4种柑桔汁的缓冲能力与氮及灰分的二元线性回归关系

果汁含量是果汁的一项重要指标,但目前果汁含量检测方法还不完善,即使有一些检测方法,检测手段也比较繁琐、费时,同时费用较高。对于同一种果汁而言,果汁缓冲能力与果汁的含量呈线性相关关系,但同一类水果不同品种之间缓冲能力是否存在差异以及缓冲能力与水果的那些内在指标密切相关还不清楚。作者选择了南丰蜜桔,砂糖橘、皇帝柑和平远脐橙4种柑桔类水果,制备了相应的柑桔汁,并分别采用检测添加柠檬酸后H+浓度变化的方法检测了其果汁的缓冲系数,采用凯氏定氮法检测了其果汁中氮含量,采用灰化法检测了其灰分质量分数,结果显示这4种柑桔汁缓冲系数与氮含量和灰分呈二元线性相关,回归方程的建立能为利用缓冲能力检测果汁含量的方法提供理论依据。

Binary Linear Regression Relationship Between Buffering Capacity of Four Citrus Juices with Nitrogen and Ash

Although juice content is important when assessing the quality of juice drink, there are no published methods to determine it, particularly simple ones for routine inspection of juice drinks. Buffering coefficient is one of the characteristic index of fruit juice, which has a linear relationship with juice content. However, if there are differences between different varieties of the same fruit and if there are some ingredient closely related to buffering capacity is not clear. The buffering coefficient, ash and nitrogen in four citrus cultivars, Nanfen, Shatang, Huangdi, and Qicheng were detected. Citric acid was added to pure citrus dilutions in distilled water containing 100%, 80%, 60%, 40%, 20% citrus juice. The pH of the dilutions was measured to obtain a linear model for the molar H+ concentration as a function of the added citric acid (g/L) amount. The slope was conducted and defined as buffering coefficient. Nitrogen content was detected by using kjeldahl method and ash content was detected by using ashing method. Results show that the buffering coefficient has binary linear regression relationship with nitrogen and ash. The relationship can be expressed as, buffering coefficient = 50.83N +2088A+2331, where N is nitrogen content in unit of mg/100 g and A is ash content in unit of mg/g.