Želatinski film s mikrokapsulama antocijana izoliranih iz plavog graška (Clitoria ternatea) kao prehrambena ambalaža s učinkom suzbijanja patogenih mikroorganizama

Research background. Microbial contamination of food products is one of the significant causes of food spoilage and foodborne illnesses. The use of active packaging films incorporated with antimicrobial agents can be a measure to improve food quality and extend shelf life. Nevertheless, antimicrobial agents such as silver, copper, titanium and zinc in the packaging films have raised concerns among consumers due to toxicity issues. Experimental approach. The current study aims to develop biodegradable gelatine-based edible films incorporated with microcapsules of Clitoria ternatea-derived anthocyanins as a natural antimicrobial agent. The impact of incorporation of microcapsules with anthocyanins on the morphology, thermal, mechanical, water vapour barrier and physicochemical properties of the gelatine films was evaluated in this study. The effectiveness of the developed films against foodborne pathogens and their application for perishable food protection were also investigated. Results and conclusions. The results show that incorporating anthocyanin microcapsules enhances the gelatine film physical and mechanical properties by increasing the thickness, tensile strength, Young\u27s modulus and elongation at break of the films. Scanning electronic microscopy analysis revealed that the film surface morphology with anthocyanin microcapsules had a homogeneous and smooth surface texture compared to the control. The thermogravimetric analysis also showed a slight improvement in the thermal properties of the developed films. Agar well diffusion assay revealed that the developed films exhibit significant inhibition against a broad-spectrum of bacteria. Furthermore, the films composed of gelatine with anthocyanin microcapsules significantly reduced the total viable count of microorganisms in the bean curd during storage for 12 days compared with the control films. Novelty and scientific contribution.Increasing global awareness of healthy and safe food with minimal synthetic ingredients as preservatives has sparked the search for the use of antimicrobial agents of natural origins in active food packaging material. In this study, a safe and effective active packaging film was developed using an environmentally friendly biopolymer, gelatine film incorporated with microcapsules of Clitoria ternatea-derived anthocyanins as a natural antimicrobial agent. This study demonstrated that such a method is not only able to improve the film physical properties but can also significantly prolong the shelf life of food products by protecting them from microbial spoilage.Pozadina istraživanja. Mikrobna kontaminacija je jedan od važnijih uzroka kvarenja hrane i pojave bolesti koje se prenose hranom. Primjenom aktivnih filmova za pakiranje hrane obogaćenih antimikrobnim agensima može se poboljšati kakvoća hrane i produljiti njezina valjanost. No, potrošači su sve više zabrinuti zbog moguće toksičnosti mnogih antimikrobnih agensa koji se primjenjuju u tim filmovima, kao što su srebro, bakar, titan i cink. Eksperimentalni pristup. Svrha je ovoga rada bila izraditi biorazgradive jestive filmove od želatine obogaćene mikrokapsulama antocijana izoliranih iz plavog graška (Clitoria ternatea) kao prirodnih antimikrobnih agensa. Ispitan je utjecaj mikrokapsula s antocijanima na morfologiju, toplinska, mehanička i fizikalno-kemijska svojstva filmova, te njihovu propusnost vodene pare. Također je ispitan učinak dobivenih filmova na patogene mikroorganizme u hrani i zaštitu lako pokvarljivih proizvoda. Rezultati i zaključci. Rezultati pokazuju da su se fizikalna i mehanička svojstva filmova poboljšala s dodatkom mikrokapsula antocijana, koje su povećale gustoću, vlačnu čvrstoću, Youngov modul elastičnosti i istezljivost filma. Ispitivanjem morfoloških značajki pretražnom elektronskom mikroskopijom utvrđeno je da film obogaćen antocijanima imao homogenu i glatku površinu, za razliku od kontrolnog uzorka. Termogravimetrijskom je analizom potvrđeno blago poboljšanje toplinskih svojstava filmova. Difuzijom u jažicama agara otkriveno je da dobiveni filmovi imaju znatan inhibicijski učinak na širok spektar bakterija. Osim toga, filmovi od želatine s dodatkom mikrokapsula antocijana smanjili su ukupni broj živih stanica mikroorganizama u tofuu tijekom 12 dana skladištenja, u usporedbi s kontrolnim uzorcima. Novina i znanstveni doprinos. Veća svijest ljudi o važnosti zdrave i sigurne prehrane sa što manjim udjelom sintetičkih konzervansa potakla je potragu za antimikrobnim agensima iz prirodnih izvora koji se mogu upotrijebiti u materijalima za aktivno pakiranje hrane. U ovom je radu razvijen siguran i učinkovit aktivni ambalažni film s dodatkom ekološki prihvatljivog biopolimera, želatinskog filma obogaćenog mikrokapsulama antocijana izoliranih iz plavog graška (Clitoria ternatea) kao prirodnih antimikrobnih agensa. Istraživanje je pokazalo da se ovom metodom mogu poboljšati fizikalna svojstva filma, ali i bitno produljiti vrijeme skladištenja hrane, jer ih dobiveni film štiti od mikrobnog kvarenja

Poboljšanje mikrobiološke ispravnosti borovnica pomoću polimernih nanočestica s timolom

Research background. The presence of Yersinia enterocolitica on raw food products raises the concern of yersiniosis as most of the berries are consumed raw. This is a challenging issue from the food safety aspect since it could increase the occurrence of foodborne diseases among humans. Thus, it is crucial to implement an effective sanitation before the packaging. Experimental approach. This study aims to synthesize and characterize thymol-loaded polyvinyl alcohol (Thy/PVA) nanoparticles as a sanitizer for postharvest treatment of blueberries. Thy/PVA nanoparticles were characterized by spectroscopic and microscopic approaches, prior to the analyses of antimicrobial properties. Results and conclusions. The diameter size of the nanoparticles was on average 84.7 nm, with a surface charge of −11.73 mV. Based on Fourier transform infrared (FTIR) measurement, the Thy/PVA nanoparticles notably shifted to the frequency of 3275.70, 2869.66, 1651.02 and 1090.52 cm-1. A rapid burst was observed in the first hour of release study, and 74.9 % thymol was released from the PVA nanoparticles. The largest inhibition zone was displayed by methicillin-resistant Staphylococcus aureus (MRSA), followed by Y. enterocolitica and Salmonella typhi. However, amongst these bacteria, the inhibition and killing of Y. enterocolitica required a lower concentration of Thy/PVA nanoparticles. The treatment successfully reduced the bacterial load of Y. enterocolitica on blueberries by 100 %. Novelty and scientific contribution. Thymol is a plant-based chemical without reported adverse effects to humans. In this study, by using the nanotechnology method of encapsulation with PVA, we improved the stability and physicochemical properties of thymol. This nanoparticle-based sanitizer could potentially promote the postharvest microbiological safety of raw berries, which may become an alternative practice of food safety.Pozadina istraživanja. Prisutnost bakterije Yersinia enterocolitica u sirovim prehrambenim proizvodima izaziva zabrinutost zbog moguće pojave jersinioze, s obzirom na to da se bobičasto voće najčešće konzumira sirovo. S aspekta sigurnosti hrane ova bakterija predstavlja problem, jer može povećati učestalost pojave bolesti koje se prenose hranom. Stoga je neophodno provesti učinkovitu sanitaciju voća prije pakiranja. Eksperimentalni pristup. Svrha je ovoga rada bila sintetizirati i okarakterizirati nanočestice poli(vinil-alkohola) s timolom kao dezinficijensom za obradu borovnica prije pakiranja. Nanočestice su okarakterizirane pomoću spektroskopije i mikroskopije, a zatim su ispitana njihova antimikrobna svojstva. Rezultati i zaključci. Prosječni promjer nanočestica bio je 84,7 nm, s površinskim nabojem od −11,73 mV. Rezultati Fourier transformirane infracrvene spektroskopije (FTIR) pokazuju značajan pomak pika nanočestica poli(vinil-alkohola) s timolom prema frekvencijama od 3275,70; 2869,66; 1651,02 i 1090,52 cm-1. Iznenadni porast količine timola oslobođenog iz nanočestica opažen je u prvih sat vremena ispitivanja njegovog kontroliranog otpuštanja, a ukupno je otpušteno 74,9 % timola. Opažena je najveća zona inihbicije rasta bakterije Staphylococcus aureus otporne na meticilin (MRSA), a zatim bakterija Y. enterocolitica i Salmonella typhi. Međutim, za inhibiciju i ubijanje bakterija Y. enterocolitica bile su potrebne manje koncentracije nanočestica poli(vinil-alkohola) s timolom. Ovim je postupkom broj bakterija Y. enterocolitica uspješno smanjen za 100 %. Novina i znanstveni doprinos. Timol je spoj biljnog porijekla, koji ne narušava zdravlje čovjeka. U ovome smo radu inkapsulacijom u omotaču s poli(vinil-alkoholom) povećali stabilnost i poboljšali fizikalno-kemijska svojstva timola. Primjenom nanočestica tog dezinficijensa može se poboljšati mikrobiološka ispravnost sirovog bobičastog voća, što se u praksi može primijeniti za očuvanje sigurnosti hrane

HBVに対する宿主応答の解析に関する研究

配架番号：217

HBVに対する宿主応答の解析に関する研究 [論文内容及び審査の要旨]

配架番号：217

Dual production of poly(3-hydroxybutyrate) and glutamate using variable biotin concentrations in Corynebacterium glutamicum

We previously synthesized poly(3-hydroxybutyrate) [P(3HB)] in recombinant Corynebacterium glutamicum, a prominent producer of amino acids. In this study, a two-step cultivation was established for the dual production of glutamate and P(3HB) due to the differences in the optimal concentration of biotin. Glutamate was extracellularly produced first under the biotin-limited condition of 0.3 μg/L. Production was then shifted to P(3HB) by addition of biotin to a total concentration of 9 μg/L. The final products obtained were 18 g/L glutamate and 36 wt% of P(3HB)

Nucleic Acid Sensors Involved in the Recognition of HBV in the Liver–Specific in vivo Transfection Mouse Models—Pattern Recognition Receptors and Sensors for HBV

Cellular innate immune system recognizing pathogen infection is critical for the host defense against viruses. Hepatitis B virus (HBV) is a DNA virus with a unique life cycle whereby the DNA and RNA intermediates present at different phases. However, it is still unclear whether the viral DNA or RNA templates are recognized by the pattern-recognition receptors (PRRs) to trigger host antiviral immune response. Here in this article, we review the recent advances in the progress of the HBV studies, focusing on the nucleic acid sensors and the pathways involved in the recognition of HBV in the liver–specific in vivo transfection mouse models. Hydrodynamic injection transfecting the hepatocytes in the gene-disrupted mouse model with the HBV replicative genome DNA has revealed that IFNAR and IRF3/7 are indispensable in HBV eradication in the mice liver but not the RNA sensing pathways. Interestingly, accumulating evidence of the recent studies has demonstrated that HBV markedly interfered with IFN-β induction and antiviral immunity mediated by the Stimulator of interferon genes (STING), which has been identified as a central factor in foreign DNA recognition and antiviral innate immunity. This review will present the current understanding of innate immunity in HBV infection and of the challenges for clearing of the HBV infection

Characterization of bacterial cellulose produced via fermentation of acetobacter xylinum 0416

The production of plant-based cellulose products had contributed to the increasing rate of deforestation activities. Bacterial cellulose (BC) produced via fermentation process can be considered as an alternative. In this study, BC was produced by fermentation of Acetobacter xylinum 0416 and further analyzed to determine its physiochemical properties. The characterization of the BC was carried out through fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscope (FESEM), thermogravimetric analysis (TGA), pH, moisture content, compressibility index and swelling properties. Then, it was compared with plant-based cellulose products which are carboxymethyl cellulose (CMC) and cellulose powder (CP). FTIR analysis demonstrated the similar properties between BC, CMC and CP while FESEM depicted a smoother surface and nanostructure of the BC. The TGA analysis indicated that BC has the highest thermal stability compared to CMC and CP. The other characterization results showed that BC displayed promising properties compared to CMC and CP. These findings further support the potential of substituting the use of plant-based cellulose products in the market with BC produced by A. xylinum 0416