Title MIKROBIOLOŠKO KVARENJE VOĆNIH SOKOVA IZ KONVENCIONALNE I EKOLOŠKE PROIZVODNJE
Title (english) THE MICROBIOLOGICAL SPOILAGE OF FRUIT JUICES FROM CONVENTIONAL AND ORGANIC PRODUCTION
Author Chiara Košuta
Mentor Mateja Ožanič (mentor)
Mentor Valentina Marečić (komentor)
Committee member Darinka Vučković (predsjednik povjerenstva)
Committee member Mateja Ožanič (član povjerenstva)
Committee member Marin Tota (član povjerenstva)
Granter University of Rijeka Faculty of Medicine (Department of Microbiology and Parasitology) Rijeka
Defense date and country 2022-07-05, Croatia
Scientific / art field, discipline and subdiscipline BIOMEDICINE AND HEALTHCARE Clinical Medical Sciences Medical Microbiology
Scientific / art field, discipline and subdiscipline BIOTECHNICAL SCIENCES Food Technology Food Microbiology
Abstract Kvarenje hrane je svaka promjena u hrani kojom se ona pretvara iz zdravstveno ispravne u neprihvatljivu te opasnu za čovjeka. Uslijed rasta i razmnožavanja mikroorganizama u hrani dolazi do promjene boje, mirisa, okusa i sastava hrane. Cilj ovog istraživanja, koje je provedeno u svrhu diplomskog rada, bio je ispitati mikrobiološku ispravnost četiri uzorka voćnih sokova ispravnog roka trajanja. Prvi uzorak je voćni sok miješanog voća iz koncentriranog soka sa sladilima obogaćen vitaminima iz konvencionalne proizvodnje. Drugi uzorak je sok multivitamin ekološke proizvodnje. Treći uzorak voćnog soka predstavlja sok od jabuke od koncentriranog soka jabuke s udjelom voća 100% iz konvencionalne proizvodnje, dok je četvrti uzorak voćnog soka organski sok od jabuke iz ekološke proizvodnje. U svim uzorcima ispitivana je prisutnost ukupnih aerobnih mezofilnih bakterija, bakterija Enterobacteriaceae, Salmonella, E. coli, L. monocytogenes, B. cereus, S. aureus, Enterococcus te prisutnost kvasaca i plijesni. S obzirom da niti u jednom uzorku nije došlo do pozitivnog porasta ovih mikroorganizama, zaključeno je da su ispitivani uzorci mikrobiološki ispravni. Nakon što je dokazana mikrobiološka ispravnost voćnih sokova, cilj je bio odrediti kinetiku rasta S. aureus, soj ATCC 29213 S. aureus, odnosno bakterije E. coli, soj ATCC 25922. Kinetika rasta ispitivana je pri tri različite temperature ( 4 °C, 25 °C, 37 °C) tijekom vremenskog razdoblja od dvanaest dana, a broj bakterija određivan je trećeg, sedmog, devetog te dvanaestog dana od dodatka bakterija u voćne sokove. Baird Parker je podloga korištena je za određivanje broja bakterija S. aureus, dok je TBX agar podloga na kojoj rastu bakterije E. coli. Rezultati ovog istraživanja pokazuju da su svi ispitani uzorci voćnih sokova iz konvencionalne i ekološke proizvodnje mikrobiološki ispravni te da bakterije E. coli pokazuju bolju sposobnost preživljavanja u voćnim sokovima u odnosu na S. aureus. Bakterije S. aureus imaju sposobnost preživljavanja u voćnom soku multivitamin ekološke proizvodnje pri 4 °C, 25 °C i 37 °C . Dokazano je da bakterije E. coli preživljavaju u uzorku voćnog soka mješovitog voća multivitamin ekološkog podrijetla pri 4 °C te 25 °C i uzorcima sokova od jabuke konvencionalne i ekološke proizvodnje pri 4 °C te 25 °C. Nadalje, dokazano je da bakterije S. aureus i E. coli nemaju sposobnost rasta i razmnožavanja u uzorcima voćnih sokova koji su korišteni tijekom istraživanja.
Abstract (english) Food spoilage is considered as a change in food that turns it from healthy to unacceptable and dangerous for humans. Growth and replication of microorganisms in food could lead to changes in color, smell, taste and composition of food. The aim of this research, which was conducted for the purpose of the master thesis, was to examine the microbiological correctness of four samples of fruit juices. The first sample is fruit juice of mixed fruit composed of concentrated juice with sugars and sweeteners enriched with vitamins from conventional production. The second sample is multivitamin juice of organic production. The third sample of fruit juice is an apple juice made from concentrated apple juice with a 100% fruit content from conventional production, while the fourth sample of fruit juice is an apple juice from organic production. The presence of total aerobic mesophilic bacteria, Enterobacteriaceae, Salmonella, E. coli, L. monocytogenes, B. cereus, S. aureus, Enterococcus and yeasts and molds was examined in all samples. All samples were negative for tested microorganisms, so we concluded that the tested samples are microbiologically correct. Further, the aim was to analyse the growth kinetics of S. aureus and E. coli in all juice samples. Growth kinetics were tested at three different temperatures (4 °C, 25 °C, 37 °C) over a period of twelve days, and the number of bacteria was determined on the third, seventh, ninth and twelfth day from the addition of bacteria to fruit juices. Baird Parker is the medium used to determine the number of S. aureus, while TBX agar is the selective medium for E. coli determination. All together, the results of this study showed that all tested samples of fruit juices from conventional and organic production are microbiologically correct and that E. coli shows a better ability to survive in fruit juices compared to S. aureus. S. aureus has the ability to survive in fruit juice multivitamin from organic production at 4 °C, 25 °C and 37 °C. E. coli has been shown to survive in a sample of mixed fruit juice of multivitamin of organic origin at 4 °C and 25 °C and samples of apple juice of conventional and organic production at 4 °C and 25 °C. However, both S. aureus and E. coli showed no ability to grow and reproduce in fruit juice samples used during the study.
Keywords
S. aureus
E. coli
voćni sokovi
kinetika rasta
mikrobiološka ispravnost
Keywords (english)
S. aureus
E. coli
fruit juices
growth kinetics
microbiological correctness
Language croatian
URN:NBN urn:nbn:hr:184:535797
Study programme Title: Study of Sanitary Engineering Study programme type: university Study level: graduate Academic / professional title: magistar/magistra sanitarnog inženjerstva (magistar/magistra sanitarnog inženjerstva)
Type of resource Text
File origin Born digital
Access conditions Open access
Terms of use
Created on 2022-07-02 08:56:55