Bava Metzia 60A

ואין צריך לומר, חדשים בישנים.

And needless to say, one may not intermingle new produce with old produce, in the event that the old produce is superior, as with grains, since intermingling lowers its value.

באמת אמרו: ביין התירו לערב קשה ברך, מפני שהוא משביחו. אין מערבין שמרי יין ביין, אבל נותן לו את שמריו.

Actually, they said: With regard to wine, they permitted one to mix strong wine with weak wine, because one thereby enhances it. One may not intentionally mix wine sediment with the wine, but one may give the buyer wine with its sediment; the seller is not required to filter the wine.

מי שנתערב מים ביינו, לא ימכרנו בחנות, אלא אם כן הודיעו. ולא לתגר, אף על פי שהודיעו, שאינו אלא לרמות בו. מקום שנהגו להטיל מים ביין ⁠– יטילו.

One who had water mix with his wine may not sell it in the store, unless he informs the buyer that it contains water. And he may not sell it to a merchant, even if he informs him of the mixture, as, although he is aware that there is water mixed with the wine, it will be used for nothing other than deceit because the merchant will likely not inform the buyer that it is diluted. In a place where they are accustomed to place water into the wine to dilute it and everyone is aware of that fact, one may place water in the wine.

התגר נוטל מחמש גרנות ונותן לתוך מגורה אחת, מחמש גתות ונותן לתוך פיטום אחד, ובלבד שלא יהא מתכוין לערב.

The prohibition against mixing different types of produce applies only to an individual selling the produce of his field. By contrast, a merchant may take grain from 5 threshing floors belonging to different people, and place the produce in one warehouse. He may also take wine from 5 winepresses and place the wine in one large cask [pitom], provided that he does not intend to mix low-quality merchandise with high-quality merchandise.