Morelli, Michela (2025) Innovative Enzymatic Cleaning Technologies for Biological Lines in Food Production. [Tesi di dottorato]

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Abstract

The Italian agri-food industry is the third country in Europe, with an annual turnover of 140 billion euros in 2018. Modern methods for the processing of food products, are based on the use of safe technologies for the washing and sanitation of facilities; among these of great importance is the automated closed-loop cleaning system, Clean in Place (CIP), which realizes a recirculation of detergents (Guerrero-Navarro A. E. et al., 2021). Enzymes for industrial purposes are produced from fungi such as Aspergillus oryzae or bacteria such us Bacillus subtilis, Bacillus thermoproteolyticus, Bacillus megaterium, Bacillus cereus e Bacillus thuringiensis. The production of enzymes by bacteria occurs through the use of a process called submerged fermentation. Fermentation takes place in large vessels called fermenters with volumes up to 1,000 m3 During our work, two different types of enzymes were selected to be tested (lipase and protease) against two different types of industrial dirt: dirty tomatoes and dirty condensed milk, these were produced artificially on stainless steel plates and tubes. The results were then compared with those obtained by cleaning with deter-gents of a chemical nature. In addition, two model systems (IP1 and IP2) were created to evaluate the best dosage, time and temperature to obtain satisfactory cleaning. At the end of washing, the enzyme blend has been inactivated under conditions which are similar to those generally undertaken after sanitation. The biocidal potential of these substances in relation to potentially pathogenic microorganisms has also been assessed like us Escherichia coli ATCC 25922, Listeria monocytogenes ATCC 19115, Pseudomonas aeruginosa ATCC 27853, Salmonella Typhimurium ATCC 14028, the different formulations examined showed the ability to break down microbial loads of 106 CFU/mL and 104 CFU/mL of microorganisms, believed to be the main food pathogens. In addition, analyses of the Minimum Inhibitory Concentration (MIC) of the detergents used against the target bacteria also used in previous analyses have been carried out, obtaining excellent results even at more intensive dilutions of the products. In conclusion, the enzymes tested with the two pilot systems were effective on the dirty tomato and milk and have the ability to decrease the microbial load of potentially pathogenic microorganisms, although with longer contact times, making such CIP cleaning systems using organic deter-gents a viable environmentally sustainable proposition for companies that want to adopt an environmentally friendly detergent profile.

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