Taste activity value

In recent years, non-volatile taste compounds have been becoming more important in the area of modern flavour development. Therefore, the principal approach of the OAV has been adapted for the taste side in the form of the so-called taste-activity value. In order to facilitate the search for taste-active materials and for a better understanding of the taste dimension of foodstuffs, a new instrumental setup called LC-Taste has been developed [58]. 

To verify whether the volatiles listed in Table 6.32 are actually the key odorants, an aroma model was prepared by using an unripened cheese (UC) as base ]53J. The odorants and in addition the compoimds showing high taste activity values ]54] were quantified in UC and in Swiss cheese ]53]. The differences in the concentration of these compounds in both samples were calculated, and, accordingly, the compounds were dissolved in water and/or sunflower oil and then added to freeze-dried UC. The flavour model obtained agreed in colour, pH, water, protein and fat content with grated Swiss cheese, only the texture was more grainy ]53]. 

Using odor activity value (ratio of concentration to odor threshold), Forss et al. (23), Urbach et al. (24), and Stark and co-worker (25-27) reported 5-decalactone, 8-octalactone, decanoic acid, dodecanoic acid, skatole, and indole as important contributors to the flavor of butter oil. In addition, the data of Siek et al. (28) indicated that in fresh butter, the levels of butanoic acid, caproic acid, 5-decalactone were above their taste threshold. 

Besides nutrients, foods contain many substances that influence the food sensory impression and its organoleptic properties. These food constituents are known as sensoriaUy active compounds. They determine the sensory value (quality) of foods, inducing an olfactory sensation (perception), which is described as the aroma, odour and smell, gustative perception, which is the taste, visual perception, which is the colour, haptic (tactile) perception, which is the touch and feel, and auditorial perception, which is the sound. The olfactory sensation is derived from odour-active compounds and the gustative perception from taste-active compounds. Flavour is the sensory impression determined by the chemical senses of both taste and smell and is caused by flavour-active food components. Haptic sensation is the texture, which is affected mainly by high molecular weight compounds, such as proteins and polysaccharides, often referred to collectively as hydrocoUoids. Geometric aspects of texture that evoke both haptic and visual sensations symbolise the terms appearance and shape. 

Volatile aldehydes and ketones are the most important odour-and taste-active substances. They occur in foods as primary substances, as components of various essential oils and also result from enzymatic and chemical reactions from various precursors as secondary substances. They are often desirable flavour-active components of foods, but in some cases may also carry undesirable odour and taste. Then they serve as indicators of unwanted changes in sensory or nutritional value of foods (such as autoxidation of lipids). 

Because overblanching may result in undesirable changes in color, flavor, taste, and texture and the loss of nutritive value, it is as important to avoid overblanching as underblanching. The availability of a method for the detection of overblanching is indicated, but so far as the writer is aware, none exists at the present time. In view of the fact that complete peroxidase inactivation is not required for quality protection, a measurement of residual peroxidase activity might provide the basis for such a test. 

Commercially available black pepper comes from the entire unripe fruit of a Piper nigrum L. plant and is valued for its pungent taste and aroma. Besides its hot flavor, there are many folk medicine remedies using black pepper. It has antiallergic activity. Piperine strongly inhibits hepatic arylhydrocarbonhydroxylase and UDP-glucuronyl transferase activities. Some proven uses for black pepper extracts are as an insecticide and as a tumor inhibitor. To research claims such as these, it is necessary to isolate the components of pepper. 

At alkaline pH, an interesting situation occurs. The activation parameters for C—N rotation in DMA at pH 11.8 are AGt = 19.0 kcal/mol, AHt = 16.3 kcal, —TASt = 2.7 kcal/mol (Gerig, 1971). The large contribution to AG that is made from the entropy term may indicate nucleophilic participation of hydroxyl leading to the formation of a tetrahedral adduct. At the stage of this tetrahedral species, the C-N bond has lost all double-bond character and rotation will be energetically more favorable. This may be reflected in the low AHt value. 

Properties Brownish-yellow oil or soft fat characteristic odor somewhat acrid taste. D 0.940 iodine value 85-105 (based on type), optically active. Solu-... 

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