In any case, with a 'hash-linked-chain-of-blocks' attempted forks are really easy to prove.
Because of this situation it is natural to assume that a blockchain-based system must either have a decentralization aspect to it, or that the architects of the system are incompetent. And we don't want to assume there's such gross incompetence at IBM, do we? ;-)
Blockchain is a decentralised way to create trusted record without a trusted counterparty, i.e. centralised.
In this case, there is nothing decentralised, you need to go through IBM as with a regular system. Blockchain is only mentioned as marketing to convince you they are reliable. A bit how some hosting service tell you their are using S3 to convince you they are not going to lose your data.
edit: The problem is the title of the article that let you imagine there is some interesting blockchain tech being developed. Instead that's about as interesting as "Walmart uses SAP"
This article explains it well: https://berk.es/2018/09/19/the-private-blockchain-fallacy
Here's the closest I could find to technical info:
> IBM Food Trust's blockchain solution, on the other hand, is permissioned so invited members know exactly with whom they are transacting, similar to what happens between business partners today. Participants also determine what data is seen by whom, thereby providing information on a need-to-know basis. Smart contracts also run on our blockchain, allowing business logic to help solve disputes, automatically execute contracts, and build trust.