Sour peptides

Masnda O, Nakamura Y, Takano T. (1996) Anti-hypertensive peptides are present in aorta after oral administration of sour milk containing these peptides to spontaneously hypertensive rats. JNutr 126 3063-3068. 

Sweetness Production by the Combination of Bitter and Sweet Tastes. Sensory tests using typically bitter compounds such as brucine, strychnine, phenylfiiiourea, caffeine and bitter peptides were performed. Sensory tests using typically bitter compounds such as brucine, strychnine, phenylthiourea, caffeine and bitter peptides were performed. Sensory taste impression were also measured for combinations of acetic acid (sour) and typical bitter compounds (5). The data from these studies indicated that the tastes of ese bitter/sour mixtures changed to a sweet taste regardless of their chemical structure of the bitter component (Table II). 

BTR) and "sour" (SOU), increase. Most "bitter" and "sour" flavors are thought to originate from the degradation/decomposition of proteins to bitter and sour flavored peptides and amino acids. 

MW peptide fractions (7). Both the "fresh-cooked" and "cooked- -stored" samples resolve into separate regions, i.e., a hydrophilic region and a hydrophobic region. Hydrophilic peptides are commonly associated with flavors such as "sweet" and possibly, "meaty" and "cooked beef/brothy", whereas the hydrophobic peptides are usually associated with the more undesirable flavors like bitter" and "sour". 

Expansion or enhancement of the proposed mechanism of Nakamura and Okai is shown in Figure 12. Their model is based on the demonstration that several synthetically prepared di- and tri- peptide fragments composed of basic or acidic amino acids, produced individual tastes such as salty (lys-gfy sweet (lys-gfy-asp), sour (asp-glu-glu) and bitter (ser-leu-ala 31). Tlie expanded mechanism we propose is shown in Figure 12 and is based on the data tabulated in Table 1 (31, 38). 

Sullivan, J. J., Mou, L., Rood, J. I. and Jago, G. R. 1973. The enzymic degradation of bitter peptides by starter streptococci. Aust. J. Dairy Technol. 28, 20-26. Sundman, V. 1953. On the microbiology of Finnish ropy sour milk. 13th Int. Dairy Congr. 3, 1420-1427. 

Wine is one of the most complex and interesting matrices for a number of reasons. It is composed of volatile compounds, some of them responsible for the odor, and nonvolatile compounds which cause taste sensations, such as sweetness (sugars), sourness (organic acids), bitterness (polyphenols), and saltiness (mineral substances Rapp and Mandary, 1986). With a few exceptions, those compounds need to be present in levels of 1%, or even more, to influence taste. Generally, the volatile components can be perceived in much lower concentrations, since our organs are extremely sensitive to certain aroma substances (Rapp et ah, 1986). Carbohydrates (monosaccharides, disaccharides, and polysaccharides), peptides, proteins, vitamins, and mineral substances are among the other wine constituents. 

In recent years, a few fermented dairy products with naturally occurring antihypertensive peptides have been launched in both the Japanese and Finnish market. The Japanese sour milk product Calpis is made by inoculating skim milk with a starter containing L. helveticus and S. cerevisiae. The fermented drink is rich in the peptides Val-Pro-Pro and Ile-Pro-Pro, which have proven to lower blood pressure both in animal model studies and in clinical trials with hypertensive humans (Takano 2002). 

Nakamura, Y., Yamamoto, N., Sakai, K., and Takano, T. 1995b. Antihypertensive effect of sour milk and peptides isolated from it that are inhibitors to angiotensin I-converting enzyme. J. Dairy Sci. 78, 1253-1257. 

In the evaluation of contribution to taste, amino acids and peptides are being studied as to sweet, salty, bitter, sour and umaml [brothy mouth-feel, see (19)] sensations. In the production of gravies and soups, proteins are hydrolyzed to smaller molecules which evoke... 

Free amino acids and/or some peptides have some sweetness, bitterness, sourness, saltiness and umami, and are very important as taste substances in foods. 

Several dipeptides having L-Glu at N-terminus elicit the umami taste, though its umami taste intensity is much less than that of MSG. Aral et al. ( ) synthesized L-Glu-X (X= amino acid) and examined their taste in aqueous solution containing NaCl at pH 6. Glu-Asp, Glu-Thr, Glu-Ser and Glu-Glu were found to produce the umami taste. Ohyama et (30) showed that Asp-Leu and Glu-Leu were umami substances. In section "Sour Taste", the peptides containing Asp or/and Glu were shown to elicit a sour taste in water. However, several of their peptides besides Glu-Asp and Glu-Glu may also be umami stimuli in aqueous solutions containing NaCl at pH 6. 

The simplest tastant, the hydrogen ion, is perceived as sour. Other simple ions, particularly sodium ion, are perceived as salty. The taste called umami is evoked by the amino acid glutamate, often encountered as the flavor enhancer monosodium glutamate (MSG). In contrast, tastants perceived as bitter or sweet are extremely diverse. Many bitter compounds are alkaloids or other plant products of which many are toxic. However, they do not have any common structural elements or other common properties. Carbohydrates such as glucose and sucrose are perceived as sweet, as are other compounds including some simple peptide derivatives, such as aspartame, and even some proteins. 

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. 

According to several authors, cheese taste is mainly due to the compounds found in the cheese water-soluble extract (WSE) (1, 2). Thus, to study cheese taste, the focus is usually on the cheese WSE which contains small polar molecules such as minerals, acids, sugars, amino acids, peptides and some volatile compounds produced by different processes such as lipolysis, proteolysis microbial metabolism (3). These compounds are responsible for the individual taste sensations like sourness, bitterness and saltiness which are the main taste descriptors for cheese. However, in a complex mixture they also exert otiier taste sensations due to taste / taste interactions (4). Peptides are generally considered to be the main bitter stimuli in cheese (5). However, it was shown that in goat cheese, bitterness resulted mainly from die bitterness of calcium and magnesium chlorides, partially masked by sodium chloride (6). 

The results of omission tests (12) including other compounds in WSE and attributes are reported in Table 3. Cheese sourness was explained by die enhancing effect of sodium chloride on the sourness due to hydronium ions concentration. Cheese bitterness was explained by the enhancing matrix effect on bitterness due to small peptides. Cheese saltiness was respectively explained by a partially masking effect of die matrix on the WSE salty taste due to sodium chloride. 

Short oligopeptides play an important role in the sensorial appreciation of food and much attention has been paid to the relationship between the structure of peptides and their taste, based on four basic taste sensations (sweet, bitter, sour and salty). 

The delicious peptide Lys-Gly-Asp-Glu-Glu-Ser-Leu-Ala, is an octapeptide which was isolated from the gravy of beef and its primary structure was proposed in 1978 (3). It possesses a taste profile umami/sour... 

Three fragments of the delicious peptide sequence lysine-glycine, serine-leucine-alanine and aspartic acid-glutamic acid-glutamic acid possess separately umami/salty, bitter and sour taste respectively but mixtures or combinations of them produce a similar taste of that corresponding to the complete octapeptide. The synthesis of CBZ-Lys-Gly-OMe and CBZ-Ser-Leu-OMe were carried out using immobilized trypsin and thermolysin. We have studied the influence of reaction medium (pH, temperature and substrate concentration) on the yield and initial reaction rate of synthesis. 

Peptides with different bioactivities have been identified in many fermented milks, such as sour milk, yogurt, kefir and dahi, as reviewed by Fitzgerald and Murray (2006), Korhonen (2009) and Hernandez-Ledesma et al. (2011). In addition to anti-hypertensive peptides, casein phosphopetides, antimicrobial, antioxidative and immunomodulatory peptides have been found depending on the origin of milk, dairy cultures and technology applied in production. 

Pan, D., Guo, Y. (2010). Optimization of sour milk fermentation for the production of ACE-inhibitory peptides and purification of a novel peptide from whey protein hydrolysate. International Dairy Journal, 20,472-479. 

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