Identification of bitter compounds in whole wheat bread

Area of Science:

• Food Science
• Analytical Chemistry
• Organic Chemistry

Background:

• Bitterness in whole wheat bread reduces consumer acceptance.
• Identifying the specific compounds responsible for bitterness is crucial for product improvement.

Purpose of the Study:

• To identify the primary bitter compounds in a commercial whole wheat bread.
• To elucidate the mechanisms responsible for bitterness generation in wheat bread.

Main Methods:

• Sensory-guided fractionation of bread crust using liquid-liquid extraction, solid-phase extraction, and ultra-filtration.
• Two-dimensional offline RPLC (Reversed-Phase Liquid Chromatography) for compound separation.
• Structural elucidation using accurate mass-TOF, MS/MS, 1D and 2D NMR spectroscopy.

Main Results:

• Eight bitter compounds were identified: Acortatarins A, Acortatarins C, 5-(hydroxymethyl)furfural (HMF), 2,3-dihydro-3,5-dihydroxy-6-methyl-4(H)-pyran-4-one (DDMP), N-(1-deoxy-d-fructos-1-yl)-l-tryptophan (ARP), Tryptophol (TRO), 2-(2-formyl-5-(hydroxymethyl-1H-pyrrole-1-yl)butanoic acid (PBA), and Tryptophan (TRP).
• Compounds with the highest bitterness intensities were prioritized for structural identification.
• The identified compounds support two main bitterness generation pathways: fermentation and Maillard reactions.

Conclusions:

• The study successfully identified key contributors to whole wheat bread bitterness.
• Findings provide insights into the chemical pathways (fermentation and Maillard) responsible for bitterness.
• This knowledge can guide strategies to reduce bitterness and improve whole wheat bread quality.