From Dregs to Riches

By: Rabbi Tzvi Rosen

Fall 2024

In medieval folklore, alchemists were supposedly able to transform lead into gold. Their craft was the stuff of fantasy. But in contemporary life, through the wonders of kosher food science, we are witness to a veritable world of transformation. An impressive example of chemical transformation that would make an alchemist envious is the production of silica gel.

The Chemical Transformation of Sand

Silica gel is a desiccant. It is a highly versatile industrial product, used to absorb moisture in toothpaste, paint and telephone wires, among a myriad of other uses. Granules of silica gel fill the little white packets marked “do not swallow” in your shoe boxes. Kosher food applications include silica gel in spices as an anti-caking agent or as an absorbent in an oil refinery.

Chemically, the basic raw material for silica gel is sodium silicate. More simply, we know it as sand. When sodium silicate is mixed with sulfuric […]

West Meets East: The Beauty of Sephardi Minhagim

By: Rabbi Emanuel Goldfeiz

Fall 2024

True to Hashem’s promise, the children of Avraham, Yitzchak and Yaakov are today scattered in countries across the globe, upholding the teachings of the Avot and perpetuating our beautiful mesorah, each according to his own traditions.

A Brief History

Until the 1970s, American Jewry – then comprised mainly of Ashkenazim – was largely unfamiliar with the minhagim of Sephardi Jews[1] and the Bnei Edot Hamizrach.[2] That changed after 1976, when Rabbi Herman Neuberger zt”l embarked on a daring mission to travel to Iran and bring a small group of young Iranian bochurim to Baltimore to learn at Ner Israel. Iranian Jewry in those days had few opportunities to study Torah. This took place during the reign of the westernized, secular leader Shah Mohammad Reza Pahlavi. Rabbi Neuberger’s plan was that once they earned semicha, the newly ordained rabbis would return to Iran to teach.

Hashem had other plans. […]

A Higher Calling: Maintaining Kedushas Kehuna on Land, Air and Sea

By: Rabbi Mordechai Frankel

Fall 2024

The Torah tells us that Ahron and his sons were appointed by Hashem to serve as the first kohanim. The status of kehuna passes from father to son, in that a son of a male kohen is also a kohen. The kohanim were ordained to serve in the Beis Hamikdash and commanded to fulfill specific mitzvos.[1]

Among these is the obligation for male kohanim to preserve their kedusha and to prohibit becoming tamei meis – that is, becoming defiled through contact or exposure to a dead body.[2] Even though we no longer have a Beis Hamikdash, kohanim in our time are still required to observe all the halachos of tumas meis, both in and outside of Eretz Yisroel.[3] A kohen is restricted from becoming tamei even from an akum meis (the body of a deceased aino Yehudi).[4] At times of significant need, […]

Going Up: All About Shabbos Elevators

By: Rabbi Mordechai Frankel

Summer 2024

Historians claim that two hundred and twenty-four slaves were needed to operate the pulleys of the elevator system in the Colosseum of Rome. Thankfully, technology has come a long way since then. Modern elevators run on electricity which has necessitated the development of a Sabbath Mode. In Sabbath Mode, an elevator cab moves continuously up and down the elevator shaft, stopping at every floor. However, as will be explained, not all Sabbath Modes are the same.

Physics 101: How Elevators Work

There are two basic types of elevators in common use today: hydraulic and traction.

Hydraulic-Type Elevators

Hydraulics make use of the principle that liquid moved with low force over a large distance can be converted to movement with high force over a short distance. Take, for instance, a simple hydraulic jack (see Fig. 1). If the piston on the right has a surface area ten times that of the piston on […]

Warming Up: Do’s and Don’ts of Slow Cookers and Hot Plates on Shabbos

By: Rabbi Yaakov Heinemann

Summer 2024

Slow cookers and hot plates are the workhorses of many kosher kitchens as they enable the Sabbath-observant hostess to serve piping hot dishes to her family and guests to enhance the Shabbos seuda. In recognition of their importance in a Jewish home, it behooves us to review the halachos involving these appliances about which many users might not be aware.

This article will try to clarify the potential issues and how to address them in a practical way.

Slow Cookers

There are two basic types of electric slow cookers: an insert type (often referred to as a Crockpot®), in which a stoneware vessel sits inside a heated base; and a flatbed type, in which a metal pot sits atop a griddle base. Halachic issues involving their use include hatmana, shehiya and chazara. These will be explained below. (There are some more expensive models equipped with variable thermostats which make their usage on […]

Keeping Your Cool: Using a Refrigerator on Shabbos

By: Rabbi Chananya Jacobson

Summer 2024

As electricity began to be used as an energy source in the late 1800s and early 1900s, poskim considered how to view electricity from a halachic perspective. The posek hador, Rav Chaim Ozer Grodzinski zt”l, ruled that electric incandescent lighting is considered fire and, to reinforce this psak, he himself would recite Borei Meorei Haesh on an unfrosted incandescent light bulb. While this psak rapidly gained universal acceptance,[1] it only covered incandescent light bulbs, which are very similar to fire in that they generate both light and heat. What about the many other applications of electric power which do not share these characteristics?

Electricity and Halacha

There are two basic approaches to this issue. The Chazon Ish writes that activating any electric device is boneh (building), since the completion of a circuit involves attaching two parts and bringing the electrical device “to life.”[2]

Other poskim, especially Rav Shlomo […]

For Good Measure: Baking with Gluten-Free Blends, Whole Wheat Flour, Sourdough and at Challah Bakes

By: Rabbi Dovid Heber

Spring 2024

[For a related article on the general laws of hafrashas challah, click here.]

Once upon a time, baking a loaf of bread was simple. Today, when gluten-free blends and processed whole wheat flour are found in many homes, that is no longer the case. Baking with sourdough starters and group baking at “challah bakes” have also become popular. The halachos involved are complex and bear examination.

Let’s begin with a review of the measurements necessary for mitzvos related to regular wheat flour.[1]

Mitzvos Involving Wheat Flour

► Separating Challah (hafrashas challah) Without a Bracha – One should separate challah without a bracha when kneading a dough that contains at least 8 ⅔ cups of wheat flour (on average 2.6 lbs.).[2]

► Separating Challah With a Bracha – There are differences of opinion as to how much flour is needed to recite a bracha. Some individuals do so when kneading at least 12 ¼ cups of flour (slightly more […]

Producción de Carne Kasher: Shechita Flies South

By: Rabbi Zvi Holland

Spring 2024

From time immemorial, no matter where in the far-flung Diaspora, the presence of a Jewish community has always meant that there was shechita in proximity. The position of community shochet was one of a klei kodesh and the shochtim of a community were subject to the supreme jurisdiction of the local rav and/or Beis Din.

Here, in the U.S., it was no different. On November 15, 1660, a man named Asser (Asher) Levy acquired a license to serve as the first kosher butcher in the small Dutch-controlled hamlet of Nieuw Amsterdam – now better known as New York City.[1] Ever since, maintaining a reliable supply of kosher beef has been an integral part of Jewish communal life in the U.S. Previous Kashrus Kurrents articles have offered a glimpse into the challenges shechita has faced on these shores and the changes to the way kosher meat is supplied […]

Acids in Digestion

By: Rabbi Tzvi Rosen

Spring 2024

When my father z”l went to pharmacy school at George Washington University, his course of study had a heavy concentration of chemistry. His background in chemistry proved extremely useful in his forty-year career as an examiner in the U.S. Patent Office. On his workbench, he had shoe boxes with all his pharmacological paraphernalia: Bunsen burners, beakers, and little vials of litmus paper. As a child, I remember my fascination with watching the red litmus paper turn blue when dipped into a base and the blue litmus paper turn red when dipped into an acid. These were literal litmus tests, a term which over time has crept into everyday language to denote a means of determining an outcome.

Although the world of industrial kashrus may not require the deep analysis found in chemistry textbooks, it behooves kashrus administrators and mashgichim to have a working knowledge of chemical compositions and formulations. Solid […]

Yoshon: To Keep or Not to Keep

By: Rabbi Mordechai Frankel

Winter 2024

The Gemara seems to conclude that the prohibition on the consumption of chodosh applies worldwide.[1] However, many shomrei mitzvos outside Eretz Yisrael do not restrict themselves to eating only yoshon grain. Various reasons have been proposed:

► The Rema says that people rely on the fact that for any particular product that are two uncertainties. It is possible that there the food was made from a previous year’s wheat crop and is yoshon. It is also possible that this year’s crop took root before 16 Nissan and is yoshon. As there are two areas of doubt – a sfek sfeika – one can be lenient.[2] Others disagree and maintain that there is only one uncertainty here, whether the grain is chodosh or yoshon, and one should be stringent.[3]

► The Bach says that the prohibition does not apply to grain produced in a field owned […]

What’s “New” in Chodosh

By: Rabbi Sholom Tendler

Winter 2024

The Torah states[1] that chodosh (new) crops of the five grains may not be eaten until after the second day of Pesach (outside of Israel, not until the third day).[2] Thus, grain harvested in the summer of 2023 would not be allowed until Pesach 2024. On the other hand, yoshon (old) crops, which were harvested in the summer of 2022, became permitted after Pesach 2023. Grain planted at least two weeks or more before Pesach are permitted upon harvest, since they took root before Pesach.[3]

Outside of Israel, there are various customs based on numerous sources as to whether or not one needs to be stringent about using only yoshon products (see Rabbi Mordechai Frankel’s article in this issue). Each person should consult their rav for guidance. In Israel, however, these leniencies do not apply. Therefore, any product from Israel bearing a reliable kosher […]

Controlling Your Temper

By: Rabbi Tzvi Rosen

Winter 2024

The baalei mussar, our guides in ethical character development, have instructed us that in order to develop and refine one’s behavior, one has to control one’s temper.

Controlling temper in manufacturing is a means to refine and improve the quality of the product in question. When steel is tempered, the resiliency of the steel is improved through the process of heating and cooling. When chocolate is tempered, through a similar process of heating and cooling (albeit at a much lower temperature), the chocolate acquires a lustrous, luxurious sheen, impervious to changes in color.

Likewise, tempering grain for milling improves the grain so that the final product – wheat flour – is rendered white and fluffy. The source of this final product is the humble wheat kernel.

A wheat kernel or berry is the seed of the wheat plant and is comprised of three edible parts: the nutritious bran wrapped protectively around the […]

Navigating the Ins and Outs of Renting an Airbnb (Including Guidelines for Shabbos and Pesach)

By: Rabbi Zvi Goldberg

Winter 2024

Who would have imagined, just a few years ago, that you could go on vacation and rent a stranger’s private home? But that is exactly what people now do every day, with the rise of Airbnb and similar short-term rental platforms that list millions of units in over 100,000 cities.[1]

A Torah-observant individual who enters into such an arrangement will encounter numerous halachic challenges when signing up as an Airbnb “guest.” This includes properties listed as “kosher” – even ones in Israel – since an owner usually cannot vouch for every renter who has used the kitchen, nor for each renter’s kashrus standards, which can vary widely. Likewise, one who owns and is the “host” of an Airbnb property will have to address his own set of halachic concerns. Let’s analyze some of the more common ones.

Kashrus Concerns During the Year (Excluding Pesach)

The primary area of concern for […]