I thing Blockchain will bring major changes in the food industry for sure. One use case I see well :
You are on the market and you want to buy tomatos, you'd be able to scan the QR code with your phone, and have access to all the journey and the transaction associated to it from the grower to the delivery. Then you will be fully able to choose between paying a bit more for maybe a tomato which was not grown far away, or maybe you'll choose another one where you can check that at least X% of the price you are paying is for the producer.

Having all this trustable information accessible to the costumer will change our way to shop, and give us the right tools to change our consumption for the better.