Magistère biotechnologie

Screening d’activités hydrolytiques extracellulaires chez des souches bactériennes aérobies thermophiles isolées à partir de sources thermales terrestres de l’Est Algérien.

2012-01-01T00:00:00Z

Screening d’activités hydrolytiques extracellulaires chez des souches bactériennes aérobies thermophiles isolées à partir de sources thermales terrestres de l’Est Algérien. Gomri, Mohamed Amine; Kharroub, Karima Thermophilic and hyperthermophilic microorganisms inhabiting hot environments such as terrestrial hot springs have interesting molecular adaptation capacities and constitute an important source of bioactive molecules emerging from unique molecular and biochemical mechanisms. Hydrolytic enzymes of these organisms offer major advantages and give new possibilities to ameliorate existing processes or to create new ones. With the purpose of studying some of their enzymatic potentials, 83 thermophilic, aerobic bacteria strains were isolated from water and sediment samples taken from different points divided between the regions of Guelma and Ouargla located in North-Eastern and SouthEastern of Algeria, respectively. Phenotypic characterization has been realized, and allowed to obtain some morphological, biochemical and physiological proprieties of these microorganisms, these data led to realize a dendrogram by numerical taxonomy. Four types of hydrolytic activities were investigated by using seven different substrates. Strains were generally rods and filaments, Gram positive in most cases; they were moderately thermophiles, aerobes and neutrophiles. Numerical analyses clustred them into 3 principal phenons, based on similarity between strains. Screening for hydrolytic activities led to find one or several types of hydrolases in seventy-seven strains, proteolytic and amylolytic activities were mostly found.

Caractérisation du fromage traditionnel algérien

2017-07-03T00:00:00Z

Caractérisation du fromage traditionnel algérien; Medeghissa Khoualdi, Ghania; Zidoune, Mohamed Nasr Medeghissa is a traditional Algerian cheese known among the Chaouia under its original name Imedeghest. It is a melted cheese, prepared by cooking semi dry Klila in whole milk from cow, goat or sheep, on low heat. The aim of our work is the characterization Medeghissa basing on two integrated and dependent axes, namely a characterization by means of a field survey carried out in the Wilaya of Oum El-Bouaghi and Affected 105 women of rural origin; And an experimental characterization of the collected samples from farms and controlled manufactures (physicochemical, microbiological and sensorial analyzes). The cheese-making diagram was based on survey results and verified on the laboratory scale. 84 women questioned know this cheese but its manufacture was limited on 3.8% of them. Madghessa is eaten as a snack and appreciated for its elasticity and taste by all women surveyed. The manufactured Madghessa has a pH average of 4.82 ± 0.15 and an acidity of 0,41±0,15 g / 100 g. The recorded dry extract is 34.78 ± 1.2 g / 100 g. This result is similar to that of the collected samples (33.64 ± 4.13 g / 100 g). This cheese has an average fat content of 7.78 ± 1.99 g / 100 g and a protein level of 25.94 ± 4.53 g / 100 g. According to codex alimentarius STAN A-6 (1978), this cheese can be classified under lean, soft cheese (MG / ES <10%), HRED> 67%). According to the microbiological analyzes on the different samples, the cheese has a good hygienic quality marked by a total absence of the contamination indicator germs and pathogenic germs namely: total and fecal coliforms, faecal streptococci, Salmonella and Staphylococus aureus As well as spores of sulfito-reducing anaerobes. Madghessa has a low microbial load in the range of 102 to 103 CFU / g for the total mesophilic flora. The mesophilic and thermophilic lactic bacteria reach values of the order 104 CFU / g. On the other hand, the number of yeasts and molds shows variability from zero to 103 CFU / g. On the organoleptic level, Madghessa is a soft cheese, with a weak acid taste. The paste of the cheese is elastic with pseudoplastic character when it is hot and becomes firm with the cooling. Its smell and aroma are mainly of the lactic family.

Effet de l’incorporation de deux extraits (extrait polyphénolique et jus frais) de la caroube verte sur la coagulation du lait (cas du yaourt).

2017-03-02T00:00:00Z

Effet de l’incorporation de deux extraits (extrait polyphénolique et jus frais) de la caroube verte sur la coagulation du lait (cas du yaourt). Bechri née Tarmoul, Houria; Barkat, Malika Carob is considered as a potential source of natural antioxidants (polyphenols). Indeed, researchers and manufacturers in food industry give an increasing importance for polyphenols due to their antioxidant properties, their great abundance in our diet, and their crucial role in the prevention and treatment of several diseases. Thus, recent interest from consumers for functional foods and the need to replace the synthetic antioxidants by natural antioxidants has led to the use of these molecules to formulate new products. The combination of antioxidant components from some fruit with milk proteins is the best example that has been reported by several authors. The objective of the present work is the polyphenolic assessment of green carob’s extracts (Polyphenolic extract and juice extracted from the fresh pods) and study the possibility of their incorporation in a formulation of a yogurt and their effects on the precipitation of milk proteins. This is mainly motivated by the research of a wide range of rich or enriched foods in polyphenols, particularly in case of dairy products. The evaluation of polyphenols in the studied extracts gave high contents of phenolic compounds namely total polyphenols, flavonoids and tannins. Therefore, the assessment of antioxidant activity, by DPPH andironreducing power tests, depicted a high antioxidant activity for both extracts. Green carob is therefore considered as an important source of natural antioxidants. Coagulation test revealed a precipitation of proteins with the juice at a level of 10%. The latter allowed to obtain a dense coagulum with a slight whey syneresis. In fact, juice from green carob seems to be more appropriate as a coagulating agent of milk protein in dairy industry, especially in yoghurt production. Physicochemical analyses of the obtained coagulum showed a pH of 5.07, an acidity of 63,66 ° D and a total dry extract of 22,74%. This coagulum is significantly different from the control yoghurt. Microbiological analyses reported that the coagulum formulated showed a good stability towards pathogens and germs of contamination.

Viande cunicole

2017-03-15T00:00:00Z

Viande cunicole; situation de l’élevage dans l’Est algérien, comparaison des paramètres physico chimiques, biochimiques, etsensoriels de la race Néo-Zélandaise et la population locale « El Arbia » Sanah, Ibtissem; Kharroub, Karima The first objective of this research was to study the situation of the cunicultural sector in eastern Algeria by launching a survey with herders, butchers and consumers, the second objective being the comparison of morphological, physico-chemical, biochemical and sensory parameters determining the quality of the meat for the local Algerian breed ""El Arbia"" and the ""New Zealand"" foreign breed. To reach our objectives, a survey was carried out among 80 breeders, 32 butchers and 360 consumers across 15 towns in eastern Algeria. The main results of the survey show that rabbit farms are concentrated mainly in Mila, Setif, Bordj Bou Arreridj, and Constantine. The situation of cuniculture has been judged to be continuously evolving, but several constraints hinder its development. As for butchers, rabbit meat is considered among the most expensive meats. Concerning consumers, rabbit meat is as appreciated as that of broilers. But its frequency of consumption is low. Thirty rabbits (15/15) of the two breeds were used for the extraction of the muscle Longissimus dorsi (LD), for the analysis of the physicochemical and biochemical parameters as well as the instrumental measurement of tenderness at Penetrometer. While the thighs were taken for use in sensory analysis, and muscle weight loss. Comparison of morphological, biochemical and physico-chemical parameters revealed the following main results: The breed factor has significantly affected slaughter yields, muscle weight loss, as well as the juiciness of the meat, and also morphological parameters such as: length Total, length of the loins ... at 5% threshold An identical pattern of fall in temperature, pH, water holding capacity, cooking losses, myofibril fragmentation index, the profile of penetration depth, the electrophoretic characterization (SDS-PAGE) of sarcoplasmic and myofibril proteins The results obtained morphologically confirm the defects of the local population; on the other hand, the quality of the meat seems to be very interesting organoleptically and technologically.