OPTIMIZATION OF BIOPROCESS CONDITIONS AND PARAMETERIZATION OF GROWTH CURVE OF PROBIOTIC BIOPOPULATION PROPAGATION IN ECOLOGICAL MILK

Onesnaženost okolja je pripeljala tako daleč, da je v sodobni družbi moč zaslediti povečano povpraševanje po bio-izdelkih in izdelkih, ki ugodno vplivajo na naše zdravje. V to skupino živil sodijo tudi probiotiki in prebiotiki. Kot probiotik z zdravilnimi učinki se že stoletja uporablja kefir, ki ga najpogosteje pripravimo iz polnomastnega kravjega mleka. V diplomskem delu pa smo se osredotočili na tradicionalno gojenje kefirnih zrn v bio-mleku. S Taguchijevo metodo načrtovanja eksperimentov smo določili optimalne vrednosti procesnih parametrov (temperaturo, vrtilno frekvenco mešala, masno koncentracijo kefirnih zrn) in sestavo fermentacijskega medija, pri katerih smo dobili najvišjo dnevno prirast mase kefirnih zrn, tradicionalno gojenih v bio-mleku. Poleg tega smo z grafično in statistično analizo ANOVA določili relativne vplive procesnih parametrov glede na izbran optimizacijski kriterij. Z optimalnimi vrednostmi procesnih parametrov smo v nadaljevanju izvedli matematično modeliranje in bio-parameterizacijo rastne krivulje kefirnih zrn, gojenih v bio-mleku. Uporabili smo računalniški program SigmaPlot®10.0. V tretjem delu raziskav smo z ReactIRTMiC10 analiznim sistemom pri različnih sestavah fermentacijskega medija določili količino nastalega etanola v kefirju med 24 urno fermentacijo. Celotno serijo eksperimentov smo izvajali v avtomatiziranem laboratorijskem šaržnem reaktorju RC1 (reakcijski kalorimeter). Fermentacije so potekale 24 ur.Environmental pollution is the main reason why in modern society an increased demand for bio-products with their health characteristics is detected. This food group among others includes also probiotics and prebiotics. As a probiotic with health effects kefir has been used for the centuries and it is usually prepared from the whole fat cows milk. In this work we focused on the traditional cultivation of kefir grains in bio-milk. With Taguchi method, we determined the optimal values of process parameters (temperature, rotational frequency of the stirrer, initial mass concentration of kefir grains) and the composition of fermentation medium with the highest daily kefir grains increase, inoculated in bio-milk. In addition, we determined the relative influences of process parameters on the selected optimization criterion with graphically and statistically analysis by ANOVA. Using optimal values of process parameters, we carried out a mathematical modelling and parameterisation of growth curve of kefir grains, inoculated in bio-milk, with the software SigmaPlot®10.0. In the last part of the experimental work, we used ReactIRTMiC10 analytical sistem for determination of the mass concentration of ethanol in kefir, during the 24-hours fermentation at different compositions of fermentation medium. All experiments were performed in a laboratory batch bioreactor RC1 (reaction calorimeter). The duration of fermentation was 24 hours for each experiment