Amino Acid Composition of the Fermented Milk Probiotic Preparation and the Starter Culture Components of Direct Application

Abstract

The study subject was the amino acid profile of probiotic bifidobacteria and their exometabolites. The research aimed at the composition and content assessment of amino acids in the finished fermented milk product and in the components of the direct-applied starter culture used for its manufacture. The authors applied consortium of Bifidobacterium bifidum 791 and B. longum B 397M in the study. A man determined the composition and amount of amino acids by reverse-phase HPLC on a Shimadzu LC-20 Prominence chromatograph (Japan) with diode-matrix detection. There was a high proportion of essential amino acids in the culture fluid supernatant (45.516 %) and bacterial mass (41.529 %), while non-essential amino acids prevailed in fermented milk bifidumbacterin (71.74 %). There were high levels of proline (320.3 mg/g) and serine (101.69 mg/g) in fermented milk bifidumbacterin. The cysteine content was 48.5 mg/g, which is 10 times higher than in the starter culture supernatant (p = 0.002). The content of methionine in fermented milk bifidumbacterin and in the starter culture supernatant was similar – 52.19 and 57.34 mg/g, respectively, in the bacterial mass of methionine – 7 times less (p = 0.0001). The supernatant of starter cultures and the washed bacterial mass demonstrated a high content of threonine (232.38 and 218.93 mg/g, respectively) and glutamic acid (133.78 and 182.27 mg/g, respectively). The maximum tryptophan content was in the bacterial mass compared to other samples – 96.23 mg/g of protein (p = 0.004). The results are relevant to develop functional nutrition products intended as additional sources of amino acids.