Moisture Sorption Isotherms of Sweet Cherry (Prunus Avium L.): Comparative Study of Kinetics and Thermodynamic Modeling of Five Varieties.

Moisture sorption isotherms of five sweet cherry cultivars (Prunus avium L.) at three temperatures of 30°C, 40°C, and 50°C, and water activity range of 0.057-0.898 were determined using the static gravimetric method. The sorption isotherms of all cultivars decreased with increasing temperature, and they all exhibited type II behavior according to the classification of IUPAC (International Union of Pure and Applied Chemistry). The isosteric heat of sorption, differential entropy, spreading pressure, and water surface area were determined, and the energy associated with the sorption processes was defined. The curves were fitted to GAB, PELEG, and ENDERBY models, and the GAB model gave the best fit for the whole set of data. The enthalpy-entropy compensation proved that the process occurs spontaneously and is fully controlled the enthalpy. The spreading pressure value varied with temperature in all sweet cherry cultivars in both the desorption and adsorption processes. The average surface area varied from 78.05 to 214.02 m2/g for desorption and from 49.0 to 204.4 m2/g for adsorption from 30 to 50°C.

Energetic Bio-Activation of Some Organic Molecules and Their Antioxidant Activity in the Pulp of the Moroccan Argan Tree «Argania spinosa L.¼.

Argania spinosa L. Skeels is an emblematic tree in Morocco, known worldwide for its medicinal and nutritional value. Its fruits contain kernels used to prepare an edible oil, the leaves are used to feed livestock, and its wood is used as fuel. If the oil acquires high importance, the other components of the fruit of the argan are undervalued. Our objective is to invest the waste of the argan industry. Particularly, our study aimed to assess the effect of thermal activation of argan pulp on its therapeutic value, its phenolic profile and its functional and physicochemical properties. After heat treatment, the HPLC analysis for the average total phenolic content varied from 2% to 37%, depending on temperature. The antioxidant activity was increased with heat treatment. Higher values of antioxidant activity, polyphenol and pigment content were recorded at 70 °C. Functional properties analysis indicated that water solubility index and water absorption capacity were significantly affected by heat stress. Physicochemical analysis showed that moisture content, titratable acidity and soluble solids were affected.

Impact of particle size on functional, physicochemical properties and antioxidant activity of cladode powder (Opuntia ficus-indica).

Particle size is an important quality parameter of pharmaceutical and processed food products. The present study aimed at evaluating the effect of powder fractionation on the functional, physicochemical properties and antioxidant activity of cladode powder with particle size ranging from < 45 to 500 µm. Granulometric study presented bimodal granules' volume distribution explaining the irregular shape of particles. The results indicated that functional properties were significantly (p < 0.05) affected by particle size distribution and the critical fraction size was 63-80 µm. Scanning electron microscopy showed that morphology of cladode powder granules was highly related to the grinding treatment. Physicochemical analysis showed that ash content and soluble solids were more affected contrary to moisture, pH and titratable acidity. Chlorophylls (a, b) and carotenoids content of fractionated powder were affected significantly unlike color (b* value). The granulometric classes (80-100 µm) had the highest polyphenol and flavonoids content (605.30 mg GAE/100 g and 476.33 mg CE/100 g respectively). Two fractions "100-200 µm" and "80-100 µm" exhibited a high rise in the antioxidant activity as determined by the DPPH, ABTS and FRAP essays compared to other fractions. The chemical composition and bioactive compounds analysis of cladode powder confirmed a differential distribution of chemical composition and bioactive compounds according to particle size.

An arabinogalactan from the skin of Opuntia ficus-indica prickly pear fruits.

The cold-water extract from the skin of Opuntia ficus-indica fruits was fractionated by anion-exchange chromatography. The major fraction, which was purified by size exclusion chromatography, consisted of a polysaccharide composed of galactose and arabinose residues in the ratio 6.3:3.3, with traces of rhamnose, xylose and glucose, but no uronic acid. The results of methylation analysis, supported by (13)C NMR spectroscopy, indicated that this polysaccharide corresponded to an arabinogalactan having a backbone of (1-->4)-linked beta-D-galactopyranosyl residues with 39.5% of these units branched at O-3. The side-groups consisted either of single L-arabinofuranosyl units or L-arabinofuranosyl alpha-(1-->5)-linked disaccharides. This polysaccharide is thus an arabinogalactan that can be classified in the type I of the arabinogalactan family.

First evidence for the presence of weddellite crystallites in Opuntia ficus indica parenchyma.

Calcium oxalate crystallites occur very often in the plants tissues and their role is still poorly known. We report here the experimental protocol leading to the isolation of two forms of calcium oxalate crystallites differing in their hydration level in the parenchymal tissues of Opuntia ficus indica (Miller). Whereas the whewellite crystallites are habitual in all Opuntia species, the weddellite form has never been isolated from these species before, which is probably due to their small size (about 1 microm). We have identified these forms using X-ray diffraction and scanning electron microscopy.

Effect of gamma-irradiation combined with washing and waxing treatment on physicochemical properties, vitamin C, and organoleptic quality of Citrus clementina Hort. Ex. Tanaka.

To enhance the shelf life of a late variety of Moroccan Citrus clementina (Nour), ionizing treatments were applied at 0.3 kGy, as well as washing (cold water) and waxing treatments. It has been found that, despite the irradiation treatment, the washing and waxing treatment do not improve the quality of C. clementina, but rather result in yellower peels, peel injury, and reductions of vitamin C content, acidity, and soluble solids. However, gamma-irradiation alone enhanced significantly (p

Isolation and structure of D-xylans from pericarp seeds of Opuntia ficus-indica prickly pear fruits.

Xylans were isolated from the pericarp of prickly pear seeds of Opuntia ficus-indica (OFI) by alkaline extraction, fractionated by precipitation and purified. Six fractions were obtained and characterized by sugar analysis and NMR spectroscopy. They were assumed to be (4-O-methyl-D-glucurono)-D-xylans, with 4-O-alpha-D-glucopyranosyluronic acid groups linked at C-2 of a (1-->4)-beta-D-xylan. The sugar composition and the 1H and 13C NMR spectra showed that their chemical structures were very similar, but with different proportions of D-Xyl and 4-O-Me-D-GlcA. Our results showed that, on average, the water soluble xylans have one nonreducing terminal residue of 4-O-methyl-D-glucuronic acid for every 11 to 14 xylose units, whereas in the water non-soluble xylans, xylose units can varied from 18 to 65 residues for one nonreducing terminal residue of 4-O-methyl-D-glucuronic acid.