magistrsko delo
Ines Uršnik (Author), Petra Golja (Reviewer), Marko Kreft (Mentor), Damjan Janeš (Co-mentor)

Abstract

Boza je gosta pijača kiselkastega okusa. Okus vahko variira zaradi količine dodanega sladkorja, vrste žita, mikroorganizmov in dolžine fermentacije. Značilna je za Albanijo, Bolgarijo, Romunijo, Turčijo in druge balkanske države. V Turčiji se pije toplo pripravljena boza predvsem v zimskem času, saj segreje telo, zaradi česar naj bi pomagala proti sezonskim okužbam dihal. V Romuniji pijejo ohlajeno, osvežilno bozo predvsem v poletnih mesecih. Zaradi vsebnosti vitaminov A, C, E in štirih vrst vitamina B, je dragoceno hranilo telesno dejavnih ljudi. Še posebej primerna je za vegetarijance in vegane, saj je v celoti rastlinskega izvora in je dober vir vitaminov in dober nadomestek mlečnih napitkov. V magistrski nalogi smo spremljali spremembo pH zmesi za bozo, pripravljene iz moke in bakterij, z namenom ugotoviti, kako hitro se pH v omenjeni zmesi niža. Ugotovili smo, da nižanje pH v zmeseh iz različnih mok in ob dodatku različnih bakterij ni enako hitro. Prav tako smo ugotovili, da se pH po 48 urah po dodanih bakterijah v zmes razlikuje glede na dodane bakterije. Izvedli smo tudi titracijo zmesi za bozo z namenom določiti količino nastale kisline med procesom fermentacije. Ugotovili smo, da za zmesi iz škroba od dodatku katerihkoli bakterij ni potrebno veliko baze za nevtralizacijo kisline, ki je nastala med procesom fermentacije. Zanimala nas je tudi rast bakterij v vzorcu, ki smo jo ocenili s pomočjo plošč Petrifilm®. Ugotovili smo, kakšno rastno krivuljo imajo bakterije iz kisle smetane v proseni moki. S plinsko kromatografijo in masno spektrometrijo smo kvalitativno in kvantitativno določili lahkohlapne snovi v vzorcih boze v različnih časih po dodatku bakterij v zmes, z namenom ugotoviti, ali in kako se te lahkohlapne snovi med fermentacijo spreminjajo. Ugotovili smo, da se vsebnost nekaterih analiziranih spojin med fermentacijo značilno spreminja. Nazadnje smo v učnem načrtu za osnovne šole pregledali cilje, ki se nanašajo na našo temo in jih analizirali, da bi ugotovili, kako so te teme zastopane v potrjenih učbenikih. Na osnovi našega raziskovalnega dela smo razvili dva delovna lista za učence, kot alternativo dosedaj opisanim poskusom (t.j. kisanje mleka) s področja fermentacije.

Keywords

boza;rast bakterij;GC-MS;priprava poskusa;

Data

Language: Slovenian
Year of publishing:
Typology: 2.09 - Master's Thesis
Organization: UL PEF - Faculty of Education
Publisher: [I. Uršnik]
UDC: 57:543.544.3(043.2)
COBISS: 12145993 Link will open in a new window
Views: 476
Downloads: 132
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Other data

Secondary language: English
Secondary title: Preparation of teaching materials for fermentation of boza experiment – beverage made from cereal grains
Secondary abstract: Boza is a dense beverage of sour taste. The taste may vary according to the amount of added sugar, the type of cereals and micro-organisms used, and the length of fermentation. It is a typical beverage found in Albania, Bulgaria, Romania, Turkey and other Balkan countries. In Turkey, warm boza is consumed primarily during the winter due to the effect of warming of the body and as a result it is expected to help against seasonal respiratory infections. In Romania, they drink chilled, refreshing boza, especially during the summer months. As it contains vitamins A, C, E and four types of vitamin B, it is a valuable nutrient for physically active people. It is especially suitable for vegetarians and vegans, since it is entirely plant-based, and is a good source of vitamins and a good substitute for milk drinks. In the present Master's degree thesis, a change in pH of the mixture of flour and bacteria was monitored in order to determine how quickly the pH of mixture decreases. We found that the rate of pH decrease of mixtures from various types of flour and also with the addition of different bacteria types differs. We also found that the pH of the mixtures 48 hours after the addition of bacteria differs according to the type of bacteria added. We also carried out titration of the boza mixture in order to determine the amount of acid produced during the fermentation process. We found that for a boza mixture prepared with starch, the addition of any type of bacteria does not require a lot of base in order to neutralize the acid produced during the fermentation process. We were also interested in the growth of bacteria in the sample, which was assessed with the Petrifilm® plate. We described the growth curve of bacteria obtained from sour cream in an millet flour. By means of gas chromatography and mass spectrometry, the volatile substances in the boza samples were determined qualitatively and quantitatively on several occasions, in order to evaluate if and how these volatile substances change during fermentation. We demonstrated that the content of some of the analyzed volatile substances varies significantly during fermentation. Finally, we reviewed and analyzed the objectives that pertain to our topic in the curriculum for primary schools, to assess how these topics are represented in certified textbooks. On the basis of our experimental work, we developed two worksheets for pupils, as an alternative to the previously described experiments (i.e. acidification of milk) on the topic of fermentation.
Secondary keywords: biology;biologija;
File type: application/pdf
Type (COBISS): Master's thesis/paper
Thesis comment: Univ. v Ljubljani, Pedagoška fak., Poučevanje, Predmetno poučevanje: Biologija-kemija
Pages: VI, 48 f.
ID: 10973377