Pornrat, however, is not convinced that producers have added saccharin - a type of artificial sweetener widely used in preserved fruits - to bottled fruit juice as speculated.
"Considering the cost of sugar which is not really high, I don't think vendors would find saccharin preferable," Pornrat said. " Also saccharin has a sharp taste and therefore will make it difficult for vendors to adjust the flavour of the juice so that people like it."
For safety, Pornrat suggested that consumers only buy fruit juice from vendors or carts they are familiar with.
"Consumers need to keep a watchful eye on people who sell them food and drink," she advised. "Check if they and their products look clean, how they wear their hair, things like that." If worse comes to worst, according to Patchara, street food licensing might be a good way to go.
"If consumer confidence is of top priority, licensing might be necessary," she noted. "When the time comes, all foods should be required to be labelled and stated by whom and when they were manufactured. Of course, this will increase the production cost but it will probably help."
Putting aside legal protocols, social measures are also paramount in making sure street-side fruit juice is safe for consumption, said Patchara. Markets and authorities in the area where products are sold should also play the role of watchdog checking if things available there look suspicious.
"Vendors must also keep monitoring each other because if only one of them goes bad, the rest will look bad, too," he said. "Consumers especially tourists buying stuff out of their neighbourhood should be more careful and examine thing they are about to buy. State organisations already act as a gatekeeper to a certain extent. But consumers should help out in keeping themselves safe, too.