Proteome Profiles of Digested Products of Commercial Meat Sources

Abstract

This study was designed to characterize in vitro-digested products of proteins from four commercial meat products, including dry-cured ham, cooked ham, emulsion-type sausage, and dry-cured sausage. The samples were homogenized and incubated with pepsin and trypsin. The digestibility and particle sizes of digested products were measured. Nano-LC-MS/MS was applied to characterize peptides. The results showed the highest digestibility and the lowest particle size in dry-cured ham (P < 0.05), while the opposite was for cooked ham (P < 0.05). Nano-LC-MS/MS analysis revealed that dry-cured ham samples had the greatest number of 750-3,500 Da Mw peptides in pepsin-digested products. In the digested products of cooked ham and emulsion-type sausage, a lot of peptides were matched with soy protein that was added in the formulations. In addition, protein oxidation was also observed in different meat products. Our findings give an insight into nutritional values of different meat products.

Keywords: LC–MS/MS; digestibility; in vitro digestion; meat products; oxidation; particle size.

Figure 1

In vitro protein digestibility of four meat products (means ± SDs, n = 7). a, b, different letters indicated significant differences in digestibility after pepsin digestion; x, y, z, different letters indicated significant differences in digestibility after trypsin digestion.

Figure 2

Representative total ion chromatogram spectra of ethanol-soluble fragments from in vitro digested products of four meat products. (A) In vitro digestion with pepsin; (B) in vitro digestion with pepsin followed by trypsin.

Figure 3

Statistics of peptides from in vitro-digested products of four meat products. (A) General statistics for pepsin and trypsin digesta. For cooked ham, 33 of 114 peptides in pepsin digesta were matched with soy proteins, and 80 of 628 peptides in pepsin/trypsin digesta were matched with soy proteins. For cooked emulsion sausage, 43 of 78 peptides in pepsin digesta and 132 of 311 peptides in pepsin/trypsin digesta were matched with soy proteins. (B,C) Statistics of peptides on the basis of molecular weights after pepsin and trypsin digestion, respectively.

Figure 4

Venn diagrams of peptides obtained from meat products (n = 7). (A) In vitro pepsin digesta. Ten of 25 cooked ham-specific peptides were matched with soy proteins, while 21 of 27 cooked emulsion sausage-specific peptides were matched with soy proteins. (B) In vitro pepsin/pepsin digesta. Fifteen of 145 cooked ham-specific peptides were matched with soy proteins, while 69 of 99 cooked emulsion sausage-specific peptides were matched with soy proteins.