Mikroinkapsulacija soja Lactobacillus sakei MRS_296 s potencijalom primjene kao starter kultura

master's thesis

• Title (english): Microincapsulation of a strain Lactobacillus sakei MRS_296 with potential application as a starter culture
• Author: Anita Boras
• Mentor: Mirna Mrkonjić Fuka (mentor)
• Committee member: Mirna Mrkonjić Fuka (predsjednik povjerenstva)
• Committee member: Marko Vinceković (član povjerenstva)
• Committee member: Ivica Kos (član povjerenstva)
• Granter: University of Zagreb; Faculty of Agriculture; (Microbiology); Zagreb
• Defense date and country: 2019-09-30, Croatia
• Scientific / art field, discipline and subdiscipline: BIOTECHNICAL SCIENCES; Agronomy

Abstract

Za spriječavanje proliferacije potencijalnih patogena, ubrzavanje fermentacijskog postupka, poboljšanje organoleptičkih svojstava te postizanje visoke razine sigurnosti hrane i njene kvalitete u tradicionalnim fermentiranim kobasicama, primjena starter kultura je nužnost. Soj Lactobacillus sakei MRS_296 je selekcioniran i detaljno molekularno-biološki i tehnološki karakteriziran u Laboratoriju za mikrobiologiju namirnica Sveučilišta u Zagrebu Agronomskog fakulteta. Bakterijski soj zadovoljio je... More vrlo stroge kriterije selekcije i može biti primijenjen kao dio starter kultura za standardizaciju proizvodnje kobasica od divljači. Kako bi se broj mikrobnih kultura koje se apliciraju kao starter kulture održao visokim kroz čitav proces proizvodnje kobasica, stanice se mogu inkapsulirati. Mikroinkapsuliranjem se mikrobne stanice mogu učinkovito zaštiti od biotičkih i abiotičkih stresova te se može povećati njihova biomasa i vijabilnost. U ovom radu ispitan je potencijal mikroinkapsuliranja u sustavu nosača na bazi natrijevog alginata tehnikom ionskog geliranja, s ciljem povećanja brojnosti i vijabilnosti inkapsuliranog soja. Cilj rada je pripremiti mikrosfere natrijevog alginata ispunjene sojem Lb. sakei MRS_296, koje će nakon procesa biti čuvane u tekućem BHI mediju kroz 40 dana i ispitati dinamiku njihovog otpuštanja i preživljavanja u alginatnim mikrosferama. Pokazano je da se soj Lb. sakei MRS_296 počinje otpuštati odmah nakon inkapsulacije (4,82 ± 0,07 log CFU/ml) i najviše se otpušta do 5. dana (7,65 ± 0,05 log CFU/ml). Sličan trend dokazan je i za preživljavanje ispitivanog soja u mikrosferama gdje je najveća brojnost u mikrosferama detektirana 5. dan (9,32 ± 0,05 log CFU/g). Između brojnosti soja Lb. sakei MRS_296 u mikrosferama i njegovog otpuštanja iz mikrosfera postoji jaka značajna pozitivna korelacija (r = 0,98; p < 0,01). Istovremeno, dokazana je i jaka značajna negativna korelacija između otpuštanja soja Lb. sakei MRS_296 iz mikrosfera i promjene pH vrijednosti medija (r = -0,81; p = 0,03). Kod čuvanja mikrosfera pri 25 °C soj Lb. sakei MRS_296 ostaje vijabilan i nakon 40 dana, međutim postotak njegovog preživljavanja je iznimno nizak (0,0002 – 0,0008 %). Less

Abstract (english)

To prevent proliferation of potential pathogens, accelerate the fermentation process, improve organoleptic properties and achieve high levels of food safety and its quality in traditional fermented sausages, the application of meat starter cultures is a necessity. Strain Lactobacillus sakei MRS_296 was selected and molecular-biologically and technologically characterized in the Laboratory of Food Microbiology at the University of Zagreb Faculty of Agriculture. This bacterial strain satisfied... More very strict selection criteria and it may be used as a part of starter cultures for the standardization of game meat sausages production. In order to maintain high microbial culture counts throughout the whole sausage production, cells can be encapsulated. Microencapsulation can efficiently protect microbial cells from biotic and abiotic stress which can result in the increase of their biomass and viability. In this study, the potential of carrier system based on sodium alginate formed by ionizing gelation technique for increasing the number and viability of encapsulated strain was investigated. The aim of this master’s thesis is to prepare sodium alginates microspheres by ionizing gelation, filled with strain Lb. sakei MRS_296, which will then be stored in the BHI broth for 40 days and to follow their release and survival dynamics in alginate microspheres. It has been shown that strain Lb. sakei MRS_296 begins to release immediately after encapsulation (4.82 ± 0.07 log CFU/ml) and the majority is released by day 5 (7.65 ± 0.05 log CFU/ml). A similar trend was detected for the survival of the tested strain in the microspheres where the highest abundance was detected on day 5 (9.32 ± 0.05 log CFU/g). A strong significant positive correlation (r = 0.98; p <0.01) between the abundance of strain Lb. sakei MRS_296 in the microspheres and its release from the microspheres was detected. At the same time, a strong significant negative correlation between the release of strain Lb. sakei MRS_296 from the microspheres and pH changes of the medium (r = -0.81; p = 0.03) was detected. When storing the microspheres at 25 °C, strain Lb. sakei MRS_296 remains viable after 40 days, however, its survival rate is extremely low (0.0002 - 0.0008%). Less

• Keywords: BMK; Lactobacillus sakei; tradicionalne fermentirane kobasice; starter kulture; mikroinkapsulacija
• Keywords (english): LAB; Lactobacillus sakei MRS_296; traditional fermented sausages; starter cultures; microencapsulation
• Language: croatian
• URN:NBN: urn:nbn:hr:204:835936
• Study programme: Title: Agroecology; Study programme type: university; Study level: graduate; Academic / professional title: magistar/ magistra inženjer/inženjerka agroekologija (magistar/ magistra inženjer/inženjerka agroekologija)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2019-10-21 13:12:03