Polysaccharides from Tossa jute (Corchorus olitorius L.) leaves: Extraction, antioxidant and antibacterial activities

The biological proprieties of mucilaginous polysaccharides (PSc) extracted from Tossa jute leaves (Corchorus olitorius  L.) using an ethanol precipitation method were studied. The results showed that PSc had higher total polyphenols and flavonoids and greater antioxidant activities. At 1.5 mg/ml PSc, the antioxidant activities were about 90% against 1,1-diphenyl-2-picryl hydrazyl radical (DPPH•) and 78% against lipid peroxidation. The PSc with a FRAP assay at the same concentration showed an effective protection against hydroxyl radicals and DNA breakage. Furthermore, the extracted PSc had a wide spectrum of antibacterial activities against all bacteria tested (Gram+ and Gram-). The overall data suggested that this natural PSc may be used as a competitive antioxidant and antimicrobial additive in food and in medicinal preparations

Moringa oleifera leaves: LC-ESI-MS analysis of phenolic compounds and antioxidant activities

Research on bioactive compounds derived from medicinal plants is still topical and their applications are of interest to food industry, phytopharmacy and cosmetics. The present study deals with the phenolic compounds profile and antioxidant activities of Moringa oleifera Lam. leaves. Therefore, this work is a contribution to study the potential of M. oleifera as a new crop in Tunisia. Composition of phenolic compounds was realized using LC-ESI-MS analysis. Antioxidant activities were assessed using many complementary methods. Extracts from Moringa leaves contained interesting amounts of total phenolics (33–99 mg GAE/g extract) and flavonoids (7–18 mg QE/g extract), with appreciable antioxidant activities in Fe3+ reducing (EC0.5: 0.5–1.1 mg/ml), DPPH• radical-scavenging (IC50: 0.6–1.9 mg/ml), β-carotene/linoleic acid bleaching (IC50: 66–120 µg/ml) and Fe2+ chelating (IC50: 0.5–0.8 mg/ml) assays. Quinic acid, gallic acid, quercetin-3-O-galactoside and quercetin-3-O-rhamnoside were the major compounds measured in the different extracts (5.5–13.5 mg/g extract). M. oleifera grown in oasis of Chenini-Gabes, southeastern Tunisia, can be a source of potent antioxidants for various food, nutraceutical or cosmeceutical applications

Développement d’une nouvelle saucisse de dromadaire : Effet de l’incorporation d’éleusine (Eleusine coracana L.) sur la qualité sensorielle et la stabilité

L’objectif de cette étude est de formuler une saucisse à base de viande de dromadaire qui s’aligne avec la tendance des « allégations santé » visant à réduire la consommation de viandes rouges conventionnelles et de graisses animales. Par ailleurs, l’effet de la substitution de la fécule de pomme de terre, couramment utilisé en tant qu’agent liant dans les produits charcutiers, par la farine intégrale d’éleusine (Eleusine coracana L.) sur la qualité de la saucisse a été étudié. L’éleusine est cultivée dans l’oasis de Chenini-Gabès, située dans le sud-est de la Tunisie. L’analyse de sa composition révèle une teneur 70,19% en carbohydrates, dont 11,5% sont des fibres alimentaires, 13,53% de protéines, 2,75% de cendres, 1,81% de lipides et 0,25% de composés phénoliques. Sa capacité de rétention d’eau atteint 150 g d’eau/100 g. Par ailleurs, l’activité anti-DPPH• de l’extrait eau/éthanol révèle une valeur de CI50 de 60 µg/ml. Ensuite, la stabilité de la saucisse de dromadaire a été suivie pendant 21 j de stockage réfrigéré. L’introduction de la farine d’éleusine n’a pas altéré la qualité sensorielle, et a réussi à maintenir les caractéristiques texturales, à stabiliser la couleur et les pigments héminiques, et à limiter l’oxydation des lipides. Les résultats de cette étude suggèrent que la farine d’éleusine se positionne comme un substitut prometteur de la fécule de pomme de terre dans la fabrication de saucisses. Il est intéressant d’approfondir les recherches dans ce domaine afin d’explorer davantage les applications potentielles de la farine d’éleusine dans l’industrie alimentaire

Gélatines de poisson : Préparation, propriétés et applications [Fish gelatins : Preparation, properties and applications]

Foods and pharmaceutical industries all over the world attend an increasing demand for gelatin, a biopolymer derived from collagen. Gelatins are widely used due to their biocompatibility, biodegradation, physical and functional properties. Porcine and bovine gelatins, the most commonly used, are subject to major constraints and skepticism among consumers, this is due to socio-cultural and health-related issues. Therefore, there is an increasing demand for alternative sources. The by-products generated by fish-processing industries are a potential source for the production of gelatins. Fish gelatin possesses interesting characteristics and may thus be considered as an alternative to mammalian gelatin for use in food, pharmaceutical and photographic products. This review enumerates gelatin preparation processes, as well as, their physical properties, and their potential applications in many fields, such as food, pharmacy and photography industries

Antioxidant and antibacterial activities, interfacial and emulsifying properties of the apo and holo forms of purified camel and bovine α-lactalbumin

International audienceThe antioxidant and antibacterial activities of camel and bovine α-lactalbumin (α-La) in both calcium-loaded (holo) and calcium-depleted (apo) forms were investigated and compared. Antioxidant assay showed that camel and bovine α-La exhibited significant Ferric-reducing antioxidant power (FRAP), ferrous iron-chelating activity (FCA) and antiradical activities especially in their apo form. Camel apo α-La also exhibited attractive antibacterial activities against Gram-negative bacteria (Pseudomonas aeruginosa) and against fungal pathogens species (Penicillium bilaiae, Aspergillus tamari and Aspergillus sclerotiorum). Likewise, emulsifying properties (emulsification ability (EAI) and stability (ESI) indexes) and the surface characteristics (surface hydrophobicity, ζ-potential and interfacial tension) of the α-La were assessed. Maximum EAI were found at pH 7.0, with higher EAI values for the camel apo α-La (EAI ~19.5 m2/g). This behavior was explained by its relative high surface hydrophobicity and its greater efficiency to reduce the surface tension at the oil-water interface. Furthermore, emulsions were found to be more stable at pH 7.0 compared to pH 5.0 (ESI ~50%) due to the higher electrostatic repulsive forces between oil droplets at pH 7.0 in consistence with the ζ-potential results. This study concluded that the camel apo α-La has antibacterial, antioxidant, and emulsifying properties in agricultural and food industries

Design of Gelatin Pouches for the Preservation of Flaxseed Oil during Storage

International audienceFlaxseed oil (FO) is composed mainly of polyunsaturated fatty acids that are very sensitive to oxidation induced by oxygen, temperature, and light. To overcome this problem, gelatin-based films containing glucose are crosslinked via the Maillard reaction (MR) at 120 °C and used for the conception of pouches in which the FO was packaged. The prepared pouches, as well as the oil alone, are incubated at 50 °C for 21 days. The results show that the peroxide index of the oil stored in the gelatin-based pouches is almost stable and decreases on the 21st day. The specific extinction coefficients prove a more pronounced degradation of the non-package oil (control). In addition, the results of thiobarbituric acid reactive substances (TBARs) test reveal higher values in the control, with a tendency to continuously increase up until the 21st day. However, the oil stored in the pouches reveals less TBARs content, decreasing with oxidation time. The non-heated glucose-supplemented pouches showed the best results, suggesting a moderate and gradual development of the MR at 50 °C. The application of pouches based on gelatin films seems to be an effective and interesting tool for protecting FO against lipid oxidation, acting as perfectly biodegradable and sustainable containers for small doses

Effect of ultrasound pretreatment and Maillard reaction on structure and antioxidant properties of ultrafiltrated smooth-hound viscera proteins-sucrose conjugates

The effect of ultrasound (US) pre-treatment on the evolution of Maillard reaction (MR), induced between low molecular weight (LMW) peptides and sucrose, was studied. LMW peptides (<1 kDa) were obtained by the ultrafiltration of smooth hound viscera protein hydrolysates, produced by Neutrase, Esperase and Purafect. MR was induced by heating the LMW peptides in the presence of sucrose for 2 h at 90 °C, without or with US pre-treatment. During the reaction, a marked decrease in pH values, coupled to the increase in colour of the Maillard reaction products (MRPs), were recorded. In addition, after sonication, the glycation degree was significantly enhanced in Esperase-derived peptides/sucrose conjugates (p < 0.05). Moreover, results showed that thermal heating, particularly after US treatment, reduced the bitter taste and enhanced the antioxidant capacities of the resulting conjugates. Hence, it could be concluded that US leads to efficient mixing of sugar-protein solution and efficient heat/mass transfer, contributing to increase the MR rate.This work was funded by the Ministry of Higher Education and Scientific Research, Tunisia. Emerging Research Group Grant from Generalitat Valenciana in Spain (GV/2015/138) and JAEDOC-CSIC postdoctoral contract of L.M. cofounded by the European Social Found are acknowledged.Peer reviewe

Bioactive films based on cuttlefish (Sepia officinalis) skin gelatin incorporated with cuttlefish protein hydrolysates: Physicochemical characterization and antioxidant properties

International audienceThe objective of this study was to apply cuttlefish (Sepia officinalis) skin protein isolate (CSPI) and hydrolysates (CSPH), using commercial Savinase® and Purafect® enzymes, as bioactive additives in the elaboration of gelatin-based films. CSPH and CSPI enriched films were colored and exhibited a higher UV-barrier properties compared to gelatin film. In addition, compared to CSPI added film, an increase of the glass transition temperature by 20 % and 4 %, respectively, for Purafect and Savinase hydrolysates enriched films was noted. However, elongation at break decreased significantly for CSPH incorporated films by 2.5-fold. The tensile strength was reduced by 28.2 % and 44.4 % for Purafect and Savinase hydrolysates added films, respectively. Furthermore, a decrease of water contact angle by 45 % and 51 % for films added with Purafect and Savinase hydrolysates, respectively, was displayed compared to gelatin film. Interestingly, CSPH enriched films also displayed higher antioxidant potential than control gelatin films evaluated by several in vitro assays

Influence of Maillard reaction and temperature on functional, structure and bioactive properties of fish gelatin films

International audienceThis study aims to assess the effect of heating temperatures on structure, physicochemical and antioxidant properties of fish gelatin films crosslinked by the temperature and/or with glucose by the Maillard reaction.Glucose was incorporated at a 0.5 glucose/lysine molar ratio into the fish gelatin film forming solutions. The products of the Maillard reaction were generated by heating the films during 24 h in a temperature range of 90–130 °C. An enhancement of some films properties was obtained after the induction of the Maillard reaction. Indeed, the water solubility and wettability were reduced. On the contrary, a rise of color intensity, UV-barrier property, radical scavenging activities and iron reducing effects was observed. These enhancements occurred also without glucose addition thanks to the heating treatment, but to a lesser extend. In addition, an increase of thermal stability due to structural changes was revealed by means of XRD, TGA and DSC analyses. As evidenced by the different experiments used for the determination of the antioxidant activity (DPPH• and ABTS free radicals scavenging activity, reducing power and β-carotene bleaching inhibition) the antioxidant activity of films containing glucose displayed an optimum after being treated at 90 °C. On the contrary, it decreased or kept constant at higher temperatures, probably due to the degradation or further stages of Maillard reactions. Moreover, the thermal treatment alone (T ≥ 100 °C) can be a useful tool for enhancing the antioxidant activity of gelatin films. Finally, the Maillard reaction has a good potential to induce and generate bioactive compounds in gelatin films for food protection

Extraction of Protein and Bioactive Compounds from Mediterranean Red Algae (Sphaerococcus coronopifolius and Gelidium spinosum) Using Various Innovative Pretreatment Strategies

International audienceIn this study, the release of proteins and other biomolecules into an aqueous media from two red macroalgae (Sphaerococcus coronopifolius and Gelidium spinosum) was studied using eight different cell disruption techniques. The contents of carbohydrates, pigments, and phenolic compounds coextracted with proteins were quantified. In addition, morphological changes at the cellular level in response to the different pretreatment methods were observed by an optical microscope. Finally, the antioxidant capacity of obtained protein extracts was evaluated using three in vitro tests. For both S. coronopifolius and G. spinosum, ultrasonication for 60 min proved to be the most effective technique for protein extraction, yielding values of 3.46 ± 0.06 mg/g DW and 9.73 ± 0.41 mg/g DW, respectively. Furthermore, the highest total contents of phenolic compounds, flavonoids, and carbohydrates were also recorded with the same method. However, the highest pigment contents were found with ultrasonication for 15 min. Interestingly, relatively high antioxidant activities like radical scavenging activity (31.57–65.16%), reducing power (0.51–1.70, OD at 700 nm), and ferrous iron-chelating activity (28.76–61.37%) were exerted by the different protein extracts whatever the pretreatment method applied. This antioxidant potency could be attributed to the presence of polyphenolic compounds, pigments, and/or other bioactive substances in these extracts. Among all the used techniques, ultrasonication pretreatment for 60 min appears to be the most efficient method in terms of destroying the macroalgae cell wall and extracting the molecules of interest, especially proteins. The protein fractions derived from the two red macroalgae under these conditions were precipitated with ammonium sulfate, lyophilized, and their molecular weight distribution was determined using SDS-PAGE. Our results showed that the major protein bands were observed between 25 kDa and 60 kDa for S. coronopifolius and ranged from 20 kDa to 150 kDa for G. spinosum. These findings indicated that ultrasonication for 60 min could be sufficient to disrupt the algae cells for obtaining protein-rich extracts with promising biological properties, especially antioxidant activity