The Kiddush That Wasn't

What is the halacha in the following instance? Reuven made hamotzi for his friend on Shabbos when Reuven had not yet made kiddush but thought he did. There are a few such examples: He thought that in his kiddush cup there was wine but in fact it was cranberry juice. Or he made kiddush on beer which is חדש [the מקדש is מיקל on חדש in חוץ לארץ but the listener is not in which case the listener is not יוצא]. Or he thought that there is enough wine in the כוס but there was not the requisite shiur. Or he thought he drank enough but he didn't. The מקדש then makes hamotzi for his friend. Do we say that since there was no kiddush the hamotzi also doesn't count [because we need kiddush before the seuda]. Or do we say that since the Mishna Brura paskens [סימן קצו מ"ב סק"ד] that when a person eats forbidden food בשוגג he should still make a bracha achrona - in this case the bracha counts since the kiddush was invalid but only בשוגג. One can further argue that since many poskim disagree with the Mishna Brura [see the sefer Piskei Tshuvos סימן קצו for a list] and hold that one does NOT make a bracha achrona on forbidden food eaten בשוגג here too when בשוגג he made kiddush that wasn't motzi himself, the bracha of hamotzi wouldn't count.

However, one could make a distinction between eating forbidden food and our case. There the food is itself is forbidden so it is less likely that he should make a bracha. In our case the food itself was completely kosher, it just wasn't yet the right time to make hamotzi. So maybe the hamotzi [predicated on the invalid kiddush] would be valid. A proof that one should make a bracha on food when eaten before its proper time can be found in סימן רעא סעיף ה where it says that if one accidentally made hamotzi before havdala he should eat the bread [so it shouldn't be a bracha li-vatala] and then make havdala. We see that even though it is not yet the time for eating, a bracha is still required [otherwise we wouldn't try to prevent a bracha li-vatala because it would be li-vatala no matter what].

עפ"י הספר בני ראם סי' נט
לגאון ר' אברהם בן גיטא גנחובסקי שליט"א
שה' ישלח לו רפואה שלימה בתוך שאר חולי ישראל
ויהיו דברי תורה אלו זכות לרפואתו