title: Identification of bitter peptides in aged cheddar cheese.
abstract: The compounds responsible for the bitter taste of aged "sharp" Cheddar cheese were characterized. Sensory-guided fractionation techniques using gel permeation chromatography and multi-dimension semi-preparative reversed-phase high-performance liquid chromatography revealed the presence of multiple bitter compounds. The compounds with the highest perceived bitterness intensity were identified by tandem mass spectrometry de novo peptide sequencing as GPVRGPFPIIV, YQEPVLGPVRGPFPI, MPFPKYPVEP, MAPKHKEMPFPKYPVEPF, and APHGKEMPFPKYPVEPF; all originated from β-casein. Subsequent quantitative liquid chromatography-tandem mass spectrometry analysis reported that the concentrations of GPVRGPFPIIV, YQEPVLGPVRGPFPI, and MPFPKYPVEP increased during maturation by 28.7-, 3.1-, and 1.8-fold, respectively. When directly compared to young "mild" Cheddar, APHGKEMPFPKYPVEPF was reported only in the sharp Cheddar cheese, whereas the concentration of MAPKHKEMPFPKYPVEPF did not change. Further taste re-engineering sensory experiments confirmed the importance of the identified peptides to the bitterness of sharp Cheddar. The bitter intensity of the aged "sharp" Cheddar model (mild Cheddar with equivalent concentrations of the five bitter peptides in the sharp sample) was rated as not significantly different from the authentic sharp Cheddar cheese. Among the five peptides, GPVRGPFPIIV was reported to be the main contributor to the bitterness intensity of sharp Cheddar. Furthermore, a difference from control sensory test also confirmed the significance of the bitter taste to the overall perception of aged Cheddar flavor. The sharp Cheddar model was reported to be significantly more similar to aged "sharp" Cheddar in comparison to the young "mild" Cheddar cheese sample.
authors: Department of Food Science and Nutrition, University of Minnesota , 145 FScN Building, St. Paul, Minnesota 55108, United States.
authors: Konstantinia
authors: K
authors: Karametsi
authors: Smaro
authors: S
authors: Kokkinidou
authors: Ian
authors: I
authors: Ronningen
authors: Devin G
authors: DG
authors: Peterson
mesh_terms: D000595:Amino Acid Sequence; D002364:Caseins / Q000032:analysis* / Q000737:chemistry / Q000302:isolation & purification; D002611:Cheese / Q000032:analysis* / Q000191:economics; D002850:Chromatography, Gel; D056148:Chromatography, Reverse-Phase; D005513:Food Inspection; D063427:Food Quality; D061353:Food Storage; D008401:Gas Chromatography-Mass Spectrometry; D006801:Humans; D008910:Minnesota; D009842:Oligopeptides / Q000032:analysis / Q000737:chemistry / Q000302:isolation & purification; D010446:Peptide Fragments / Q000032:analysis* / Q000737:chemistry / Q000302:isolation & purification; D010455:Peptides / Q000032:analysis* / Q000737:chemistry / Q000302:isolation & purification; D059748:Proteolysis; D012677:Sensation; D021241:Spectrometry, Mass, Electrospray Ionization; D053719:Tandem Mass Spectrometry; D013649:Taste
chemical_list: D002364:Caseins; D009842:Oligopeptides; D010446:Peptide Fragments; D010455:Peptides