Comparative Quantitation of Kokumi γ-Glutamyl Peptides in Spanish Dry-Cured Ham under Salt-Reduced Production

Abstract

Salting is a crucial step during the production of dry-cured ham and it is not well known whether it has an impact on the generation of taste-active peptides. The present study focused on the quantitation of kokumi γ-glutamyl peptides in low-salted Spanish dry-cured hams with 12 months of processing. By using mass spectrometry, peptides were quantitated from samples obtained after ethanolic deproteinization-based and non-ethanolic deproteinization-based extraction methods. Peptides γ-EA, γ-EE, and γ-EL registered mean values of 0.31, 2.75, and 11.35 µg/g of dry-cured ham, respectively, with no differences observed between both extraction protocols. However, γ-EF, γ-EM, γ-EV, γ-EW, γ-EY, and γ-EVG presented significantly (p < 0.05) higher concentrations in the ethanolic deproteinized samples showing values of 5.58, 4.13, 13.90, 0.77, 3.71, and 0.11 µg/g of dry-cured ham, respectively. These outcomes reflect the importance of protocols for the extraction of peptides to achieve the most feasible results. In addition, potential precursors for the formation of γ-glutamyl peptides are generated during dry-curing under salt restriction. The kokumi activity of these γ-glutamyl peptides could enhance the sensory attributes countering the taste deficiencies caused by the salt restriction.

Keywords: dry-cured ham; kokumi; peptide extraction; peptidomics; salt; γ-glutamyl peptides.

Figure 1

Quantitated γ-glutamyl peptides in low-salted 12-month-aged Spanish dry-cured hams according to 2 extraction protocols: NED-based extraction refers to the extraction protocol that does not require ethanolic deproteinization. ED-based extraction refers to the extraction protocol that uses ethanolic deproteinization. Same letters indicate non-significant differences.

Figure 2

Quantitated γ-glutamyl peptides in low-salted 12-month-aged Spanish dry-cured hams according to two extraction protocols: NED-based extraction refers to the extraction protocol that does not require ethanolic deproteinization. ED-based extraction refers to the extraction protocol that uses ethanolic deproteinization. Same letters indicate non-significante differences.

Figure 3

PCA results. (A) Score plot of amino acids and γ-glutamyl peptides identified in low-salted 12-month-aged Spanish dry-cured hams, to assess the variance among the compounds generated using two different extraction protocols (n = 3); and (B) loading plot showing the peptides affecting the score plot distribution. ED indicates ethanolic deproteinization-derived samples and NED is for non-ethanolic deproteinization-derived samples.