An insatiable appetite for homemade delicacies and an app are transforming the way overseas Chinese prepare and eat their meals, although some concerns have been raised about food safety.

Developed by Chinese tech giant Tencent and released in 2011, WeChat now has more than 800 million users. The app has also spurred the underground food industry to flourish among Chinese Americans.

It's a blend of a social media network and e-commerce platform - and "basically Facebook, Amazon, Yelp, Twitter, Venmo and Netflix rolled into one" - as Hans Tung, managing partner at GGV Capital, once called it. WeChat enables large or small-scale vendors, the so-called WeChat business (weishang), to advertise and sell whatever merchandise that might interest members to a social group capped at 500 members.

A B2C or P2P business model is based on whether the vendor is a business entity or individual. weishang especially thrives in the culinary sector thanks to overseas Chinese peoples' limitless desire for hometown delicacies and fresh, healthy food ingredients.

Lily Zhang, a Sichuan native and now a resident of the San Francisco Bay Area, said she couldn't find authentic Sichuan cuisine at any local restaurants after she moved from the east coast to northern California in 2005.

"That's until this January, after I joined our local Pleasanton Diners WeChat group," she said, adding that now she can order homemade crown daisy rice cakes, chicken with cayenne pepper, spicy sausage and steamed jujube flower buns from vendors.

"They taste just as good as they did in my memories," she said.

Zhang said the vendor usually sends messages about food availability with pictures and a short description to the WeChat group, answering questions on ingredients, preparation and delivery times.

Customers can choose from several sites for food pickups.

"Once you've submitted the form, you're done. It's very convenient and easy," Zhang said. "Online food shopping on WeChat is now my biggest expenditure every month. It can be as much as $1,000 and I think it's worth it."

Athena Li, a business analyst on a hectic work schedule and a mom to a 5-month old, said she turns to weishang for instant dinner solutions.

"I don't have the luxury of two to three hours for dinner preparation, so the ready-to-cook combination of meat and vegetables, both organic and freshly raised and picked up from local farms, has become my top choice," Li said.

The analyst routinely orders organic cauliflower, broccoli, kale, squash and beet, together with pork, beef and chicken, and asks for same-day home delivery.

"As a new mom feeding my daughter, I can't afford to have polluted or heavily-processed food," Li said, adding that her online-to-offline food-shopping experience so far has been pleasant.

"I've asked several times about where the food comes from and they said within a radius of 30 miles," she added.

Despite the appeal of ordering online, there are some food safety concerns, because most of the individual vendors are not licensed or regulated. The State of California in 2012 passed a so-called cottage food law that allows some homemade food to be sold on a small scale.

On the law's non-potentially hazardous food list are jams, pastries and confections such as fudge and flavored popcorn. Meat is prohibited from any transactions.

The issue of food safety and integrity is a concern of Jun Wang, a chemist in south San Francisco.

"The fear of food-borne illness and being uncomfortable with the sources of food sold on WeChat keeps me away from them, although they really make my mouth water sometimes," Wang said.

"(But) I would rather resist the temptation than ending up with a visit to a hospital emergency ward," he said.

"Food storage, transportation and processing; the whole process needs high-standard quarantine and temperature and humidity controls. I don't think weishang vendors are sufficiently equipped with the required knowledge."

Regulations for weishang and food vendors through WeChat are not in place. There are no US regulations saying people can't buy from unlicensed vendors.

"I will continue to (buy) until one day the government bans them," Lily Zhang said, adding that she was about to pick up a new order of steamed pork buns and dumplings.

junechang@chinadaily.com.cn