Production of a new chitinase from Nocardiopsis halophila TN-X8 utilizing bio-waste from the blue swimming crab: enzyme characterization and immobilization.

In accordance with the framework of the Circular Blue Bioeconomy in the Mediterranean region, the objective of this study was to evaluate the biotransformation of blue swimming crab (Portunus segnis) residues obtained from the port of Sfax by an extracellular chitinase produced by Nocardiopsis halophila strain TN-X8 isolated from Chott El Jerid (Tozeur, Tunisia). From the analysis of multiple extremophilic Actinomycetota, it was determined that strain TN-X8 exclusively utilized 60 g/L of raw blue swimming crab as its carbon and energy source, achieving a chitinase activity of approximately 950 U/mL following a 6-day incubation period at 40 °C. Pure chitinase, designated as ChiA-Nh30, was obtained after heat treatment, followed by ammonium sulfate fractionation and Sephacryl® S-200 column chromatography. The maximum ChiA-Nh30 activity was observed at pH 3 and 75 °C. Interestingly, compared with cyclohexamidine, ChiA-Nh30 showed a good antifungal effect against four pathogenic fungi. Furthermore, when using colloidal chitin as substrate, ChiA-Nh30 demonstrated a higher degree of catalytic efficiency than the commercially available Chitodextrinase®. In addition, ChiA-Nh30 could be immobilized by applying encapsulation and encapsulation-adsorption techniques. The kaolin and charcoal used acted as excellent binders, resulting in improved ChiA-Nh30 stability. For the immobilized ChiA-Nh30, the yield of N-acetyl-D-glucosamine monomers released from 20% (w/v) blue swimming crab residues increased by 3.1 (kaolin) and 2.65 (charcoal) times, respectively.

Microbiological quality of gluten-free meals, naturally gluten free foods, and gluten free-labelled products.

Background: The rising prevalence of gluten-related disorders such as celiac disease explains the increased consumption of gluten-free foods (GFF). However, these foods must be safe in terms of both gluten content and contamination by pathogenic microorganisms in order to avoid food poisoning. Objective: The objective of this study was to assess the microbiological quality of gluten-free meals, naturally gluten free foods, and gluten free-labelled products. Material and Methods: We collected 62 GFF samples including 20 meals (M-GF), 22 naturally gluten free (N-GFF) and 20 labelled (L-GFF) products, which were investigated for microbiological contamination according to Moroccan regulations guidelines, issued by the International Organization for Standardization (ISO). The analysis consisted of the detection of Salmonella and Listeria monocytogenes in each sample, and the quantification of the microbial load of the following six micro-organisms: total aerobic mesophilic flora, total coliforms, fecal coliforms, Staphylococcus aureus, Sulphite-Reducing Anaerobic, and yeasts and molds. Results: A total of 372 analyses were carried out, showing a microbiological contamination rate of 5.1%. This contamination concerned N-GFF in 8.3% (predominantly with yeasts and molds), and meals prepared at home in 11.7 (predominantly with Staphylococcus aureus and coliforms). Only one case (0.8%) of contamination was observed in products labelled gluten-free and no contamination was noticed in meals prepared in food services. Listeria monocytgenes and Salmonella were not detected in any samples of food analyzed. These results indicate a good compliance of L-GFP and M-GF prepared in food services, while unsatisfactory quality was observed in N-GFF and M-GF prepared at home. Conclusion: Therefore, rigorous hygienic practices and adequate corrective measures should be considered by celiac patients, especially regarding the N-GFF and M-GF prepared at home.

Biodiversity and biotechnological properties of lactic acid bacteria isolated from traditional Moroccan sourdoughs.

The present study aimed at characterizing lactic acid bacteria (LAB) strains isolated from traditional sourdoughs collected in different regions of Morocco. Isolated strains were firstly identified using Gram staining and catalase reaction test. Presumptive LAB strains were then checked for various phenotypical properties including growth at 45 °C, resistance to NaCl, enzyme production, acidification capacity, diacetyl and exopolysaccharide (EPS) production, and antifungal activity. Finally, selected LAB strains were identified using 16S rDNA sequencing. Results showed that 32.1% of the isolates were thermophilic (45 °C) and 83.9% were resistant to NaCl (6.5%). Moreover, 51.7 and 37.5% were able to produce diacetyl and EPS, respectively. Regarding enzyme production, 55.3 and 7.1% of the isolates showed lipolytic and proteolytic activities, respectively. Low pH values (3.37-3.76) were obtained after 24 h of incubation of LAB strains in de Man, Rogosa and Sharpe (MRS) broth. Antifungal activity test against Aspergillus flavus, Aspergillus niger and Penicillium spp. showed an inhibition rate up to 50%. Bacterial DNA sequencing showed that LAB isolates belong to seven species, chiefly Levilactobacillus brevis, Lentilactobacillus parabuchneri, Lactiplantibacillus plantarum, Pediococcus pentosaceus, Enterococcus hirae, Bifidobacterium pseudocatenulatum, and Companilactobacillus paralimentarius. These findings, for the first time in Moroccan sourdoughs, indicate that the isolated LAB strains have good multifunctional properties and could be suitable as good starters for sourdough bread production under controlled conditions.

Aflatoxins and Ochratoxin A in dried fruits from Morocco: Monitoring, regulatory aspects, and exposure assessment.

The present study aims to investigate the presence of Aflatoxins (AF) in 180 samples dried fruits and Ochratoxin A (OTA) in 210 samples dried fruits and grape juices collected in Morocco. Mycotoxins were analyzed by high performance liquid chromatography (HPLC) coupled to fluorescence detection and immunoaffinity columns (IAC) cleanup. Contamination levels were compared with the maximum regulatory limits (MRL) recently adopted in the country, and mycotoxin exposure of adult consumers was assessed. Results showed that 13.8% of samples were contaminated with AF, with incidences of 23.3, 23.3, 20, 13.8, and 3.3%, in raisins, figs, nuts, peanuts and pistachio, respectively. There were 12 samples (6.6%) that exceeded the MRL of 2-12 ng/g set for aflatoxin B1 (AFB1). While OTA was detected in 17.1% of samples, with incidences of 3.3, 3.3, 30, 30, and 53.3% in walnuts, pistachios, peanuts, raisins and figs, respectively, and a maximum value of 99.1 in dried raisins, that exceeded the MRL (10 ng/g) set for OTA. The co-occurrence of OTA and AF was observed in 4.7% of total samples. Dietary intake showed that the OTA exposure level was lower than safety guidelines set by The Joint FAO/WHO Expert Committee on Food Additives (JECFA) at 100 ng/kg b.w./week.

Microbiological and physicochemical quality of raw milk of Beni Mellal-Khenifra.

Background: Milk is a nutritious food for humans, but it is also an ideal growth medium for pathogenic bacteria such as Salmonella, Listeria monocytogenes or Campylobacter spp, which can cause food poisoning. Objective: For this reason, we evaluated the microbiological, physicochemical and hygienic quality of raw milk samples in 9 milk collection centres and cooperatives in the Beni-Mellal-Khenifr region before and after the implementation of the quality management system, hazard analysis and critical control points (HACCP). Materials and Method: The microbiological and physico-chemical quality of 184 raw milk samples in 9 milk collection centres and cooperatives in the Beni-Mellal-Khenifra region was evaluated before and after the implementation of the quality management, hazard analysis and critical control points (HACCP) system. Results: The physico-chemical results obtained after the implementation of HACCP revealed that 78% of the samples analysed were below the maximum limits authorised at international level. A pH between 6.6 ±0.11 and 6.8±0.02, an acidity of 15°D, the milk is stable according to the Ramsdell test which is negative at 0.9. The temperature remains within the acceptance range with an average of 6.62 ±0.45°C to 7.7 ±0.36°C and the fat content is between 33 and 45g/ml. We also noted an improvement in the microbiological quality of milk in 81% of collection centres and cooperatives. The level of contamination by total coliforms is from 2.5x104 to 11.5x104 CFU/ml lower than the Moroccan standard (NM 08.0. 100) of 1.5x104 CFU/ml to 20.3x104 CFU/ml, the total aerobic mesophilic flora and the psychrotrophs have an average of 2.5x105 germs/ml to 82x105 germs/ml lower than before improvement (12.5x105 germs/ml to 192x105 germs/ml). Conclusion: We can conclude that the work done leads to an improvement and satisfaction of the quality of raw milk compared to the standard after the implementation of HACCP.

Evaluation of the physicochemical and hygienic quality of cow's milk and its derivatives in El Jadida city Morocco.

Background: Despite the efforts and investments made for traceability and the guarantee of a fair and safe milk product, the informal sector threatens the safety of milk. In fact, during this circuit, the product does not undergo any treatment and therefore presents serious risks for the health of the consumer. In this context, studies have been carried out on samples of peddled milk and products derived from it. Objective: The purpose of this study is to evaluate the relevance of the informal circuit in Morocco's Doukkala region (El Jadida Province) by physicochemical and microbiological investigation of raw milk and its derivatives at various points of sale. Materials and method: 84 samples were taken between (23 for raw milk, 30 for the «Lben¼, and 31 for the «Raib¼) between January 1st, 2021 and October 30th, 2021. According to Moroccan rules, microbiological analyses revealed an extremely high non-compliance rate in most samples obtained at the level of outlets situated in the El Jadida region, with a non-compliance ratio of 65 percent for raw milk sold, 70 percent for the «Lben¼, and 40 percent for the «Raib¼. Results: Likewise, these analyses revealed that majority of the samples did not fulfill international criteria for the pH values of raw milk samples «Lben¼ and «Raib¼, which are respectively between 5.85 and 6.71; 4.14 and 4.43 and 4.5. Other characteristics, including lactose, proteins, fat, mineral salts, density, and additional water, have also yielded results. Conclusion: This has allowed us to analyze the major impact of the peddling circuit at the regional level, which is a risk factor for consumer health.