Study on the methods to decrease cariogenicity of food stuffs

降低食品致酸性的方法被认为是降低其致龋性最有效的方法。本研究以5种具有缓冲能力的物质为研究对象，考察了葡萄糖溶液和低分子壳聚糖(LMCs)对变形链球菌细胞悬浮液产酸和菌斑pH反应的缓冲作用。此外，还制备了7种不同相对分子质量和脱乙酰度(DAC)的LMC。采用自动滴定法和pH下降法对变形链球菌细胞悬浮液的体外产酸进行了评价，并采用乳酸恒定加入量的方法进行了研究。用离子敏感晶体管电极评价体内产酸情况。在这项研究中，获得了来自五名人类志愿者的数据。对每个LMC的努力的评价由四个标准确定：1)面积(试验/续)PH 5.5以下的比率，2)时间(实验/持续)PH值低于5.5，3)最小pH值，4)pH值。LMCs(pKA：6.4)和苹果酸(pKA：6.2)，pKA：6.5左右。在5%葡萄糖溶液中加入5个LMC(1%)可减少菌斑的pH下降，并迅速恢复到静止值。添加两个相对分子质量分别为3,000和500，DAC：50和95%的LMC效果最好。两种低分子壳聚糖在四项指标上的差异有统计学意义(p&lt；0.01)，说明低分子壳聚糖可作为食品添加剂来降低食品的生酸性。

The methods to decrease acidogenicity of food stuffs have been considered to be most effective on decreasing their cariogenicity. The purpose of this study was to evaluate the effort of buffer capacity of the substances, especially low molecular chitosan(LMCS), in addition to a glucose solution upon acid production of S.mutans cell suspensions and human plaque pH responses.The five kinds of test substances having buffer capacity were used in this study. In addition, seven LMCS with different molecular weight and degree of deacetylation(DAC) were prepared for this study. Acid production in vitro were evaluated by the Automatic Titration Method and pH-fall experiment using S.mutans cell suspensions and also the constant addition method of lactate was used in this study. Acid production in vivo was evaluated by an ion-sensitive transistor electrode. Data from five human volunteers were obtained in this study. Evaluation of the effort of each LMCS was determined by four criteria, 1)area(exp./cont.) ratio below pH 5.5, 2)time(exp./cont.) ratio below pH 5.5, 3)minimal pH, 4) pH.The most effective effort on pH drop in vitro from pH 7.0 was obtained by the substances, ex. LMCS(pKa:6.4) and malate(pKa:6.2), with pKa:around 6.5. The additions(1%) of five LMCS to a 5% glucose solution decreased plaque pH drop and the pH returned rapidly to resting value. The most effective effort was obtained with the addition of two LMCS with MW:3,000 and 500, DAC:50 and 95%, respectively. The two LMCS resulted in statistically significant differences (p<0.01) in the four criteria.The findings indicate that low molecular chitosan is useful as a food additive to decrease acidogenicity of foods.