Extracts of polyphenols were obtained from black chokeberry, green tea, and walnut using acetone-water and ethanol-water system (8:2, v/v). The extracts were subjected to sensory evaluation using the method of sensory scaling and quantitative descriptive analysis (QDA). In sensory scaling a trained panel rated the samples for astringency which was expressed as Sensation of Astringency Coefficients (SAC). The QDA was applied for quantitative and qualitative characteristics of the extracts. To determine the content of tannins three spectrophotometric methods were used (n- butanol- HCl hydrolysis, BSA precipitation assay and PVP binding assay). The results proved that both the source of tannins and the type of solvent used for extraction had significant effects on the astringency and sensory profiles of the extracts. The analysis of multiple regression demonstrated that astringency of the extracts examined was affected to the greatest extent by tannins determined with the method of their binding on polyvinylpyrrolidone (PVP) sorbent.
The objective of the study was to compare parallel immunoreactive properties and sensory characteristics of lentil (Lens culinaris) and mung bean (Vigma radiata L.) sprouts. The seeds were germinated with and without light at 20°C up to 3 days. The changes in immunoreactivity of the sprouts were determined by competitive ELISA method using rabbit polyclonal antisera to lentil and mung bean proteins. The sensory quality of samples was evaluated by quantitative descriptive analysis (QDA). In QDA a trained panel (n=9) rated the sprouts for odour, taste and texture. The results indicated that the effects of germination on the immunoreactive properties of sprouts with cotyledons depended on the type of legumes. The presence or absence of light during the germination process did not affect the results achieved. The removal of the cotyledons almost completely reduced immunoreactivity of samples (97% for lentil and 99% for mung bean). The effects of germination on the sensory profile of sprouts were found to depend on the type of legumes but as far as the sprouts of mung bean are concerned also on the processing conditions. The QDA demonstrated significant differences between the sprouts for the following attributes: bitterness (p<0.001), “pea-pod” taste (p<0.01), flourness (p<0.001) and juiciness (p<0.01).
Extracts obtained from seeds of hazelnut, walnut, almonds, vetch, buckwheat and buckwheat grits were examined for their sensory astringency, contents of polyphenolic compounds and total antioxidant activity. The sensory astringency of this material was evaluated using the method of sensory scaling and expressed as Sensation of Astringency Indices (SAI). The contents of polyphenolic compounds and their total antioxidant activity were determined by spectrophotometric methods. The HPLC analysis was performed for phenolic acids evaluated in the extracts. The statistical analysis of the results indicated a statistically significant correlation between SAI and tannins, assayed by protein precipitation capacity, as well as SAI and total antioxidant activity. The HPLC analysis of the extracts demonstrated the presence of phenolic acids such as coffeic, p-coumaric, ferulic and sinapic.
Seeds of mung bean (Vigma radiata L.) were germinated for 7 days in dark, and the sensory quality of their sprouts was compared using a descriptive sensory analysis and consumer testing. In the descriptive analysis a trained panel (n=9) rated the sprouts for appearance, odour, taste and texture. In the affective tests the panelists rated the sprouts for overall quality. Changes in the contents of total phenolics and tannins were monitored for 7 days of germination using spectrophotometric methods. The results proved that the time of germination had a significant effect on the sensory profiles of the samples. All analysed attributes differentiated statistically significantly the sensory profiles of the sprouts. The overall sensory quality of 3-day-old sprouts was essentially better than that of the other samples. A statistically significant correlation was found between the total phenolics and the overall quality (p=0.05), the total phenolics and bitterness (p=0.01), the total phenolic and astringency (p=0.05), proanthocyanidins and bitterness (p=0.01), astringency and the overall quality (p=0.05), as well as bitterness and the overall quality (p=0.05).
Buckwheat flour was studied as an ingredient of commercial gluten-free formulation NISKOBIAŁKOWA. The effect of exchange of formulation mass by buckwheat flour (BF) in 10, 20, 30, 40 and 50% was analysed and experimental products were subjected to sensory evaluation. Higher contents of nutrients, proteins and elements were determined in gluten-free bread with buckwheat flour. Also, the increase of resistant starch content was noticed. The sensory evaluation was carried out with the method of sensory profiling (QDA) and in hedonic tests. In QDA a panel (n=8) rated the breads for colour, odour, taste and texture. In the affective tests the consumers (n=30) evaluated the samples for overall quality. The results proved that the overall quality of bread with BF was significantly higher than that of pure formula (control). The average overall quality of scores for BF bread ranged from 4.9 units (50% BF) to 5.8 units (30% BF), whereas 3.4 units for the control. The QDA demonstrated significant differences (p<0.05) between the breads for the following attributes: colour, rancid odour, “rancid” taste, buckwheat odour and “buckwheat” taste, bitter taste, aftertaste and moistness. The principal component analysis (PCA) indicated that the first (PC1) and the second (PC2) component together explained 97.15% of the variation of sensory quality of the experimental gluten-free bread.
The influence of food gums (guar, xanthan, arabic) and carboxymethylcellulose (CMC) on bitterness and astringency of caffeine and tannic acid has been studied. The study was performed in critical concentrations (c*) for particular hydrocolloids as well as for values above and below c*. The ability of hydrocolloids to reduce the astringency and bitterness was evaluated using the method of taste indicator and expressed as a percentage of unreduced sensation. The results indicated that the ability of hydrocolloids to mask the astringency and bitterness was differential and depended both on the concentration and the type of the hydrocolloids used. CMC indicated the highest ability to mask bitterness and astringency among the hydrocolloids. It was found that the ability of these polymers to reduce the astringency was increasing above the c* concentrations.