A Vietnamese style black sandwich. Photo courtesy of Bamito. 

Whether its bread, ice cream or moon cake, Vietnamese are increasingly preferring it to be black-colored. 

Tuan, owner of a bakery in northern Ha Long Town, sells 300-700 black banh mi (Vietnamese sandwich) a day for VND25,000-45,000 ($1.08-1.94) each.

He makes the bread using flour and bamboo charcoal, which is believed to be a natural detoxifier though there has been no formal research into it.

He said many people come to buy the sandwiches for their unusual look and taste.

Similar black sandwiches are also sold in Ho Chi Minh City, Binh Duong and Dong Nai in the south.

Hieu in HCMC’s Phu Nhuan District sells over 1,000 of them a day. A friend had suggested the idea to him after returning from Japan, where bamboo charcoal is a popular ingredient in food and beauty products.

During the Mid-Autumn Festival this year, on October 1, black charcoal moon cake was a sought-after item.

Hang in HCMC’s District 3 sold out all 3,000 of her black moon cakes a week before the festival though they cost more than regular cakes.

A person holds a black ice cream. Photo courtesy of Benuscream.

Bamboo charcoal is also used in ice cream. Mai Truong Giang, owner of fried chicken chain Otoke Chicken which sells this product, said bamboo charcoal has been used in food in many countries for long to create an unusual look.

But there are concerns about the use of imported bamboo charcoal without quality standards, he said.

Coloring food black could just be a fad and fade away after a while, he speculated.