Caractérisation microbiologique et de la protéolyse du fromage traditionnel Algérien'Bouhezza' de ferme.

Abstract

Bouhezza is a traditional cheese known in the area of "chaouia", in the east of Algeria. The aim of this study was to contribute to the characterization of microbiological and proteolysis of Bouhezza cheese of farm. Six samples of Bouhezza cheese have been collected in the rural areas in the wilaya of Oum El Bouaghi. A count of the principal microbial groups indicates that the microflora of bouhezza was consists essentially of lactic acid bacteria (lactobacilli and lactic streptococci). Fungal flora represents only a very small fraction of microbial populations, total and fecal coliform are absent. The detection of the three pathogens by BAX® system method has demonstrated the absence of Salmonella, Listeria monocytogenes and Escherichia coli O157: H7 in the six samples of bouhezza. A global picture of bacterial communities of bouhezza is carried out by the PCRTemporal Temperature Gel Electrophoresis, showed that the bacterial ecosystem is not very rich, with a dominance principally of Lactobacillus plantarum and Lactococcus lactis subsp. cremoris in all samples, and secondarily of Lactococcus helveticus and/or Lactococcus acidophilus and/or Lactococcus crispatus in four samples. Staphylococcus equorum subsp. linens are present in three others. Proteolysis of bouhezza is not very large, with a rate of maturation which varies from 8.49% to 16.23% for the six samples. Electrophoretic separation of the insoluble nitrogen fraction at pH 4.6 by urea-PAGE detects different bands representing the diversity of casein fragments resulting from hydrolysis of casein by enzymes from the milk and/or from microflora of bouhezza. The analyses by Reverse Phase High Performance Liquid Chromatography of the fractions soluble at pH 4.6, soluble and insoluble in 70% of ethanol, show that only the chromatographic profiles of the ethanol insoluble fraction of six samples show similarities. The percentages of free amino acids in the three fractions are smaller compared to the percentages of peptides. The percentage of hydrophilic peptides is higher in both soluble fractions (40.1% to 54.5% for the soluble fraction at pH 4.6 and 45.8% to 52.6% for the soluble fraction of ethanol). However the proportion of hydrophobic peptides is higher in the insoluble fraction in ethanol (between 41.5% and 61.8%).