Cacl2

The L. delbrueckii subsp. bulgaricus probiotic bacteria were used from the stock culture collections in the Food Microbiology Laboratory at the University of Melbourne. Fructooligosaccharides (FOS), Na-alginate, enzymes (salivary α-amylase, porcine pepsin, pancreatin), HCl, acetone, acetic acid, epicatechin, catechin, procyanidin B1, procyanidin B2, quercetin 3-O-galactoside, quercetin 3-O-glucoside were purchased from Sigma Aldrich (Castle Hill, NSW, Australia). A standard mixture of short chain fatty acids (SCFAs) was purchased from Cayman Chemical (Ann Arbor, MI, USA). The selective media DeMan, Rogosa and Sharpe (MRS), nutrient agar & broth, AnaeroGen sachets, yeast extract, beef extract, protease peptone, n-hexadecane, L-cysteine hydrochloride, bile salts, and trichloroacetic acid were purchased from Thermo Fisher Scientific Pty Ltd (Melbourne, VIC, Australia). NaOH, phosphate-buffered saline, CaCl₂, dextrose, K₂HPO₄, (NH₄)₂SO₄, MgSO₄·7H₂O, NaCl, KCl, NaHCO₃, MgCl₂(H₂O)₆, (NH₄)₂CO₃, potassium persulfate, potassium acetate, aluminum chloride were ordered from the Chem-Supply Pty Ltd. (Melbourne, VIC, Australia). Chocolates with 45% and 70% cocoa mass, cocoa powder (pure), cocoa liquor, cocoa butter, sugar, soy lecithin were purchased from local supermarket (VIC, Australia).

The expanded poly(tetrafluoroethylene) (ePTFE) membrane was obtained from Pall Corporation under the trade name of Zefluor™ 1.0 μm, where the 1.0 μm refers to the pore size in the membrane. This membrane has a thickness of 0.01 mm. Grafted membranes were prepared as previously published. Samples AA(0.3)-R and AA(1.3)-R were prepared by gamma irradiation grafting of acrylic acid (AA) at a dose of 10 kGy and monomer concentrations of either 0.3 or 1.3 M with the addition of Mohr's salt [17] , [18] . Sample AA/IA(3)-R was prepared by gamma irradiation induced grafting at a dose of 10 kGy of a monomer mixture of AA (70%) and itaconic acid (IA) with a total monomer concentration of 3.0 M with the addition of Mohr's salt [18] . Sample AA-P was prepared by argon plasma-induced grafting exposing the membrane to the plasma generated at 100 W for 150 s and subsequently reacting with a 2.6 M solution of AA for 3 h [19] . HAP and tricalcium phosphate (TCP) were from Merck. The chemicals used for preparation of simulated body fluid (SBF and 1.5 × SBF) were: NaCl (99%), NaHCO₃ (99.7%), K₂HPO₄.3H₂O (≥99%) and Na₂SO₄ (99%) were from Ajax Finechem, KCl (≥99.5%) was from Merck, MgCl₂.6H₂O (98%) was from Sigma Aldrich, Tris(hydroxymethyl)aminomethane (99.8%) was from Spectrum Chemical MFG Corp. and CaCl₂ (93%) was from Chem-Supply. MilliQ water was used throughout.