Synergistic taste effectiveness of citric acid

1)大鼠岩浅大神经支配软腭的实验结果表明，构皮素处理后，岩浅大神经对六种糖和糖精的综合反应明显降低，降低幅度达40%。对D-氨基酸的反应比L-氨基酸更显着抑制gurmarin处理。这些结果表明，氨基酸的受体分子和/或转导机制的差异是类似的甜味物质在大鼠。在碱性和中性氨基酸溶液中加入无机酸降低pH值，可使大鼠鼓索神经反应增强，这与氨基酸分子中α-氨基的电荷有关。因此，柠檬酸的味觉刺激效果可能不仅与作为二碳酸的刺激剂有关，而且与作为酸通过降低pH来增强氨基酸的刺激效果有关。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。然而，柠檬酸NA（CitNa）没有改变可溶性淀粉对甜度的增强效果。两瓶偏好实验中，大鼠对MSG + CitNa的偏好比大于MSG，且对MSG + IMP + CitNa的偏好大于MSG + IMP，提示CitNa可能对哺乳动物的鲜味有增强作用。

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.