Hybrid Approach in the Analysis of Bovine Milk Protein Hydrolysates as a Source of Peptides Containing Di- and Tripeptide Bitterness Indicators

Abstract

BSA, bovine serum albumin; B, bromelain; B-MPC, bromelain hydrolysate of milk protein concentrate; F, fi cin; F-MPC, fi cin hydrolysate of milk protein concentrate; MLR, multivariate linear regression; MPC, milk protein concentrate; O-MPC, non-hydrolyzed milk protein concentrate; P, papain; P-MPC, papain hydrolysate of milk protein concentrate; PK, proteinase K; PK-MPC, proteinase K hydrolysate of milk protein concentrate; RP-HPLC, reversed-phase high performance liquid chromatography; RP-HPLC-MS/MS, reversed-phase high performance liquid chromatography and mass spectrometry; Rcaf., the ratio of caffeine (the threshold concentration for 1 mM caffeine solution as a standard (Rcaf. = 1.0); t R predicted , theoretical retention time; t R experimental , experimental retention time; α s1 , casein; α s2-CN, α s2-casein; α-La, α-lactalbumin; β-Lg, βlactoglobulin; β-CN, βcasein; κ-CN, κ-casein; and TFA, trifl uoracetic acid.

Soybean (Glycine max) Protein Hydrolysates as Sources of Peptide Bitter-Tasting Indicators: An Analysis Based on Hybrid and Fragmentomic Approaches

“…Afterwards, all hydrolysates were heated at 90 • C for 15 min to inactivate the enzymes and then freeze-dried. Finally, four SPC hydrolysates were produced, namely B-SPC, F-SPC, P-SPC, and PK-SPC, the abbreviations referring to bromelain-, ficin-, papain-, and proteinase-K-SPC hydrolysates, respectively, according to the convention used in the previous paper [9]. The fifth sample, 0-SPC, was a reference sample being the non-hydrolyzed SPC solution.…”

“…RP-HPLC (reversed-phase high performance liquid chromatography) was applied to observe the progress in the hydrolysis of SPC using the above-mentioned enzymes. The preparation of SPC/SPC hydrolysate samples taken for RP-HPLC and RP-HPLC-MS/MS (reversed-phase high performance liquid chromatography online with tandem mass spectrometry), as well as the parameters of devices for chromatography were exactly the same as in the protocol by Iwaniak et al [9].…”

“…Then, six-hundred-eighty microliters of 6 M urea solution in a mixture of ACN and H 2 O (v/v; 100: 900; pH 2.2 was adjusted by the addition of TFA) were added to the sample and stirred. Finally, the samples were centrifuged (10 min; 10,000× g) [9].…”

“…For example, a sequence identified (i.e., precursor/parent peptide) that contains peptide motifs with confirmed bitterness (i.e., bitter-tasting motifs) may suggest the bitter-tasting potential of a parent sequence. Such an idea of research was applied by Iwaniak et al [9] for the hybrid analysis of bovine milk protein hydrolysates as sources of bitter-tasting motifs, especially those with an "indicator" status.…”

“…Taking into account these two facts, the aim of this study was to apply the hybrid protocol for an analysis of soybean protein hydrolysates as sources of peptides likely to be bitter due to the presence of bitter-tasting motifs, particularly those defined as bitter-tasting indicators. According to the definition introduced by Iwaniak et al [9], bitter-tasting indicators should be literally understood as "shorter motifs with known bitterness, which found in the sequences of peptides, may potentially determine their taste".…”