Peptides sensory properties

Peptides have a wide range of flavors, from bitterness to more desirable savory flavors, and their importance in the sensory perception of foods has been recognized. Table 2 shows an example of peptides with sensory properties. 

Table 2 Examples of Peptides with Sensory Properties...

Low-molecular-weight peptides play an important role in the flavor intensity of meat and beef broth (27b). A beefy meat peptide isolated of beef imparts desirable sensory properties and has potential as a flavor enhancer in heat-processed foods (27c,d). Peptides released in dry-cured ham during processing were evaluated by HPLC and related to the ham flavor formation (27e,f). 

Many microbial metabolites are volatile compounds and in terms of their sensory properties can be broken into two broad categories odorants and tastants (Table 1). Tastants include salty, sour, sweet, and bitter compounds such as amino acids, peptides, and sugars. Primary odorants typically are quite volatile and include carbonyl compounds, esters, and terpenes. There is considerable overlap between the two categories lactones, for example, have both taste and odor properties. In keeping with the theme of this symposium, volatile aroma substances will be the primary focus. 

A number of other proteins contribute to the formation and stability of foam in sparkling wines. Peptides exhibit surfactant and sensory properties that can influence the organoleptic characteristics of product. 

A proteinase-catalyzed reaction including splitting and synthesis of peptide bonds is a process also suitable for covalent amino acid incorporation into peptide chains. This type of enzymatic modification reaction of food proteins is useful for different purposes alteration of sensory properties, solubility, nutritional quality, functional properties, antifreeze character, and different biological activities. Recently, special proteinase-catalyzed reactions have been elaborated by which proteins can be modified with particular respect to their primary structure and conformation. 

Peptides play an important role in the flavour and sensory properties of foods such as yeast extract, cheese and fruit juices. 

Some peptides enjoy the property of masking the bitter taste of foods. Ohyama et al. (24) conducted sensory analyses using synthetic peptides and found that neutralized peptides consisting of aspartic acid and glutamic acid had a taste similar to that of monosodium glutamate. They termed this umami taste or relish. ... 

In wines, peptides are the least known nitrogen compounds, in spite of the fact that they are involved in diverse properties such as tensioactivity (Gonzalez-Llano et al. 2004), sensorial activity (Desportes et al. 2001) and antihypertensive activity (Pozo-Bay6n et al. 2005), among others. Also they can act as nutrients for yeasts... 

AMI and PM3 for the description of the secondary structure in peptides and proteins has been performed recently [116], and it was shown that the description of the peptide conformers is considerably improved by OM1 and OM2 compared with AMI and PM3, although in some cases, there still were discrepancies with available ab initio data. MNDO-PSDCI molecular orbital theory has recently been used to calculate the spectroscopic properties of sensory rhodopsin from Natronobacterium pharaonis [117], demonstrating that MNDO is also a reliable tool for the calculation of optical spectra. 

This chapter deals with protein structure-function relationships resulting from proteolytic modification, covalent amino acid incorporation, and the effects of these enzymatic modifications on sensory and nutritional quality, on the functional properties, and on the biological activities of proteins and peptides. 

The first new compound to be identified that appeared to offer flavor potentiation is the Beefy Meaty Peptide (BMP). This peptide was found in a papain digest of beef by Yamasaki and Mackawa [53]. The authors identified the peptide as an octapeptide (Lys-Gly-Asp-Glu-Glu-Ser-Leu-Ala). This peptide upon synthesis and sensory evaluation was reported to have beefy flavor properties [54]. Substantial additional research has been conducted on this peptide, and Spanier and Miller [55] have reviewed much of this work. 

The versatility of the plastein reaction is also demonstrated by examples wherein undesired amino acids are removed from a protein. A phenylalanine-free diet, which can be prepared by mixing amino acids, is recommended for certain metabolic defects. However, the use of a phenylalanine-free higher molecular weight peptide is more advantageous with respect to sensory and osmotic properties. Such peptides can be prepared from protein by the plastein reaction. First, the protein is partially hydrolyzed with pepsin. Treatment with pronase under... 

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