane (PDMS) membrane sheet was studied with and without a dissolved vegetable protein in the feed solution. Total flux and ethanol selectivity were measured at different feed temperatures (40, 50, and 60°C) and permeate-side pressures (1, 10, 20, and 40 mm Hg). An analysis of variance was done to detect effects and interactions. Protein at 10 g/L did not foul the membrane under the conditions used and had no significant effect on flux or selectivity. The effects of protein and temperature on ethanol selectivity interacted slightly.

Catalytic oxidation of 4-chloroguaiacol reaction kinetics and catalytic studies

Abstract This paper describes the non-catalytic oxidation and the solid-catalysed oxidation of a chlorinated organo-compound contained in softwood pulp mill effluents. The oxidation of 4-chloroguaiacol was catalysed efficiently using Pt/alumina, manganese/cerium and cobalt/bismuth composite oxide catalysts. Self-inhibition of the parent pollutant, recalcitrance of highly stable organic by-products, and catalyst deactivation were the main causes that prevented full mineralization of the waste-water organic load. A comprehensive homogeneous–heterogeneous deactivation reaction network model was used to account for the distribution of carbon in the liquid, in the gas and on the solid phases. The model combined a two-parallel reaction scheme for the non-catalytic oxidation and a Langmuir–Hinshelwood approach for the catalyst-mediated oxidation.

Phytosterols, unsaturated fatty acid composition and accumulation in the almond kernel during harvesting period: Importance for development regulation

The evolution of the composition of sterols and squalene during the maturation of the fruit of three cultivars (Achaak, Perlees and Mazetto) almond (Prunus amygdalus Batsh) was investigated. At the same time the evolution of oleic, linoleic and linolenic fatty acids was also studied. The qualitative and quantitative analyses were made by GC-MS and GC-FID. The present study is based on three axes: The first one is the structural and molecular identification of compounds sterolic and squalene, which are based on the principal of cleavage and the fragmentation characteristic of each peak provided by mass spectrometry. The second axis is interested in the physiological phenomenon of phytosterols accumulation: biosynthesis, evolution, and their relation with squalene as well as their interconversion. The third axis is an emergence of a relationship, which seems to exist, between the biosynthetic compounds of the glyceridic fraction of almond oil (mainly fatty acids) and those of the unsaponifiable fraction (particularly sterols). This relation may be established by 24-methylene cholesterol.

Spice use in food: Properties and benefits

ABSTRACT Spices are parts of plants that due to their properties are used as colorants, preservatives, or medicine. The uses of spices have been known since long time, and the interest in the potential of spices is remarkable due to the chemical compounds contained in spices, such as phenylpropanoids, terpenes, flavonoids, and anthocyanins. Spices, such as cumin (cuminaldehyde), clove (eugenol), and cinnamon (cinnamaldehyde) among others, are known and studied for their antimicrobial and antioxidant properties due to their main chemical compounds. These spices have the potential to be used as preservatives in many foods namely in processed meat to replace chemical preservatives. Main chemical compounds in spices also confer other properties providing a variety of applications to spices, such as insecticidal, medicines, colorants, and natural flavoring. Spices provide beneficial effects, such as antioxidant activity levels that are comparable to regular chemical antioxidants used so they can be used as a natural alternative to synthetic preservatives. In this review, the main characteristics of spices will be described as well as their chemical properties, different applications of these spices, and the advantages and disadvantages of their use.

An efficient method for high-purity anthocyanin isomers isolation from wild blueberries and their radical scavenging activity

An efficient process for the purification of anthocyanin monomeric isomers from wild blueberries of Lake Saint-Jean region (Quebec, Canada) was developed and easy scalable at industrial purpose. The blueberries were soaked in acidified ethanol, filtered, and the filtrate was cleaned by solid phase extraction using silica gel C-18 and DSC-SCX cation-exchange resin. Anthocyanin-enriched elutes (87 wt.%) were successfully fractionated by preparative liquid chromatography. The major anthocyanins mono-galactoside, -glucoside and -arabinoside isomers of delphinidin, cyanidin, petunidin, peonidin and malvidin were isolated with a purity up to 100% according to their LC-MS and (1)H NMR spectra. The oxygen radical absorbance capacity (ORAC) of the obtained pure anthocyanins was evaluated. Delphinidin-3-galactoside has the highest capacity (13.062 ± 2.729 μmol TE/μmol), and malvidin-3-glucoside the lowest (0.851 ± 0.032 μmol TE/μmol). A mechanistic pathway preview is suggested for the anthocyanins scavenging free radical activity by hydrogen transfer.