Despite the pressure build-up duirng cooking the film is peelable, ...
FFP Packaging Solutions’ Estersteam microwave steam lidding system has been used on Taiko Foods’ new Dim Sum Chinese dumplings, sold in Waitrose stores in the UK.
The dumplings are packed in a clear tray, with the Estersteam film heatsealed to the top. The film incorporates a special valve that allows steam to escape in a controlled way during microwaving. By controlling the steam release FFP says the valve contributes to flavour and succulence; “steam is retained in the pack during the early part of cooking in a way that not possible, for example, if the consumer pierced the lidding film”.
Temperature and pressure increases as the food cooks, and the valve opens to release the steam through a measured aperture.