Potential of soya substrates for lactic acid fermentation with addition of Lactobacillus plantarum

master's thesis

• Title (croatian): Pogodnost sojinih supstrata za mliječno kiselu fermentaciju uz dodatak bakterije Lactobacillus plantarum
• Author: Elena Dujmić
• Mentor: Lidija Šver (mentor)
• Granter: University of Zagreb; Faculty of Food Technology and Biotechnology; (Department of Biochemical Engineering); (Laboratory for Biology and Microbial Genetics); Zagreb
• Defense date and country: 2017-09-27, Croatia
• Scientific / art field, discipline and subdiscipline: BIOTECHNICAL SCIENCES; Nutrition

Abstract

In this work, growth dynamics of Fresco DVS 1010 culture and human derived isolate Lactobacillus plantarum in milk- water- or lactose-free milk-based soya substrates with sucrose or flavouring compounds (chocolate or caramel) were evaluated. Static anaerobic fermentation was carried out for 8 hours at 37 ± 0.5°C (5% CO2), afterward with storage period for 3 weeks at 6 ± 0.5°C. Although milk is a typical growth medium for lactic acid bacteria, presumable viable counts of Fresco culture reached levels 109 CFU mL-1 after 8 h. Potentially probiotic isolate L. plantarum added after the fermentation process maintained its viability during cold storage above the limit 106 CFU mL-1. Furthermore, the effect of temperature (8-40°C) on the growth dynamics of L. plantarum in a model environment of UHT lactose-free milk (1.5% fat) was investigated. Final densities of studied isolate reached counts 107 CFU mL-1 in stationary phase at all studied temperatures (except for marginal 8°C). During the growth and multiplication of L. plantarum, as a result of metabolic activity, the decrease of pH from initial values about 0.17-1.16 units was recorded. Experimentally, it was found that optimal temperature was close to 34°C, where the fastest growth rate in an exponential phase was recorded (Gr = 0.1684 log CFU mL-1 h-1, td = 1.8 h).

Abstract (croatian)

U ovom radu ocijenjena je dinamika rasta Fresco DVS 1010 kulture i humanog izolata Lactobacillus plantarum u sojinim supstratima na bazi mlijeka, vode ili bezlaktoznog mlijeka s dodatkom saharoze ili okusa (čokolada ili karamela). Statička anaerobna fermentacija provedena je tijekom 8 sati na 37 ± 0,5°C (5% CO2), nakon čega su proizvodi uskladišteni na 3 tjedna pri 6 ± 0,5°C. Iako je mlijeko tipičan medij za rast bakterija mliječne kiseline, nakon 8 h broj Fresco culture dosegao je brojku od 109 CFU mL-1. Broj potencijalno probiotičkog izolata bakterije L. plantarum dodanog nakon fermentacije ostao je iznad granice od 106 CFU mL-1 tijekom hladnog skladištenja. Nadalje, istražen je učinak temperature (8-40°C) na dinamiku rasta bakterija L. plantarum u modelu okoliša UHT bezlaktoznog mlijeka (1,5% masti). Konačna gustoća promatranog izolata dosegla je brojke 107 CFU mL-1 u stacionarnoj fazi pri svim promatranim temperaturama (osim marginalne 8°C). Tijekom rasta i razmnožavanja bakterija L. plantarum zabilježen je pad pH od početnih vrijednosti oko 0,17-1,16 jedinica kao rezultat metaboličke aktivnosti. Eksperimentalno je utvrđeno kako je optimalna temperatura za rast blizu 34°C, gdje je zabilježena najbrža stopa rasta u eksponencijalnoj fazi (Gr = 0,1684 log CFU mL-1 h-1, td = 1,8 h).

• Keywords: soya; lactic acid bacteria; Lactobacillus plantarum; growth parameters
• Keywords (croatian): soja; bakterije mliječne kiseline; Lactobacillus plantarum; parametri rasta
• Language: english
• URN:NBN: urn:nbn:hr:159:052442
• Study programme: Title: Nutrition; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra nutricionizma (magistar/magistra nutricionizma)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2017-11-13 13:47:40