A huge concern for the rabbis was the consumption of gentile wine, as it could be used in libations, which was a problematic issue for the rabbis. In a discussion of using jugs that gentiles had previously owned (beginning on the bottom of AZ 33a (starting with תנו רבנן: קנקנים של עובדי כוכבים)), while the tannaim did not seem to have concerned themselves with discussions of placing beer into these jugs (or, at the very least, if they did, such texts did not make it into this pericope), the amoraim did (AZ 33b):
איבעיא להו מהו ליתן לתוכו שכר
רב נחמן ורב יהודה אסרי
רבינא שרא ליה לרב חייא בריה דרב יצחק למירמא ביה שכרא
אזל רמא ביה חמרא ואפילו הכי לא חש לה למילתא אמר אקראי בעלמא הוא
It was asked of them: “What about placing beer in [a jug that had previously been possessed by a gentile]?
Rav Nahman and Rav Yehudah forbade [doing it].
And Rava permitted [doing it].
Ravina permitted doing it for Rav Hiyya, son of Rav Yizhak to pour beer into it.
He went and poured wine into it; and even this did not concern Ravina one bit, saying, “It just happened to have occurred.”
Unsurprisingly, the rabbis of the Talmud opined divergently on the matter, with two rabbis forbidding one to put beer into jugs that had formerly been owned by gentiles, who presumably had kept their [problematic] wine in them, and the other two rabbis permitting it. Curiously, at no point in this text do we come across an articulated reason as to why it should either be forbidden or permitted. This, then, is cause for speculation.
Possibility of Issues at Hand
With some disagreements in the Talmud, the disagreement is positioned as all the disputants agreeing upon a particular question upon which the matter at hand hinges. It would be very easy to see that mechanic at play here, as well, although it may also be that those who forbade had one issue in mind, while the permitting rabbis had another issue in mind. Alternatively, it could be even multiple issues. The most obvious issue is that of the problematic (possibly libated) gentile wine imparting its flavor into the beer being stored in these jugs. This most likely serves as the primary motivating factor for the forbidding rabbis. For the permitting rabbis, they may have opined that this gentile wine did not significantly affect the beer’s flavoring. An additional mitigating possibility for the permitting rabbis is the financial feasibility of acquiring jugs and storing one’s beer. A further financial possibility is along the lines of Jewish financial protectionism: these rabbis wanted to focus Jews’ purchasing of jugs to those that had only been owned by fellow Jews (thank you, Jordan Rosenblum).
A Further Factor: Diachrony
An additional factor in understanding these opinions is when these rabbis lived. Rav Yehudah, a second generation amora, died around the turn of the fourth century CE, while Rav Nahman, a third generation amora, died a couple of decades later, both of whom forbade this practice of keeping one’s beer in jugs formerly owned by gentiles. Rava, however, a fourth generation amora, died in the mid-fourth century, with Ravina, a fifth/sixth generation amora, died in the early part of the fifth century, both of whom permitted this practice. Could the conditions have been changing for the Jews in Sasanian Persia from the third century to the fourth centuries in their consumptive (and productive) practices surrounding beer? Alternatively, even if the Jews were not getting any more heavily involved in the consumptive (and productive) practices surrounding beer during this time, perhaps the rabbis in Sasanian Persia took a greater notice of it and an increasing concern developed out of it.
This text witnesses Rav Nahman opining on a potentially problematic beer question, similar to his opinion that gentile beer is to be prohibited due to exposure [and vulnerability to being poisoned by snake venom] (AZ 31b). While it seems unclear what his relationship to beer was, one thing that does seem clear is that he seemed to have been quite disconnected from it: both in its fermenting and storage processes, as well as a seeming lack of concern surrounding the economics or ease of procuring a good beer jug.
Even Rava, who did not care much for beer (preferring water of soaked flax over beer (Pesahim 107a)) may have understood the growing prevalence for beer drinkers and for appropriately storing one’s beer in such jugs, even if they were more easily purchased from gentiles.
In considering using jugs for beer (not dissimilar to our present-day practice of storing beer in growlers for easy portability), four rabbis across different generations were posed the question about them having been previously owned by gentiles, with earlier amoraim forbidding such activity, while later amoraim permitted such storage. While unclear as to what the reasons were for either forbidding/permitting such storage, it seems to be most likely due to the impact of flavor of the gentile (possibly libated) wine on the beer, with the earlier rabbis finding it significant and the later rabbis finding it insignificant. A further factor may be the ubiquity of storing beer in these containers and/or the feasibility of acquiring them, making it easier to have acquired them from gentiles.