If I could offer you an interest savings rate of between 20% and 50%, with a quick return of just a few weeks, you would think it too good to be true, a scam etc. You would probably be correct in a money savings account.
However, from a food saving point of view, it isn't a scam and IS good value for money so to speak.
For example, two weeks ago, I bought wonky bell peppers for £0.99p. This week they were £1.19, that is a 20% increase.
We quite like easy peeler mini oranges, they are usually £0.99p for 6. This week they were £1.49, almost 50% increase. We bought 6 satsumas instead for £0.99p.
See what I mean? If you apply those figures to almost everything on your shopping list, that can be stored long term, that would be a huge saving for the future. The money would be in your pocket and not those of the shops.