An overview of binary taste-taste interactions

The human gustatory system is capable of identifying five major taste qualities: sweet, sour, bitter, salty and savory (umami), and perhaps several sub-qualities. This is a relatively small number of qualities given the vast number and structural diversity of chemical compounds that elicit taste. When we consume a food, our taste receptor cells are activated by numerous stimuli via several transduction pathways. An important food-related taste question which remains largely unanswered is: How do taste perceptions change when multiple taste stimuli are presented together in a food or beverage rather than when presented alone? The interactions among taste compounds is a large research area that has interested electrophysiologists, psychophysicists, biochemists, and food scientists alike. On a practical level, taste interactions are important in the development and modification of foods, beverages or oral care products. Is there enhancement or suppression of intensity when adding stimuli of the same or different qualities together? Relevant psychophysical literature on taste–taste interactions along with selected psychophysical theory is reviewed. We suggest that the position of the individual taste stimuli on the concentration-intensity psychophysical curve (expansive, linear, or compressive phase of the curve) predicts important interactions when reporting enhancement or suppression of taste mixtures.

Oral zinc sulfate solutions inhibit sweet taste perception

We investigated the ability of zinc sulfate (5, 25, 50 mM) to inhibit the sweetness of 12 chemically diverse sweeteners, which were all intensity matched to 300 mM sucrose [800 mM glucose, 475 mM fructose, 3.25 mM aspartame, 3.5 mM saccharin, 12 mM sodium cyclamate, 14 mM acesulfame-K, 1.04 M sorbitol, 0.629 mM sucralose, 0.375 mM neohesperidin dihydrochalcone (NHDC), 1.5 mM stevioside and 0.0163 mM thaumatin]. Zinc sulfate inhibited the sweetness of most compounds in a concentration dependent manner, peaking with 80% inhibition by 50 mM. Curiously, zinc sulfate never inhibited the sweetness of Na-cyclamate. This suggests that Na-cyclamate may access a sweet taste mechanism that is different from the other sweeteners, which were inhibited uniformly (except thaumatin) at every concentration of zinc sulfate. We hypothesize that this set of compounds either accesses a single receptor or multiple receptors that are inhibited equally by zinc sulfate at each concentration.

The effect of zinc on human taste perception

Zinc salts are added as a nutritional or functional ingredient in food and oral care products. The 1st experiment in this study investigated the taste and somatosensory effect of zinc salts (chloride, iodide, sulfate, bromide, acetate). The zinc salts had very little taste (bitter, salty, savory, sour, sweet), and the taste that was present was easily washed away with water rinses. The major oral quality of zinc was astringency, and the astringency lingered beyond expectoration. The 2nd experiment combined zinc salts with prototypical stimuli eliciting basic tastes. Zinc was a potent inhibitor of sweetness and bitterness (>70% reduction in taste) but did not affect salt, savory, or sour taste.

Taste sensitivity to NaCl is associated with liking of salty foods and BMI

Background – It is widely acknowledged that sodium is consumed in excess in most developed countries. Sodium (Na) consumption has been a target of public health interventions in recent years due to its link to numerous adverse health affects such as hypertension and cardiovascular disease. While much of the current research is directed at strategies to reduce sodium in foods and the diet, little is known about the factors which determine salt consumption and preference. Currently, there is no research relating NaCl taste sensitivity and liking of food, or if NaCl taste sensitivity may manifest in changes in BMI.
Objective – Establish whether a relationship exists between NaCl taste sensitivity, preference for salty foods and BMI.
Design – Taste sensitivity to NaCl was determined for 119 subjects (104 female) according to the procedure laid out by “ISO 3972:1991 – Method of investigating sensitivity of taste”. In a separate session subjects rated their liking of generic biscuit with 2 levels of added NaCl [low (2.9g/100g) & high (19.1g/100g)] using the 9-point hedonic scale. BMI was calculated from self reported height and weight data collected. Spearman’s rank order correlation was used to determine whether an association existed between NaCl taste sensitivity, preference for salty foods and BMI.
Outcomes – A significant positive correlation was found between BMI and NaCl taste sensitivity (r=0.204, p<0.05). In addition there was a significant positive correlation between BMI and liking of low NaCl biscuits (r=0.267, p<0.01). No significant associations were identified between the high NaCl cracker and NaCl taste sensitivity or BMI. A paired t-test showed there was no significant difference in liking of the low and commercial NaCl crackers (p=0.078).
Conclusion – This study revealed that individuals with a higher BMI have a greater liking of low NaCl biscuits, and this may be due to their increased NaCl taste sensitivity. The results suggest that NaCl taste sensitivity may be a factor in foods consumed by an individual which in turn may influence weight status.

The relationship betwen NaCl concentration and taste perception of saltiness in bread

Background – Sodium (Na+ ) is present in food in the form of sodium chloride (NaCl). There is strong evidence that high dietary Na+ intakes increase the risk of developing various adverse health conditions. Many international organisations encourage Na+ reduction in both the diet and the food supply. One of the major dietary sources of NaCl is bread, where NaCl has the essential function of imparting flavour. At present, no literature has been published examining taste interactions that may play a role in limiting the maximum saltiness perception in bread.
Objective – To determine the extent the physical structure of bread inhibits salty taste perception. Additionally, to determine whether common commercial bread additives suppress saltiness of bread.
Design – Subjects (n=14, 12 females) tasted and rated samples with varying NaCl concentrations in water (0 – 1724 mg NaCl/100 g) and bread (125 – 1550 mg NaCl/100 g) using the general Labelled Magnitude Scale. Psychophysical curves plotting NaCl concentration against NaCl intensity were constructed for water and bread. Breads of fixed NaCl concentration (1125 mg NaCl/100 g) and various common additives (sucrose, soya flour, canola oil, gluten) were also rated to assess perceived saltiness.
Outcomes – There was a significant difference between Na+ psychophysical curves in water and bread (P<0.05) with the bread matrix suppressing maximum possible saltiness by 25% to 70%. Suppression of saltiness was observed after the addition of sucrose (55% decrease) or soya flour (60% decrease) during bread production compared to prototypical bread (both P<0.05).
Conclusions – The physical structure of bread and some common additives have a major influence on perceptual saltiness of bread. The removal of additives that suppress saltiness combined with strategies to modify the texture of bread could lead to significant reduction in dietary Na+, whilst maintaining optimal salty taste.

Fruit consumption of boys (8–11 years) is related to preference for sour taste

The present study investigated whether the most preferred balance between sweet and sour taste of children (n=50, 9.2±0.9 yrs of age) are related to their consumption of fruit. Taste preferences were measured with a rank-by-elimination procedure with seven sweet orangeades that differed in added citric acid (i.e. 0.009−0.065 M). Fruit consumption was assessed with a questionnaire that was completed by the children's parents. Results showed that boys' but not girls' most preferred balance between sweet and sour taste was positively correlated with their consumption of fruit: that is, the more added citric acid was preferred the more fruit was consumed. We conclude that preference for high concentrations of citric acid in a sweet context may be associated with the consumption of fruit in boys. In girls, the optimal balance between sweet and sour taste seems to be of less importance; their consumption of fruit may be more influenced by their parents, availability and health related motives.

Sour taste preferences of children relates to preference for novel and intense stimuli

Previous research has suggested that some children have a preference for sour tastes. The origin of this preference remains unclear. We investigated whether preference for sour tastes is related to a difference in rated sour intensity due to physiological properties of saliva, or to an overall preference for intense and new stimuli. Eighty-nine children 7–12 years old carried out a rank-order procedure for preference and category scale for perceived intensity for four gelatins (i.e. 0.0 M, 0.02 M, 0.08 M, 0.25 M added citric acid) and four yellow cards that differed in brightness. In addition, we measured their willingness to try a novel candy and their flow and buffering capacity of their saliva. Fifty-eight percent of the children tested preferred one of the two most sour gelatins. These children had a higher preference for the brightest color (P < 0.05) and were more likely to try the candy with the unknown flavor (P < 0.001) than children who did not prefer the most sour gelatins. Preference for sour taste was not related with differences in rated sour intensity, however those who preferred sour taste had a higher salivary flow (P < 0.05). These findings show that a substantial proportion of young children have a preference for extreme sour taste. This appears to be related to the willingness to try unknown foods and preference for intense visual stimuli. Further research is needed to investigate how these findings can be implemented in the promotion of sour-tasting food such as fruit.

Conditioned taste aversion reduces fox depredation on model eggs on beaches

Context:  Conditioned taste aversion (CTA) is induced by an association of a food item with a negative experience, such as illness, which causes animals to avoid subsequent consumption of that particular food item. Inducing CTA may help reduce depredation rates of threatened fauna where predator population control is undesirable, impractical or unsuccessful.

Aims:  We investigated whether CTA could be induced among foxes (Vulpes vulpes) to model eggs which mimicked those of the threatened hooded plover (Thinornis rubricollis).

Methods:   Model eggs treated with a potential CTA-inducing chemical (sodium carbonate) and control eggs free of the agent were exposed to fox depredation for 28 days to simulate a hooded plover incubation period. To investigate whether CTA would persist in wild foxes, we implemented a part-time agent treatment (an initial 14 day exposure period of model eggs with the CTA agent followed by a second 14 day period when model eggs were free of the agent).

Key results:  Similar intervals to the first depredation event were found for all model eggs regardless of treatment. After the first depredation event by foxes, the rate and likelihood of fox depredation was significantly lower in treated eggs than in control eggs. The likelihood or rate of depredation across the three treatments did not differ between the first and second periods.

Conclusions: Our results suggest that during an exposure period of at least 28 days, CTA can be induced in wild foxes to eggs on beaches. Our results also suggest that 14 days may be insufficient time for wild foxes to develop a lasting CTA to familiar food items such as eggs.

Implications:  Treatment of eggs with a CTA-inducing chemical may present a viable alternative to traditional predator control techniques for hooded plovers, as well as other ground-nesting birds, provided that an extended exposure to the CTAinducing agent occurs.

Fat taste sensitivity

Hyposensitivity to fatty acid taste is associated with greater intake of fat, higher BMI and attenuated gastrointestinal (GI) function. These observations are consistent amongst healthy and overweight/obese subjects, who display attenuated taste and GI function, and consume excess fat.

In the Syrian taste : crusader churches in the Latin East as architectural expressions of orthodoxy

This paper explores how the architectural expression of orthodoxy in the Eastern churches was transferred to Europe before the Crusades and then reinforced through the Crusaders’ adoption of the triple-apsed east end “in the Syrian Taste” in the Holy Land. Previously, I have shown how it can be deduced from the archaeological remains of churches from the 4th-6th C that early church architecture was influenced by the theological ideas of the
period. It is proposed that the Eastern orthodox approach to church
architecture as adopted by the Crusaders paralleled the evolution of medieval theology in Europe and can be seen as its legitimate expression.