SELECTION OF AN ASTRINGENCY REFERENCE STANDARD FOR THE SENSORY EVALUATION OF BLACK TEA

Astringent and bitter sensations are characteristic sensory qualities of black tea. Three different classes of potential astringent reference standards (two concentrations each of alum and tannic acid and three fruit juices) were evaluated in this study. The perceived astringency, bitterness and sourness of each were profiled using computerized time-intensity and compared with the astringent intensity of a standardized brew of black tea. The differences in temporal profiles of potential reference standards across taste attributes were evident and intensity ratings were found to be dependent upon the stimulus and its concentration. Both concentrations of tannic acid were evaluated as the highest in perceived bitterness. For the juices, a strong sour taste was perceived in addition to astringency. It was concluded that the best reference standard for the astringency of black tea is a solution of 0.7 g/L alum as it is low in perceived bitterness and sourness.     

Flavoring and extending the shelf life of cucumber juice with aroma compounds-rich herbal extracts at 4 °C through controlling chemical and microbial fluctuations

This work aims to enhance the flavor of functional cucumber juice using herbal extracts of peppermint, basil, lavender, and lemongrass ethanolic extracts and extend its lifetime by controlling the chemical and microbial fluctuations. Cucumber juices were processed as; non-supplemented (J-Con), J-PME, J-BE, J-LE, and J-LEE supplemented with peppermint, basil, lavender, and lemongrass ethanolic extracts, respectively. Peppermint extract was significantly scavenged 88% of DPPH radicals and inhibited the growth of tested gram-positive, gram-negative bacteria and fungi followed by the lemongrass extract. The antioxidant activity of cucumber juices increased due to polyphenols and aroma compounds in the added extracts. However, the antioxidant content was decreased after two months of storage at 4 °C, due to the decrease in polyphenols. The flavor compounds were determined using GC mass, wherein hydrocarbons, acids, alcohols, and carbonyl compounds were the main aroma contents in cucumber juices, and their contents decreased with storage time. Peppermint and lemongrass extracts were significantly (p ≤ 0.05) increased the whiteness of J-PME, and J-LEE, respectively. The highest score of flavor and taste was observed in J-PME that scored 8.3 based on panelists' reports followed by J-LEE. The PME was significantly maintained 91% of the odor and color of J-PME as compared to other juices.     

Flavoring and extending the shelf life of cucumber juice with aroma compounds-rich herbal extracts at 4 °C through controlling chemical and microbial fluctuations

This work aims to enhance the flavor of functional cucumber juice using herbal extracts of peppermint, basil, lavender, and lemongrass ethanolic extracts and extend its lifetime by controlling the chemical and microbial fluctuations. Cucumber juices were processed as; non-supplemented (J-Con), J-PME, J-BE, J-LE, and J-LEE supplemented with peppermint, basil, lavender, and lemongrass ethanolic extracts, respectively. Peppermint extract was significantly scavenged 88% of DPPH radicals and inhibited the growth of tested gram-positive, gram-negative bacteria and fungi followed by the lemongrass extract. The antioxidant activity of cucumber juices increased due to polyphenols and aroma compounds in the added extracts. However, the antioxidant content was decreased after two months of storage at 4 °C, due to the decrease in polyphenols. The flavor compounds were determined using GC mass, wherein hydrocarbons, acids, alcohols, and carbonyl compounds were the main aroma contents in cucumber juices, and their contents decreased with storage time. Peppermint and lemongrass extracts were significantly (p ≤ 0.05) increased the whiteness of J-PME, and J-LEE, respectively. The highest score of flavor and taste was observed in J-PME that scored 8.3 based on panelists'' reports followed by J-LEE. The PME was significantly maintained 91% of the odor and color of J-PME as compared to other juices.     

Effects of the long-term anosmia combined with vision deprivation on the taste sensitivity and feeding behavior of the rainbow trout <Emphasis Type="Italic">Parasalmo</Emphasis> (=<Emphasis Type="Italic">Oncorhynchus</Emphasis>) <Emphasis Type="Italic">mykiss</Emphasis>

We compared taste preferences, taste sensitivity, and behavior in testing food objects in the group of intact and two groups of sensory deprived rainbow trout Oncorhynchus mykiss yearlings. We demonstrated that long-term anosmia (for 9 months), as well as anosmia (for 9 months) combined with enucleation (object vision deprivation for 4 months), does not change the taste preference of fish for the agar pellets containing amino acids (L-alanine, L-proline, L-histidine, or glycine; 0.1 M). For all groups of fish, the threshold L-alanine concentration in pellets that caused a significant increase in consumption is 0.01 M. We showed that sensory deprived fish change their behavior of gustatory testing, namely, the rate of repeated snaps decreases as well as the pellet retention time in the mouth cavity. These results demonstrate that long-term anosmia combined with a partial vision deprivation does not significantly change the taste preferences and sensitivity in the fish that have no external taste buds. However, the observed reduction in the testing time of food objects and other changes in fish feeding behavior may suggest some functional alterations in the intraoral sensory systems (gustatory and/or tactile).     

TASTE ACUITY IN THE ELDERLY: THE IMPACT OF THRESHOLD, AGE, GENDER, MEDICATION, HEALTH AND DENTAL PROBLEMS

This study was designed to assess taste threshold and investigate the effect of age, dental problems, health disorders/diseases and multiple medications on the distortion of taste and to determine if the loss of taste increases with age. One hundred seven elderly from rural congregate feeding sites and senior centers in Northern Alabama volunteered to participate in this study. Water solutions of varying concentrations for sweet, salty, sour, and bitter were prepared to determine recognition thresholds and test the effect of other factors on the ability to taste. A questionnaire was administered to each elderly volunteer to assess overall health. Results indicated that there was no significant age difference for the basic taste sensations, except for sweetness. Gender, dental problems, health disorders, diseases and multiple uses of medications did not significantly affect taste threshold. The basic was a decrease in taste threshold independent of any extraneous factors.     

Phytochemical composition and in vitro biological activities of Morinda citrifolia fruit juice

Morinda citrifolia is a plant with broad nutraceutical and therapeutic effects and used in the traditional treatment of several ailments. The objective of this work is to investigate the phytochemistry of the fruit juice of M. citrifolia on one hand and on other hand to evaluate its antiradical and antibacterial activity. The phytochemical investigation was carried out by tube staining tests of the extract of two types of fruit juice of M. citrifolia. The antioxidant activity of these juices was evaluated by reducing the DPPH radical method. Concerning the antibacterial activity, it was tested on the in vitro growth of 10 reference bacterial strains using the well diffusion method. Qualitative phytochemistry of M. citrifolia fruit juices revealed the presence of large groups of secondary metabolites including polyphenols, reducing compounds, mucilage and terpernoids. The antioxidant activity of M. citrifolia fruit juices is dose-dependent and higher than that of ascorbic acid. Antimicrobial activity on other hand revealed that fruit juices inhibit growth inhibitory activity of Staphylococcus aureus, Pseudomonas aeruginosa, Proteus mirabilis, S. epidermidis, Proteus vulgaris, Streptococcus oralis, Enterococcus faecalis and Escherichia coli. This observed difference is significant for each juices on the strains (p < 0.001). These results support the use of M. citrifolia in traditional medicine and are the starting points for the development of a new drug to combat both dietary conditions and chronic conditions associated with oxidative stress.     

Fermentation rates of grape juice: v. Biotin content of juice and its effect on alcoholic fermentation rate

Microbiological analysis showed that juices from white grapes had less biotin than juices from red grapes. The biotin content of the juices of some varieties was significantly different from that of other varieties. We did not note any regional effects on the biotin content of the juices. Biotin content of the Cabernet Sauvignon grapes increased significantly with maturity, whereas the biotin content of a white variety did not. The biotin content, with the total nitrogen, can be used to estimate indirectly the yeast growth potential and hence to predict the fermentation rate of the juice. About 84% of the rate variation can be accounted for by the calculated regression equations.     

Taste and Smell Perception in Aging1

The taste and smell experience of other human beings cannot be known directly. Thus our understanding of age-related changes in the perception of taste and smell is derived inferentially. Inferences based on verbal reports and on the performance of tasks involving taste and smell stimuli suggest that some older individuals are impaired. The perceptual disadvantage of older adults appears to be more marked or more easily measured for complex than for simple stimuli. Some difference between older and younger adults may not be primarily sensory; others may arise from differences only incidentally associated with aging. The study of taste and smell perception in aging continues to challenge the psychophysical investigator to define the nature and extent of age-related change and to demonstrate its underlying mechanisms.     

Components Contributing to the Improvement of Meat Taste during Storage

The changes in both taste and taste components of beef, pork, and chicken during storage were examined.

The brothy taste intensity of pork and chicken was significantly stronger after conditioning than before. On the other hand, for beef, there was no significant difference in the brothy taste intensity before or after conditioning. The analysis of major taste components showed that the levels of free amino acids in all meats were higher after conditioning than before. The differences in the levels of free amino acids before versus after conditioning were large in pork and chicken and very small in beef. Oligopeptide levels were lower in beef after conditioning than before, but they were higher in pork and chicken after conditioning than before. These results corresponded to results of the sensory evaluation studies described above, indicating that free amino acids and oligopeptides contributed to the improvement of meat taste during storage.     

INTERACTION OF ASTRINGENCY AND TASTE CHARACTERISTICS1

The perception of astringency and basic taste in mixtures and their interaction effects were investigated by two procedures. In Experiment 1, focused and nonfocused testing procedures were compared using mixtures of low and high concentrations of alum and basic taste solutions. Both procedures yielded taste and astringency intensities that were modality‐dependent. Nonfocused testing was used in Experiment 2 to investigate the interactions of astringent phenolic (tannic acid) and nonphenolic (alum) compounds with each basic taste. Sweetness of sucrose increased with increased concentration with or without alum or tannin present. Changes in salty, bitter, and sour taste intensities were modality‐dependent. Astringency either remained unchanged or decreased with the addition of sucrose, sodium chloride, citric acid, or caffeine depending upon the taste concentration. Bitterness of tannin and alum at high concentrations was suppressed by the addition of sucrose, sodium chloride, or citric acid; sourness also decreased in the presence of sucrose or sodium chloride as well as a high level of caffeine.     

Effects of age and sex on taste sensitivity to phenylthiocarbamide (PTC) in the Berkeley Guidance sample

Using a modification of the Harris and Kalmus method for ascertainingthe taste threshold for phenylthiocarbamide (PTC), data werecollected on 424 Caucasian individuals from the three generationallongitudinal study of the Berkeley Guidance subjects in Berkeley,CA. Analysis of the data indicates the distribution of thresholdsis significantly different from that in the London sample ofHarris and Kalmus in that the frequency of nontasters is abouthalf that found in London. The difference is not attributedto the modifications made in the testing procedure but to areal difference in gene frequency. Both the PTC taster and nontasterphenotypes display a large amount of variation in expressionbetween individuals. They are differently expressed in malesand females, the latter being more sensitive. As people age,the expressions of their genotypes change. Neither age nor sexseem to affect the penetrance of the PTC genes which remainsthe same within each sex at all ages unless some other environmentalfactor, such as radiation, impinges. Consideration of theserelationships is necessary for the investigation of family relationships,the mechanisms responsible for maintaining this ancient geneticpolymorphism and the degree of polytypy present in the species.     

Space and time separation of taste mixture components

Under natural conditions, all component qualities of taste mixturesco-exist in space and time on the tongue surface. The significanceof space-time coherence of taste sensations was investigatedby separating mixture components on the tongue. First, it wasshown that a mixture of sucrose plus sodium chloride is judgedto have a qualitatively different sweet taste from a mixtureof sucrose plus quinine sulphate when all taste qualities aretogether in space and time. This occurred even though mixtureswere matched for sweetness intensity, and the saltiness of theformer matched the bitterness of the latter. When, however,mixture components were spatially and temporally separated,the judged quality differences were eliminated. When the componentswere separated in space only, quality difference judgments werereduced in magnitude, but not eliminated. The results are consistentwith the hypothesis that space-time coherence of taste sensationsresult in perceptual blending and a consequent failure of selectiveattention to any single component. It is suggested that tastemixtures can be considered as single tastes even though componentqualities can be reliably identified using other techniques.     

A RESEARCH NOTE: COMPARISON OF TIME-INTENSITY AND THRESHOLD MEASURES FOR DETERMINING BITTER TASTE SENSITIVITY OF CAFFEINE USER AND NONUSER

Two taste sensitivity measures (detection threshold and time-intensity [T/I]) were applied to evaluate bitter taste sensitivity of caffeine in both caffeine nonusers (n = 12) and users (n=12, caffeine consumption level; > 300mg/day). Taste thresholds of caffeine were significantly different between nonusers and users in two test sessions (p < 0.01 in first and p < 0.05 in second). In T/I measures, only the difference in peak height was observed between the two groups in one of two test sessions. The other two measures, half width and area of T/I curves showed no significant difference.     

Taste preferences and feeding behavior of three-spined stickleback Gasterosteus aculeatus of populations of basins of the Atlantic and Pacific oceans

The absence of population specificity of taste spectra in fish was confirmed. It was found that the three-spined stickleback Gasterosteus aculeatus of populations of the North (Norway), Baltic (Latvia), and Okhotsk (Kamchatka Peninsula) seas has similar taste preferences to classical taste substances (sodium chloride, calcium chloride, and sucrose—10%; citric acid—5%) and to 21 free amino acids (L-isomers, 0.1–0.001 M). For fish of all populations, glutamine, glutamic and aspartic acids, and alanine have the most attractive taste; cysteine, asparagine, and histidine have slightly less attractive taste. In Baltic Sea and Sea of Okhotsk sticklebacks, relatively not numerous amino acids that cause a significant decrease in pellet consumption—phenylalanine, tryptophane, leucine, and tyrosine—coincide (in the North Sea stickleback, substances with deterrent taste were not revealed). In sticklebacks of different populations, no differences in manifestation of feeding behavior were found, and correlations between different elements of fish response to pellets are similar or close the same. It was shown that intraoral sensory testing of food objects in three-spined stickleback can proceed along two alternative behavioral stereotypes similar in fish of the studied populations. The dependence of stereotypes of intraoral testing on taste qualities of the food object was revealed for the first time.     

Inactivation of Escherichia coli and Shigella in acidic fruit and vegetable juices by peroxidase systems

AIMS: To study the bactericidal properties of the lactoperoxidase (LPER)-thiocyanate and soybean peroxidase (SBP)-thiocyanate systems at low pH, their efficiency for inactivation of Escherichia coli and Shigella in acidic fruit and vegetable juices, their effect on colour stability of the juices and interaction with ascorbic acid. METHODS AND RESULTS: Three-strain cocktails of E. coli and Shigella spp. in selected juices were supplemented with the LPER or SBP system. Within 24 h at 20 degrees C, the LPER system inactivated both cocktails by > or = 5 log10 units in apple, 2-5 log10 units in orange and < or = 1 log10 unit in tomato juices. In the presence of SBP, browning was significant in apple juice and white grape juice, slight in pink grape juice and absent in orange or tomato juice. Ascorbic acid protected E. coli and Shigella against inactivation by the LPER system, and peroxidase systems significantly reduced the ascorbic acid content of juices. CONCLUSIONS: Our results suggest a different specificity of LPER and SBP for SCN-, phenolic substrates of browning and ascorbic acid in acidic juices. The LPER system appeared a more appropriate candidate than the SBP system for biopreservation of juices. SIGNIFICANCE AND IMPACT OF THE STUDY: This work may open perspectives towards the development of LPER or other peroxidases as biopreservatives in acidic foods.     

Tactile interaction with taste localization: influence of gustatory quality and intensity

Taste is always accompanied by tactile stimulation, but little is known about how touch interacts with taste. One exception is evidence that taste can be "referred" to nearby tactile stimulation. It was recently found (Lim J, and Green BG. 2007. The psychophysical relationship between bitter taste and burning sensation: evidence of qualitative similarity. Chem Senses. 32:31-39) that spatial discrimination of taste was poorer for bitterness than for other tastes when the perceived intensities were matched. We hypothesized that this difference may have been caused by greater referral of bitterness by touch. The present study tested this hypothesis by comparing localization of quinine sulfate and sucrose under conditions that minimized and maximized the opportunity for referral. In both conditions, stimulation was produced by 5 cotton swabs spaced 1 cm apart and arranged in an arc to enable simultaneous contact with the front edge of the tongue. Only one swab contained the taste stimulus, whereas the rest were saturated with deionized water. In both conditions, the swabs were stroked up-and-down against the tongue 5 times. Subjects were asked to identify which swab contained the taste stimulus 1) 5 s after the fifth stroke (touch-removed condition) and 2) immediately at the end of the fifth stroke, with the swabs still in contact with the tongue (touch-maintained condition). Ratings of taste intensity were obtained to assess the possible effect of perceived intensity on spatial localization. Taste localization was surprisingly accurate, especially for sucrose, with errors of localization in the range of 1 cm or less. For both stimuli, localization tended to be poorer when the tactile stimulus was present while subjects made their judgments, but the difference between conditions was significant only for the lower concentration of quinine. The results are discussed in terms of both the surprisingly good spatial acuity of taste and the possibility of having a close perceptual relationship between touch and bitter taste.     

alpha-Amylase from human pancreatic juice as an electrophoretically pure isozyme.

Human pancreatic juice collected antiseptically and strictly free from other body fluids and juices, was examined for the isozyme composition of alpha-amylase. Unlike those of the extract of and exudate from pancreatic tissue, the composition of alpha-amylase isozyme in the secreted juice was simple and consisted of only two isozymes, a major one and a minor one, and the reason for difference in the isozyme composition is discussed. The major alpha-amylase isozyme was obtained in a crystalline state with a molecular weight of 5.4-5.5 X 10(4).