…I contend that the words in Exodus xii. 19, “that which is leavened,” which in Hebrew are rendered מַחְמֶצֶת, or machmetzeth, was a beer similar to the modern Egyptian paste or bread beer (Boosa), now used both as a beer and as a leaven or bread-raiser. During the epoch of the Israelites in the “land flowing with milk and honey,” it is not improbable that a beer of so inferior a taste as that of the Egyptian bondage may have ceased to exist, much in the same manner as the ale of the present day differs from that of our Saxon forefathers. The beer made by the Israelites in Egypt during their hardest of slaveries could only have been of the poorest description, and must not therefore be regarded as identical with the “leaven ” forbidden to be eaten with the meat-offering of the later and luxuriant period of the hierarchy, or with the bière de luxe, the Egyptian Hek.
The literal translation of “anything leavened” to mean wine is hardly admissible. Wine was always a luxury in Egypt, even amongst the Egyptians. How, then, can it be supposed to have been drank by the down-trodden Hebrews? The Revised Version of the Bible interpolated with the Hebrew renderings of leaven is given on p. 76, which I would request the reader to refer to at once. It will be observed that the subject matter of the verses 15 and 17 of the English Version is apparently repeated in verses 18, 19, 20; but in the Hebrew Version a new description or word for leaven is introduced. The Jewish authorities translate this word machmetzeth as “something leavened or fermented, literally what causes to ferment.” This description fully applies to the eatable beer Boosa. One considerable linguist informs me that this word does not refer to the leaven of dough stale dough—but to some form of it. The most able scholars appear to have been perplexed by these various meanings of leaven. … I will not trouble the general reader on this philological question further than to state that I contend מַחְמֶצֶת, machmetzeth, was the ancient beer of the Hebrews (which could also be used as a leaven to raise dough); that it applies to malt products; and that its mention in verse 19 is the sole mention of beer in the Bible. Leviticus x. 9 reads, “Drink no wine” יַיִן (yayin) “or strong drink,” שֵׁכָר Shechar; but this is interpreted to refer to any strong drink, such as fermented honey, sugar or vegetable juices, beer, &c. These Hebrew words for malted and leavened articles only occur in the Pentateuch; this circumstance alone is sufficient to point to their great antiquity.
James Death, The Beer of the Bible: One of the Hitherto Unknown Leavens of Exodus (London: Trübner & Co., 1887), 55-56.