A consumer and a trained descriptive panel was utilized to determine liking ratings and flavor profiles, respectively, for commercial brands of pre-stirred yogurt. Once the consumer and descriptive panel data was collected, the data was combined to determine the interrelationship of these two sets of data and to determine the conditions necessary to optimize the sensory characteristics of commercial yogurt. This study was broken down into two parts: (1) evaluation by a 90 to 182 member consumer panel and an 11 member descriptive panel for 14 strawberry and 6 lemon yogurt brands, and (2) correlation of the sensory measures of sweetness and sourness, and analytical measures of sugars and acids for 14 strawberry, 12 raspberry, 6 lemon, and 17 plain yogurt brands. Large sensory differences were found between yogurts for both flavors (strawberry and lemon) by both panels. Correlation and principal component analysis (PCA) indicated that two distinct groups of descriptors contributed to the liking of the yogurts: one associated with the fruity and sweetness characteristics, and the other related to the plain yogurt and sourness descriptors. Consumers based their overall liking ratings on fruit flavor, sweetness, sourness, and a balance of sweetness/sourness liking. Males and females rated samples differently by as much as one full scale value on a 9-pt. hedonic scale. Use of PCA to relate the two panels revealed that high consumer acceptance corresponded with the PC loaded with fruity and sweet characteristics while lower consumer acceptability was noted with high loadings on PC2 which was comprised of plain yogurt, acetaldehyde, and sourness descriptors. The results from the first part of the study indicate that to produce a highly acceptable yogurt, processors should strive to provide a balance between sweetness and sourness and provide enough fruit flavor to mask plain yogurt characteristics. In the second part of this study, titratable acidity and pH were measured for all the yogurts, while sugars were measured by HPLC only for the fruit flavored yogurts. Consumer overall liking was significantly correlated with sweetness intensity, sweetness:sourness (sw:so) ratio, and the summed impact of sweetness and sourness from the trained panel for strawberry and raspberry yogurt. No correlations between analytical measures and overall liking were found for any of the yogurts. A sw:so ratio greater than 1.0 for strawberry, and .8 for raspberry and lemon appeared necessary for high consumer acceptance. Generally, it was found that the sweeter the yogurt, the higher the consumer acceptance of fruit flavored yogurt. No relationships were found for any sensory and analytical measures for predicting the overall liking of plain yogurt. However, the best predictors of consumer liking of fruit flavored yogurt were the descriptive panel ratings. / Graduation date: 1991

Please read the abstract in the front section of this document. / Dissertation (M Inst Agrar (Food Production and Processing))--University of Pretoria, 2005. / Food Science / unrestricted

This research focused on studying the sensory quality of low fat bacon when pale, soft and exudative (PSE) pork is used during processing. Low fat bacon is different from normal bacon in that the amount of visible fat in low fat bacon has been reduced. This is as a result of consumer interest in weight control and cholesterol, creating a demand for meat and meat products with reduced fat levels. PSE pork is a condition in which certain muscles are very pale, soft and watery. It is produced when the rate of post-mortem glycolysis is fast and a high level of acidity is reached while the carcass temperature is still high. Different researchers have reported that PSE pork absorbs less brine during curing and this may have a negative effect on the sensory quality and acceptance of both the uncooked and cooked finished products as it is mainly the curing brine that is responsible for the development of the typical colour, flavour, aroma and texture associated with cured meat products. Thirty pig carcasses, 15 PSE and 15 normal pH, suitable for production of low fat bacon, were selected over a period of three weeks at an abattoir in Olifantsfontein to study the effect of PSE meat on the sensory quality of low fat bacon. The carcasses were further processed into low fat bacon at a meat processing plant. Data were collected on the % brine uptake of PSE and normal pH meat after curing; the rating scores on the descriptive sensory attributes of both PSE and normal pH low fat bacon and the % salt concentration and residual nitrite of PSE and normal pH low fat bacon. A consumer test to determine the buying preferences for packaged PSE and normal pH low fat bacon and the eating quality preferences of cooked PSE and normal pH low fat bacon was also conducted. No significant difference (p > 0.05) was found in the % brine uptake between PSE and normal pH meat. There were no significant differences (p > 0.05) in the descriptive sensory attributes of PSE and normal pH low fat bacon. The residual nitrite concentration of normal pH low fat bacon was significantly higher than that of PSE low fat bacon. There was however no significant difference (p > 0.05) in the % salt concentration of PSE and normal pH low fat bacon. Correlation matrices showed significant positive correlations (p ≤ 0.05) between % brine uptake and % salt concentration and between % salt concentration and perceived saltiness of normal pH low fat bacon. For PSE low fat bacon, the correlations between % brine uptake and % salt concentration and between % salt concentration and perceived saltiness was not significant. The correlation between % brine uptake and residual nitrite content was however not significant (p > 0.05) for both the PSE and normal pH low fat bacon. A significantly higher number of consumers indicated that they would prefer to buy samples representing PSE low fat bacon. The pale colour of PSE meat was not masked after curing, which was noticed by the consumers during the evaluation of buying preferences for PSE and normal pH packaged low fat bacon. However, regarded as even more important than colour, the consumers mentioned fat content as the main deciding factor for purchasing low fat bacon. No significant difference (p > 0.05) was found in the preference for the eating quality of cooked PSE and normal pH low fat bacon. It was concluded that PSE meat can successfully be used to produce low fat bacon products of consistent quality. This conclusion is drawn from the analytical sensory test results, where the use of PSE meat did not affect the sensory quality characteristics of low fat bacon. For low fat bacon, fat content is an important factor, regarded as very influential to consumers when making purchases. It is therefore important to produce products with consistent fat content according to specifications. / Dissertation (M Inst Agrar ( Food Production and Processing))--University of Pretoria, 2002. / Food Science / unrestricted

As a major wheat exporter to countries all over the world, the United States has to produce wheat that satisfy different quality requirements requested by their customers. Over the past decade the United States has encountered a major problem, that of losing market share in Asia to Canada and Australia. The major reason was that the United States was unable to supply Asian countries with quality wheat suitable for noodle production. To overcome the problem, the U.S. wheat industry needs to understand the specific quality requirements required for Asian noodles. Research on understanding sensory characteristics of Asian noodles was proposed to bridge the communication barrier regarding Asian noodle quality. Descriptive analysis was utilized for this study to provide sensory characteristics of noodles from different Asian countries. In the first study, four classes of U.S. wheat flour samples were evaluated for their ability to make high quality Taiwanese noodles. Taiwanese noodle industry representatives came to the United States and made 4 major types of their noodles using U.S. wheat flours; they evaluated them by employing both the Taiwanese industries' scoring system and modified descriptive analysis. The results of this study indicated that hard white wheat was suitable for making two types of Taiwanese noodles (dry and yee noodles), a blend of hard red winter and hard red spring wheat was suitable for wet noodles, and a blend of hard red winter and white wheat was suitable for fresh noodles. The second study was undertaken to better understand the texture profile of noodles from various Asian countries. Sensory texture characteristics of fresh noodles from Taiwan, Thailand, and Malaysia were identified. A total of 16 patent flour samples for Taiwan, and 18 straight grade flour samples each for Thailand and Malaysia, were milled from hard white wheat varieties and made into each Asian country's noodles. A texture profile of each country's noodles was developed by an Oregon State University descriptive panel while quality evaluation was performed by each countries' noodle experts. The results characterized the Taiwanese noodles as the smoothest, springiest, and highest in integrity of noodles; the Thai noodles were the hardest, most dense, cohesive noodles and also higher in starch between teeth and toothpull; and the Malaysian noodles were the softest, least dense, cohesive, and sticky noodles. The optimum protein to achieve specific texture quality for each country was identified. / Graduation date: 1998

No description available.

Addition of acids to foods allows for enhanced food safety. Acids are the primary form of defense against microbial contamination in refrigerated foods, while use of acids in conjunction with heat or high hydrostatic pressure processing lowers energy usage resulting in cost reduction. However, addition of acids to food or beverage formulations often reduces palatability due to higher sourness and this has limited the food industry's ability to better utilize them as preservatives. This study was aimed at gaining a better understanding of sourness suppression and its underlying mechanisms so that such limitations might be ultimately overcome. This work was divided into three parts dealing with the suppression of the sourness of citric, lactic and malic acids, as perceived by a trained sensory panel in a) binary mixtures with sugars, b) binary mixtures with salts and c) tertiary mixtures. The results of the first part showed that suppression was not mediated by sugar molarity or weight, but was significantly influenced by its perceived sweetness intensity in most cases. Sucrose and fructose were more effective than glucose in suppressing acid sourness and the data supported a separate receptor site/mechanism for glucose. Suppression was thought to have both central and peripheral components. In binary acid-salt mixtures sodium acetate (NaAc) affected the most sourness reduction, along with the largest concurrent pH increase (above 4.4). Sodium chloride (NaCl) mixtures showed significant suppression without a pH increase. Sodium gluconate (NaGluc) mixtures showed moderate suppression with citric and malic acids with pH increases remaining below 4.4, but showed little effect on lactic acid sourness. Saltiness appeared to drive suppression only in the case of NaCl, while pH change was responsible for reduction of sourness with NaAc and NaGluc. The tertiary trials indicated that a two-component multiple masker was more effective when its components stimulated different (as opposed to similar) receptors/receptor mechanisms in the taste system, irrespective of taste quality. Furthermore, a two-component masker was more effective than each component alone, and both components of a two-component masker did not have to be effective individually for them to function together as an effective multiple masker. / Graduation date: 2002

The effect of sweeteners on fruit flavor perception was studied through the use of fruitiness power functions for unsweetened and sweetened model systems. In the first part of the study, two isosweet concentrations of aspartame and sucrose were determined and combined with five concentrations of orange and strawberry flavorants. Fruitiness power functions were developed and compared to determine the effect of each sweetener on the fruit flavor. For the second part of the study in the first experiment, one isosweet concentration of sucrose, aspartame, acesulfame-K and 1:1 blended APM/Ace-K was combined with five concentrations of each of three orange flavorants. Fruitiness power functions were developed and compared to determine how each sweetener effected the fruit flavor of each flavorant. The second experiment addressed the question of whether or not subjects associated sweet taste with fruitiness or if there was an actual change in the volatile composition of the aroma between the unsweetened reference and the sweetened solutions. Fruit aroma of the middle concentration of each flavorant sweetened with the four sweeteners was compared to the corresponding unsweetened reference. Enhancement of fruitiness was observed in the aspartame sweetened systems at low flavor levels. The power function slopes of both flavorants were lowered by the addition of aspartame which resulted in a slower rate of growth in fruitiness perception with the addition of flavorant to the system. In both the orange and strawberry flavored systems the aspartame sweetened solutions were rated higher in fruitiness than the sucrose sweetened solutions. The enhancement was more pronounced in the orange flavored system, suggesting a flavorant effect. The sweeteners affected the fruitiness perception of the three orange flavorants in different magnitudes but the patterns were similar. The three fruitiness slopes were all lowered by the addition of each sweetener. Flavor enhancement was greatest in flavor 1 sweetened with aspartame or aspartame/acesulfame-K. The higher relative placement and low slope of the fruitiness power functions in aspartame sweetened systems caused the enhancement effect to be greatest over the lower concentrations of each flavorant. In the second experiment, the fruit aroma of aspartame sweetened solutions in flavor 1 was significantly higher than the other sweetened solutions. The fruit aroma of the second and third flavorants was not significantly changed by the sweeteners. / Graduation date: 1992

'Gala' is an apple cultivar with a distinctive aroma and flavor. 'Gala' storage season is short in regular atmosphere (RA). Controlled atmosphere (CA) extends 'Gala' storage but volatile production is reduced. 'Gala' odor-active aroma compounds were identified using Osme, a gas chromatography and olfactometry technique. Changes in aroma after RA and CA storage were characterized by Osme and descriptive sensory analysis (DSA). Hexyl acetate, butyl acetate and 2-methylbutyl acetate were emitted in the largest amounts and were perceived with the strongest intensities, with "ripe apple", "solvent" and "fruity" descriptors. Production of hexyl acetate and butyl acetate after CA storage decreased significantly compared to apples stored in RA, along with perceived intensities. 2-Methylbutyl acetate only decreased in apples stored 20 weeks in CA. Other esters with an apple odor were butyl 2-methylbutyrate and hexyl 2-methylbutyrate. Methyl 2-methylbutyrate, ethyl 2-methylbutyrate and propyl 2-methylbutyrate had sweet, fruity, and berry-like odors. Ester production after CA storage decreased at different rates. The non-ester compounds 4-allylanisole (anise) and 0-damascenone (grape juice) as well as an unidentified compound (watermelon), were perceived mostly from RA stored fruit. Other unidentified peaks had cucumber, mushroom, adhesive tape or skunk odors. Comparison of mixtures of 'Gala' odor-active compounds in water with whole 'Gala' apples revealed that hexyl acetate, hexanal and butyl acetate were necessary to impart an apple odor. 2-Methylbutyl acetate and methyl 2-methylbutyrate also contributed to the least difference between mixture solutions and apples. DSA of 'Gala' apples stored in RA and CA confirmed the general decrease in fruity aroma following CA storage. A floral descriptor was also significantly affected by CA storage. A musty note appeared in CA stored fruit, which may have corresponded to a garlic odorant peak detected during Osme. 'Gala' apples stored 16 weeks in CA followed by 4 weeks in RA emitted more volatiles than fruit stored 20 weeks in CA. The difference in volatile production was perceived by Osme analysis, and differences in overall fruity aroma between 16 and 20 weeks CA stored fruit were perceived only for whole fruit. There was no difference between those two types of storage for fruit flavor. / Graduation date: 1998

The German hop Hallertauer, hallertauer is highly valued because of its "noble aroma", but it has a very low yield when cultivated in the U.S. Two new crosses of Hallertauer, U.S.D.A. 21455 and 21459, have high yields and promising aroma characteristics. In order to predict sensory properties of beers as a function of the varieties of hop used in brewing, a more complete sensory and chemical characterization of hop oils is necessary. The aims of this study were to compare the aroma profiles of the new crosses against the German variety by determining their most important odor active compounds, and correlating the sensory attributes evaluated by a descriptive sensory panel (DSP) with the odor intensities detected during the gas chromatograph (GC) effluent detected during the gas chromatograph (GC) effluent sniffing. Oxygenated fractions were spiked into spring water and evaluated by the DSP. The same samples were injected into the GC and the effluents were evaluated quantitatively and qualitatively by four subjects using a special data collection device. Samples were then analyzed by mass spectrometry (MS). There were no significant differences among the three varieties based upon the DSP results and the "aromagrams" obtained during the sniffing of the GC effluents. Important odor active peaks were associated with humulene oxidation products. A number of statistical correlations existed between the sensory attributes and the odor active peaks. In summary, the new varieties are potential contributors to "noble aroma". Trials with beers brewed with these hops are underway in order to establish their contribution to beer flavor. / Graduation date: 1990

Digitized by Kansas Correctional Industries