As the sun rises on a crisp March morning, a van from the Hebei Dongfang Green Tree Food Company picks up Rabbi Nosson Rodin at his home in Beijing.

During the four-hour journey to the company’s factory in Shenzhou, Rodin calls for a break to recite his morning prayers. He wraps his tefillin at a rest stop as curious truck drivers look on, then gets back into the vehicle.

For the Amidah prayer, the van pulls off the dusty road and Rodin consults the small green compass on his watchband. He needs to pray facing west, toward Jerusalem.

It’s all part of a routine day for Rodin, 24, a Chabad-Lubavitch emissary who does Jewish outreach in Beijing and also travels the countryside performing kosher inspections in China for U.S. companies.

America’s largest kosher-certification company, the Orthodox Union, now inspects more than 300 factories in China — doubling the number of certifications it’s provided in the past two years.

The kosher food market here has experienced tremendous growth. Half of China’s $2.5 billion in exports of food ingredients to the United States are kosher, up 150 percent from two years ago, according to Bloomberg News.

Green Tree first looked into kosher certification in 2005, about the same time the company began exporting its products.

“We met a Jewish customer who wore a small hat on his head,” recalls Lucy Zhang, Rodin’s interpreter from Green Tree. “He asked us if our food was kosher. He explained if it was kosher, then Jewish people could eat it.”

“The only way to explain kosher to a company here is to explain it’s for export,” says Rabbi David Markowitz of Shatz Kosher Services, a kosher certification label.

Kosher certification costs $3,000 to $5,000 per year on average, Markowitz says. In exchange for access to the $11.5 billion kosher food market in the United States, many Chinese companies are willing to pay the price.

Markowitz opened Shatz Kosher Services in China five years ago and recently added a location in Vietnam. The rabbi lives in Israel but spends about two weeks each month working in China.

Aside from its office near Hong Kong, Shatz also has one in China’s Shandong Province, where many fruits and vegetables are grown and processed.

Canned, frozen and dried fruits and vegetables are the most common kosher products from China, but many chemical additives and finished products, such as candy, also are certified here.

Providing kosher supervision means paying attention to a product’s components. Instead of conducting scientific health tests, kosher inspectors check a

company’s compliance with rules about its ingredients and preparation.

Most factories have a few scheduled inspections each year. In situations in which sweeping changes are required to make a product kosher, kashrut services usually decline to certify the product.

During his visit to the Green Tree plant, Rodin is as interested in what lies behind closed doors as he is with what’s on the apple chip production line.

He insists on opening the doors, even inspecting a flattened cardboard box with an unfamiliar label that lies discarded in the corner. As possible evidence of unaccounted-for ingredients that could be nonkosher, the discarded box is suspect.

“Since they don’t really understand what I am looking for, they don’t know what to hide,” Rodin says.

Although kosher certification has been around for years in China, the landscape of food quality control in the country is undergoing drastic change.

In September 2007, following negative publicity in the United States and elsewhere about the discovery of tainted food products, Chinese regulators began requiring companies to use numbered codes on packaging to identify the plants of origin for products. This way, all ingredients could be traced to their sources.

The Orthodox Union began using a similar oversight system in China as far back as 2001, an O.U. representative said.

Most Chinese who work with kosher supervisors still know little about kosher laws, but no longer are they completely ignorant about the practices of their Jewish colleagues.

Rabbi Amos Benjamin of the Baltimore-based Star-K kosher certification company has been certifying products in China as kosher since 1987.

“Ten years ago when you visited a factory here, they had generally no idea what kosher certification was,” he said. “Now, 10 years down the track, they understand more.”

Though the food companies under inspection provide English-speaking interpreters, some of the rabbis here have picked up basic Mandarin.

Benjamin, who speaks several languages, says Chinese is the most difficult to learn. Perhaps it’s because his conversations in Chinese are so unusual.

“I don’t know the last time you sat around the coffee table discussing techniques of fermentation, but I can do that in Chinese,” he says.