Survivability of Lactobacillus rhamnosus during the Preparation of Soy Cheese

Abstract

Svrha je ovog istraživanja razvoj novog probiotičkog sira od soje na bazi kineskog sira sufu. Sir je dobiven fermentacijom sojinog mlijeka s pomoću bakterijskih starter kultura (DH1 i GH4) i L. rhamnosus 6013. Nakon zrenja uspoređene su ocjene senzorskih svojstava probiotičkog sira od soje (standard SB/T 10170-93) s kontrolnim uzorkom. Ispitani su promjena pH-vrijednosti, rast bakterija i preživljavanje potencijalne probiotičke kulture L. rhamnosus 6013 tijekom fermentacije i skladištenja na 10 °C. Nakon 6 sati fermentacije, L. rhamnosus 6013 bio je sposoban rasti u sojinom mlijeku sve do 108-109 CFU/mL. Nakon skladištenja tijekom 30 dana pri 10 °C primijećeno je slabo opadanje pH-vrijednosti i broja živih stanica bakterija. Broj živih stanica nakon 30 dana iznosio je 107 CFU/g L. rhamnosus 6013, 106 CFU/g DH1 i 106 CFU/g GH4. Udio stahioze, rafinoze i saharoze u siru od soje određen je visokodjelotvornom tekućinskom kromatografijom. Rezultati pokazuju da L. rhamnosus 6013 može koristiti oligosaharide soje kao izvor ugljika. Dodatak od 2 do 4 % soli nije značajnije utjecao na preživljavanje kulture L. rhamnosus 6013, što znači da ta bakterija može podnijeti tehnološku preradu bez negativnog utjecaja na fermentaciju i senzorska svojstva sira od soje.The aim of this study was to develop a new probiotic soy cheese on the basis of chinese sufu. The soy cheese was made from soymilk fermented with soy cheese bacterial starter cultures (DH1 and GH4) and L. rhamnosus 6013. After ripening, probiotic soy cheese sensory scores (standard SB/T 10170-93) were compared to the control. The changes in pH, bacterial growth and the survivability of the potential probiotic L. rhamnosus 6013 during fermentation and storage at 10 °C were examined. After 6 h of fermentation, L. rhamnosus 6013 was capable of growing in soymilk as high as 108–109 CFU/mL. After being stored for 30 days at 10 °C, slight decrease in pH and the viable counts of the strain was noticed. The viable counts of L. rhamnosus 6013, DH1 and GH4 were 107, 106 and 106 CFU/g, respectively, after storage for 30 days. The levels of stachyose, raffinose and sucrose in soy cheese were determined by high performance liquid chromatography. The results indicated that L. rhamnosus 6013 could utilize the soybean oligosaccharides as carbon sources. In addition, 2–4 % of NaCl had little effect on the survivability of L. rhamnosus 6013. It indicated that L. rhamnosus 6013 could withstand the technological processing of soy cheese and had no negative effect on the fermentation and the sensory properties of the soy cheese