How to apply best sushi reward?

How do you know the sushi-rice are already spoilt?

• With my knowledge, I understand that the sushi-rice cannot keep for ONE day. Even if you already make the maki, sushi or others, the sushi rice only can keep for 2 hours only. But, some Japanese restaurants in Singapore, some cook are using the overnight sushi-rice to make makimono, sushi, temaki,nigiri sushi,inari sushi and Gunkan. I have bought and ate it with my friends. My friends told me that the sushi-rice are spoilt and has become bad. Why those Japanese restaurant use the over night sushi rice to make maki, sushi and others to sell to customers? I asked the cook, if the overnight sushi-rice are not spoil, sushi-rice are still eatable. But, as a novice sushi eater, how do you know the sushi-rice are already spoilt? I got some answer here:- 1. The Cook smell whether the Sushi-Rice is good or not. If the sushi-rice are bad, the sushi rice smell soury or smelly. Otherwise, smell aroma of sushi-rice. 2. The colour of sushi-rice. If the sushi -rice got a bit yellow spot, then the whole container of sushi rice are spoilt although smell good. 3. The sushi rice is too wet or too mushy. So, please help. I really want to know how the sushi rice are already spoilt? Why those Japanese Restaurant are still using the overnight sushi rice to make maki,sushi and others to sell to customers?

• Answer:

  I've heard comments that sushi rice is deemed spoilt if / when: (1) they have turned colour, ie. off white, kind of yellowish (2) they emitted a bad or sourish odour, not the usual rich, fragrant smell of sushi rice. However, these are comments i have heard and i would love confirmation.