Full disclosure: I live in Sichuan and think its strong-aroma baijiu is the best spirit China produces. But the Chinese seem to have my back on this one. Somewhere between about twenty-five and seventy percent of the baijiu on the market is produced in Sichuan (a lot of the baijiu “produced” elsewhere is made with alcohol from Sichuan, about which more in a later post). The secret to strong-aroma baijiu is in a complex, labor-intensive process that goes back roughly 500 years.
Preparation of ingredients: There are two distinct strong-aroma varieties: single-grain and multigrain. Single-grain strong-aromas use sorghum, whereas multi-grain can use just about anything. The most famous multi-grain, Wuliangye 五粮液, uses sorghum and also glutinous rice, long-grain rice, corn and buckwheat. A similar mixture is used by Jiannanchun 剑南春 and Shuijingfang 水井坊 (who substitute wheat for buckwheat). As always, the ingredients are washed, steamed and cooled.
Preparation of qu: Sichuanese baijiu uses wheat-based bricks of “big qu.”
Saccharification and fermentation: The defining characteristic of strong-aroma baijiu is the use of fermentation pits. These are typically rectangular earthen pits a few meters deep, in which the ingredients and qu are buried for a period of several weeks (sometimes months) to ferment. Over time the bacteria and microorganisms, as well as some of the alcohol itself, seeps into the walls. This is supposed to enhance the flavor and overall quality of the pits. It takes a few years of use before a pit is considered good enough to produce high-quality spirits, and around thirty years before it is considered top shelf.
The oldest pits in continuous operation are in Luzhou – the Guojiao 国窖 (National Cellar) 1573 pits. Chengdu’s Shuijingfang 水井坊 also claims the oldest pits. The Quanxing company (Shuijingfang’s former parent company) uncovered Ming dynasty pits under one of its distilleries in an archeological excavation in the late nineties, and have since incorporated bacteria discovered at the site into the Shuijingfang pits.
Spent grains from distillation are often mixed with fresh grains and returned to the same pit (what’s known as a sour mash), to ensure continuity between batches. Some producers prefer to employ what is called “pit running,” by which grains rotate from one fermentation cycle to the next – the number of cycles also varies.
Distillation: When the mud casing is removed from the top of a pit, the mash is taken out and distilled a layer at a time. The mash enters the still in a solid state and is essentially steamed in order to collect the alcohol.
Aging: The baijiu is moved to earthenware vats and typically aged for at least a year, sometimes several years. It is then mixed with water to achieve the desired strength.
Making strong-aroma is a labor-intensive process that results in an excellent spirit with a complex taste profile and a thick, pungent aroma. If it is not the best baijiu category, it is certainly the most expensive at the high-end. This is also where the great bulk of foreign investment in baijiu is seen, as most believe the spirit has the highest potential as an international luxury product.
Next up, in the final installment in our series on making baijiu, is strong-aroma’s southwestern cousin: sauce-aroma.
 I agree that this is a fairly large range, but reliable statistics on the baijiu business are hard to come by. I’d guess the real figure lies somewhere in between, but in any case Sichuan almost certainly produces more baijiu than any other province.