How do you say 'serving' in Chinese as it relates to nutrition?
If it is restaurant food or fast food, you can use either '份' or the corresponding count word (量词). For example, 每份套餐, 每份薯条, 每个汉堡, 每份红烧肉, etc.

If it is a snack or drink, we directly use the mass or volume for 'serving'. For example: 每 100 mL 可乐 (cola)，每 100 g 薯片, etc.

Below is an empty nutrition label (used as the standard format) published by Ministry of Health of P.R.C. (中国卫生部). See http://www.gov.cn/gzdt/2008-01/11/content_856260.htm. What you want is the title of the second column.