Analysis of diacetyl in yogurt by two new spectrophotometric and fluorimetric methods

Rapid gas-chromatographic method for the determination of diacetyl in milk, fermented milk and butter

“…The presence of significant amounts of diacetyl in the fresh raw milk sample, if confirmed, is certainly interesting be used as a basis for further research in dairy science. With regards to butter and yoghurt (Table 3), diacetyl contents measured by GLC method was higher than values generally reported in the scientific literature and these differences were probably due to the analytical techniques used (Bakirci, Ç elik, & Ö zdemir, 2002;Beshkova et al, 2003;Guerra Hernández et al, 1995). In particular, when headspace analysis is used, only volatile diacetyl was found (Monnet et al, 1994).…”

Capillary zone electrophoresis for enumeration of Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus in yogurt

“…bulgaricus and S. thermophilus in yogurt samples. Previously, only products from the fermentation process were determined, for example, volatile and non-volatile products of milk fermentation process [24], furosine in dairy products [25], citrate and inorganic phosphate in milk [26] and diacetyl in yogurt [27]. The BGE containing PEO was essential for the separation of both bacteria, other key factors such as the use of low energy process (i.e.…”

Sensomics-Assisted Flavor Decoding of Dairy Model Systems and Flavor Reconstitution Experiments

“…24−27 ■ MATERIALS AND METHODS Chemicals. The following compounds were obtained commercially from Sigma-Aldrich (Steinheim, Germany), if not specifically mentioned: 3-nitrophenylhydrazine hydrochloride (3-NPH), pyridine, N-(3-(dimethylamino)-propyl)-N′-ethylcarbodiimide hydrochloride (EDC), formic acid, hydrochloric acid (37%), hydrochloric acid (1 N), sodium hydroxide (0.1 N), diethyl ether, glutaric anhydride, 1-undecylbromide, 1-bromotridecane, copper(I) iodide, ethanol, D 2 O, methanol-d 4 , chloroform-d, 3-(trimethylsilyl)propionic-2,2,3,3-d 4 acid sodium salt (TMSP), ethylenediamine-tetraacetic acid (EDTA), gum arabic from acacia tree, highly refined mineral oil, BiPRO whey protein isolate (Davisco Foods International, Le Sueur, Minnesota, USA), hexanal (1), methional (2) (Merck KGaA, Darmstadt, Germany), cis-3-hexenal (3) (Merck), cis-2-nonenal (4) (in-house synthesis), trans-2-nonenal (5), trans,trans-2,4-nonadienal (6), trans,cis-2,6-nonadienal (7), trans,trans-2,4-decadienal (8), trans-4,5-epoxy-(E)-2-decenal (9) (Merck), trans-2-undecenal (10), trans-2-dodecenal (11), acetaldehyde (12), 2,3-butanedione (13), 3hydroxy-2-butanone (14), 1-hexen-3-one (15) (Alfa Aesar, Haverhill, Massachusetts, USA), 1-octen-3-one (16) (Alfa Aesar), butyric acid (17), 2-methylbutanoic acid (18) (Fluorochem, Hadfield, UK), 3methylbutanoic acid (19), pentanoic acid (20), hexanoic acid (21) (Merck), octanoic acid (22), nonanoic acid (23), decanoic acid (24), dodecanoic acid (25), tetradecanoic acid (26), phenylacetic acid (27), benzaldehyde (28), phenylpropanoic acid (29), vanillin (30), 2aminoacetophenone (31) (Merck), sotolon (32), 2-acetyl-1-pyrroline (33) (in-house-synthesis), 2-acetyl-2-thiazoline (34), δ-tetradecalactone (35), δ-hexadecalactone (37) (aromaLAB, Martinsried, Germany), δ-octadecalactone (39) (aromaLAB), sodium thiomethoxide (41), dimethyl sulfide (42), lactose (43) (VWR, Geldenaaksebaan, Belgium), galactose (44), sucrose (45), acetic acid (46), lactic acid (47...…”