Effect of the lactoperoxidase system on proteolysis and physicochemical changes in ultra high temperature milk during storage

Indirect semi-skimmed ultra high temperature (UHT) milk was made from refrigerated milk preserved by the lactoperoxidase system (LPS). The effect of the LPS on the physicochemical and biochemical properties of UHT milk during storage period of 6 months at 30°C was assessed. The levels of soluble nitrogen at pH 4.6 and non protein nitrogen in all UHT milk samples increased during storage. However, control UHT milk, manufactured with refrigerated milk which LPS was not activated; showed the highest values (p < 0.01). Less hydrophobic amino acids concentrations, such as found in nitrogen soluble fraction, were lower in activated LPS UHT milk. Also, bacterial proteinase activities, measured using o-phthaldialdehyde (oPA) as substrate, increased during storage. They were found higher in control UHT milk than in treated milk (p < 0.01). However, a decrease of total fatty acids in UHT milk, dependent on time of storage and LPS activation, was found during UHT milk storage.Keywords: Lactoperoxidase, ultra high temperature UHT milk, proteolysis, lipolysis, storageAfrican Journal of Biotechnology Vol. 12(16), pp. 2041-205

Effect of water quality of milking parlor cleaning and cattle watering on milk quality of Tunisian farms

Notre travail vise à étudier l’impact de la qualité de l’eau d’abreuvement et de nettoyage de la salle de traite sur la qualité physico-chimique et bactériologique du lait. Pour se faire, on a fait la collecte des échantillons de lait et d’eau de six fermes agricoles du Nord de la Tunisie. Il ressort de cette étude que les résultats des analyses physico-chimiques du lait sont généralement compris dans des intervalles proches des normes retenues pour le lait mais la majorité des échantillons de lait collectés peuvent être qualifiés de mauvaise qualité hygiénique. La qualité de l’eau de nettoyage de la salle de traite, d’après les résultats statistiques, affecte la flore mésophile aérobie totale ainsi que les coliformes totaux du lait. Alors que la qualité de l’eau d’abreuvement, d’après les analyses statistiques, influe sur le taux de matière grasse du lait. Il apparaît clairement que la qualité de l’eau n’est pas le seul facteur qui affecte la qualité du lait. Ainsi, la recherche des sources de contamination sur tout le circuit du lait cru autre que la qualité de l’eau d’abreuvement et de nettoyage de la salle de traite a montré que les pratiques d’hygiène (la préparation à la traite) et le type de traite constituent les sources de contamination du lait par la flore aérobie mésophile totale (FAMT), les coliformes totaux (CT), les coliformes fécaux (CF) et Escherichia coli (EC). Enfin, l’augmentation de la charge bactérienne du lait tout au long de la chaîne de production à la ferme est le résultat des contaminations successives associées aux mauvaises pratiques d’hygiène lors de la traite. Mots-clés: Lait, eau, qualité, hygiène, bactériologie.Our study is on the impact of the water quality of milking parlor and cattle drinking on the physico-chemical and bacteriological quality of the milk. For this, milk and water samples were collected from six farms in northern Tunisia. Results of the study showed that milk physico-chemical properties were generally within intervals close to the required standards for milk but the majority of the collected milk samples can be qualified as having poor hygienic quality. The milking parlor’s cleaning water quality, based on statistical results, affected total aerobic mesophilic flora (TAMF) as well as total milk coliforms. Cows drinking water quality, based on statistical analysis, affected milk fat content. It is clear that water quality was not the only factor affecting the quality of milk. Thus, the search for sources of contamination throughout the raw milk circuit, other than the quality of drinking water and cleaning of the milking parlor, has shown that hygiene practices (preparation for milking) and type of milking constitute the major sources of milk contamination by TAMF, total coliforms (TC), fecal coliforms (FC) and Escherichia coli (EC). After all, the increase of milk bacterial load throughout the production chain on the farm is the result of successive contaminations associated with poor hygiene practices during milking. Keywords: Milk, water, quality, hygiene, bacteriology

Value adding search among a selection of Tunisian fennel (Foeniculum vulgare Mill.) cultivars: Nutritional composition, chlorophyll and β-carotene contents of fennel seeds

Foeniculum vulgare has an important medicinal and economic role due to the frequent use of different parts of the plant. However, fennel seeds are the most exploited especially in culinary preparations and food industries. In order to highlight the benefits of this spice, physico-chemical composition of 7 fennel cultivars was carried out. Results revealed high contents of sugars, proteins and ash, and low contents of fat and water. The highest sugar content was displayed by the cultivar Cv2 (61±1.87 %) and the lowest one was obtained by cultivar Cv5 (31.41±1.77 %). Statistically significant differences between the 7 fennel cultivars were shown among their respective protein contents. Interestingly, all of the 7 cultivars, except one (Cv3: 7.91±0.07 %), revealed high levels of protein contents. Moreover, assessment of physiological parameters of the 7 cultivars gave evidence of high β-carotene contents. Despite, chlorophyll assessment results gave moderate content levels. Taking into account results from the present work, in addition to our previous published findings, 4 fennel cultivars were selected, essentially, based on their nutritional composition while searching for future potential industrial applications

Value adding search among a selection of Tunisian fennel (Foeniculum vulgare Mill.) cultivars: Diversity assessment and selection among a local fennel germplasm

Fennel (Foeniculum vulgare Mill.) is a very popular, aromatic, herbaceous plant that belongs to the Apiaceae family. It is among most important spices and medicinal species over the world. Nevertheless, in Tunisia fennel cultivation doesn't cover the local market needs. Also, fennel seeds are produced by farmers traditionally, and none of the local cultivars is named nor labelled in the market. Efforts have been deployed during the present work aiming to the characterization and valorization of genetic fennel resources. Hence, morphological diversity assessment was carried out among 62 entries of fennel acquired from different origins. Two steps principle component analysis (PCA) were applied. It came out with 7 selected cultivars of fennel representative of the initial diversity as assessed within the 62 collected fennel entries. Interestingly, among these latter, some of them exhibited particular phenotypic features linked to production traits

Probiotički jogurt od devinog mlijeka s dodatkom inulina: antibakterijsko, antioksidacijsko i antidijabetičko djelovanje

Similar to cow’s milk, camel milk also contains the essential nutrients as well as potentially therapeutic compounds with antihypertensive, and antioxidant properties. In the current study, camel milk was used for developing a new probiotic camel milk yoghurt with commercial prebiotic (inulin). The camel yoghurt samples were evaluated by monitoring the changes in some physicochemical properties (pH, total acidity and synerisis) and bacterial viability and survival of Limosilactobacillus fermentum CABA16 during storage. Besides, antibacterial, ⍺-amylase and ⍺-glucosidase inhibitions and antioxidant activities and the sensory evaluation of this novel product were assessed. The pH values of samples decreased whereas total acidity values increased throughout 21 days of storage and Limosilactobacillus fermentum CABA16 maintained good viability with counts higher than 107 CFU g-1 at the end of storage. α-Glucosidase and α- Amylase Inhibitions Water-Soluble Extracts were higher than 35 and 55% respectively in probiotic (PY), prebiotic (InY) and symbiotic (SY) camel yoghurts at the end of storage period. Moreover, the highest antioxidant activities of the WSEs from camel yoghurts were around 49 and 61% by DPPH and ABTS assays respectively. The fortified probiotic camel yoghurts exhibited comparable antibacterial activities with maximum diameter of 12±0.07 mm on Staphylococcus aureus and Listeria monocytogenes strains. Lastly, the addition of probiotic and inulin significantly improved the sensory characteristics, except the colour, of camel yoghurts.Devino mlijeko poput kravljeg sadrži esencijalne hranjive tvari kao i potencijalno korisne spojeve s antihipertenzivnim i antioksidativnim svojstvima. U ovom je istraživanju korišteno devino mlijeko kao sirovina za razvoj novog probiotičkog jogurta s komercijalnim prebiotikom (inulin). U uzorcima devinog jogurta tijekom skladištenja praćene su promjene nekih fizikalno-kemijskih svojstava (pH, ukupna kiselost i sinereza) te preživljavanje bakterija uključujući i soj Limosilactobacillus fermentum CABA16. Osim toga, proizvedeni uzorci jogurta su senzorski ocijenjeni te im je određivana su antibakterijska i antioksidacijska aktivnost, kao i sposobnost inhibicije α-amilaze i β-glukozidaze. Tijekom 21 dana skladištenja, pH vrijednosti uzoraka su padale, dok su vrijednosti ukupne kiselosti porasle, a soj Limosilactobacillus fermentum CABA16 pokazao je dobru sposobnost preživljavanja budući je na kraju skladištenja broj poraslih kolonija iznosio preko 107 CFU g-1. Inhibicije α-glukozidaze i α-amilaze u ekstraktima topljivim u vodi bile su veće od 35 odnosno 55 % u probiotičkom (PY), prebiotičkom (InY) i simbiotičkom (SY) devinom jogurtu na kraju razdoblja skladištenja. Štoviše, najveće antioksidacisjke aktivnosti ekstrakta topljivog u vodi (WSE) dobivenog obradom uzoraka devinih jogurta bile su oko 49 odnosno 61 % prema DPPH i ABTS testovima. Obogaćeni probiotički devini jogurti pokazali su slično antibakterijsko djelovanje na sojeve Staphylococcus aureus i Listeria monocytogenes, s maksimalnim promjerom zona inhibicije od 12±0,07 mm. U konačnici, dodatak probiotika i inulina značajno je poboljšao sva senzorska svojstva devinih jogurta osim boje

Conception raisonnée de catalyseurs bifonctionnels : élaboration de catalyseurs Pt0/zéolithe-Alumine

Bifunctional hydrocracking catalysts require both Brønsted acid sites and metal sites. Hence, the intimacy between acid sites and metal sites can influence the activity and selectivity of the reaction. We intended to explore the effect of metal sites-acid sites distance on the conversion of n-heptane by designing platinum catalysts supported on alumina-zeolite nanostructures. For this, we studied the synthesis of nanoscale colloidal suspensions of zeolite NaY (20 nm) beta (30 nm), ZSM-5 (50 nm). Composite materials were then prepared either by direct synthesis in the presence of a support, or by contacting these colloidal suspensions (at appropriate pH conditions) with suspensions of boehmite (turning into γ-alumina by calcination). Zeolite-core@alumina-crown composite crown) were thus obtained. The platinum particles were thereafter selectively formed on the alumina or zeolite domains of these composites using the appropriate precursor of platinum in a suitable pH range (pH = 5-8). The thus-prepared catalysts were compared with other catalysts, for which the distance between the acid sites and the metal sites varies between nm and μm scales, to form a series of catalysts with variable acid-metal distances and accessibilities. Catalytic study concluded that improving accessibility to the active sites (Pt0 / Alumina-nanozéolithe) improves the selectivity to isomerization, while the distance plays an inhibitory role only when it reaches a scale of several microns.Les catalyseurs bifonctionnels pour l’hydrocraquage nécessitent à la fois des sites acides de Brønsted et des sites métalliques. L’intimité entre sites acides et sites métalliques peut donc influer sur l’activité et la sélectivité de la réaction. Nous nous sommes proposés d’explorer l’effet de la distance sites métalliques-sites acides sur la conversion du n-heptane en concevant des catalyseurs à base de platine supportés sur des nanostructures alumine-zéolithe. Pour cela, nous avons étudié la synthèse de suspensions colloïdales nanométriques de zéolithes NaY (20 nm) beta (30 nm), ZSM-5 (50 nm). Des matériaux composites ont ensuite été préparés, soit par synthèse directe en présence d’un support, soit par mise en contact de ces suspensions colloïdales (dans les conditions appropriés de pH) avec des suspensions de boehmite (se transformant en γ-alumina par calcination). Des composites cœur-zéolithe@couronne(alumine) ont ainsi été obtenus. Les particules de platine ont été par la suite sélectivement formées sur les domaines alumine ou zéolithe de ces composites en utilisant le précurseur approprié de platine dans un domaine de pH adapté (pH=5-8). Les catalyseurs ainsi préparés ont été comparés à d’autres catalyseurs pour lesquels la distance entre sites acides et sites métalliques varie entre le nm et le μm, pour former une série de catalyseurs avec des distances métal-acide et des accessibilités aux sites différentes. L’étude catalytique a permis de conclure que l’amélioration de l’accessibilité aux sites actifs (Pt0/Alumine-nanozéolithe) améliore la sélectivité a vers les produits d’isomérisation, alors que la distance ne joue un rôle inhibiteur que quand elle atteint une échelle de plusieurs μm

Rational design of bifunctional catalysts : development of Pt0/zeolithe-alumina catalysts

Les catalyseurs bifonctionnels pour l’hydrocraquage nécessitent à la fois des sites acides de Brønsted et des sites métalliques. L’intimité entre sites acides et sites métalliques peut donc influer sur l’activité et la sélectivité de la réaction. Nous nous sommes proposés d’explorer l’effet de la distance sites métalliques-sites acides sur la conversion du n-heptane en concevant des catalyseurs à base de platine supportés sur des nanostructures alumine-zéolithe. Pour cela, nous avons étudié la synthèse de suspensions colloïdales nanométriques de zéolithes NaY (20 nm) beta (30 nm), ZSM-5 (50 nm). Des matériaux composites ont ensuite été préparés, soit par synthèse directe en présence d’un support, soit par mise en contact de ces suspensions colloïdales (dans les conditions appropriés de pH) avec des suspensions de boehmite (se transformant en γ-alumina par calcination). Des composites cœur-zéolithe@couronne(alumine) ont ainsi été obtenus. Les particules de platine ont été par la suite sélectivement formées sur les domaines alumine ou zéolithe de ces composites en utilisant le précurseur approprié de platine dans un domaine de pH adapté (pH=5-8). Les catalyseurs ainsi préparés ont été comparés à d’autres catalyseurs pour lesquels la distance entre sites acides et sites métalliques varie entre le nm et le μm, pour former une série de catalyseurs avec des distances métal-acide et des accessibilités aux sites différentes. L’étude catalytique a permis de conclure que l’amélioration de l’accessibilité aux sites actifs (Pt0/Alumine-nanozéolithe) améliore la sélectivité a vers les produits d’isomérisation, alors que la distance ne joue un rôle inhibiteur que quand elle atteint une échelle de plusieurs μm.Bifunctional hydrocracking catalysts require both Brønsted acid sites and metal sites. Hence, the intimacy between acid sites and metal sites can influence the activity and selectivity of the reaction. We intended to explore the effect of metal sites-acid sites distance on the conversion of n-heptane by designing platinum catalysts supported on alumina-zeolite nanostructures. For this, we studied the synthesis of nanoscale colloidal suspensions of zeolite NaY (20 nm) beta (30 nm), ZSM-5 (50 nm). Composite materials were then prepared either by direct synthesis in the presence of a support, or by contacting these colloidal suspensions (at appropriate pH conditions) with suspensions of boehmite (turning into γ-alumina by calcination). Zeolite-core@alumina-crown composite crown) were thus obtained. The platinum particles were thereafter selectively formed on the alumina or zeolite domains of these composites using the appropriate precursor of platinum in a suitable pH range (pH = 5-8). The thus-prepared catalysts were compared with other catalysts, for which the distance between the acid sites and the metal sites varies between nm and μm scales, to form a series of catalysts with variable acid-metal distances and accessibilities. Catalytic study concluded that improving accessibility to the active sites (Pt0 / Alumina-nanozéolithe) improves the selectivity to isomerization, while the distance plays an inhibitory role only when it reaches a scale of several microns

Application of physical agents to corneal bioengineering and crystalline lens biomechanics

La cornée et le cristallin jouent un rôle capital dans le pouvoir convergent de l’œil. La cornée, tissu transparent et avasculaire, permet la transmission des rayons lumineux alors que le cristallin, lentille biconvexe, va les focaliser sur la rétine afin de transmettre l’information visuelle reçue au cerveau. A l’échelle mondiale, au moins 2,2 milliards de personnes présentent une déficience visuelle qui touche la vision de près ou de loin. Ceci comprend les personnes atteintes de cécité cornéenne (88,4 millions) et de presbytie non prise en charge qui touche le cristallin (826 millions). Le premier objectif de cette thèse repose sur la bio-ingénierie cornéenne (projet RECOR) qui a comme objectif de lutter contre la cécité cornéenne en exploitant deux tissus oculaires rebut de banques : le stroma cornéen et la capsule cristallienne. Le deuxième objectif consiste à mettre en évidence les protéines impliquées dans les mécanismes de mécanotransduction entre le stroma et les CEChs (projet CONDUCTION) afin de limiter la perte cellulaire en augmentant les signaux de survie via un signal mécanique tel que la pression. Enfin, le dernier objectif de cette thèse se base sur la mise au point de techniques histologiques, coloration et immunohistochimie du cristallin afin de caractériser les effets du laser femtoseconde et des ultrasons (projet PRESBINNOV), deux types d’agents physiques qui pourront être les traitements de demain pour la presbytie.The cornea and the crystalline play a capital role in the convergent power of the eye. The cornea, a transparent and avascular tissue, allows the transmission of light rays while the crystalline lens, a biconvex lens, focuses them on the retina in order to transmit the visual information received to the brain. At least 2.2 billion people in the worldwide have a visual impairment that affects near or distance vision. This includes people with corneal blindness (88.4 million) and untreated presbyopia that affects the lens (826 million). The first objective of this thesis is based on corneal bioengineering (RECOR project) which aims to fight against corneal blindness by exploiting two banked ocular tissues: the corneal stroma and the lens capsule. The second objective is to identify the proteins involved in the mechanotransduction mechanisms between the stroma and the CEChs (CONDUCTION project) to limit cell loss by increasing the survival signals via a mechanical signal such as pressure. Finally, the last objective of this thesis is based on the development of histological techniques, staining and immunohistochemistry of the lens for the characterization the effects of femtosecond laser and ultrasound's effects (PRESBINNOV project), two types of physical agents which could be the future treatments for presbyopia

Value adding search among a selection of Tunisian fennel (Foeniculum vulgare Mill.) cultivars: Diversity assessment and selection among a local fennel germplasm

Fennel (Foeniculum vulgare Mill.) is a very popular, aromatic, herbaceous plant that belongs to the Apiaceae family. It is among most important spices and medicinal species over the world. Nevertheless, in Tunisia fennel cultivation doesn't cover the local market needs. Also, fennel seeds are produced by farmers traditionally, and none of the local cultivars is named nor labelled in the market. Efforts have been deployed during the present work aiming to the characterization and valorization of genetic fennel resources. Hence, morphological diversity assessment was carried out among 62 entries of fennel acquired from different origins. Two steps principle component analysis (PCA) were applied. It came out with 7 selected cultivars of fennel representative of the initial diversity as assessed within the 62 collected fennel entries. Interestingly, among these latter, some of them exhibited particular phenotypic features linked to production traits

Value adding search among a selection of Tunisian fennel (Foeniculum vulgare Mill.) cultivars: Nutritional composition, chlorophyll and β-carotene contents of fennel seeds

Foeniculum vulgare has an important medicinal and economic role due to the frequent use of different parts of the plant. However, fennel seeds are the most exploited especially in culinary preparations and food industries. In order to highlight the benefits of this spice, physico-chemical composition of 7 fennel cultivars was carried out. Results revealed high contents of sugars, proteins and ash, and low contents of fat and water. The highest sugar content was displayed by the cultivar Cv2 (61±1.87 %) and the lowest one was obtained by cultivar Cv5 (31.41±1.77 %). Statistically significant differences between the 7 fennel cultivars were shown among their respective protein contents. Interestingly, all of the 7 cultivars, except one (Cv3: 7.91±0.07 %), revealed high levels of protein contents. Moreover, assessment of physiological parameters of the 7 cultivars gave evidence of high β-carotene contents. Despite, chlorophyll assessment results gave moderate content levels. Taking into account results from the present work, in addition to our previous published findings, 4 fennel cultivars were selected, essentially, based on their nutritional composition while searching for future potential industrial applications