Rice Dumplings

Introduction

Rice dumplings, also known as Zongzi (粽子) or Bak Chang, are traditionally eaten by the Chinese to celebrate the Mid-Autumn or Dragon Boat Festival (端午节), which falls on the fifth day of the fifth lunar month. The dish is made of glutinous rice (or sticky rice) with different fillings such as salted duck egg, meat, Chinese sausage and mushrooms. The rice dumplings are then wrapped in banana, bamboo or lotus leaves, and held together by strings – typically made of plastic (raffia) or cotton.

Is it safe to eat rice dumplings that are tied and cooked with plastic or cotton strings?

Some consumers have raised food safety concerns that chemicals from the strings used to tie rice dumplings may dissolve into the boiling water. These chemicals may then be absorbed by the food directly through the boiling water, or indirectly through the steam.

SFA has conducted studies to assess the safety of rice dumplings that are tied and cooked with plastic and cotton strings. Samples of plastic and cotton strings, as well as rice dumplings from various manufacturers in Singapore were tested for the presence of any chemical contaminants before and after the dumplings were cooked.

Results from our studies showed that the concentration of chemicals that migrated from both plastic and cotton strings into the dumplings was low. As there is no direct contact between the strings and the rice dumplings, the concentration of chemicals absorbed by the rice dumplings from plastic and cotton strings during the cooking process was also low. Given that the level of chemicals found in the dumplings was low, there is thus low food safety risk with consuming dumplings that are tied and cooked with plastic or cotton strings.

Rice dumplings are also often cooked in a large volume of water, which will further dilute the already low level of any chemicals present. Hence, both plastic and cotton strings are of low risk to food safety and are safe to use for tying rice dumplings.