PubMed · 4514945
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H Myhre. 1973. [Why mineral enriched bread?].. https://pubmed.ncbi.nlm.nih.gov/4514945/
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Roasted notes contribute to the flavor of thermally processed foods such as meat and bread. 2-Acetyl-2-thiazoline is one of the key volatile compounds responsible for the roasted and popcorn-like aroma character. We report here on the biogeneration of flavoring preparations with intense roasted notes, which are characterized by a high content of 2-acetyl-2-thiazoline. These flavoring preparations were obtained by fermentation of cysteamine, ethyl-L-lactate, and D-glucose with baker's yeast. The precursor of 2-acetyl-2-thiazoline, 2-(1-hydroxyethyl)-4,5-dihydrothiazole, was prepared under mild conditions by microbial reduction of the carbonyl group of 2-acetyl-2-thiazoline using baker's yeast as biocatalyst. The addition of 2-(1-hydroxyethyl)-4,5-dihydrothiazole as aroma precursor to pizza dough resulted in an increase of the roasted note.
Cyclodextrin glucanotransferase from Bacillus stearothermophilus ET1 (CGTase ET1) is a potential antistaling enzyme with cyclodextrin (CD)-forming activity. To reduce cyclization activity of CGTase ET1, phenylalanine residues at 191 and 255 were replaced with a glycine (F191G-CGTase ET1) and an isoleucine (F255I-CGTase ET1), respectively. Temperature optima of both mutant enzymes were lower than that of the wild-type. Cyclization activities of both mutants decreased dramatically, but F255I-CGTase ET1 showed a 2-fold higher hydrolytic activity than the wild-type enzyme. CD content of bread loaf treated with F191G-CGTase ET1 was 28.6% of that treated with wild-type, whereas no CD was detected in the loaf treated with F255I-CGTase ET1. Loaves treated with CGTase ET1 or either of the two mutants contained more of the larger maltooligosaccharides such as maltopentaose and maltohexaose than the control and the commercial antistaling enzyme-treated loaves. Retrogradation rates decreased significantly in the loaves treated with either mutant, which indicates the applicability of CGTase ET1 in the bread industry by modulating the cyclizing and hydrolyzing activities of the enzyme.
(1)H nuclear magnetic cross-relaxation spectroscopy was used to probe the molecular mobility/rigidity in bread and its components during storage. The Z-spectra lineshapes, attributed to the solid-like polymer fractions of the samples, differed for the bread, gelatinized waxy starch (GX), gelatinized wheat starch (GW), heated flour (HF), and heated gluten (HG). Upon storage, no change was observed in the Z-spectrum of the bread sample, while the Z-spectra for GX, GW, and HG increased in the width at half height of the decomposed broad component (increased rigidity). These trends in the Z-spectra detected by NMR were contradictory to the DSC results that showed an increase in amylopectin retrogradation enthalpy for all samples containing starch, including bread. These trends in the Z-spectra detected by NMR were not reflected by the DSC results that showed an increase in amylopectin retrogradation enthalpy for all samples, including bread. The differences in molecular mobility could not be therefore, due to recrystallized amylopectin and may be attributed to the role of gluten and/or redistribution of water in the amorphous regions of the samples.