Despite their childhood misgivings, Americans have been eating a lot more green stuff in recent years—(even spinach!). For kosher consumers, however, eating green vegetables is no simple matter since many of them serve as a nutritious haven for bugs. Biblical law forbids consuming a particular food if it is known to contain bugs. In fact, one cannot consume a vegetable even suspected of containing a bug.
In order to gain the health benefits of leafy vegetables without having to adhere to a rigorous regimen of soaking, washing and checking each one, many kosher consumers opt to buy vegetables, both frozen and fresh, which are certified by kashrut agencies such as the Orthodox Union.
In its never-ending quest to improve procedures and to raise kashrut standards, the OU recently enlisted the help of Dr. Bruce Bukiet, an applied mathematician, to improve its system of sampling for frozen herbs such as dill, basil and parsley. When it comes to bug infestation, halachah views 10 percent as statistically significant. What this means is that if one finds at least one bug in ten parsley sprigs on average, according to halachah that particular herb is considered infested and must always be checked. The question is how much checking must be done? Must a mashgiach check each and every sprig in a batch of thousands? That’s where Dr. Bukiet comes in. The OU needed him to come up with a statistical model to determine how many sprigs in each batch must be checked in order to determine whether the particular batch is infested. Dr. Bukiet was told to devise a system of sampling that would predict with greater than 90 percent accuracy whether the level of infestation in a particular field’s harvest of parsley (or any other herb) is less than 10 percent.
Referred to the OU by his West Orange, New Jersey neighbor (who happens to be an OU rabbinic field representative), Dr. Bukiet, an associate professor in the Department of Mathematical Sciences at the New Jersey Institute of Technology in Newark, has been applying math to practical life throughout his career. After earning a doctoral degree from New York University in gas and fluid dynamics, he developed mathematical models for weapons detonation in Los Alamos and even for predicting the likelihood of the Yankees winning the World Series. (Dr. Bukiet serves as WCBS’s statistical consultant to predict the outcome of the World Series when the Yankees are playing in it.)
Up until he received a phone call from OU Rabbinic Coordinator Rabbi David Bistricer, Dr. Bukiet admits he never thought seriously about bugs in his lettuce. Nonetheless, he welcomed the opportunity to use his skills to assist the OU. “It’s very gratifying when the work one is doing can actually be used to help people,” he says. “At first I was a bit queasy at the thought that for years I may have been eating bugs. But as a kosher consumer and mathematician with the utmost respect for the OU, I was intrigued by the idea of using mathematical modeling and statistics to raise the sanctity of the US kosher food supply,” says Dr. Bukiet, who worked pro bono on this project.
Devising a Debugging System
Rabbi Bistricer reviewed the relevant halachot with Dr. Bukiet, who then went to work developing a statistical model that the kashrut staff could implement.
The OU regularly calls upon experts to better understand issues pertaining to kashrut supervision. Dr. Anthony Shelton, associate director of international agriculture at Cornell University and an expert on agricultural biotechnology, recently sharpened the OU’s understanding of the distinction between insect infestation in sauerkraut as compared to cabbage (the brine used in sauerkraut significantly reduces insect infestation levels); Dr. Robert Hagenmeier, an employee of the Agricultural Research Services, a federal agency, was consulted to explain the types of coatings used on fresh fruits and vegetables, and Dr. Robert Weinstein of Firmenich, a Swiss-based flavor house, explained to OU employees how certain flavors are derived.
Dr. Bukiet’s work in kashrut quickly earned him a winning reputation at the OU and among its client companies. It also piqued the curiosity of his West Orange shul mates at the OU shul Congregation Ahawas Achim B’nai Jacob and David, many of whom now refer to him as “Dr. Bug.” Dr. Bukiet recently accepted an enthusiastic invitation from SupHerb Farms—an OU supervised herb company in Turlock, California, that currently uses Dr. Bukiet’s methodology—to visit its facility so that he could witness his work in action.
As the OU and its public reap the benefits of Dr. Bukiet’s invaluable assistance, the professor feels privileged to have been able to serve the kosher community. A longtime OU member, he views the agency as “the gold standard” in kashrut supervision. He says he has also gained a greater appreciation for his wife’s diligence in checking and soaking vegetables. “Having one’s work used in the ‘real world’ is the most exciting thing,” says Dr. Bukiet. “It’s not often that a mathematician in academia gets an opportunity to have his work influence decisions and processes in industry. [This project] combines the two things I hold dear—math and Yiddishkeit.”
Enjoy your Caesar salad!
Bayla Sheva Brenner is senior writer in the OU Communications and Marketing Department.
Dr. Bukiet’s Model Mishkenot Ya’akov (Rabbi Yaakov ben Aaron of Karlin, d. 1844) rules that fruits, vegetables or berries that are, on average, found to be infested at a rate of 10 percent or more, always require checking beforehand. This 10 percent or higher probability of an unfavorable outcome is termed miut hamatzui. A less than 10 percent likelihood of an unfavorable outcome is considered statistically and halachically insignificant in this area.
How It Works: Dr. Bukiet used basic probability methods in order to determine the criterion the OU could use. Thus, if a field were infested at an unacceptable level of 10 percent, the odds would be 9 to 1 that every sample that is checked would not contain an insect. Although each individual, successive sampling would have the same odds of not having a bug, the likelihood of a result repeating itself continuously diminishes with each additional sample. This is similar to the probability of a pregnant woman giving birth to a boy or a girl. The chances are 50-50 with each pregnancy. However, the chances of the same woman giving birth to 10 boys or 10 girls are much less than that.
The probability of not finding an insect in the first sample taken is represented by the figure .9 (which is 90 percent). The chances of taking two random samples and not finding a bug is 81 percent (.9 x .9). If you take the number .9 to the 22nd power, the probability of finding 22 clean samples taken at random is less than 10 percent.
Therefore, Dr. Bukiet concluded, if 22 samples taken at random are found to be free of bugs, this represents a less than 10 percent likelihood of a marginally unacceptable field of produce being accepted.
Dr. Bukiet also created a statistical model that determined progressive tolerance levels of finding insects in a batch based on increasing sampling volume to come to the same conclusion.
Rabbi David Bistricer