Evaluation of bitterness in Ragusano cheese

Area of Science:

• Food Science
• Dairy Chemistry
• Biochemistry

Background:

• Bitter taste is an undesirable defect in cheese production.
• Ragusano cheese, a traditional Italian cheese, can be susceptible to bitterness.
• Understanding the biochemical basis of bitterness is crucial for quality control.

Purpose of the Study:

• To investigate the biochemical factors contributing to bitterness in Ragusano cheese.
• To compare the proteolysis and peptidolysis profiles of bitter and non-bitter Ragusano cheeses.
• To identify key chemical markers associated with cheese bitterness.

Main Methods:

• Comparative analysis of bitter and reference Ragusano cheeses.
• Chemical, electrophoretic (Urea-PAGE), and chromatographic (RP-HPLC) analyses.
• Quantification of primary and secondary proteolysis markers (pH 4.6-soluble N, TCA-soluble N, free amino acids).

Main Results:

• Bitter cheeses exhibited significantly higher primary proteolysis and lower secondary proteolysis compared to reference cheeses.
• Urea-PAGE revealed extensive casein breakdown in bitter cheeses.
• Reversed-phase HPLC identified a higher proportion of hydrophobic peptides in bitter cheeses, linked to high salt-in-moisture and low moisture content.

Conclusions:

• Unbalanced proteolysis and peptidolysis, resulting in an accumulation of hydrophobic peptides, are the primary causes of bitterness in Ragusano cheese.
• High salt-in-moisture and low moisture content limit enzymatic activities, hindering the removal of bitter peptides.
• Salt-in-moisture levels and the ratio of hydrophobic-to-hydrophilic peptides can predict cheese quality and bitterness risk.