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The biofilm lifestyle plays a major role in the resistance and virulence of Pseudomonas aeruginosa and Enterococcus faecalis. In this study, two microencapsulated proteases (pepsin ME-PEP and trypsin ME-TRYP) were evaluated for their biofilm dispersal activity and their synergistic effect with microencapsulated carvacrol (ME-CARV). Spray-drying was used to protect enzymes and essential oil and enhance their activities. Cell count analysis proved the synergistic activity of enzymes and carvacrol treatment as biofilms were further reduced after combined treatment in comparison to ME-CARV or enzymes alone. Furthermore, results showed that sequential treatment in the order ME-TRYP - ME-PEP - ME-CARV resulted in more efficient biofilm removal with a maximum reduction of 5 log CFU mL−1 for P. aeruginosa and 4 log CFU mL−1 for E. faecalis. This study proposes that the combination of microencapsulated proteases with ME-CARV could be useful for the effective control of P. aeruginosa and E. faecalis biofilms.

ORAL SESSION 5: FOULING IN FOOD PROCESSING; International audience; Fouling of heat exchanger and corrosion occurs in many industrial sectors which causes considerable economic losses and increases public health risks. Therefore, it is important to develop devices to monitor the formation/removal of fouling and the corrosion occurrence. Such devices permit to revisit the fouling/cleaning process and the corrosion sequences in order to minimize associated impacts and losses. In this work, a coda wave interferometry (CWI) based-sensor is used to monitor the fouling and corrosion status of surfaces. This paper aimed to give an overview of the experimental results obtained in order to assess the potential of this technique for various types of applications (wax cleaning, biofilm formation detection, fouling/cleaning monitoring for dairy derivatives-unpreceded results and corrosion formation). Overall, our work provided evidence that CWI method is applicable for monitoring fouling factor and corrosion of solid surfaces and could be easily implemented in a non-invasive way and on line.

This study aims at exploring the chemical composition of a traditional Lebanese dairy product known as Qishta, describing the process of how to prepare it and understanding the mechanisms leading to its formation. The process of making Qishta can be divided into two phases: a hot phase during which milk is heated in a stainless-steel large shallow vessel, and a cold phase consisting of draining, cooling and packaging. According to milk temperature, two reaction zones were identified: zone A with an average temperature of 100 &deg, C, and zone B with an average temperature of 60 &deg, C. The results showed that Qishta had a moisture, fat, protein, lactose and ash content of 68%, 11.7%, 12.1%, 5.4% and 1.6%, respectively. Our findings showed that Qishta is a lipoprotein product having an equal amount of fat and proteins (&asymp, 12%), this composition is almost similar to that of Ricotta cheese made from whole milk. In addition, our results assert that the interactions between caseins and whey proteins lead to gel formation. Milk initial fat percentage had a significant effect on Qishta production. The highest yields were obtained when the initial fat percentage was 3.6% (182.5 g of Qishta).

The main objective of this work is to study the characterization of physico-chemical and microbiological of fermenting green olive brines at different times of fermentation. The technological and probiotic properties of lactic acid bacteria strains isolated from brines were also characterized, 24 brine samples were sampled from Triffa conserves entreprise, an industrial zone of Oujda city in eastern Morocco, during 2014-2015 and 2015-2016 campaigns, 240 isolates of lactic acid bacteria have been isolated, and they have undergone a series of tests to finally select the so-called probiotic bacteria. 41 strains were resistant to low pH (3, 2.5, 2), bile salts (0.3 and 1%, w/v) and 7 strains among the 41 were resistant to saline stress (8%, w/v) and endowed with acidification capacity and have a good enzymatic activity and a broad spectrum of antibacterial activity against pathogenic and non-pathogenic bacteria such as (Escherichia coli, Staphylococcus aureus, Listeria innocua, Pseudomonas aeruginosa and Micrococcus luteus). These results show the ability of these strains to dominate and grow in the digestive tract.These potential probiotic strains will be used as concentrated ferments in the fermentation and bioconservation of foods., Moroccan Journal of Chemistry, Vol 8, No 2 (2020)

International audience; Nisin is a 34-amino acid peptide known as a bacteriocin. It belongs to class-Ia bacteriocins known as lantibiotics. It is the most characterized and commercially used antimicrobial peptide. It was commercialized in the 1950s for the prevention of late blowing in cheese by Clostridium. Nisin is heat-stable and a cationic, low-molecular-weight peptide produced by the bacterial dairy starter Lactococcus lactis subsp. lactis. The growth of a wide spectrum of Gram-positive bacteria, including the pathogens Listeria and Staphylococcus aureus, and spore-forming bacteria such as Bacillus and Clostridium can be prevented by nisin. Subjects addressed in the chapter include nisin structure and physicochemical properties, antimicrobial spectrum, factors affecting the antimicrobial activity (food composition, temperature, pH, proteolytic enzymes, food processes, other preservatives, bacterial load), application as a preservative to dairy products, meat products, seafood, fruits and vegetables, beverages, and other food products, use of nisin in food packaging systems, and regulatory status.

International audience