07-04-20-10-Intensityand+DA

07-04-20-10-Intensityand+DA - Ven 125 Minimum exposure to...

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Ven 125 1 Minimum exposure to fluorescent light to produce detectable difference in aroma 0 10 20 30 40 50 60 0 1 02 03 04 05 0 Hours % Correct 0 10 20 30 40 50 60 01234567 Hours 31.1 hours 3.3 hours Still wines: 18 and 3.4 hours. Calculation of threshold value (cannot always be done easily!) Repeat test! R 2 = 0.6517 0 10 20 30 40 50 60 70 80 90 0 5 10 15 20 25 ppm R 2 = 0.2257 0 10 20 30 40 50 60 70 80 90 100 0 5 10 15 20 25 ppm % Correc 1. Gives rough idea of sensory importance of compound in specified medium : MIBP: 2 ng/L in water MIMP 15 ng/L in wine Diacetyl: 0.2-2.8 ppm in wine TCA 5 ppt in wine Threshold Tests 2. Diagnostic test : Sensitivities to odors decrease (thresholds increase) with age, disease (AIDS, Parkinson’s, Alzheimer's), smoking… N.B. mg/L = ppm μ g/L = ppb ng/L = ppt Larsson, et al. 1999. Neuropsychology.,13: 47-53 Fig. 5. Detection thresholds for cis-3-hexen-1-ol odour by genotype for rs9295791. Error bars indicate the standard error of the thresholds. No error bar is provided for the threshold for genotype GG, since n =1. Jaeger et al. (2010), FQP , 21:121-131 Factors influencing threshold values Wine composition: pH, ethanol affect compound volatility •T e m p e r a t u r e Way in which test conducted a s t e v e r s u s s m e l l Ascending concentrations? Staircase? Method of Calculation: Concentration with 50% correct above chance (75% if DT or pairs) OR 50% (regardless of chance. .) Judge sensitivity at the time of the test Linalool Threshold ~ 5 ppm in Neutral White Wine and in a Gewurztraminer? Or Oaked Chardonnay? Or Sauvignon blanc? H2S ~2ppb in water…but in a Cabernet or Riesling? Bottom line: use threshold data cautiously ODOR Active Values (OAV) Amount compound = OAV Threshold
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Ven 125 2 Stevens: Measurement Levels SCAN paper Intensity measurements Ranking or Ordinal measurements Rating measurements : Interval scales Ratio scales Rank Easy Less information Minimal training Only order No reproducibility Advantage Disadvantage Rate Can measure intensity [Must train judges] Can test reproducibility Statistical Analysis of Sensory Tests Ranking: •Friedman Test & Least Significant Difference Rank Sums •Test as in Newell & McFarlane –see smartsite.myucdavis WINES judges A B C 1132 2231 3132 4123 5312 6231 7321 8132 Ranked Data Friedman is Statreview on Smartsite N&M in Smartsite 9312 10 3 1 2 11 2 3 1 12 2 3 1 13 3 2 1 14 2 3 1 15 2.5 2.5 1 16 3 2 1 17 3 2 1 18 2 3 1 sum 39.5 42.5 26 aab Friedman Test ab a b Newell 11.8 (LSRD) 15 (LSRD) = 0.05 Friedman Calculations χ 2 = {12/[K(J)(J + 1)]}S(T j 2 ) – 3(K)(J + 1) K = 18 rows J = 3 columns T j = column totals χ 2 = {12/[18*3*4]}*[(39.5) 2 + (42.5) 2 + (26) 2 ] – 3*18*4 χ 2 = 0.056 * 4042.5 – 216 = 8.58 for df = (J – 1) = 2, α = 0.05 χ 2 crit = 5.99 REJECT H 0 ; there is a difference in ranked sums LSRD = 1.96SQRT[J (J + 1)(K)/6] = 11.8
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Ven 125 3 Category or interval 1 2 3 4 5 6 7 8 9 low high Analog/line scale _____________________ REF __________|___________ _____________________ SCALES Labeled Magnitude Estimation _|_____|_____|_____|_____|_____|______|______|_____|_____|_______| Barely Weak Moderately Strong Very Strong Strongest Detectable imaginable 5 6 7 8 5 6 7 8 5 6 7 8 Effect of ethanol, sucrose and viscosity on bitterness and sweetness of vermouth 0 1 2 3 4 10 15 20 25 Bitter Sweet % Ethanol 0 1 2 3 4 7 1 21 72 2 Bitter Sweet % Sucrose 0 1 2 3 4 1.5 2.5 3.5 Bitter Sweet Viscosity(cp) Burns and Noble, J. Text. Studies 16:365, 1985
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07-04-20-10-Intensityand+DA - Ven 125 Minimum exposure to...

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