Browsing by Author "Jirangrat W"

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    Psychological biases affect hedonic ratings
    (2013-03-29) Jirangrat W; Prinyawiwatkul, W
    Psychological biases in consumer testing may lead to misinterpretation of results and lower experimental power. Reports on various hedonic scales associated with psychological biases induced by sample presentation are limited in the literature. An appropriate experimental protocol could enable sensory scientists to accurately determine if a product is more or less liked. Overall, in this study some drawbacks of hedonic scales were revealed and some recommendations were made under specific circumstances. A more powerful design (SPRCBD) helped minimize positional and First Serving Order (FSO) biases in consumer tests by extracting more explained variances, resulting in decreased Type-II error in the model. Logistic regression analysis was proven to be an alternative methodology to quantify sensory contrast effects. For sensory testing, a multidimensional attribute tended to be more affected by the contrast effects than a simpler attribute. Several scales have been used for assessing the degree of food liking/disliking. This study provided a good practice protocol, suggesting use of a regular scale length (100 mm.) for assessing a degree of food liking/disliking while Labeled Affective Magnitude (LAM) would be an alternative choice where the scale length effects may be a critical issue. Depending on the type of scale and its polarity, a negative attribute (e.g., bitterness) was more affected than was a positive attribute. When testing extremely liked product, one should be aware of contrast biases that affected more toward positive attributes than negative attributes. This study demonstrated some psychological biases that affected the hedonic ratings. There are many more factors that could sway sensory responses and prevent experimenters from getting accurate, valid and actionable outcome. Understanding of psychological biases, proper product selection, and proper data analysis should be further studied to minimize misinterpretation of hedonic ratings.
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    Sensitivity reliability and neutral tendency of hedonic ratings as affected by scale types and lengths and overall product impression
    (26/06/2012) Jirangrat W; Wang J; Corredor JAH; Sriwattana S; Prinyawiwatkul W
    Several scales are available for measuring degrees of liking/disliking. Information on characteristics of hedonic ratings as affected by scale types/lengths and overall product impression is limited. Therefore, we compared discriminatory power, sensitivity, reliablity, and neutral tendency of hedonic ratings collected from 9-point categorical (CAT), line (LIN), and labeled affective magnitude (LAM) scales (100-mm compared 300-mm length). Three grape juices (classified as A=liked, B=moderate, C=disliked) were arranged in 4 sets (AB-AC, BA-CA, AC-AB, or CA-BA; the left sample served first). Each panelist (N=60) evaluated color (OC), taste (OT), and overall-liking (OL) of 1 set (of 4 possible random serving sets) in all 6 independent sessions (3 scale types x 2 lengths). For OL determined on a 100-mm scale, the order of discriminatory power (determined by the MIXED procedure) was CAT>LAM>LIN. The 300-mm LAM scale was consistently more discriminatory than the 100-mm LAM scale for all attributes. For sensitivity (the number of significantly different pairs), CAT exhibited the highest sensitivity, considering simultaneously all products (A, B, C) categories. Regardless of attributes, product categories, and scale types, ratings tended to be lower with the 300-mm scale. For reliability (consistency of responses towards OC/OT/OL) of different scale/length types, Cronbach’s alpha values were 0.78-0.92, with slightly higher (0.89-0.92) values toward the disliked sample. Another reliability index (consistency of responses between 2 identical test samples) across different scale/length types was exhibited by Pearson’s correlation coefficients (r=0.32-0.75), with higher values toward the LAM scale; OC (a less complicated attribute) was less affected (higher r values). Product categories and scale types affected neutral tendency of responses, with moderate and disliked products being more affected when evaluated on LAM scales. This study demonstrated characteristics of hedonic scales as affected by scale lengths and overall product impression. Using proper scales to assess liking/disliking would help increase power of the experiment.
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    Sensory acceptability and chemical characteristics of healthy rib-eye steaks from forage‐finished steers
    (26/06/2012) Torrico D; Jirangrat W; Scaglia G; Malekian F; Janes ME; McMillin KW; Prinyawiwatkul W
    Consumer interest in health benefits of forage-finished beef has led to increased product demand. To date, little information on sensory characteristics of cooked forage-finished beef is available. We evaluated sensory acceptability and chemical characteristics of rib-eye steaks from forage-finished steers. Rib-eye steaks from 3 forage-finished steers [S1 (bermudagrass+ryegrass, etc.); S2 (bermudagrass+ryegrass+berseem, etc.); S3 (bermudagrass+berseem+forage soybean+brown midrib sorghum, etc.)], and one C [commercial steak], cooked by grilling and/or 2-sided grilling, were evaluated for chemical composition and microbial safety. Sensory liking [overall-appearance (OAR) and fat-appearance (FA) for raw steaks; overall-appearance (OAC), overall-flavor (OF), juiciness, tenderness, and overall-liking (OL) for cooked steaks] were evaluated by 112 Hispanic consumers. Data were analyzed (PROC MIXED, a=0.05). C (raw) had higher fat (50.2% compared to 23.0-24.9%) and lower protein (49.4% compared to 73.5-74.4%, dry weight basis) contents compared with S1 and S2. S1 and S3 had higher omega-3 (0.49-0.55 compared to 0.09%), lower omega-6/omega-3 ratio (2.51-2.81 compared to 10.07), and lower PUFA (4.31-4.77 vs. 8.4%) contents than C, thus exhibiting a healthier fatty acid profile. Concerning raw steaks, S3 had higher OAR (6.9 compared to 5.4-5.9) and FA (5.9 compared to 4.9-5.1) liking scores than other samples. Purchase intent based on visual appearance was highest for S3 (85.7%). Concerning cooked steaks, the 2 cooking methods did not cause significant differences in liking scores. Juiciness and OL scores of C steaks (both cooking methods) and S3 (2-sided grilling) were not significantly different. Purchase intent (after health benefits of forage-finished steaks was informed) increased from 62.0-73.8 to 69.8-85.7%. The mean drop of liking scores was -1.00 to -2.50 and -0.50 to -2.50 on the 9-point OL scale, respectively, when cooked steaks were not-juicy-enough and not-tender-enough. Cooked and raw rib-eye steaks were free of E. coli . This study demonstrated that forage-finished steaks are healthier than grain-fed commercial steaks and have market potential toward Hispanic population.
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    Variations in heading ratings characterized by scale polarity scale types and attributes
    (26/06/2012) Jirangrat W; Ordonez K; Wang J; Corredor JAH; Sriwattana S; Prinyawiwatkul W
    The negative side of the 9-point hedonic scale is not fully understood. When used to evaluate negative attributes (for example, bitterness), this hedonic scale may yield poor results. We evaluated hedonic ratings as affected by scale types [9-point-categorical (CAT), line (LIN) and labeled-affective-magnitude (LAM)] and polarity (uni- compared to bi-polar), and attributes (positive compared to negative). We compared sensitivity and confounding effects [contrast+panelist effects=CP] of positive- and negative-attribute ratings among 3 scales, and compared effects of uni- (negative-side only) compared to bi-polar scales on negative-attribute ratings. Grape juices (classified as A=Liked, B=Moderate, C=Disliked) arranged in 4 sets (AB-AC, BA-CA, AC-AB, or CA-BA; the left sample served first) were evaluated (N=60 consumers) for overall-liking using 3 scales. Low-sodium chicken broths (classified as M=Mild- and S=Strong-bitterness) arranged in 2 sets (MS or SM) were evaluated (N=216) for bitterness using 3 scales. Balanced/randomized presentation was practiced. With bi-polar scales: 1) consumers better differentiated negative-attribute ratings; 2) CP was higher for positive- than negative-attribute ratings [5.47 compared to 0.11, 12.41 compared to 0.09, and 82.66 compared to 0.23, respectively, for CAT, LIN, and LAM; 3) LAM was more affected by CP. With negative-attribute ratings, CP of LAM was higher for uni- than for bi-polar scales. CP was more pronounced for liked- than disliked-samples, resulting in higher score fluctuation. CAT was more affected by contrast effects whereas LIN and LAM were more affected by panelist effects. Polarity effects were obvious for the mild-bitterness sample, showing significantly different results between uni- compared to bi-polar scales [3.91 compared to 6.39, 4.28 compared to 6.49, and 41.05 compared to 63.24, respectively, for CAT, LIN, and LAM]; all ratings from bi-polar scales were not on the negative-side. For the strong-bitterness sample, uni- and bi-polar ratings were on the negative side, with LAM having more consistent pattern. This study revealed some drawbacks of hedonic scales induced by scale polarity/types and attributes.