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β‐Galactosidases produced by microorganisms are being used in food technology for hydrolysis of lactose in milk and milk by‐products. The enzyme has attracted much attention in view of lactose intolerance in human population and due to importance of milk in human diet. β‐Galactosidase hydrolyze β‐galactopyranosides, that is, lactose, and form a range of trans‐galactosylation products or galactooligosaccharides (GOS) capable of providing several health benefits as prebiotics. In addition, the enzyme also finds applications in production of lactose based sweeteners from high lactose containing effluents of cheese manufacturing industries. Currently, the enzyme is mainly obtained from Aspergillus niger and Kluyveromyces lactis, however, they are thermolabile with optimum pH between 4.0 and 6.0 accompanied by low chemical resistance and high product inhibition properties. Thermostable enzymes are suitable to perform the hydrolytic process at relatively high temperatures, minimizing pathogen contamination, psychrophilic β‐galactosidases are preferred for treatment of milk under refrigerated conditions (<15°C), without heating and maintenance of temperature. Lactic acid bacteria (LAB) are a potential source of food grade enzymes and other metabolites. Although reports on the use of β‐galactosidase of LAB in pure form is reported for hydrolysis of lactose in milk and production of fermented milk products for reduced lactose content, methods of immobilization for use in continuous bioreactors are less explored. Recombinant DNA technology has attained much significance to reveal molecular aspects of enzyme catalysis, protein structure, gene organization for expression, and enhancement of thermophilic, psychrophilic, and mesophilic β‐galactosidases. Heterologous expression of extremozymes with β‐galactosidase would help in overcoming the limitations faced within the bioprocess technology. Practical applications Lactic acid bacteria (LAB) producing extracellular cell bound β‐galactosidase have been isolated and enzyme production was carried out using modified MRS medium incorporating lactose as enzyme inducer. Process for growing probiotic lactic acid bacteria for β‐galactosidase from fermented milk products has been patented (Indian Patent No. 247904). Thermostable β‐galactosidases were also extracted from Kluyveromyces lactis a yeast, isolated from curd samples and Bacillus sp. MTCC 864. An Indian patent has been granted for a simple, cost effective perforated two compartment immobilized enzyme bioreactor was designed and fabricated for lactose hydrolysis (Indian Patent No. 264609). The bioreactor can be operated continuously at temperature between 5.0 and 75.0°C, employing different immobilized enzyme preparations for different operational temperatures. β‐galactosidase of cell confined LAB and yeast have been immobilized in agarose and galactooligosaccharides (GOS) production was observed at 40% lactose concentration in 0.05M phosphate buffer at pH 6.5. Immobilized bioreactor preparation could be used for lactos...

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Biopolymers and biopreservatives produced by microorganisms play an essential role in food technology. Polyhydroxyalkanoates and bacteriocins produced by bacteria are promising components to safeguard the environment and for food preservation applications. Polyhydroxybutyrate (PHB)-based antimicrobial films were prepared incorporating eugenol, from 10 to 200 μg/g of PHB. The films were evaluated for antimicrobial activity against foodborne pathogens, spoilage bacteria, and fungi such as Staphylococcus aureus, Escherichia coli, Salmonella typhimurium, Bacillus cereus, Aspergillus flavus, Aspergillus niger, Penicillium sp., and Rhizopus sp. The synergistic antimicrobial activity of the films in the presence of crude pediocin was also investigated. The broth system containing pediocin (soluble form) as well as antimicrobial PHB film demonstrated an extended lag phase and a significant growth reduction at the end of 24 h against the bacteria. Crude pediocin alone could not elicit antifungal activity, while inhibition of growth and sporulation were observed in the presence of antimicrobial PHB film containing eugenol (80 μg/g) until 7 days in the case of molds, i.e., A. niger, A. flavus, Penicillium sp., and Rhizopus sp. in potato dextrose broth. In the present study, we identified that use of pediocin containing broth in conjunction with eugenol incorporated PHB film could function in synergized form, providing effective hurdle toward food contaminating microorganisms. Furthermore, tensile strength, percent crystallinity, melting point, percent elongation to break, glass transition temperature, and seal strength of the PHB film with and without eugenol incorporation were investigated. The migration of eugenol on exposure to different liquid food simulants was also analyzed using Fourier transform infrared spectroscopy. The study is expected to provide applications for pediocin in conjunction with eugenol containing PHB film to enhance the shelf life of foods in the food industry.