25443
The effect of Ca ( 2 + ) in brewing water on the organic acid content , turbidity , and formation of tea cream and sediment in green tea infusions was studied .
 Ca ( 2 + )
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 Ca ( 2 + )