Menachot 70b ~ The Chemistry of Chametz

We are about six months away from Pesach, so it is time to talk about about unleavened bread, called chametz. And it comes up in today’s daf.

מנחות ע,ב

מנא הני מילי אמר ריש לקיש אתיא לחם לחם ממצה כתיב הכא (במדבר טו, יט) והיה באכלכם מלחם הארץ וכתיב התם (דברים טז, ג) לחם עוני 

והתם גופה מנלן אמר ריש לקיש וכן תנא דבי ר' ישמעאל וכן תנא דבי ר' אליעזר בן יעקב אמר קרא (דברים טז, ג) לא תאכל עליו חמץ שבעת ימים תאכל עליו מצות לחם עוני דברים הבאים לידי חימוץ אדם יוצא בהן ידי חובתו בפסח יצאו אלו שאין באין לידי חימוץ אלא לידי סירחון

How do we know that matzah must be made from one of five species of grain [wheat, barley, oats spelt and rye]?  Reish Lakish said, and likewise a Sage of the school of Rabbi Yishmael taught, and likewise a Sage of the school of Rabbi Eliezer ben Ya’akov taught, that the verse states: “You shall eat no leavened bread with it; seven days you shall eat with it matzah, the bread of affliction” (Deuteronomy 16:3). This verse indicates that only with regard to substances that will come to a state of leavening does a person fulfill his obligation to eat matzah by eating them on Passover, provided that he prevents them from becoming leavened. This serves to exclude these foods, i.e., rice, millet, and similar grains, which, even if flour is prepared from them and water is added to their flour, do not come to a state of leavening but to a state of decay [sirḥon].

The important question we need to answer here is whether there is something fundamentally different about rice when compared to the five grain species that can become chametz. And is there any scientific support to the claim that rice spoils sooner than it ferments?

The Chemistry of bread making

To get at the answers we need to remind ourselves how plants make and consume starch. They take carbon dioxide from the atmosphere and water from the soil, and using the energy contained in sunlight (and the magic of chlorophyll) convert the two into a large sugar molecule we call starch. Plants use this starch to store and provide them with energy.

If you grind up wheat (or many other species of grain) you make flour which contains loads of starch. In addition to starch, flour contains proteins and enzymes which become important when the flour is mixed with water. Without going down a rabbit-hole of detail, here in general is what happens. First, an enzyme called beta-amylase breaks the large starch molecule down into a smaller molecule called maltose which is made up of two molecules of glucose. Another enzyme, maltase, breaks down each molecule of maltose into two molecules of glucose which is then broken down further to provide the plant with energy. Here is what it looks like:

From Lloyd, James R and Kötting, Oliver (July 2016) Starch Biosynthesis and Degradation in Plants. John Wiley & Sons, Ltd: Chichester.

If you add some yeast into that mix, a chemical reaction called fermentation occurs. Yeast, which is a fungus, consumes glucose and turns it into carbon dioxide and ethanol, which is an alcohol.

As the flour and water and yeast all mix together, two proteins in the flour called gliadin and glutenin (which are glutens) give the dough mixture its characteristic body, which strengthens the more it is mixed. The dough traps the carbon dioxide that is given off by the yeast cells, which causes the bread to rise. And that gives us the leavened bread we call chametz.

Of course when matzah is made, we do not add yeast to the dough. But there are yeast particles in the air and these will inevitably land on the dough where they will act in the same way, consuming glucose and creating carbon dioxide and alcohol. This process is much slower than when yeast is added when bread is made, but the plain dough will rise a little as a result.

The differences between grains and rice

Resh Lakish (together with those sages of the schools of Rabbi Yishmael and Rabbi Eliezer ben Ya’akov) claim that unlike grains, rice does not ferment when water is added to it. Instead it spoils. That’s why it may be eaten on Passover (unless of course you are an Ashkenazi Jew, in which case you still can’t eat it, but for another reason we’re not going to get into). Is this in fact the case?

I know next to nothing about plant biology. But Dr Angus Murphy does. He is Professor and Chair of the Department of Plant Science at the University of Maryland, and wrote the textbook on plant physiology. Dr. Murphy was kind enough to have a long chat with me over the phone and he agreed with the suggestion that grains and rice do very different things when mixed with water. The wheat seed is surrounded by the endosperm, which is itself covered by the aluerone layer. This aleurone is rich in amylase which as you recall is needed to breakdown starch into glucose (which is eaten by yeast which releases carbon dioxide and alcohol which causes the dough to rise…) However (most species of) rice do not contain this aleurone layer. So they have very little amylase, which means that it takes them a much longer time to convert starch into glucose. In fact it takes so long that by the time there is enough yeast in the dough for it to start to rise, bacteria in the air will have colonized the mixture and started breaking down the proteins in the dough. And that protein breakdown is what makes the mixture spoil, and which is what the Talmud calls סירחון. To conclude, Professor Murphy thought that the Talmud’s description of the difference between grain and rice was firmly based in plant biology.

The fine print and the final verdict

Distribution of variou types of amylases in rice grains. (Beta-Amylase activity was expressed in terms of maltose mg liberated in 3 min at 30°C by 1 g of ground rice samples.) From Ryu Shinke, Hiroshi Nishira & Narataro Mugibayashi. Types of Amylases in Rice Grains. Agricultural and Biological Chemistry 1973; 37:10, 2437-2438

Of course things are a little more complicated than that. (They always are.) Different kinds of wheat flour contain different amounts of amylase. Fine bleached white flour contains less amylase than say whole wheat flour, because the aleurone layer in whole wheat flour has not been broken down. Similarly, different species of rice contain different amounts of amylase, so that while standard white rice has very little, brown rice has considerably more. During talmudic times, the wheat flour would have been far less processed than any of the flour we would use today. As a result it would contain more amylase, and would have risen faster than would today’s four-water mixtures.

But as a rule of thumb, the Talmud is, biochemically speaking, spot on. When mixed with water, the five species of grain from which matzah may be made do undergo fermentation even without the addition of yeast, while rice will spoil long before the fermentation process becomes noticeable.

Menachot 64b ~ Cursed Be He Who Raises Swine

Today we are going to talk about pigs. But before we get into it, here is some important background, courtesy of the Jewish historian of the first century, Josephus.

From here.

Following the death of their father Alexander Yannai in the first century B.C.E. two brothers, Hyrcanus and Aristobulus fought over which would ascend to the Hasmonean throne. Both appealed to Rome (which turned out to be a very bad idea) and in 63 B.C.E. the military leader Pompey turned up to sort things out. He backed Hyrcanus, who was the Cohen Gadol, (high priest) at the time, and who had been originally named as the heir. Pompey captured Aristobulus and took him off to Rome, and he let Hyrcanus remain as the Cohen Gadol. But Pompey refused to Hyrcanus become king. And that is how the Romans came to Jerusalem, or as Josephus put it “we lost our liberty, and became subject to the Romans.” OK. Now here is the relevant part in tomorrow’s Daf Yomi:

מנחות סד, ב 

תנו רבנן כשצרו מלכי בית חשמונאי זה על זה והיה הורקנוס מבחוץ ואריסטובלוס מבפנים בכל יום ויום היו משלשלין להן דינרין בקופה ומעלין להן תמידין היה שם זקן אחד שהיה מכיר בחכמת יוונית לעז להם בחכמת יוונית אמר להן כל זמן שעסוקין בעבודה אין נמסרין בידכם למחר שלשלו להן דינרין בקופה והעלו להן חזיר כיון שהגיע לחצי חומה נעץ צפרניו בחומה ונזדעזעה ארץ ישראל ארבע מאות פרסה על ארבע מאות פרסה באותה שעה אמרו ארור שיגדל חזיר וארור שילמד בנו חכמת יוונית ועל אותה שעה שנינו מעשה שבא עומר מגגות צריפין ושתי הלחם מבקעת עין סוכר

The Sages taught: When the kings of the Hasmonean monarchy besieged each other [in their civil war,] Hyrcanus was outside of Jerusalem, besieging it, and Aristoblus was inside. On each and every day they would lower dinars in a box from inside the city, and those on the outside would send up animals for them to bring the daily offerings in the Temple. A certain elderly man was there [in Jerusalem] who was familiar with Greek wisdom. He communicated to those on the outside by using words understood only by those proficient in Greek wisdom. The elderly man said to them: “As long as they are engaged with the Temple service, they will not be delivered into your hands.” Upon hearing this, on the following day, when they lowered dinars in a box, they sent up a pig to them. Once the pig reached halfway up the wall, it inserted its hooves into the wall and Eretz Yisrael shuddered four hundred parasangs by four hundred parasangs. When the Sages saw this, they said at that time: Cursed is he who raises pigs, and cursed is he who teaches his son Greek wisdom…

“Alongside circumcision and Sabbath observance, the prohibition against pork is considered one of the clearest identifiers of what a Jew does and, as such, who is a Jew.”

— Jordan Rosenblum. ‘Why Do You Refuse to Eat Pork?’’ Jews, Food, and Identity in Roman Palestine. The Jewish Quarterly Review 2011. 100 (1): 95–110

Pig Husbandry in Iron Age Israel - North vs SOuth

It has been long taken as a given that archeologists could use the presence (or absence) of pig remains to distinguish a Philistine from an Israelite settlement. For example, in known Philistine sites from Iron Age I (~950-780 BCE) like Ashdod and Ekron, pig bones account for 7-19% of the animal remains, depending on which strata you are excavating. This is a much higher percentage than is found in Israelite settlements of the same period. But in 2013 this assumption was challenged by a group of top-notch Israeli archeologists (including the controversial Israel Finkelstein) who reviewed the evidence for it. They studied data from 35 sites in Israel, and found a remarkable trend. In the territory of what was once the Northern Kingdom of Israel, pig remains account for 3-7% of all animal remains. But in the Southern Kingdom of Judah, pig remains are almost absent. (The site of Aroer is a bit of an anomaly, with more than 3% pigs. However this site seems to have been a rest stop for many international travelers and so may have served a more international cuisine.) There was a dichotomy between the kingdoms of Israel and Judah that was manifest in whether they ate pork.

Sapir-Hen, L. Bar-Oz, G. Finkelstein, I. Pig Husbandry in Iron Age Israel and Judah. New Insights Regarding the Origin of the "Taboo." Zeitschrift des Deutschen Palästina-Vereins (1953-), Bd. 129, H. 1 (2013), pp. 1-20.

Why was there a rapid rise in the frequency of pigs being eaten in northern Israelite sites during Iron Age II (the period between 870 and 680 BCE)? Among the answers proposed is that “the pig taboo could have been another Judahite cultural trait that was opposed to the situation in the north, and which the authors [of the Torah] wished to impose on the entire Israelite population.” Alternatively, it may have been a result of the larger population found in the Northern Kingdom of Israel. “This process” wrote the authors of the paper Pig Husbandry in Iron Age Israel and Judah “brought about shrinkage of the open areas that are important for sheep/goat husbandry, and could have forced the Iron Age IIB population to a shift in meat production, breeding smaller herds of sheep and goats and concentrating more on pigs, which could supply large and immediate sources of meat.” In contrast, the population of the Kingdom of Judah was much smaller than that of Israel. Hence they had more open space to raise livestock.

By the way, it was the Philistines who were responsible for importing European type pigs into the Middle East. Dr Merav Meiri of the Department of Zoology at Tel Aviv University analyzed the DNA of ancient pigs in the area, and found that they possessed a European gene signature. This raises the possibility that European pigs were brought to the region by the Sea Peoples who migrated to the Levant around 900 BCE, bringing their pigs with them.

Pigs & Ancient Rome

Whether or not pigs were eaten in some parts of Biblical Israel, there is no doubt that not eating pork became synonymous with Jewish practice. In Rome, things were different. There, eating pork was widespread and enjoyed, and it was one of the most common meats associated with its residents. And as Jordan Rosenblum points out in his 2010 paper Why Do You Refuse to Eat Pork?’’ Jews, Food, and Identity in Roman Palestine swine were one of the four most common animals used for sacrifices in Rome. It was used in the most sacred rite of the Roman religion known as the suovetaurilia, in which a pig, a sheep and a goat were sacrificed to Mars, as part of a ceremony consecrating the land to the gods. According to the Roman philosopher Epictetus “the conflict between Jews and Syrians and Egyptians and Romans, [was] not over the question whether holiness should be put before everything else and should be pursued in all circumstances, but whether the particular act of eating swine’s flesh is holy or unholy.”

Our Passage in the Talmud Yerushalmi

In the Jerusalem Talmud, there is a similar description of the story told in tomorrow’s Daf Yomi, with an important difference. Can you spot it?

תלמוד ירושלמי (וילנא) מסכת ברכות פרק ד

א"ר לוי אף בימי מלכות רשעה הזאת היו משלשלין להן שתי קופות של זהב והיו מעלין להם שני כבשים ובסוף שלשלו להן ב' קופות של זהב והעלו להם שני חזירים לא הספיקו להגיע לחצי חומה עד שנעץ החזיר בחומה ונזדעזעה החומה וקפץ מ' פרסה מארץ ישראל באותה שעה גרמו העונות ובטל התמיד וחרב הבית

R. Levi said: ‘‘Also during the days of that Evil Empire [Rome], they would lower to them two baskets of gold and they would send up to them two lambs. At the end [of the siege], they lowered to them two baskets of gold and they sent up to them two pigs. They did not reach halfway up the wall when the pig stuck [its nails] in the wall and the wall shook and [the pig] jumped forty parasangs from the land of Israel. At that moment, the sins brought about both the suspension of the continual offering and the destruction of the Temple.

Here is the difference: in the Yerushalmi version the substitution of the pig for the lambs is directly linked to the destruction of Jerusalem, and not just to a general ban on the raising of pigs. “Rome’s secret weapon in times of war with the Jews” wrote Rosenblum, “is to deploy the very animal that functions as a metonym for Rome itself.”

So pigs turn out to have played more of a role in our history than would be expected. In biblical times, eating pork may have been a marker of whether you came from Israel or Judea, and pork, or at least its symbolism, played a pivotal role in the onset of the Roman attack on the Second Temple.

“Archaeologists take pigs very seriously.”

— Israel Finkelstein cited in "Who’d Import Pigs to Israel? Ancient Europeans, Researchers Say." New York Times Nov 5, 2014. A7.

Next time on Talmudology: The Chemistry of Chametz.