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.     

A LINGUISTIC METHOD FOR SENSORY ASSESSMENT

A linguistic format for sensory assessment of foods as well as computational methods to analyze taste panel opinions have been developed within the framework of fuzzy set theory. The methodology is demonstrated via sensory analysis of roasted peanuts. Sensory analysis was represented as linguistic values and associated truth values for attributes such as roast flavor, bitterness and overall quality. This format allowed panelists to describe and discriminate different roast characteristics. Replicate analyses of the same sample were reasonably consistent. The linguistic information was simple yet rich in meaning and could be used to make inferences for quality and process control. Yager's ordered weighted median aggregation operator was used to estimate the expected linguistic values for aroma, flavor, bitterness, sweetness, color and overall quality.     

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.     

IMPACT OF MICROWAVE BLANCHING ON THE FLAVOR OF ROASTED PEANUTS

Microwave blanching of peanuts was proposed as an attractive alternative to traditional techniques of blanching, because of energy and time savings. However, the occurrence of a processing‐related off‐flavor has been reported. This study examined the effect of processing factors during microwave blanching on the MC and sensory characteristics of the peanuts. The peanuts reached a range of internal temperatures during microwave blanching treatments between 4 and 11 min. A total offnote attribute was introduced to the peanut lexicon and was used successfully to differentiate the effects of microwave treatments. The microwave‐associated off‐flavor was related (but not identical) to cardboardy/stale flavor, and was related inversely to the positive flavor attributes roasted peanutty, sweet aromatic and sweet taste. Peanuts reaching the highest internal temperatures and greatest moisture losses during blanching exhibited the most total offnote flavor; however, temperatures as high as 113C did not produce significantly increased total offnote intensity.     

The effects of water absorption and roasting conditions on fracture properties and internal structure of sesame seeds

We investigated the effects of soaking, residence time before roasting and roasting conditions on the fracture properties and structure of the cross-section of sesame seeds. Soaking time affected only the size of the side voids of the seed cross-section. The fracture force and strain of the roasted seeds decreased as residence time increased. The center void of the roasted seeds, important for seed crispness increased as residence time increased. In contrast, the side void of the roasted seeds only increased with residence time during the first 10 min. Seeds roasted at higher temperatures had smaller fracture forces and larger central voids than those roasted at lower temperatures. During roasting at 300 °C, the fracture force and strain decreased as the center void ratio increased. Overall, both a sufficient time for moisture diffusion in the seeds and a high roasting temperature were necessary to produce crisp roasted seeds.     

Combined changes of process conditions improved aromatic properties of Vietnamese Robusta

The flavor and taste of coffee are affected by roasting conditions and extraction temperature. This study assessed changes in the flavors and tastes of coffee extracted from Vietnamese Robusta with different roasting times and temperatures, as well as different extraction temperatures. Vietnamese Robusta green beans were roasted for different times ranging from 5 to 20 min and at different temperatures ranging from 100 to 250°C. The roasted coffee was then extracted at five different temperatures ranging from 90 to 120°C. The coffee flavor was evaluated in terms of 5 key odorants: guaiacol; 4-ethylguaiacol; 2-ethyl-3,5-dimethylpyrazine; 2,3-diethyl-5-methylpyrazine, and 2-furfuryl. The taste of coffee was evaluated in terms of 6 main compounds that confer bitterness and sourness: caffeine, trigonelline, chlorogenic acid and citric acid, acetic acid, formic acid. The optimized roasting and extracting conditions were identified that 200 g of VN Robusta green beans, roasting at 230°C for 18 min, and then extracted with Espresso Machine at 110°C.     

Studies on the volatile compounds of roasted spotted shrimp

The aroma of spotted shrimp (Sergia lucence Hansen) was analyzed upon roasting to determine the components that constitute the characteristic roasted shrimp flavor. Our analyses resulted in the identification of ca. 200 volatiles, including high-impact sulfur and nitrogen compounds. In addition, we synthesized all possible stereoisomers of the pyrrolidine derivatives 1 and 4, and of the imine derivatives 16 and 18-20, which are very characteristic for the aroma. The odor evaluation of these chemicals revealed distinct differences, each possessing different aroma characteristics.     

Effects of different processing methods of flaxseed on ruminal degradability and in vitro post-ruminal nutrient disappearance

The aim of the study was to determine the effects of different heat-processing methods of flaxseed on the in situ effective dry matter degradability (EDMD) and the in situ effective crude protein degradability (ECPD). The treatments included roasting, steep roasting, rolled roasting, rolled steep roasting, microwave irradiation and extrusion. Three rumen-fistulated sheep were used for in situ incubations. Furthermore, the effects of heat-processing methods on post-ruminal in vitro nutrient disappearance and total tract disappearance were measured by a three-step in vitro technique. The seeds were roasted and extruded at 140°C to 145°C. One lot of roasted seeds was gradually cooled for about 1 h (roasting) and another lot was held in temperature isolated barrels for 45 min (steep roasting). Moreover, roasted and steep roasted flaxseed was rolled in a roller mill. The lowest and highest EDMD was observed for unheated and extruded flaxseed, respectively (p < 0.05). The highest ECPD was observed for extruded flaxseed (p < 0.05). Roasting and microwave irradiation reduced ECPD of flaxseed (p < 0.05). In vitro post-ruminal disappearance of crude nutrients including fibre fractions was highest for rolled-roasted and rolled steep-roasted flaxseed (p < 0.05). The lowest and highest total tract disappearance rates of crude nutrients and fibre fractions were estimated for unheated and extruded flaxseed, respectively (p < 0.05). The post-ruminal disappearance of crude nutrients was also increased by roasting, in which rolling enhanced this effect. In conclusion, all investigated heat treatments had significant effects on in situ and in vitro degradability of nutrients. As well, rolling of roasted flaxseed enhanced the respective effects. Therefore, different methods of heat processing can be used to modify the feed value of flaxseed for specific purposes.     

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.     

Effect of roasting on degradation and structural features of polysaccharides in Arabica coffee beans

The degree and nature of polysaccharide degradation at different roasting levels was determined for three Arabica (Coffea arabica) bean varieties. Between 12 and 40% of the bean polysaccharides were degraded depending on the roasting conditions. The thermal stability of the arabinogalactans, (galacto)mannans and cellulose was markedly different. The arabinogalactans and mannans were degraded up to 60 and 36%, respectively, after a dark roast, while cellulose showed negligible evidence of degradation. Roasting led to increased solubility of both the arabinogalactans and (galacto)mannans from the bean but the structural modifications, which accompanied this change in solubility, were different for each polysaccharide. Despite the moderate degradation of the (galacto)mannans, those remaining in the bean after roasting showed no evidence of change to their molecular weight even after a dark roast. In contrast, arabinogalactans were depolymerised after a light roast both by fission of the galactan backbone and loss of arabinose from the sidechains. The recently discovered covalent link between the coffee bean arabinogalactans and protein survived roasting. The glucuronic acid component of the AG was degraded markedly after a dark roast, but approximately 30% of the original content remained as part of the AG polymer. The results show that polysaccharide degradation during roasting is more marked than previously documented, and points to roasting induced changes to the polysaccharides as major factors in the changing physicochemical profile of the coffee bean during processing.     

Studies on the Flavors of Roast Barley (Mugi-cha)

Seven weakly acidic compounds were newly detected as flavor components of roast barley by using column and gas-liquid chromatographies. These compounds were characterized and identified by MS, IR, UV and NMR spectroscopies and the mixed melting point test.

These are 5-hydroxymaltol, maltol, 5-methylcyclopent-2-en-2-ol-1-one, phenol, m-cresol, pyrocatechol, resorcinol and an unidentified compound (MW 128). Maltol, 5-methylcyclopent-2-en-2-ol-1-one and 5-hydroxymaltol have so-called “sugary flavor,” and these compounds appear to concern with the sweet fragrant flavor of roast barley together with vanillin previously identified.

Phenol, m-cresol, pyrocatechol and resorcinol which have a strong characteristic odor are supposed to concern with the smoky flavor of roast barley.     

SENSORY OPTIMIZATION OF PROCESS VARIABLES FOR PREPARING ROASTED GRAIN POWDERS

The quality of roasted grain powders is greatly affected bythe roasting process variables; viz., initial moisture content (IMC), grain-to-sand ratio (GSR), sand temperature (ST) and roasting time (RT). The sensory optimization for these variables was done in two phases. The IMC (12 ± 0.2%) and GSR (1:4) were standardized in the first phase, whereas ST (215C) and RT (1.5–2.0 min), in the second. The overall quality of the roasted grain powders was found to be greatly affected by ST followed by RT.     

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.     

Studies on Flavor Components of Roasted Barley

From the volatiles of roasted barley or those formed during roasting of barley, furfural, 2-methylbutanal, 2-methylpropanal, 3-methylbutanal, 2,3-pentanedione, ethylglyoxal and pyruvaldehyde were isolated and identified as their mono- or bis-2,4-dinitrophenylhydrazones.

Removal of the carbonyl compounds from the volatiles resulted in a loss of the characteristic aroma of roasted barley.     

Effect of roasting on ochratoxin A level in green coffee beans inoculated with Aspergillus ochraceus

The heat stability of ochratoxin A in green coffee beans inoculated with Aspergillus ochraceus was studied. Heat treatment (roasting) at 200 °C for 10 or 20 min reduced the levels of ochratoxin A by only 0–12% in the dried whole beans. Almost all of the ochratoxin A was infused into the coffee decoction when the roasted samples were ground and extracted with boiling water. Therefore, the reduction of ochratoxin A concentration of contaminated coffee beans by roasting under these conditions is ineffective.     

The effect of roasting on the fate of aflatoxin B1 in artificially contaminated green coffee beans

A study was undertaken to evaluate aflatoxin B₁ contamination in coffee beans. 41 samples of green coffee were collected from large lots of material by representative sampling. The raw samples were analyzed and showed no detectable levels of aflatoxin B₁. In order to establish the heat stability of the toxin, 3 artificially contaminated samples (average level 10/μg/kg) were roasted atca 200°C for different operation times periods so as to reproduce light and dark roasting procedures. Each sample was roasted both electrically and by gas. The percentage of toxin destruction was up to 93% for light roasted and 99% for dark roasted coffee with a slightly higher rate up to 100% for the electrically roasted coffee for light and dark roasting. In order to evaluate the potential migration of the aflatoxin B₁ into the coffee beverage, 1 sample found contaminated after roasting treatment (0.8/°g/kg) was extracted using each of the 3 most common types of coffee makers. Additional destruction of the toxin was observed (up to 99%) in two cases while only 75% of fate was obtained in the third. The process from raw coffee beans to beverage showed a meaningful destruction of aflatoxin B₁, ranging from 97 to 100% depending on the extraction technique adopted in the preparation of the beverages.