I think the title and the example given described 2 slightly different situations,
Answering strictly from the title:
I also believe that conformity is what you are looking for, or more specifically normative conformity, in relation to the "odd one out" feeling that you mentioned.
Closely related to conformity, Groupthink may also explains the phenomenon, which stated that an individual might suppresses a dissenting/opposing opinion to keep the peace & harmony of a group, though it's more commonly explained in group decision-making situations.
On the other hand, Group Polarization mainly refers to group phenomenon where a group tend to take a more extreme decisions than the initial inclinations of its members. Meaning that such decisions are less likely to be taken in individual situations.
Now, answering from the given example is a little bit harder because it depends on what made them not wanting to voice their opinion (that they hated the food).
If it's purely because none of them wanted to go against the others opinions, then it's conformity/groupthink as stated above. But how can one go against others opinion when their opinion is one and the same? I would argue that they don't necessarily know that all of them have the same opinion, instead it's very plausible that a few misreading of body-language, or some misunderstood comments would make someone thinks that everyone enjoyed the food, and thus acted accordingly, which in turn would reinforce the others to act the same way.