OPTIMIZATION OF A CHOCOLATE PEANUT SPREAD USING RESPONSE SURFACE METHODOLOGY (RSM)

Response surface methodology was used to optimize formulations of chocolate peanut spread. Thirty-six formulations with varying levels of peanut (25-90%), chocolate (5-70%) and sugar (5-55%) were processed using a three-component constrained simplex lattice design. The processing variable, roast (light, medium, dark) was also included in the design. Response variables, measured with consumers (n = 60) participating in the test, were spreadability, overall acceptability, appearance, color, flavor, sweetness and texture/mouthfeel, using a 9-point hedonic scale. Regression analysis was performed and models were built for each significant (p < 0.01) response variable. Contour plots for each attribute, at each level of roast, were generated and superimposed to determine areas of overlap. Optimum formulations (consumer acceptance rating of ≥ 6.0 for all attributes) for chocolate peanut spread were all combinations of 29-65% peanut, 9-41% chocolate, and 17-36% sugar, adding up to 100%, at a medium roast. Verification of two formulations indicated no difference between predicted and observed values.     

COMPARISON OF ATTRIBUTE LIKING AND JAR SCALES TO EVALUATE THE ADEQUACY OF SENSORY ATTRIBUTES OF MILK DESSERTS

Just-about-right (JAR) scales and attribute liking questions are usually used to study consumer perception of the sensory characteristics of food products. The aim of the present work was to compare the performance of attribute liking and JAR scales to evaluate consumers' perceived adequacy of flavor and texture of milk puddings. Two groups of consumers were asked to evaluate eight milk desserts using (1) overall liking followed by attribute liking for texture and flavor and (2) overall liking followed by JAR scales for thickness, creaminess, sweetness and vanilla flavor. Overall liking scores were significantly different when JAR scales or attribute liking questions were considered. Texture, flavor and overall liking scores were highly correlated to each other, providing the same information. JAR scales correlated better with the intensity of sensory attributes evaluated by a trained sensory panel, being JAR percentages a reliable tool to study the adequacy of sensory attributes.

PRACTICAL APPLICATIONS

Results from the present work showed that consumers might not be able to independently evaluate their liking of different sensory attributes of a product. For this reason, the use of attribute liking questions for studying the adequacy of sensory attributes in complex products would not be recommended. JAR scales were better indicators of the adequacy of sensory attributes. Consumers were able to independently evaluate texture and flavor attributes using JAR scales. However, the influence of JAR scales on overall liking scores should be taken into account when including these scales on consumer studies.     

NOTE ON COMPUTERIZED DATA COLLECTION IN CONSUMER SENSORY EVALUATION

Panelists with computer experience (n = 24) and without (n = 26) rated three foods representing liked, neutral and disliked categories using a 9-point hedonic scale on computer and paper ballots. In paired t-test results between computer and ballot ratings, no differences were found in overall acceptance, flavor and appearance attributes. Regression analysis indicated a significant (p<0.01) linear relationship between computer and paper ballot ratings. Computer ballot ratings for overall acceptance were comparable to paper ballot ratings in a consumer sensory evaluation test. Slight differences in overall acceptance were found between computer and paper ballot responses from panelists with and without computer experience. GLM indicated the group without computer experience rated overall acceptance and flavor attributes for cereal, and appearance and flavor attributes for potato chips significantly higher (p<0.05) than panelists with computer experience.     

ADJUSTING ROASTED PEANUT ATTRIBUTE SCORES FOR FRUITY ATTRIBUTE AND NONOPTIMUM CIELAB L* VALUES1

Developing peanut breeding strategies for roasted peanut flavor improvement requires that roasting be to an optimum and effects of negative environmental exposure be to a minimum. In practice it is difficult to achieve these conditions. However, statistical adjustments are possible. To ascertain the proper adjustments, surface response equations were determined relating roast color and fruity attribute scores to roasted peanut attribute score. Fruity attribute had a depressing effect on roasted peanut attribute score. Similarly, underroasting as well as overroasting led to reduced roasted peanut attribute scores. Adjusting for genotype and location had nonsignificant effects on mean optimal roast color or linear equation slope values of the fruity-roasted peanut relationship. With these findings a method for maximization of roasted peanut values was developed using a modified SAS routine. Although the capability to estimate the roasted peanut flavor of a sample with optimal roasting and environmental effects has several potential applications, our specific application is to evaluate parentage contribution to flavor enhancement or flavor reduction.     

THE ROLE OF THE KNOWLEDGE OF COLOR AND BRAND NAME ON THE CONSUMER'S HEDONIC RATINGS OF TOMATO PUREES

The objective of study was to assess the influence of the knowledge of color and brand name on consumer response to tomato purees. From focus group interviews it was found that taste and odor of fresh tomato were the most important drivers of consumer choice. To quantify that information a questionnaire was developed and it was submitted to fifty consumers of tomato puree. The questionnaires answers confirmed those coming from the focus group, although same discrepancies were found with those derived from the consumer test. Results showed that color and brand name seemed to be more important than taste and odor of fresh tomato, in fact those attributes, when consumers were tasting samples, affected not only hedonic judgments but sensory perception as well. Finally physico-chemical parameters derived from instrumental measurements have been compared to sensory data by means of PCA in order to validate the consumers'assessment of sensory attributes of tomato puree.     

RELIABILITY OF THE FOCUS GROUP TECHNIQUE IN DETERMINING THE QUALITY CHARACTERISTICS OF MUNGBEAN [VIGNA RADIATA (L.) WILCZEC] NOODLES

Two commercial samples were evaluated in five focus group sessions to determine the reliability of the focus group technique in identifying the desirable and important sensory characteristics of dry and cooked mungbean noodles and to determine its quality characteristics. Each focus group consistently identified a similar list of desirable and undesirable characteristics. These results indicated that the focus group technique was a reliable method for determining consumer criteria for quality for mungbean noodles. When there is a need to determine consumers' definition of product quality at a stage when consumer testing is not desired, the focus group technique can be used as a valuable tool. Mungbean noodle quality was found to have two distinct aspects: appearance of the dry noodles and eating quality of the cooked noodles. Color, glossiness, and transparency are the most important characteristics of dry starch noodles while mouthfeel or texture is considered the most important characteristic of cooked starch noodles. Color, taste, and odor of the cooked noodles were considered not as important.     

DEVELOPMENT OF A LEXICON FOR BEEF FLAVOR IN INTACT MUSCLE

ABSTRACT

A lexicon describing the flavor characteristics of beef across different cuts, grades, and cooking temperatures and methods was developed. Four major cuts of the United States Department of Agriculture (USDA) quality grade beef were cooked to five endpoint temperatures using braising, broiling (oven broiling and electric charbroiling), roasting and grilling (indoor and outdoor grilling). Six highly trained panelists identified and defined a total of 38 aroma and flavor characteristics in 176 beef samples. Beef identity, brown/roasted, bloody/serumy, metallic, fat‐like, overall sweet, sour aromatics and five tastes were present in practically all samples. Other attributes were present only in certain samples, depending on either the sample group or the cooking method/endpoint temperature combination used. This lexicon potentially offers the beef industry a standard tool to identify and quantify flavor attributes as impacted by temperature, cooking method, aging process, storage time, diet regime, packaging, USDA quality grades, etc.

PRACTICAL APPLICATIONS

Until now, the beef industry's main focus has been to assess beef tenderness and juiciness, with an emphasis on ways to improve beef texture. Meat companies and academic institutions have been using the 1995 American Meat Science Association guidelines to assess the flavor of beef, which are not comprehensive. Recent work has focused on flavor, and the industry needs a standardized flavor lexicon that can be used for many projects. It is important for the industry to be able to systematically identify and quantify flavor attributes that drive consumer acceptance.     

NUTRITIONAL, PHYSICAL AND SENSORY CHARACTERISTICS OF VARIOUS CHOCOLATE-FLAVORED PEANUT–SOY BEVERAGE FORMULATIONS

Mixture design and pilot‐plant scale processing protocol were developed to obtain the best chocolate‐flavored peanut–soy beverage formulation. Twenty‐eight formulations were evaluated for nutritional (lysine content), physical (viscosity [η], visual stability index [VSI]) and nine sensory (consumer liking) attributes. Lysine contents (mg/g protein) (44.1–57.1) were close to the reference (51.0) and in the desirable range observed for other peanut‐based beverages. Higher viscosity indicated lower consumer liking, but lower viscosity resulted in lower VSI. Formulation ?8 having 43.9% peanut, 36.3% soy protein isolate (SPI) and 19.8% chocolate syrup had the highest consumer liking and the best balance of physical properties (η = 41.5 mPa·s; VSI = 0.99). As compared to commercial chocolate milk (6 = slightly like to 7 = moderately like), it was rated higher for appearance (7.0), color (6.8) and sweetness (6.4). Two SPI formulations (?6 and ?7) and a soy flour formulation (?14) were rated highest for aroma (6.2), color (7.0) and flavor (6.0), respectively.     

SENSORY PROPERTIES AND CONSUMER PERCEPTION OF 'HOME-MADE'AND COMMERCIAL DAIRY ICE CREAM

Sensory properties and consumer perception of 2 'home-made'and 4 commercial dairy ice creams were examined. Conventional profiling by a trained panel found that most samples differed significantly in all attributes, but distinction of 'home-made'from commercial products was limited to few attributes. Principal component analysis separated the 'home-made'products from the commercial ones mainly on the basis of differences in appearance, aroma, creamy flavors and textural attributes. A consumer group (n=105) recorded preconception of 'home-made'ice cream acceptance, then received the product samples, in unlabeled condition, for assessment of degree of liking (DOL) and for identification as 'home-made'or commercial. Internal preference mapping of the DOL ratings showed that consumers were more closely grouped around samples which had higher intensities of certain attributes. Higher 'denseness', 'vanilla'aroma and 'buttery'flavor, were associated with more liking for commercial products. The 'home-made'high fat sample, although liked, tended to be grouped with commercial products. More marked textural attributes of 'ice crystals'and 'breakage'aided identification of the low-fat 'home-made'formulation, which was less liked overall. Overall, differences between the 'home-made'and commercial samples were small but consumer perception of the term 'home-made'was viewed favorably for dairy ice cream.     

Survival of Salmonella in peanut butter and peanut butter spread

In 1996, the first documented outbreak of salmonellosis associated with the consumption of peanut butter was reported. This study was undertaken to determine survival characteristics of high (5.68 log10 cfu g(-1)) and low (1.51 log10 cfu g(-1)) inocula of a five-serotype mixture of Salmonella in five commercial peanut butters and two commercial peanut butter spreads. Populations in samples inoculated with 5.68 log10 cfu g(-1) and stored for 24 weeks at 21 or 5 degrees C decreased 4.14-4.50 log10 cfu g(-1) and 2.86-4.28 log10 cfu g(-1), respectively, depending on the formulation. The order of retention of viability was: peanut butter spreads > traditional (regular) and reduced sugar, low-sodium peanut butters > natural peanut butter. Differences in rates of inactivation are attributed to variation in product composition as well as size and stability of water droplets in the colloidal matrix, which may influence nutrient availability. With the exception of natural peanut butter, products initially inoculated with 1.51 log10 cfu of Salmonella g(-1) (32 cfu g(-1)) were positive for the pathogen after storage for 24 weeks at 5 degrees C. At 21 degrees C, however, with the exception of one peanut butter spread, all products were negative for Salmonella after storage for 24 weeks. Post-process contamination of peanut butter and spreads with Salmonella may to result in survival in these products for the duration of their shelf life at 5 degrees C and possibly 21 degrees C, depending on the formulation.     

EFFECTIVENESS OF CATEGORY AND LINE SCALES TO CHARACTERIZE CONSUMER PERCEPTION OF FRUITY FERMENTED FLAVOR IN PEANUTS

Fruity fermented (FF) flavor is a common off‐flavor in peanuts resulting from high‐temperature curing. The 9‐point hedonic scale is the most widely used scale to determine consumer acceptance; however, research has indicated that line scales may provide equal reliability and greater sensitivity. The objectives of this study were to characterize consumer perception of FF flavor in peanuts and to compare the effectiveness of the two scale types. Consumers (n = 208) evaluated control (no FF), low‐intensity (1.0) FF and high‐intensity (3.0) FF peanut pastes for the strength/intensity of roasted peanut flavor (RPF), sweet taste (ST), fresh peanut flavor (FPF) and overall liking (OV) using randomly assigned ballots. Sensitivity in defining consumer perception of off‐flavor in peanuts was greater with use of line scales than with the hedonic scale. The line scale indicated that FF flavor in peanuts, even at low intensity, negatively impacted OV and further identified significantly lower RPF and FPF perception by consumers. The hedonic scale identified only a difference in FPF and was not sensitive enough to show a difference in OV.