Omission test

In the case of pineapples, the 12 odorants listed in Table 16.7 were dissolved in water in concentrations equal to those determined in the fruit [50]. Then the odour profile of this aroma model was evaluated by a sensory panel in comparison to fresh pineapple juice. The result was a high agreement in the two odour profiles. Fresh, fruity and pineapple-like odour notes scored almost the same intensities in the model as in the juice. Only the sweet aroma note was more intense in the model than in the original sample [50]. In further experiments, the contributions of the six odorants showing the highest OAV (Table 16.7) were evaluated by means of omission tests [9]. The results presented in Table 16.8 show that the omission of 4-hydroxy-2,5-dimethyl-3(2H)-furanone, ethyl 2-methylbutanoate or ethyl 2-methylpropanoate changed the odour so clearly that more than half of the assessors were able to perceive an odour difference between the reduced and the complete aroma model. Therefore, it was concluded that these compounds are the character-impact odorants of fresh pineapple juice. 

A mouth simulator is a valuable tool when determining what volatiles contribute to the flavor sensation during consumption of a food. This includes determining potency (e.g., Char-mAnalysis), intensity (e.g., OSME Acree and Barnard, 1994), contribution (e.g., omission tests), and effect of a compound on the flavor. Sample preparation with a mouth simulator gives a close representation of the human experience, without the expense and variability of using humans. The limitations of headspace sampling and detection sensitivity define the limits of the use of mouth simulators. 

Flavour and off-flavour compounds of black and white pepper (P. nigrum L.) were evaluated by Jagella and Grosch (1999a,b). Enantioselective analysis of optically active monoterpenes indicated ( )-linalool, (+)-a-phellandrene, (-)-limonene, myrcene, (-)-a-pinene, 3-methylbutanal and meth-ylpropanal as the most potent odorants of black pepper. Additionally, 2-isopropyl-3-methoxypyrazine and 2,3-diethyl-5-meth-ylpyrazine were detected as important odorants of the black pepper sample from Malaysia, which had a mouldy, musty off-flavour. Omission tests indicated a-and (3-pinene, myrcene, a-phellandrene, limonene, linalool, methylpropanal, 2- and 3-methylbutanal, butyric acid and 3-meth-ylbutyric acid as key odorants. A storage experiment revealed that for ground black pepper, losses of a-pinene, limonene and 3-methylbutanal were mainly responsible for deficits in the pepper-like, citrus-like, terpene-like and malty notes after 30 days at room temperature. The musty/mouldy off-flavour of a sample of black pepper was caused by a mixture consisting of 2,3-diethyl-5-methylpyrazine (2.9pg/kg) and 2-isopropyl-3-methoxypyrazine (0.2 (xg/kg). 

An organoleptic omission test on this mixture confirmed 3-hydroxy-4, 5-dimethyl-2(5H)-furanone to be the most important FIC for a raw cane sugar aroma, and the other main components in Table 1, i.e., vanillin, maltol, 4-pentyl butanolide, 4-vinyl phenol and 2,6-dimethoxy phenol, seemed to improve the overall sugary aroma. From these results, we( ) gave the trivial name sotolon" to 2-hydroxy-4,5-dimethyl-2(5H)-furanone, which is built up from "soto" (raw sugar in Japanese) and "olon" (enol lactone) as a main FIC in raw cane sugar. 

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. 

Table 3. Omission tests results made on WSE constituents.

Hashimoto, Y., Konosu, S., Fusetani, N. and Nose, T., 1968. Attractants for eels in the extracts of shortnecked clam. I. Survey of constituents eliciting feeding behaviour by the omission test. Bull. Jap. Soc. Sci. Fish, 34 78—83. 

Engel, E., C. Septier, N. Leconte, C. Salles, J.-L. Le Quere, Determination of taste-active compounds of a bitter Camembert cheese by omission tests, J. Dairy Research, 68(4), p. 675, 2001. 

In Section 7, columns C and E you must Indicate the range of influent concentration and treatment efficiency, respectively, lor each treatment system listed. The facility must estimate the efficiency and influent concentration of each air omission treatment system, as the stack test program did not determine influent concentrations. The facility has manufacturers data on the efficiency of each treatment system and should use this information along with effluent concentration data to estimate the influent concentrations. The efficiency estimates for air treatment systems are not based on operating data this must be indicated in column F of Section 7. 

Provide a means of recording inspection and test results so that any omissions can be checked at subsequent inspections. 

A literature method for preparation of chromyl acetate by interaction of chromium trioxide and acetic anhydride was modified by omission of cooling and agitation. The warm mixture exploded violently when moved [1], A later publication emphasised the need for cooling, and summarised several such previous occurrences [2], An earlier reference attributes the cause of chromium trioxide-acetic anhydride oxidation mixtures going out of control to presence of nitric acid or nitrates in the chromium trioxide, and a simple test to check this point is given [3], Mixtures used as a reagent for the remote oxidation of carboxylic esters are potentially explosive, and must be made up and used at below 25 °C under controlled conditions [4], An attempt to purify the anhydride by warming with 2% w/v of trioxide led to an explosion at 30°C [5],... 

It is important to include all of the relevant physical effects in the equations to be nondimensionalized. This can be difficult because there isn t always consensus about which effects are important. Moreover, there is controversy over how to properly represent these effects in equation form. For our purposes the question is Have all of the important parameters been included in the nondimensional equations Pragmatically, the success to date of the scaling experiments using the formulation as presented adds confidence to the use of these simplifications which will be employed. Also, a limited number of tests have verified the omission of parameters specifically related to several phenomena. 

The effect of adjusting for tied ranks is to slightly increase the value of the test statistic, H. Therefore, omission of this adjustment results in a more conservative test. 

Quality assurance tests should be applied to enhance the process. A completeness test can help identify gaps or omissions in the chronology of events, while a sufficiency test can check the logic in a sequence diagram by comparing two adjoining facts to verify if one fact always leads to the second fact. 

Most authors use a mixture of the same composition as the test mixture for the incubation control, except for omission of UDP-sugar. As outlined above, complete suppression of endogenous synthesis is preferred by the present authors for determination of enzyme activities. 

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