ANSWER
According to Regulation No. 348 to 359 of Food Regulations 1985, there are no specific regulations that stipulates the use of natural preservatives in beverages.
Reference
Ministry of Health Malaysia. (2017). Food Regulations 1985. Regulation 348-359.
So, does that mean, any type of natural preservative is allowed to be added, since there is no regulation on this? Please name some examples of natural preservatives. Thanks.