Overview
Key numbers
| Step | Variable | Value |
|---|---|---|
| SBY raw substrate | Total protein, water content (page 2, §2.1) | 57.83 ± 2.00 % protein (Kjeldahl), 79.02 ± 0.32 % water |
| SBM raw substrate | Total protein, water content (page 2, §2.1) | 48.62 ± 0.44 % protein (Kjeldahl), 11.16 ± 0.57 % water |
| SBY autolysis end-state (12 h, pH 6, 50 °C) | Soluble protein increase from t=0 | 6.69-fold rise (Fig. 1A, page 3) |
| SBM hydrolysis end-state (8 h, pH 8, 50 °C) | Soluble protein increase from t=0 | 2.67-fold rise (Fig. 1B, page 3) |
| SBY hydrolysate Mg²⁺ chelating yield (20 h) vs SBM (8 h) | Endpoint chelating-yield comparison (Fig. 2, page 4) | SBY chelating yield was 1.34× that of SBM at endpoints (paper wording, page 4 §3.2: “the chelating yield of SBY was 1.34-time higher than that of SBM”) |
| SBM hydrolysate Mg²⁺ chelating yield, 5 h plateau | Chelating yield (Fig. 2B, page 4) | ≈40 % from h 5 through h 8 (Fig. 2B, chart read; no tabulated value in text) |
| SBY 3 kDa permeate (Pe 3 kDa) specific chelating yield (Fig. 3A; abstract page 1) | Mg²⁺ chelated per g protein | 94.44 mg/g protein (highest specific yield reported in the study) |
| SBY 3 kDa permeate optimal conditions | pH for peak yield (Fig. 4A, page 5; text page 6 §3.3) | pH 2 to 4 window; peak at pH 3 with 67.05 % chelating yield at 150 mM Mg²⁺ loading |
| SBM 3 kDa permeate optimal pH (Fig. 4D, page 5; text page 6 §3.3) | pH for peak yield | Peak at pH 3 with 51.52 % chelating yield at 150 mM Mg²⁺ loading |
| SBY 3 kDa permeate Mg²⁺ loading optimum (Fig. 4C, page 5; text page 6 §3.3) | Loading mM → yield | 5 mM and 25 mM Mg²⁺ → 99.83 % chelating yield peak; declining to 74.3 % at 150 mM |
| SBM 3 kDa permeate Mg²⁺ loading optimum (Fig. 4F, page 5; text page 6 §3.3) | Loading mM → yield | 25 mM Mg²⁺ → 87.39 % peak; declining to 42.05 % at 150 mM |
| Reaction time × temperature (Fig. 4B SBY / 4E SBM) | Effect | SBY peaks 74.8 % at 30 min / 40 °C; SBM peaks 47.81 % at 30 °C; temperature and time effects “minor” per discussion (page 6) |
| FTIR amide II band shift (Fig. 5, page 6) | SBYP → Mg-SBYP | 1579.25 cm⁻¹ → 1611.71 cm⁻¹ (peptide–Mg interaction, paper’s framing) |
| FTIR N–H stretch shift | SBYP → Mg-SBYP | 3127.17 cm⁻¹ → 3271.24 cm⁻¹ (N–H vibration confirms amino-group involvement) |
| FTIR carboxyl C–O shift | SBYP → Mg-SBYP | 1398.28 cm⁻¹ → 1411.58 cm⁻¹ (–COOH interaction with Mg²⁺); additional shifts 1053.41 → 1023.34 cm⁻¹ attributed to C–O stretching of hydroxyl/carboxyl |
| Particle size distribution (PSD, Fig. 6, page 7) | Spray-dried Mg-SBYH (chelated hydrolysate) range | ≈1400 nm to ≈3500 nm (multimodal) |
| Particle size distribution | Spray-dried Mg-SBYP (chelated 3 kDa permeate) range | ≈770 nm to ≈1200 nm |
| In-vitro gastrointestinal stability (Fig. 7, page 7) | Free Mg²⁺ retention at end of 6 h simulation, MgCl2 control | 89.15 % |
| In-vitro gastrointestinal stability | Free Mg²⁺ retention at end of 6 h simulation, Mg-SBYP | 56.85 % after first 30 min gastric, hovering ≈50 % through end (lowest of the three samples) |
| Cytotoxicity (HEK293, MTT, Table 2, page 7) | Negative control, ellipticine positive control | 0 %, 93.04 ± 2.12 % cell death |
| Cytotoxicity at 256 µg/mL | MgCl2 / SBY peptide / Mg-SBYP cell death | 1.09 ± 0.02 % / 0.33 ± 0.03 % / 0.11 ± 0.02 % |
| Cytotoxicity IC50 (256 µg/mL exposure) | MgCl2, SBY peptide, Mg-SBYP | All >256 µg/mL |
| SBY 3 kDa permeate amino-acid profile, key residues (Table 1, page 4) | Glu, Asp, Lys, Arg, His | Glu 14.88 %, Asp 10.94 %, Lys 6.49 %, Arg 7.07 %, His 3.19 % |
| SBM 3 kDa permeate amino-acid profile, key residues (Table 1, page 4) | Glu, Asp, Lys, Arg, His | Glu 15.82 %, Asp 10.55 %, Lys 6.01 %, Arg 8.07 %, His 3.04 % |
Methods (brief)
Spent brewer’s yeast was Saccharomyces pastorianus collected from Habeco Co. Ltd (Hanoi) at the last day of main fermentation, transported cold, washed 1:4 v/v in distilled water, centrifuged 6,000 rpm to remove supernatant, and stored at −20 °C; soybean meal was supplied by Dabaco Co. Ltd (Vietnam), milled and sifted through mesh 80 sieve. Total protein on both substrates by Kjeldahl. Autolysis of SBY ran in a Biostat B plus bioreactor at 7 % dry-matter, pH 6.0, 50 °C, 600 rpm, 1000 mL working volume, with hourly aliquots boiled 10 min to inactivate enzymes; after 12 h the autolysate was centrifuged 10,000 rpm × 10 min and the supernatant transferred to Alcalase (Novozymes; 30 mg/g protein dosage) hydrolysis at pH 8.0, 50 °C, 600 rpm, 8 h. SBM was autoclaved at 121 °C × 15 min before enzymatic hydrolysis under the same Alcalase conditions. Hydrolysates were centrifuged 10,000 rpm × 15 min and cross-flow filtered (Quixstand bench-top CFF) through 0.2 µm (CFP-2-E-3MA), 100 kDa (UFP-100-E-3MA), 10 kDa (UFP-10-E-3MA), and 3 kDa (UFP-3-C-3MA) cartridges.
Chelation reactions ran at micro-scale (1 mL total: 50 µL of 3 M MgCl2 + 950 µL peptide solution, vortex 3 min) and macro-scale (1000 mL in Biostat B plus, 300 rpm, 10 min); chelation mixtures were centrifuged 10,000 rpm × 5 min to remove precipitate. Free Mg²⁺ was determined by colorimetric assay with 4-(2-pyridylazo) resorcinol, absorbance 506 nm on a GeneQuant 1300. Chelating yield is the ratio chelated/loaded Mg, in %; specific chelating yield is mg Mg(II) chelated per g peptide.
Spray-dried magnesium chelating peptide (MgCP) was prepared on a Buchi C-290 with 0.1 % magnesium stearate, inlet 120 °C, outlet 60 °C; total Mg in spray-dried MgCP by AOAC 968.08. Soluble protein by Lowry; α-amino by ninhydrin with glycine standard; amino-acid profile by ion-exchange chromatography (Hitachi L-8800) per ISO 13903:2005 (17 amino acids including Cys/cystine sum) and AOAC 994.12 (Cys, Met). FTIR spectra on NICOLET IS20 (Thermo Fisher) in ATR mode, 500–4000 cm⁻¹. Particle size distribution on a Zetasizer Blue (Malvern, MAL1257886) at 25 °C, refractive indices 1.45 (peptide) / 1.33 (water), equilibration 30 s.
In-vitro gastrointestinal stability followed Brodkorb et al. INFOGEST static protocol: MgCP dissolved in 0.06 N HCl pH 2 to final 10 mg/mL, pre-warmed 37 °C × 30 min, pepsin (P7000-Sigma Aldrich, 599 uranium (U)/mg, final 0.05 mg/mL) added at pH 2 for 120 min at 37 °C, 120 rpm; bile salts (Merck 1.03756.0500) added to pH 7.4 with NaOH, then pancreatin (Merck 1.071300.1000) at final 0.05 mg/mL for intestinal stage 4 h at 37 °C. Hourly aliquots boiled to stop enzymatic activity before free Mg²⁺ measurement; MgCl2 3 M control. Cytotoxicity on HEK293 in DMEM + 2 mM L-glutamine + penicillin/streptomycin + 10 % fetal bovine serum, seeded 1.5 × 10⁵ cells/well in 96-well plates; MgCP exposure at 256 to 8 µg/mL; ellipticine positive control; DMSO ≤1 % negative control; MTT assay read at 540/720 nm on Tecan Spark; n = 3 independent replicates. Cell-inhibition >50 % triggered IC50 calculation by TableCurve AISN.
Statistics: Tukey test for between-treatment significance (p < 0.05) in SPSS; descriptive statistics in Megastat (Excel add-in). All experiments in triplicate.
Related evidence
Update history
The five most recent substantive edits to this page, classified major (evidence or structure moved), correction (a published value or statement was wrong and has been fixed), or minor (narrative rewritten without changing the underlying evidence). Each description is derived from what the edit did to this page; the linked commit is the authoritative record, routine regeneration passes are excluded, and the full version history lives in git.
| Commit | Date | Change | Description |
|---|---|---|---|
| b01ec52c31 | 2026-08-04 | major | 1 section added; narrative text revised |
| 3a67e13071 | 2026-08-02 | minor | Narrative text revised |
| 3171d069e3 | 2026-08-02 | major | 1 section added |
| 90a2f9a38e | 2026-07-30 | major | 1 section added and 1 removed |
| eaa8eeeedf | 2026-07-27 | major | 1 section added; narrative text revised |