Unión monetaria

For the tetrad test analysis, values of d', and binomial probabilities for sample

differences are provided in Table 3.4. A significant difference was identified between beet and cane sugars when the samples were evaluated by aroma-only and taste and aroma without nose clips. However, samples could not be differentiated when tasted with nose clips. Because nose clips are intended to stop volatiles from entering the olfactory receptors in order to isolate taste perception, the data suggest that beet and cane sugars cannot be differentiated by their taste only. Differences between beet and cane sugars that were evaluated by tasting samples without nose clips can be attributed to retronasal aroma differences.

The descriptive analysis study was carried out to characterize the nature of the observed difference found in the tetrad test. In the descriptive analysis study, ten terms, including off-dairy aroma, oxidized aroma, earthy aroma, barnyard aroma, vanilla aroma, fruity aroma-by-mouth, burnt sugar aroma-by-mouth, sweet taste, sweet aftertaste, and burnt sugar aftertaste, were generated by panelists to describe the sample set. The attribute definitions and reference intensity ratings for each attribute given by the panelists are shown in Table 3.3.

The reference intensities are an average of each panelist’s ratings.

Analysis of variance (ANOVA) was conducted for each of the ten sensory attributes generated by the descriptive analysis panel and the results are summarized in Table 3.5. Judges scores were significantly different (p < 0.05) for eight of the ten attributes. This source of variation is common in descriptive analysis testing and may be due to panelists differing in their use of the scale when rating samples. All of the ten attributes were found to be significantly different (p < 0.05) across the sugar samples. Judge-by-sample interaction (J*S) was significant (p < 0.05) for eight of the attributes, which is telling of inconsistency among the panelists. To account for the variation due to panelists across the samples, adjusted F-values were calculated

60 for attributes whose interaction was significant. Of the eight calculated adjusted F-values, six were noted as being significantly different, including off-dairy aroma, oxidized aroma, earthy aroma, barnyard aroma, fruity aroma-by-mouth, and burnt sugar aftertaste. The adjusted F-values are shown in Table 3.5.

Mean separation analysis by LSD was conducted and the attribute means for each sugar sample are given in Table 3.6. Mean attribute scores for C&H and United Sugar Corporation cane sugars were significantly different for two of the eight attributes: barnyard aroma and fruity aroma-by-mouth. Pioneer and United Sugar Corporation beet sugars were significantly different for the attributes of off-dairy aroma, oxidized aroma, barnyard aroma, and burnt sugar aroma-by-mouth. When comparing beet sugar versus cane sugar sources, significant differences existed between at least one beet and cane sample for all eight attributes. The findings provided evidence that there is more variation between sugar sources than between brands of like sugar sources.

The data generated by ANOVA were used to perform cluster analysis. The resulting dendrogram is presented in Figure 3.2. Pioneer and United Sugar Corporation beet sugar samples formed one cluster, while United Sugar Corporation cane sugar and C&H formed a second cluster. The distance between the beet and cane sugar clusters was much greater than the difference between the clusters of brands of like sugar sources. Again, these findings confirm those from the tetrad test and agree with previous findings, which identified a sensory difference in beet and cane sugar sources, particularly in their odor (Monte and Maga 1982).

Pearson correlation coefficients are shown in Table 3.7. Significant positive correlations were observed for off-aroma attributes, including off-dairy aroma, oxidized aroma, and earthy aroma, and between barnyard aroma and earthy aroma. Positive correlations were also observed between burnt sugar aroma-by-mouth and burnt sugar aftertaste. Oxidized aroma and sweet aftertaste were significantly correlated in the negative direction.

PCA plots (Figure 3.3) were constructed from the sensory ratings generated for each sugar type across all attributes. The PCA plots captured 96.57% of the total variation with 85.95% of the variance explained by factor 1. Factor 2 accounted for the remaining 10.62% of the total variance. Two clusters were formed opposite of one another on each of the plots. On

61 the top plot, the cluster on the left is made up of the cane sugar samples and the cluster on the right is made up of the beet sugar samples. On the bottom plot, the cluster on the left includes sweet aftertaste and fruity aroma-by-mouth, while the cluster on the right is defined by off-aromas. Beet sugar samples are in close proximity to the off-aroma cluster on the plot, which includes off-dairy, oxidized, earthy, and barnyard aromas. Cane sugar samples were strongly associated with the sweet and fruity cluster on the PCA plot.

Data from the tetrad test suggested that beet and cane sugar sources can be

differentiated by aroma but not by taste only. This is in agreement with the descriptive analysis results, which found no significant differences in taste attributes between the sugars. Hence, the differences between beet and cane sugar sources reside in their aroma characteristics, which, as suggested by the literature, can be attributed to their volatile profiles. Analytical flavor chemistry techniques have been previously used to identify the compounds responsible for the characteristic off-aromas in beet sugar. Geosmin (trans-1,10-dimethyl-trans-(9)-decalol), in combination with volatile fatty acids, including butanoic acid isovaleric acids (3-methyl-butanoic acid) were found to have an odor identical to the off-aroma perceived in beet sugar (Marsili and others 1994; Godshall and others 1995; Moore and others 2004). These

compounds emit an earthy, musty aroma, which is perceivable in beet sugar. The terms generated in the descriptive analysis study herein are in agreement with the analytically-determined flavor attributes reported in the literature to characterize beet sugar aroma.

Off-aromas in beet sugar originate from soil microorganisms, the beet itself, and from the degradation of the tops, leaves, or root of the beet (Marsili and others 1994; Godshall and others 1995; Clarke and others 1995; Lu and others 2003). Crystal growth takes place in a supersaturated solution. Once the crystal reaches the desired size, the syrup is separated from the crystals by centrifugation. Though most of the syrup is removed, a thin layer always

remains. Most of the volatiles present in beet sugar reside in this thin outer layer of

concentrated syrup surrounding the crystal (Clarke and others 1995; Godshall and others 1995;

Colonna and others 1996).

Little published work is available on the elimination of off-aromas in beet sugar. Air circulation and ventilation of sugar during storage resulted in partial elimination of the

off-62 odors in beet sugar (Clarke and others 1995; Colonna and others 1996; Duffaut and others 2004). Treatment suggestions, such as additional washing in the centrifuge, have also been proposed to aid in off-aroma removal (Clarke and others 1995; Colonna and others 1996;

Duffaut and others 2004).