Two Italian studies found room-temperature white tea higher in antioxidants than hot

In 2010 a research group at Marche Polytechnic University in Italy published a comparison of five loose teas. Each was steeped two ways: in water at 90°C (194°F) for seven minutes, and in room-temperature water for two hours.

On two antioxidant assays, the hot and cold cups showed no significant difference, with one exception. White tea measured significantly higher after the cold steep¹, which the authors called "a recurrent finding in this study."

In 2014 four of the same authors repeated the comparison on white teas alone, hot water against room-temperature water. For every white tea they studied², the room-temperature infusion held more phenols, flavonoids and catechins than the hot one, and showed more antioxidant activity.

Across the five teas in that first study, antioxidant activity tracked each tea's total phenolic content and its ability to bind metals. In two further test-tube measures, the cold infusions generally did better¹ than the hot ones.

What the white-tea study measured

The 2014 study gives ranges across all its white teas. Phenols in the cold infusions ran from 4.77 to 7.63 millimoles per litre², measured as gallic acid equivalents, and in the hot infusions from 1.43 to 4.02. The lowest cold figure sat above the highest hot one. Catechins ran from 441.5 to 1,328.2 micrograms per millilitre cold, against 83.4 to 534.8 hot.

The antioxidant tests followed the same pattern. On the ABTS assay, cold infusions scored 17.09 to 34.23 millimoles per litre of Trolox equivalents, and hot ones 5.26 to 17.07². When the infusions were added to LDL in a test tube, the delay before it oxidised ran 172.4 to 271.2 minutes with cold tea and 88.4 to 145.9 minutes with hot.

Metal-binding activity was similar across all the white teas², between 0.3 and 0.6 millimoles per litre of EDTA equivalents. Hot and cold did not differ significantly except in two teas, Bvumbwe Bsp and Thyolo Bsp.

Which white teas came out ahead

The 2014 authors described a general trend among the teas in antioxidant activity and polyphenol content. Among the Chinese teas, Bai Mu Dan, Xue Ya and White Lung Ching led², each at least level with the next, ahead of Anji Needle Mao Feng. Yhin Zhen Bai Hao, the paper's spelling of bai hao yin zhen (silver needle), came last. Among the African teas, White Salima Peony led, ahead of Thyolo Bsp and then Bvumbwe Bsp.

When the cold steep lost

In 2023 Carloni and Damiani, with other colleagues, brewed teas grown in European gardens both ways again. The cold brew sat 16 hours in a refrigerator at 4 to 6°C (about 39 to 43°F); the hot brew steeped five minutes in boiling water³. In most cases the hot brew held more phenols, whatever the type of tea. Its two white teas differed. One from Germany measured 7.1 cold and 6.7 hot, in millimoles per litre of gallic acid equivalents, a gap the paper's statistics did not separate. One from the Azores measured 1.6 cold and 4.2 hot.

A 2016 study at the University of Malaya steeped white, green and black teas at a range of times and temperatures. Its white tea showed the highest activity in prolonged hot extracts⁴, and in some assays in prolonged cold ones as well; for green tea, the highest activity came from prolonged cold steeping.

How this sits with hot brewing

A 2018 study from Granada brewed white teas at 60 to 98°C (about 140 to 208°F) for 3 to 15 minutes, and below 80°C only a 15-minute steep pulled significantly more from the leaf. Given two hours, room-temperature water out-measured a hot steep on white tea in both Italian papers.