Shu (Ripe) Pu-erh generally has a milder taste and effect. Commonlly the quality of the tea depends on the quality of raw materials. The bouquet of a fine black Shu Pu-erh presents a pleasant earthy, nutty, or chocolatey flavor and velvety and deep taste. You can drink Shu Pu-erh on an empty stomach (unlike young Sheng Pu-erh) and even before bedtime (if aged) but the infusion concentration should be light. Contrary to popular belief the taste of black puerhs may change with time though not as significantly as it will in the case of Sheng Pu-erh.