The preservatives used are Citric Acid to reduce the PH level, Potassium Sorbate to stop mould and Sodium Benzoate as an antimicrobial agent.

使用的防腐剂是柠檬酸，目的是为了降低PH值和山梨酸钾，以便防止霉变。另一种是苯甲酸钠，它是一种杀菌剂。

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In addition, the kidney controls the composition of your body of many important ions, sodium bicarbonate which is important in pH balance, potassium.

此外肾脏还能控制,体内很多重要离子的浓度,例如碳酸氢钠,它对于酸碱平衡十分重要,还有钾离子

耶鲁公开课 - 生物医学工程探索课程节选