Additive Effects of L-Ornithine on Preferences to Basic Taste Solutions in Mice

In addition to the taste receptors corresponding to the six basic taste qualities—sweet, salty, sour, bitter, umami, and fatty—another type of taste receptor, calcium-sensing receptor (CaSR), is found in taste-bud cells. CaSR is called the ‘kokumi’ receptor because its agonists increase sweet, salty and umami tastes to induce ‘koku’, a Japanese word meaning the enhancement of flavor characters such as thickness, mouthfulness, and continuity. Koku is an important factor for enhancing food palatability. However, it is not well known whether other kokumi-receptors and substances exist. Here, we show that ornithine (L-ornithine but not D-ornithine) at low concentrations that do not elicit a taste of its own, enhances preferences to sweet, salty, umami, and fat taste solutions in mice. Increased preference to monosodium glutamate (MSG) was the most dominant effect. Antagonists of G-protein-coupled receptor family C group 6 subtype A (GPRC6A) abolished the additive effect of ornithine on MSG solutions. The additive effects of ornithine on taste stimuli are thought to occur in the oral cavity, and are not considered post-oral events because ornithine’s effects were confirmed in a brief-exposure test. Moreover, the additive effects of ornithine and the action of the antagonist were verified in electrophysiological taste nerve responses. Immunohistochemical analysis implied that GPRC6A was expressed in subsets of type II and type III taste cells of mouse circumvallate papillae. These results are in good agreement with those reported for taste modulation involving CaSR and its agonists. The present study suggests that ornithine is a kokumi substance and GPRC6A is a newly identified kokumi receptor.

Does Responsiveness to Basic Tastes Influence Preadolescents’ Food Liking? Investigating Taste Responsiveness Segment on Bitter-Sour-Sweet and Salty-Umami Model Food Samples

The objective of this study was to investigate the relationships between taste responsiveness and food liking in preadolescents. Model food samples of grapefruit juice (GF) and vegetable broth (VB) modified with four additions of sucrose and sodium chloride, respectively, were employed. Intensity perception for sweetness, sourness, and bitterness were measured in GF while saltiness and umami were measured in VB. The children (N = 148) also completed food choice, familiarity, stated liking and neophobia questionnaires. The test was conducted at school, with instructions provided remotely via video call. Four segments were defined differing in basic taste responsiveness. Segments and sucrose concentrations significantly affected liking for GF, while no significant effect of segments and sodium chloride concentrations occurred on liking for VB. An increasing sucrose concentration was positively associated with liking for GF only in the segment with low responsiveness to bitter and sour tastes. No significant differences across segments were found for food choice, familiarity, stated liking, and neophobia. Conclusively, relationships between taste responsiveness and liking are product and basic taste-dependent in addition to being subject-dependent. Strategies to improve acceptance by using sucrose as a suppressor for warning sensations of bitterness and sourness can be more or less effective depending on individual responsiveness to the basic tastes.

Sweet and bitter near-threshold solutions activate cross-modal correspondence between taste and shapes of cups

Recent studies have pointed out some cross-modal correspondences between flavoured beverages, as well as basic taste solutions, and specific geometric visual cues. Some of them associate known drink tastes to shapes of receptacles. In particular, sweetness is associated with curved receptacles and bitterness with sharp-angled ones. Our study aimed to test the hypothesis according to which near-threshold solutions might also activate this cross-modal correspondence. We used two different cup forms, one curved and the other sharp-angled, with pure sweet and bitter solutions just above sensorial thresholds. We designed two tasks using a two-alternative forced-choice test. Participants had to decide which drink was sweeter, Task 1, and bitterer, Task 2, from the curved and sharp-angled cups. Results showed the cross-modal correspondence but only when participants drank first from the curved cup and second from the sharp-angled cup. The effect disappeared when participants drank first from the sharp-angled cup and second from the curved cup. This suggests that the correspondence emerges using sweet and bitter near-threshold solutions in specific conditions. On the other hand, results also showed that confidence level of responses was significantly higher in the bitter task than in the sweet task. We discuss these complex results in the light of different theoretical proposals to explain this cross-modal correspondence.

Macronutrient Sensing in the Oral Cavity and Gastrointestinal Tract: Alimentary Tastes

There are numerous and diverse factors enabling the overconsumption of foods, with the sense of taste being one of these factors. There are four well established basic tastes: sweet, sour, salty, and bitter; all with perceptual independence, salience, and hedonic responses to encourage or discourage consumption. More recently, additional tastes have been added to the basic taste list including umami and fat, but they lack the perceptual independence and salience of the basics. There is also emerging evidence of taste responses to kokumi and carbohydrate. One interesting aspect is the link with the new and emerging tastes to macronutrients, with each macronutrient having two distinct perceptual qualities that, perhaps in combination, provide a holistic perception for each macronutrient: fat has fat taste and mouthfeel; protein has umami and kokumi; carbohydrate has sweet and carbohydrate tastes. These new tastes can be sensed in the oral cavity, but they have more influence post- than pre-ingestion. Umami, fat, kokumi, and carbohydrate tastes have been suggested as an independent category named alimentary. This narrative review will present and discuss evidence for macronutrient sensing throughout the alimentary canal and evidence of how each of the alimentary tastes may influence the consumption of foods.

The Acceptability of Tempeh Based Sausage Formulations with Natural Preservatives Addition

Sausage is a popular food for both children and adults. The main problem in sausage processing is their short shelf life. Synthetic preservatives such as nitrites are often added to sausage dough to extend the shelf life of sausages. Preservatives such as nitrites, if consumed too often can have harmful effects on health. The content of active compounds found in jasmine flowers is expected to be used as a source of natural preservatives in the processing of tempeh sausage in this study. This study aims to determine the acceptability of sausage formulations with the addition of natural preservatives. This study consisted of 3 treatments, namely tempeh sausage with extract variations of 0%, 0.1%, and 0.25%. This study used a completely randomized design (CRD). The concentration of jasmine flower extract had a significantly different effect on the taste of tempeh (p <0.05), where the higher the concentration of jasmine flower extract added to the tempeh sausage, the panelists' preference for the taste of the tempeh sausage would decrease. This is because the two basic ingredients of sausage, namely tempeh and jasmine flowers, already have a specific basic taste. The selection of preservatives made from natural ingredients can be a choice in developing food products, to minimize the use of synthetic preservatives in food products that are carcinogenic. Keywords: Sausage, tempeh, preservatives

Cortical processing of chemosensory and hedonic features of taste in active licking mice

Relatively little information is available on the neural dynamics of taste processing in the mouse gustatory cortex (GC). In this study we investigate how the GC encodes chemosensory and palatability features of a wide panel of gustatory stimuli when actively sampled through licking. Our results show that GC neurons broadly encode basic taste qualities but also process taste hedonics and licking information in a temporally dynamic manner.