Sushi was a preservative food to make good use of food and now it is all about the freshness. Sushis are consumed all around the world using fresh raw seafood, even though it is a great food culture it is a cause for mass food disposal due to the difficulty in quality control. The origin of sushi was a fermented food made from steamed rice and crucian carp and it was one of the best preservative foods in the past.
The reality of mass food disposal was in low cost conveyor belt sushi restaurant. They put two pieces of sushi on a plate and puts it on a conveyor belt so that customers could see it and choose their sushi. These kind of restaurant gain dominant popularity among Japanese people for its high entertainment properties and cheap prices. However to sustain the freshness of the sushi some restaurants created automated sushi disposal system. The system allows the bar code on the back of the plate to automatically distinguish sushi that went around the conveyor belt for 55 minutes and disposed it.
It is important to eat fresh food not only because they taste good but to consider about health, however people these days are extremely sensitive to the expiration date of an food. People should use the expiration date as an rough guide and not as an certainty.