Alimentary Analysis Unit

Sfax, Tunisia

Alimentary Analysis Unit

Sfax, Tunisia
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Lajnaf R.,Alimentary Analysis Unit | Lajnaf R.,Montpellier University | Picart-Palmade L.,Montpellier University | Attia H.,Alimentary Analysis Unit | And 2 more authors.
Colloids and Surfaces B: Biointerfaces | Year: 2017

The effect of pH (4.3 or 6.5) and heat treatment (70 °C or 90 °C for 30 min) on the foaming and interfacial properties of α-lactalbumin extracted from camel milk were studied. The increased temperature treatment changed the foaming properties of camel α-lactalbumin solution and its ability to unfold at the air–water interface. At neutral pH, heat treatment was found to improve foamability, whereas at acid pH (4.3) this property decreased. Foams were more stable after a heat treatment at pH 4.3 than at 6.5, due to higher levels of protein aggregation at low pH. Heat treatment at 90 °C for 30 min affected the physicochemical properties of the camel α-lactalbumin by increasing free thiol group concentration at pH 6.5. Heat treatment also caused changes in α-lactalbumin's surface charge. These results also confirm the pronounced aggregation of heated camel α-lactalbumin solution at acid pH. © 2017

Lajnaf R.,Alimentary Analysis Unit | Lajnaf R.,Montpellier University | Picart-Palmade L.,Montpellier University | Cases E.,University of Burgundy | And 3 more authors.
Food Chemistry | Year: 2018

The effect of heat treatment (70 °C or 90 °C for 30 min) on the foaming and interfacial properties of acid and sweet whey obtained from bovine and camel fresh milk was examined. The maximum foamability and foam stability were observed for acid whey when compared to sweet whey for both milks, with higher values for the camel whey. This behavior for acid whey was explained by the proximity of the pI of whey protein (4.9–5.2), where proteins were found to carry the lowest negative charge as confirmed by the zeta potential measurements. Interfacial properties of acid camel whey and acid bovine whey were preserved at air water interface even after a heat treatment at 90 °C. These results confirmed the pronounced foaming and interfacial properties of acid camel whey, even if acid and sweet bovine whey exhibited the highest viscoelastic modulus after heating. © 2017 Elsevier Ltd

Ennouri M.,Higher Institute of Applied science and Technology of Mahdia | Ennouri M.,Alimentary Analysis Unit | Khemakhem B.,University of Sfax | Hassen H.B.,University of Sfax | And 4 more authors.
Journal of the Science of Food and Agriculture | Year: 2013

Background: In Tunisia, prickly pear fruit grow spontaneously; it is consumed as fresh fruit, juice or jam. When the fruit is used for juice production, the seeds are discarded and go to waste. Our study aimed to extract biomolecules from seeds by producing value-added products from the fruits. Results: An amylase from Opuntia ficus-indica seeds was extracted and purified to homogeneity. An increase in specific activity of 113-fold was observed. The apparent molecular mass of the enzyme is 64 kDa. The optimum pH and temperature for enzyme activity were pH 5 and 60 ?C, respectively. Under these conditions, the specific activity is 245.5 U mg-1. The enzyme was activated by Co2+ and Mg2+ (relative activity 117% and 113% respectively) at lower ion concentrations. It was strongly inhibited byMn2+ and Fe2+. Cu2+ inhibited totally the activity of this enzyme, but Ca2+ has an inhibitory effect which increases with ion concentration. Conclusion:The extractedenzymebelongs to the exo type of amylasesandis classified as aβ-cyclodextringlycosyltransferase since it generates mainly β-cyclodextrin from starch. It exhibits high thermal stability and a broad range of pH stability, making it a promising prospect for industrial and food applications. © 2012 Society of Chemical Industry.

Ennouri M.,Higher Institute of Applied science and Technology of Mahdia | Ennouri M.,Alimentary Analysis Unit | Ammar I.,Alimentary Analysis Unit | Khemakhem B.,University of Sfax | Attia H.,Alimentary Analysis Unit
Journal of Medicinal Food | Year: 2014

Opuntia ficus-indica f. inermis (cactus pear) flowers have wide application in folk medicine. However, there are few reports focusing on their biological activity and were no reports on their chemical composition. The nutrient composition and hexane extracts of Opuntia flowers at 4 flowering stages and their antibacterial and antifungal activities were investigated. The chemical composition showed considerable amounts of fiber, protein, and minerals. Potassium (K) was the predominant mineral followed by calcium (Ca), magnesium (Mg), sodium (Na), iron (Fe), and zinc (Zn). The main compounds in the various hexane extracts were 9.12-octadecadienoic acid (29-44%) and hexadecanoic acid (8.6-32%). The antibacterial activity tests showed that O. inermis hexane extracts have high effectiveness against Escherichia coli and Staphylococcus aureus, making this botanical source a potential contender as a food preservative or food control additive. © 2014, Mary Ann Liebert, Inc. and Korean Society of Food Science and Nutrition.

Ennouri M.,Alimentary Analysis Unit | Ennouri M.,Higher Institute of Applied science & Technology of Mahdia | Ben Hassan I.,University of Sfax | Ben Hassen H.,University of Sfax | And 3 more authors.
Journal of Food Science and Technology | Year: 2015

Purple carrot juice was clarified by microfiltration. Two modes of filtration, batch concentration and total recycle were tested and the effect of microfiltration process on permeate flux and membrane fouling was studied. Intrinsic membrane resistance was negligible compared with the fouling resistances, which was less than 5 % of total resistance. Determination of membrane hydraulic permeability showed that water cleaning could permit a recovery of about 7 % of initial hydraulic flux. The analysis of color parameters of feed, permeate and concentrate juice during filtration shows that the a* and b* values decrease for the permeate corresponding respectively to changes from green to red and from blue to yellow. The total sugar and reducing sugars increase in permeate and decrease in concentrate. This work showed that it was possible to clarify the purple carrot juice by microfiltration with a real amelioration of the juice appearance. © 2014, Association of Food Scientists & Technologists (India).

Ammar I.,Alimentary Analysis Unit | Ennouri M.,Alimentary Analysis Unit | Ennouri M.,Higher Institute of Applied science and Technology of Mahdia | Khemakhem B.,University of Sfax | Attia H.,Alimentary Analysis Unit
Industrial Crops and Products | Year: 2012

The chemical composition of hexane extracts from flowers belonging to two species of prickly pear, Opuntia ficus-indica (L.) Miller and Opuntia stricta (Haw.) Haworth has been studied by gas chromatography-mass spectrometry in four developmental stages of flower: vegetative, initial flowering, full flowering, and post-flowering stages. Remarkable differences were noted between the flowers' compositions. The main compounds were carboxylic acid (28-97%), terpenes (0.2-57%), esters (0.2-27%), and alcohols (<1.8%).The study of the biological activities showed that extracts were active in vitro towards four bacteria and two fungal strains. It exhibited remarkable activity against Pseudomonas aeruginosa, Staphylococcus aureus, and Escherichia coli.Antioxidant activity of the flowers extracts was evaluated by the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical method.Our findings demonstrate the interest of Opuntia flowers extract as a source of bioactive substances and its potential preservative use in food. © 2011 Elsevier B.V.

Baccouche A.,Alimentary Analysis Unit | Ennouri M.,Alimentary Analysis Unit | Ennouri M.,Higher Institute of Applied science and Technology of Mahdia | Felfoul I.,Alimentary Analysis Unit | Attia H.,Alimentary Analysis Unit
Food Hydrocolloids | Year: 2013

This study aimed at the development of whey-based prickly pear (WBP) beverages. Prickly pear juice and acid whey were characterized and a factorial design was used to study the effect of three factors. Four formulations of whey-based prickly pear beverages were prepared using the fractional 23-1 factorial design. To note, the three factors considered were whey treatment (WT) and added sugar and pectin (Sand P). Two levels for each factor were tested, namely added sugar (5 or 10%), whey treatment (with or without heat treatment) and added pectin (0 or 0.05%). The turbidity percentage increase, the color-index percentage decrease, the sedimentation percentage increase, as well as the serum separation percentage were evaluated after 40 days of storage condition at 4°C. The three factors optimization for the beverages' maximum stability were implemented by testing the main and interaction effects plots, the analysis of variance (ANOVA), the normal probability plots of standardized effects and residuals, the Pareto charts and the contour plots. The achieved results showed that the beverages were physically stabilized by sugar and HM-pectin amount increase using the heat-treated whey. Hence, regression models were suggested, which fitted the experimental data very well (R2 >75% and p<0.05). © 2013 Elsevier Ltd.

Ammar I.,Alimentary Analysis Unit | Ennouri M.,Alimentary Analysis Unit | Ennouri M.,Higher Institute of Applied science and Technology of Mahdia | Attia H.,Alimentary Analysis Unit
Industrial Crops and Products | Year: 2015

The effect of different extracting solvents used by two methods on the total polyphenols and flavonoids contents of Opuntia ficus-indica flowers was studied. The antioxidant activity of these extracts was investigated by using DPPH radical scavenging, reducing power and β-carotene bleaching assays. The results showed that extracts exhibited different levels of polyphenols contents and antioxidant activity. Thus, solvents with different polarities had significant effect on antioxidant activity. The methanolic and aqueous extracts proved best in terms of high extraction of phenolic compounds and antioxidant activity. Moreover, it can be concluded that extracts obtained by Soxhlet method were the most interesting in terms of antioxidant activity and proved that polyphenols responsible for the antioxidant activity of O. ficus-indica flowers are thermostable. These results showed that O. ficus-indica flowers could be a potential natural source of antioxidants that can be used in food and nutraceutical applications. © 2014 Elsevier B.V.

Kamel B.,Higher Institute of Biotechnology of Monastir | Boubaker K.,Higher Institute of Biotechnology of Monastir | Attia H.,Alimentary Analysis Unit
International Food Research Journal | Year: 2013

Despite the acknowledged contribution of Small and Medium Enterprises (SMEs) to the food industry, there is increasing evidence that Hazard Analysis Critical Control Point (HACCP) implementation is limited in this sector, with the burden of implementation perceived as potentially insurmountable. The purpose of this study was to modify the generic HACCP model for Tunisian ricotta cheese production based on actual conditions in this cheese plant. A specific model was developed to ameliorate the safety and quality of ricotta cheese products in this plant. Food safety measures were used at each step in the supply chain, but most of these measures were prerequisite programs rather than critical control points from a HACCP system.

PubMed | Alimentary Analysis Unit and Montpellier University
Type: | Journal: Colloids and surfaces. B, Biointerfaces | Year: 2016

The aim of this work was to examine foaming and interfacial behavior of three milk protein mixtures, bovine -lactalbumin--casein (M1), camel -lactalbumin--casein (M2) and -lactoglobulin--casein (M3), alone and in binary mixtures, at the air/water interface in order to better understand the foaming properties of bovine and camel milks. Different mixture ratios (100:0; 75:25; 50:50; 25:75; 0:100) were used during foaming tests and interfacial protein interactions were studied with a pendant drop tensiometer. Experimental results evidenced that the greatest foam was obtained with a higher -casein amount in all camel and bovine mixtures. Good correlation was observed with the adsorption and the interfacial rheological properties of camel and bovine protein mixtures. The proteins adsorbed layers are mainly affected by the presence of -casein molecules, which are probably the most abundant protein at interface and the most efficient in reducing the interfacial properties. In contrast of, the globular proteins, -lactalbumin and -lactoglobulin that are involved in the protein layer composition, but could not compact well at the interface to ensure foams creation and stabilization because of their rigid molecular structure.

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