We have previously checked and seals and extra plastic wraps do not add any extra freshness to the product. The screw lid is already completely airtight. So as there was no freshness advantage we generally do not put seals on our products.
However, we are starting in retail soon and in that environment it may be a good idea to put a tamper seal on it as people other than the purchaser may have handled it. It is for this reason that all our products are being moved onto production lines that allow the application of seals.
Over the next couple of years we will gradually include tamper seals on all our products where possible. Some products with flip lids cannot be given tamper seals.