Application of probiotic starter cultures in cheese production

Abstract

Cilj ovog rada je bio proizvesti sušene svježe sireve s dodanom funkcionalnom vrijednošću primjenom probiotičkih autohtonih sojeva Lactobacillus brevis D6, Lactobacillus plantarum D13, Lactococcus lactis ZG7-10 i Lactobacillus fermentum D12. Sojevi su dio zbirke mikroorganizama Laboratorija za tehnologiju antibiotika, enzima, probiotika i starter kultura, Sveučilišta u Zagrebu, te su nakon provedenih znanstvenih istraživanja u istom laboratoriju, prema strogim selekcijskim kriterijima, odabrani kao probiotički sojevi. Svaki od njih ima određeno funkcionalno metaboličko svojstvo koje doprinosi aromi, teksturi i kvaliteti proizvedenog sira. Prema provedenim analizama udjela suhe tvari i mliječne masti, proizvedeni sušeni svježi sir pripada kategoriji „ekstra tvrdi sir“ i „polumasni sir“. Sekvencioniranje ukupne DNA iz uzoraka sireva je potvrdilo prisutnost svih dodanih probiotičkih sojeva, a broj živih bakterijskih stanica u proizvedenom siru je nakon proizvodnje i tijekom skladištenja bio veći od 106 CFU/g, što je minimalni preporučeni broj po gramu probiotičkog proizvoda. MALDI-TOF masenom spektrometrijom detektiran je ukupno 51 peptid u uzorcima proizvedenog sira u omjeru mase i naboja raspona od 312,130 do 4508,877, koji mogu imati potencijalno bioaktivno djelovanje.The aim of this research was to produce batches of dry curd cottage cheese, with its functional value enriched, using probiotic autochthonous strains: Lactobacillus brevis D6, Lactobacillus plantarum D13, Lactococcus lactis ZG7-10 and Lactobacillus fermentum D12. These strains are a part of the microorganism collection at the Laboratory for Antibiotic, Enzyme, Probiotic and Starter Cultures Technology, at the University of Zagreb, and were chosen (based on extensive research and criteria) as probiotic strains. Each of these strains has a certain metabolic property which contributes to the cheese aroma, texture and overall quality. By analysing the dry matter and fat content of milk it was determined that this cheese falls into the 'hard cheese' and 'medium fat cheese' categories. Collective DNA sequencing confirmed the presence of all added probiotic strains and the number of live bacteria (after production and during storage) was over 106 CFU/g, which is the minimal recommended quantity per gram for probiotic products. Using MALDI-TOF mass spectrometry, a total of 51 peptides (with a mass-to-charge ratio from 312,130 to 4508,877), which may potentially exhibit bioactive activity, were detected in cheese samples