N. M’hiri ^{1, 2*}

I. Ioannou²

M. Ghoul²

N. Mihoubi Boudhrioua^1*

¹ UR11ES44, Ecophysiologie et Procédés Agroalimentaires, Institut Supérieur de Biotechnologie de Sidi Thabet, Univ. Manouba, BP-66, 2020 Ariana-Tunis, Tunisie

² Université de Lorraine, ENSAIA- Laboratoire d’Ingénierie de biomolécules (LIBio), 2 avenue de la Forêt de Haye, TSA 40602 Vandoeuvre Cedex 54518, France

Abstract: The aim of this work is to investigate the global chemical characteristics of Tunisian Maltease orange peel and to determine the effect of air temperature (40, 60, 80°C) on phenols and antioxidant activity kinetics of orange peel. Maltease orange peel is rich in nutritional ingredients such as soluble sugars (46.241±0.015 g/100g d.b), proteins (8.120±0.120 g/100g d.b) and minerals (3.170±0.035 g/100g d.b). It contains antioxidant such as phenols (2.685±0.062 g/100 g d.b) and vitamin C (0.105±0.003 g/100 g d.b). Phenolic compounds of Maltease orange peel, expressed as g/100g orange peel powder are: neohesperidin (1.312±0.031), followed by hesperidin (0.990±0.011), naringin (0.060±0.001), nobiletin (0.109±0.001), narirutin (0.031±0.001), didymin (0.049±0.001), sinensetin (0.047±0.000), eriocitrin (0.061±0.005), 3’,4’,5,5’6,7,-hexamethoxyflavone (0.0070±0.0001) and tangeretin (0.019±0.001). Glycosylated flavanones (eriocitrin, narirutin, naringin, hesperidin, neohesperidin, didymin) and polymethoxylated flavones (sinensetin, 3’,4’,5,5’6,7,-hexamethoxyflavone, tangeretin, nobiletin) show similar behavior during air drying (at 40, 60 and 80°C): a rapid decrease of 79.86%, 81.88% and 80.46% for neohesperidin and 88.17%, 87.55% and 81.37% for hesperidin during the first hour of air drying and then amounts show little variations until the end of drying. Drying during 75 min at 80°C allows the lowest degradation of total phenols (81.72%) compared to 85.06% at 60°C (during 120 min) and 88.40% at 40°C (during 240 min). The antioxidant activity variation shows similar behavior.

Keywords: orange peel characterization, air drying, phenolic compounds, antioxidant activity, kinetic.

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I. Messaoudi ¹

N. M’hiri ¹

D. Mihoubi ²

R. Ksouri 

R. Chekir ¹

N. Boudhrioua Mihoubi *¹

¹ UR11ES44, Ecophysiologie et Procédés Agroalimentaires, Institut Supérieur de Biotechnologie de Sidi Thabet, Univ. Manouba, BP-66, 2020, Ariana-Tunis, Tunisie

² Laboratoire des Procèdes Thermiques, Centre de Recherches et des Technologies de l’Energie, B.P. 95, Hammam-lif, 2050, Tunisie

³ Laboratoire des Plantes Extrêmophiles, Centre de Biotechnologie à la Technopôle de Borj-Cédria, BP 901, 2050 Hammam-Lif, Tunisie

Abstract - The aim of this work was to establish a comparative investigation of the effects of microwave drying (160, 350, 500, 650, 750 W), air drying (50, 75°C), infrared drying (40, 50, 60, 70°C) and combined air-microwave drying (50°C-160 W; 50°C-350 W, 75°C-160 W; 75°C-350 W) on color, phenol content and antioxidant activity of mallow leaves (Malva parviflora). Drying time of the mallow leaves sharply decreased with increasing drying temperature from 40 to 70°C and/or applied microwave power level from 160 to 750 W. Microwave drying and combined air-microwave drying allowed obtaining short drying times and high drying rates. Page Model described adequately all drying kinetics of mallow leaves (R²>0.9911). Whatever the drying process, the value of colorimetric parameters (a*: greenness/redness and b*: yellowness / blueness) decreased if compared to those of fresh leaves. Total phenolic and flavonoid contents of dried leaves significantly increased (except for air drying at 50°C and combined air-microwave drying at 350 W-50°C and at 350 W-75°C) if compared to fresh ones. The maximal phenolic contents are recorded for leaves dried by microwave drying. The mallow leaves extract concentration providing 50% inhibition (IC50) of 2, 2-Diphenyl-1-picrylhydrazyl (DDPH) varies from 2.574±0.098 to 3.100±0.115 mg /ml.

Key words: Malva parviflora, phenol, flavonoid, IC50, color parameters, drying.

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A. Gritli ¹*

I. Belkahla ²

M. Ben Moussa ³

M.S. Abassi ⁴

¹Laboratoire Militaire d’Analyses Alimentaires, Avenue des Etats-Unis, le Bardo 2000, Tunis; ²Laboratoire de Biodiversité et Biotechnologie Marine, Institut National des Sciences et Technologie de la Mer, Salambo-Tunis; ³Laboratoire de microbiologie-Hôpital Militaire Principal d’Instruction de Tunis; ⁴Institut de la Recherche Vétérinaire de Tunisie, Bab Saadoun, Tunisia.

Abstract - A healthy diet requires raw vegetable intake. However, Escherichia coli, one of the bacteria constituting the human and animal intestinal microflora, sometimes contaminate vegetables, including lettuce. In places where food is prepared on a large scale, the presence of Escherichia coli constitutes a reliable indication of fecal contamination. The aim of this study was to assess the levels of Escherichia coli contaminating 100 raw lettuce heads destined for consumption at a military hospital, and to characterize the 27 isolates recovered therefrom, with regard to their susceptibility to antibiotics as well as their phylogenetic groups and the occurrence of class 1 and 2 integrons. Ten specimens were bacteriologically non-satisfactory. Furthermore, 17 isolates (63%) were sensitive to all antibiotics tested, whereas 10 isolates (37%) were resistant to different antibiotics. Among these, 18.5% were resistant to 3 antibiotics, 11.11% were resistant to 3 other antibiotics and 7.4% were resistant to yet 2 other antibiotics. The majority of isolates (74%) segregated into phylogenetic groups A and B1, suggesting that they are commensal strains. However, 26% fell into groups B2 and D, hence constituting potentially virulent entities. Among the isolates, 51.8% harboured class 1 integrons, while 48.15% were devoid of integrons. The isolates exhibiting resistance to different antibiotics carried class 1 integrons. Our study revealed high levels of E.coli contaminating lettuce, thus a potential risk for foodborne outbreaks. The isolates displayed resistance to different antibiotics correlating with the presence of class 1 integrons, and are armed with a pathogenic potential due to strains of B2 and D groups.

Key words: Lettuce, Antibiotic resistance, Escherichia coli, phylogenetic group, integrons.

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A. Gritli ¹*

T. Daboussi ²

M. Ben Moussa ³

M.S. Abassi ⁴

¹Laboratoire Militaire d’Analyses Alimentaires, Avenue des Etats-Unis, le Bardo 2000, Tunis; ²Laboratoire de Biodiversité et Biotechnologie Marine-Institut National des Sciences et Technologie de la Mer, Salambo, Tunis; ³Laboratoire de microbiologie-Hôpital Militaire Principal d’Instruction de Tunis, MontFleury, Tunis; ⁴Institut de la Recherche Vétérinaire de Tunisie, Bab Saadoun, Tunis, Tunisia.

Abstract - Salmonella is a major cause of foodborne infections world-wide. Salmonella outbreaks linked to consumption of poultry meat and eggs constitute a major public health problem in view of the increasing consumption of these relatively inexpensive products. The aim of this study was to determine the presence of Salmonella in chicken consumed in Tunisian military cantines. In addition, we sought to characterise the isolates with regard to their sensitivity to antibiotics as well as their virulence. To this end, a total of fifty rawchicken carcasses were assessed for the presence of Salmonella. As the number of isolates turned out to be limited, and to provide significant data, we analysed sixteen additional pre-existing chicken-derived isolates. In addition to classic methods for Salmonella isolation and serotyping, the isolate's antimicrobial susceptibility was tested using the agar diffusion assay. Finally, the presence of class 1 and 2 integrons as well as virulence genes were determined by the Polymerase Chain Reaction assay. we found thatSalmonellacontaminated 16% of the samples and that all the isolates were of the Enteritidis serotype. Furthermore, while all the isolates were devoid of extended-spectrum beta-lactamase-producing Salmonella, 29.16% were resistant to two antibiotics. Among these, 16.66% were resistant to nalidixic acid, whereas 12.5% displayed resistanceto tetracyclines. In addition, the isolates were free of integrons, however they expressed virulence genes, including invE/A, ttrC, mgtC, sopB, and spvC. Overall, we show a high prevalence of Salmonella in chicken meat intended for military cantines. The Enteritidis serotype is resistant to some antibiotics and is endowed with an alarming potential for pathogenicity owing to expression of virulence genes.

Key words: chicken, Salmonella, antibiotic resistance, integrons, virulence genes.

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S. Boudiche^1* 

M. Ameur² 

S. Moussi³ 

S. Mlaouhi⁴

^1,3 Ecole Supérieure des Industries Alimentaires de Tunis,ESIAT

² Ecole Supérieure d’Agriculture du Kef, ESAK

⁴ Institut National de Recherche Agronomique de Tunis, INRAT

Résumé - Les consommateurs tunisiens ont exprimé à plusieurs occasions d’importantes préoccupations face à volatilité croissante des prix des produits agro-alimentaires pendant la période qui a suivi la révolution de 2011. L’objectif de ce travailconsiste à analyser la variation des prix des produits agroalimentaires et leur impact sur l’évolution de l’IPC global.Dans ce but, nous avons procédé à une modélisation de l’IPC en fonction de la volatilité des prix des produits agroalimentaires. Nous avons appliqué,dans une première étape,la méthode de l’Analyse de Composantes Principales (ACP) afin de pouvoir regrouper les 43 produits agroalimentaires analysés selon leur tendance commune d’évolution des prixmensuels au cours de la période 2009-2014 (viandes, ovo produits, laits et dérivés, conserves alimentaires, céréales, …). Dans une deuxième étape, nous avons essayé d’expliquer l’IPC en fonction de l’évolution desprix des produits agroalimentaires regroupés résultant de l’ACP. Pour ce faire, nous avons construit une équation linéaire ayant selon la méthode de moindre carrés ordinaires (MCO) afin d’expliquer les facteurs ayant un effet significatif sur l’IPC.Il apparait que l’impact le plus significatif provient des viandes rouges (+2,740) et les conserves de légumes (+2,013)ayant subi une augmentation considérable de leurs prix. En revanche, les boissons, les produits laitiers et l’huile d’olive ont eu l’effet le moins important sur l’IPC (+0,744).Les produits subventionnés tels que le pain et les pâtes alimentaires ont également un impact significatif sur l’IPC mais avec effet négatif.Le modèle conçu est utile dans le cas de certains scenarios de suppression de subventions et constitue ainsi un outil d’aide à la décision et à la prévision de son impact sur la consommation future.

Mots clés: IPC, prix, produits alimentaires, Analyse en Composantes Principales (ACP), moindres carrées ordinaires MCO.

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S. Souilem^1,2

H. Debbabi¹

C. Demmargi¹

S. Bellegha¹

¹ Department of Food Technology,Tunisian National Institute of Agronomy 43, Avenue Charles Nicolle, 1082 Tunis Mahrajène , Tunisia

² Laboratory of Environnemental Bioprocesses of Center of Biotechnology of Sfax, BP : 1177, 3038 Sfax, Tunisia

Abstract - In this research, effectiveness of the use of microwave energy (MW) to produce orange jam was compared to conventional heating (CH) method. The final jam concentration was in the range of 63°Brix was achieved in the range (70-110 min) for conventional heating and (12-23 min) for microwave processed samples. Zero- and First-order kinetic models were applied to describe color change. Both models were found to describe the experimental (L, a, and b) kinetics adequately. The Hunter parameters kinetics were more influenced by the MW process but no significant difference was found in the final product. Spreadability texture test showed that MW processed samples presented lesser hardness and work of shear than CH processed samples. MW energy can be introduced successfully as an alternative method in the concentration process of orange jam.

Keywords: Orange Jam; Conventional heating; Microwave ; Texture ; Colour.

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