Authorities in China's Qinghai and Gansu provinces announced on Monday that they will investigate the planting and processing of goji berries following a media report alleging that farmers used chemicals to enhance the berries' appearance.

The Golmud city government in Qinghai said in a statement that a special task force has been established to conduct overnight inspections of the production, processing, and sales of goji berries in response to a report by China Media Group (CMG). The report accused some merchants of illegally using sodium metabisulfite, a chemical with whitening and preservative properties, to process goji berries.

"Those found responsible for illegal activities will be severely punished according to the law," the Golmud city government said. The results of the investigation and any subsequent actions will be promptly disclosed to the public, it added.

The food safety authority in Jingyuan County, Gansu, also announced the formation of a joint investigation team to examine the planting and processing of goji berries. A special inspection will be conducted throughout the county, and the findings will be made public, the authority said in a statement.

The CMG report, which aired Monday evening, revealed that some farmers in Golmud and Jingyuan were adding sodium metabisulfite or industrial sulfur during the production of goji berries to improve their color and appearance. In Golmud, local regulations explicitly prohibit the use of sodium metabisulfite and its substitutes in the production and processing of goji berries and related products.

Despite the regulations, farmers at a farm in Golmud admitted to using the chemical to enhance the appearance of goji berries that were otherwise unsellable due to poor quality. The farmers claimed they would suffer financial losses without the use of sodium metabisulfite.

In Jingyuan, where goji berry cultivation covers approximately 280,000 mu (about 18,667 hectares), the CMG investigation found that freshly picked goji berries were being washed with sodium metabisulfite and fumigated with sulfur to maintain their appearance during unfavorable weather conditions.

Sulfur, which is toxic and poses health risks, should not be used in food processing. Some merchants in Jingyuan were reportedly using industrial sulfur to cut costs. The investigation uncovered several plastic sheds set up by merchants in Jingyuan villages for the purpose of sulfur fumigation. These sheds, emitting pungent gases that made breathing difficult, were dismantled by daylight.

The CMG report indicated that sulfur-treated goji berries were sold to hot pot restaurants and pharmacies, and used to make goji berry wine.