Synergistic taste effectiveness of citric acid

1)大鼠岩大浅神经支配软腭的实验结果表明，葛根素治疗后，大鼠岩大浅神经对6种糖和糖精的综合反应显著降低至40%。古尔马林对D-氨基酸的抑制作用比对L-氨基酸的抑制更明显。这些结果表明，氨基酸与甜味物质在受体分子和/或转导机制上的差异与大鼠相似。通过添加无机酸降低碱性和中性氨基酸溶液的pH值，可增强大鼠鼓索的神经反应，这与氨基酸分子中α-氨基的带电有关。因此，柠檬酸的味觉刺激效应可能不仅与作为双碳酸的刺激剂有关，还可能与通过降低pH作为酸来增强氨基酸的刺激效应有关。2)在人体中，溶解在可溶性淀粉中的蔗糖比溶解在蒸馏水中的蔗糖具有更大的甜味强度。柠檬酸钠(CitNa)不改变可溶性淀粉对甜度的增强作用。3)在两瓶偏爱实验中，大鼠对味精+CitNa的偏好比倾向于MsG+IMP+CitNa，而对Msg+IMP+CitNa的偏爱程度高于MsG+IMP。

1) Result from the experiment of the rat greater superficial petrosal (GSP) nerve innervating the soft palate revealed that the integrated responses from the GSP to six sugars and saccharin were significantly depressed to 40% after gurmarin treatment. Responses to D-amino acids were more significantly inhibited than that to L-amino acids by the gurmarin treatment. These results suggest that the difference of receptor molecule and/or transduction mechanisms for amino acids is similar to those for sweet substances in the rat. Lowering the pH of basic and neutral amino acid solutions by adding inorganic acids resulted in the enhancement of neural responses in the rat chorda tympani, concerning to the charge of a-amino group in the amino acid molecule. Therefore, taste stimulatory effectiveness of citric acid may not only be concerned to a stimulant as di-carbonic acids but also to the enhancement of stimulatory effectiveness of amino acids by lowering pH as acid.2) In humans, a greater sweetness intensity occturred to sucrose dissolved in a soluble starch than for sucrose dissolved in distilled water. However, citric acid NA (CitNa) did not alter the enhancement effect on sweetness by soluble starch. A greater umami intensity occurred in response to CitNa.3) A two-bottle preference test in the preference ratio for MSG + CitNa tended to be larger than that for MSG.Also, the rat tended to prefer MSG + IMP + CitNa to MSG + IMP.These results suggest that CitNa may have enhancing effects on umami taste in mammals.