Author Archives: Rabbi Zvi Goldberg

Raising Cane: The Kashrus and Other Halachic Issues of Cane Sugar

By: Rabbi Zvi Goldberg

Summer 2026

The first reference to sugar in the Torah is in Shir HaShirim (5:1): “yaari im divshi – “my forest with my honey” – which some commentators [1] deem to be referring to cane sugar and deduce that sugar canes are considered trees.

Sugar is a fascinating commodity. It was not always as plentiful or cheap as it is today. A homemaker living in London in 1319 would have had to pay two shillings for a single pound of sugar – the equivalent of roughly $50 in today’s dollars – and was unaffordable by most people. Even in the 1700s, sugar was considered a luxury item and referred to by some as “white gold.”

Fast forward to the current sugar market. Refineries nowadays can store more than 100,000 tons of raw sugar at a time. To put that staggering quantity into perspective, if all […]

Eretz Tzvi: Halachos of Visiting Eretz Yisroel

By: Rabbi Zvi Goldberg

Winter 2025 | Updated June 2026

Eretz Yisroel is also called Eretz Tzvi. Chazal explain that, like the skin of a tzvi (a deer), which stretches beyond its natural state, the Land of Israel likewise expands to accommodate its inhabitants.[1] The Talmud states that anyone who walks four amos in Eretz Yisroel merits a place in the World to Come.[2] From here, some poskim derive that one fulfills a mitzvah merely by visiting Eretz Yisroel, even if one intends to stay for just a short while.[3]

Anyone planning a trip should be mindful of several pertinent halachos. We will review some of these below.

Scheduling the Flight

Do not plan to land too close to Shabbos; a flight landing on Friday morning is halachically acceptable.[4]

Try to avoid leaving Israel on a fast day, as the fast will be extended and you will not […]

The Intriguing World of Jewish Time

By: Rabbi Zvi Goldberg

Listen here.

Listen to host Rabbi Zvi Goldberg and his guest, Jewish time expert Rabbi Dovid Heber discuss Jewish time (10/6/21). They answer your questions in addition to discussing:

• a ‘behind the scenes’ review of Rabbi Heber’s new book, The Intriguing World of Jewish Time

• how time affects kashrus certification

• the “World Calendar” and how it would have affected Jewish life

• why a girl cannot become bas mitzva in Adar 1

The Jewish calendar is complex, but Rabbi Heber makes the topic clear and easy to understand. In addition to his newly published work which includes 150 questions and answers on Jewish time, he previously authored Sefer Shaarei Zmanim.

STAR-K Webinar Audio: Medical Devices Certified for Shabbos

By: Rabbi Zvi Goldberg

Medical Devices Certified For Shabbos

The Audio for this episode can be found here.

STAR-K Webinar Audio: Chocolate Production in Peru

By: Rabbi Zvi Goldberg

Peru Visit – Chocolate Production

The Audio for this episode can be found here.

STAR-K Webinar Audio: Passover Products 2022

By: Rabbi Zvi Goldberg

Passover Products 2022

Audio for this webinar can be found here.

Quinoa, the Grain That’s Not: Then Why the Need for Passover Certification?

By: Rabbi Zvi Goldberg

January 2026

Tired of potatoes, potatoes and more potatoes on Pesach? Maybe give quinoa a try.

Quinoa is one of the most nutritious foods on the planet – cooked like rice, is gluten-free and loaded with vitamins and minerals. Even NASA has considered quinoa for its long-duration planetary space flights. Quinoa has become increasingly popular in the United States, Canada, Europe, China and Japan, where the crop is not typically grown.

What is Quinoa?

Quinoa (pronounced kin-wa) is a species of seeds of the Chenopodium (or “goosefoot”) family, which includes sugar beets and beet root, and is botanically related to spinach. It was first brought to the United States from South America in the 1980s. Seeds range in color from pink and orange to blue-black, purple, and red. However, once their natural saponin coating is washed off, the seeds are pale yellow.

Quinoa has been cultivated in the Andes Mountains […]

Feeding Your Pet: Barking Up the Right Tree

By: Rabbi Zvi Goldberg

Reviewed February 2026

To some people, the concept that there are restrictions regarding what can be fed to animals may seem amusing. They wonder, “Really now, must dogs also eat kosher?” Of course, animals don’t need to eat kosher food. However, Halacha clearly instructs people regarding what, how and when to feed them.

The Talmud Yerushalmi1 states that before acquiring an animal, one must be sure he will be able to properly provide for it. Certainly, the owner must also know the applicable halachos. The following is a discussion of some of these halachos, including the subjects of meat and milk mixtures, Pesach, buying and selling non-kosher pet food, feeding animals on Shabbos and Yom Tov, and feeding animals before you eat.

STAR-K is not necessarily recommending ownership of pets; rather, we are providing information for those owners who require it. We recommend that you discuss with […]

The Traveler’s Halachic Guide to Hotels

By: Rabbi Zvi Goldberg

Spring 2010 | Updated December 2025

Yosef chose the hotel he was staying in for its many amenities, not the least of which was the free Continental Breakfast it offered its guests. Surely, when kosher symbols on products are becoming more and more prevalent, he wouldn’t starve! The breakfast menu included cereals, pancakes, waffles, muffins, pre-cut fruits and vegetables, hardboiled eggs, as well as hot coffee and juices. Can Yosef eat anything offered on the Continental Breakfast menu, or should he prepare his own breakfast using the microwave and coffeemaker in his hotel room?

Chana’s brother’s bar mitzvah, held in a hotel during Shabbos, turned out to be a real nightmare! The closet light went on automatically when she opened the closet door; the housekeeper had turned off the light in her room, preventing her from reviewing her parsha notes; she drank a bottle of water from her room’s […]

Navigating the Ins and Outs of Renting an Airbnb

By: Rabbi Zvi Goldberg

Winter 2024 | Reviewed January 2026

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 […]

Delivery and Ride Apps – Halachically App-roved?

By: Rabbi Zvi Goldberg

Kashrus Kurrents Summer 2021 | Updated August 2026

With the advent of the latest apps, a whole new world of halachic scenarios has arisen.[1] These include shailos about using food delivery services, working for a food delivery or ride app, and even calling and using a ride service. These various situations will be addressed here.[2]

Ordering from Meal Delivery Apps

Meal delivery apps like Uber Eats,
Grubhub, DoorDash and Postmates have seen tremendous growth over the last few
years. For our discussion, we will use Uber Eats as our example, but the concerns
raised apply to the comparable apps.

A customer orders from a restaurant that has contracted with Uber Eats. When it is ready, an Uber Eats driver picks it up from the restaurant and delivers it to the customer. Here are some points to consider when ordering from a kosher restaurant:

Is the food properly sealed?

Delivered food must […]

Getting Into Hot Water: Urns & Pump Pots in Halacha: Part 2 – Shabbos & Yom Tov

By: Rabbi Zvi Goldberg

Spring 2020 | Updated January 2025

Electric urns greatly enhance our oneg Shabbos and Yom Tov by allowing us to effortlessly enjoy hot drinks. However, the technological advances that permit us to use urns on demand come along with a host of halachic considerations that must be carefully reviewed.1

A summary of the various halachic considerations in the usage of electric urns, pump pots and commercial urns are addressed in this article. An urn is a heater that lets the water out through gravity using a lever at the bottom of the urn. A pump pot uses a pump at the top to force the water out. In this article, the term urn is used generically to refer to a pump pot, as well (except as noted in the section about the water level tube).

Keep in mind that there are many different types of devices, and not every […]

Don’t Miss the Boat: Halachic Guidelines of Kosher Cruises

By: Rabbi Zvi Goldberg

Fall 2018 | Updated June 2026

The task of food preparation aboard a modern cruise ship is enormous. Activity begins even before the first passenger comes aboard. Needless to say, food is central to a cruise. “Kosher Cruise” may simply imply that the food is kosher; other halachic issues may not have been addressed by the kosher certification agency. In this article, we will examine kashrus, as well as other topics including Shabbos, davening and tznius.

Kashrus

Providing kosher supervision on a cruise ship is not an easy task. “Mega-ships” can carry over 4,000 guests.1 Food preparation occurs around-the-clock in multiple locations. Most often, a ‘kosher cruise’ means that an entrepreneur has booked a number of cabins aboard a large ship. In such an arrangement, kosher and non-kosher food will be prepared and served simultaneously.

The traveler must have confidence in the kashrus agency that is certifying the cruise. In order to instill confidence, a reliable kashrus organization […]

Kashrus Konnections For the Kashrus Professional

By: Rabbi Zvi Goldberg

Periodically, Star-K distributes “Kashrus Konnections”, a compilation of policies meant for the kashrus professional. Some items may be of interest to consumers as well. Below are some of the topics addressed in past issues. To sign up to receive the publication via e-mail, send a blank e-mail to [email protected].

I am going to a Star-K restaurant over Chol Hamoed Sukkos. Will I have to take the food out or will there be a sukkah on the premises?

Star-K policy is that eateries must have a sukkah available for customers on Sukkos. (It is important to note that due to the kedusha of a sukkah, a garbage can may not be put inside.)

If an electric coil on a range-top does not get red-hot, may it still be kashered?

Yes, it may be kashered as long as it gets to libun kal (550°F). Any residue […]

Shiluach Hakan

By: Rabbi Zvi Goldberg

Spring 2017 | Updated September 2026

Shiluach Hakan1 (sending away the mother bird before taking her young) is a mitzvah that is infrequently performed. Its reward is the blessing of a long life – similar to the mitzvah of honoring one’s parents. Let’s examine how, when and where to perform the mitzvah of Shiluach Hakan.

“If a bird’s nest happens to be before you…young birds or eggs, and the mother is roosting…you shall not take the mother with the young. You shall surely send away the mother and take the young for yourself, so that it will be good for you and will prolong your days.”2

Possible Reasons for the Mitzvah

The Rabbis ruled that a person may not state that the reason for the mitzvah is compassion for the mother bird. One commentator interprets the Talmud’s prohibition as applying strictly to reciting this in one’s prayers, as […]

Getting Into Hot Water: Urns and Pump Pots in Halacha: Part 1 – Tevila and the Workplace

By: Rabbi Zvi Goldberg

Spring 2014 | Updated June 2026

Remember when making coffee meant putting a kettle on the stovetop and waiting until it whistles? Today, electric heating has taken over the market in order to fill the need of having hot water on-demand.

Two of the popular types of electric hot water heaters on the U.S. market are the common aluminum urn with a plastic spout, and the relatively newer ‘pump pot’, which requires that you push down on the top plunger to pump out the water.

TEVILA

The Torah requires that utensils used for a meal be immersed in a mikvah if they were in possession of an aino Yehudi at any time. The Talmud1 states that mechamei chamin, hot water kettles, also require tevila. Rav Moshe Feinstein2 explains that there is a novelty in this ruling. One can argue that a kettle requires no tevila at all. The kettle doesn’t perform any meal preparation function since heated water has not really changed; it is just […]

Laws of Biur Ma’aser

By: Rabbi Zvi Goldberg

Published Spring 2015 | Updated March 2026

The Land of Israel follows a unique seven-year cycle. For the first six years, fruits and vegetables grown there are tithed.1 The seventh year is Shemita, the sabbatical year, which has its own set of special laws. These laws mainly affect those living in Israel, but also those living in the Diaspora if they are in possession of Israeli-grown produce.2

For the tithing of the first six years, the Torah 3 sets an end date for the process called Biur Ma’aser. Biur Ma’aser includes a number of components, which are still applicable today:

Biur Ma’aser

Any untithed produce (tevel) in one’s possession must be tithed by Erev Pesach 4 of the fourth and seventh years of the Shemita cycle.5

Ma’aser Sheini is the second tithe separated on produce harvested in the […]

Hydroponics

By: Rabbi Zvi Goldberg

The AeroGarden is a unique hydroponic system, enabling home-growing of vegetables. ( Note: STAR-K no longer certifies The Aerogarden) The entrance of this system into the marketplace presents an opportunity to discuss the history and halachos of hydroponics.

Shmitta 5768

By: Rabbi Zvi Goldberg

Published Fall 2007

Dates of Kedushas Shviis, sfichim, and biur can be found in our 2008 Pesach Directory, click here.

For over nineteen hundred years, the Jewish people have longed to return to Eretz Yisroel, the land of Israel. It is only there that we can realize our full potential as a nation, and the Torah’s blueprint for life can be completely fulfilled. Throughout the millennia, the most important dimension of this yearning was to once again be able to fulfill the mitzvos hatluyos ba’aretz (agricultural laws), the commandments that can be observed only in the land of Israel. With Hashem’s help, many of us in this past generation have realized part of this two thousand year-old dream. Yet, this realization has presented us with new challenges.

Raising Cane: The Kashrus and Other Halachic Issues of Cane Sugar

By: Rabbi Zvi Goldberg

Summer 2009

It is noteworthy that in both Jewish and secular sources, the first recorded references to cane sugar are attributed to Jewish kings. In Shir HaShirim1, Shlomo Hamelech writes “Yaari Im Divshi,” “My forest with my honey.” Some commentators2 deem this to be referring to cane sugar and deduce that sugar canes are considered trees. Secular sources indicate that cane sugar was first used by man in Polynesia, and from there it spread to India. Darius of Persia invaded India, where he found “the reed which gives honey without bees”. Darius was the son of Achashveirosh and Esther[...] Read More

Getting a Handle On Your Faucet

By: Rabbi Zvi Goldberg

Winter 2012 | Updated May 2025

Torah-observant Jews know that turning on the hot water faucet during Shabbos causes cold water to be heated, which transgresses the melacha of Bishul, cooking. What many don’t know is that even turning on what you think is cold water can be a problem – if it’s a one-handled faucet.

Let’s first analyze why using hot water causes cold water to be heated. In a typical home setting, cold water arrives from the city supply under pressure. Turning on the hot water faucet allows this cold water into the hot water tank which, in turn, forces out the hot water already in the tank. Since the water in the tank is typically more than 120°F (the minimum temperature for bishul on Shabbos), the incoming cold water is immediately heated by the hot water that is already in the tank. [...] Read More

The Visitor’s Halachic Guide to Hospitals

By: Rabbi Zvi Goldberg

Published Spring 2009
Updated Fall 2018

A person visiting a hospital patient is performing the great mitzvah of bikur cholim . It is one of the mitzvos for which a person reaps benefits in this world, while the principal reward is saved for the next world. While visiting the sick, some halachic issues may arise. This article addresses these issues from the visitor’s point of view. Questions affecting the patient (such as adjusting the bed, using the call button, and asking the staff to perform tasks on Shabbos ) are important issues that should be posed to one’s rabbi.