Jiuqu (), also simply known as qu, is a type of dried fermentation starter used in the production of traditional Chinese alcoholic beverages. The word jiuqu specifically refers to a type of yeast () used to make alcohol () such as huangjiu (cereal wine), baijiu (distilled spirits) and jiuniang (alcoholic rice pudding).
Other forms of starters are used for different fermentations, such as soy sauce, rice vinegar, fermented bean curd, and paste. The starter culture for these foods are also known as qu.Shurtleff, W.; Aoyagi, A. History of Koji - Grains and/or Soybeans Enrobed with a Mold Culture (300 BCE to 2021). Lafayette, California: Soyinfo Center. 660 pp. (1,560 references; 142 photos and illustrations, Free online)Jiuqu is similar to, but distinct from, the more widely known Japanese starter known as koji. Science and Civilisation in China
The starter creation process in China traditionally took place in homes, villages, or small manufacturing facilities, later shifting to large-scale facilities.
History
In China, particular cultivars of jiuqu are known as , , or simply as qu. Qū is known as nuruk in Korea, much or marcha in India and Nepal, banh men in Vietnam, pacing in Laos, loog pang in Thailand, Ta-Say in Myanmar, mae domba in Cambodia, ragi in Indonesia and Malaysia, and bubo in the Philippines. The tradition of making qū is believed to have originated in China 3000–4000 years ago, and introduced throughout East Asia, Southeast Asia, and South Asia.Shurtleff, William, and Akiko Aoyagi. History of Koji-Grains And/or Soybeans Enrobed with a Mold Culture (300 BCE To 2012): Extensively Annotated Bibliography and Sourcebook. Soyinfo Center, 2012.
Qu is mentioned in the Book of Documents, one of the Five Classics of ancient Chinese literature and a foundational work in Confucianism. A book from the Shang dynasty () states that "to make wine or sweet liquor one needs qū nieh". Most authorities concur that qū describes the preparation of ferments, while nieh refers to sprouted grain. They may have formed separate elements of liquor production (both qū and nieh) or might refer to a single preparation made of fermenting sprouted grains (qu nigh). The Book of Documents predates 500 BC, so the ancient predecessor of qū may be the world's oldest example of biotechnological manufacturing.
Qu is mentioned in the Zhouli (), a collection of texts from the Eastern Zhou dynasty. It is described in preparing fermented meat and a grain–meat paste. At Mawangdui (200 BC10 AD), bamboo strips in Han Tomb Number 1 documented an inventory of tomb contents that included two sacks of qu. The Liji (100 AD), a collection of texts from the Eastern Han dynasty, mentions qū as one of six requisites to make good wine. Another almanac from the Eastern Han dynasty, the first-century AD Shuowen Jiezi records a character for qū modified to include the yellow chrysanthemum flower. This was interpreted as referring to the distinctive yellow color formed on qū by sporulating molds. The Shiming (151) mentions several types of qu, which are interpreted as distinguished by the source of the starch and the form of the substrate. It claims that since the Han dynasty qū was produced in China from mostly wheat or barley and pressed into cakes or bricks for handling. The earliest reference to the actual preparation of qū appears in the Qimin yaoshu (544) of the Northern Wei dynasty. There the techniques employed for making nine separate kinds of qū nigh are described in detail, along with their usage in the manufacture of 37 wines. The usage of qū in making vinegar, soybean pastes, and soy sauces are documented. The Qing yilu (, 965) recorded the use of a special red starter for the first time.
The fourth-century Nanfang Caomu Zhuang has the earliest description of preparing a natural "herb ferment" with rice, used to make a special wine for marriage ceremonies. "In [Nanhai, in Guangzhou] there are many fine wines, prepared not with yeast leaven but by pounding rice flour mixed with many kinds of herb leaves and soaked in the juice of Gelsemium elegans (). The dough, the size of an egg, is left in dense bushes under the shade. After a month, it is done and is used to mix with glutinous rice to make wine. Therefore, when consumed in large quantities, occurs, hot and sweaty head even after the effects of intoxication have subsided, as the drink contains toxic herbs. The roots of yege are poisonous."
Production Making qu involves cultivating microbes in starchy materials and is a separate process that precedes the fermentation of grains and legumes into food or alcoholic beverages. Traditional practices vary and diverge from the later processes used for industrially-produced qu.Xiaoqing Mu et al "Solid-State Fermented Alcoholic Beverages", in Chen, Jian, and Yang Zhu, eds. Solid State Fermentation for Foods and Beverages. CRC Press, 2013.
The major manufacturing principles are:
Preparation of cereal grains, usually rice, or a dough made from them Inoculation with previously grown microbiota (generally 4–8% mass) Incubation in a warm, humid environment for a set duration to stimulate the growth and metabolism of the microbiota Desiccation to preserve the functional properties
Qu can be sold fresh or stored for up to three years, without significant loss of viability.
Substrate ingredients vary across China by regional preferences, availability, and the type of qu ultimately being produced. The most common flours used in daqu are wheat and barley/peas. The preparation of hong involves only whole rice grains. Herbs of many kinds are variously included in the rice dough of many xiao preparations.
Traditional methods have changed little since the publication of the Qimin Yaoshu (544 CE). Grains or flours are saturated with water (e.g., steaming rice or mixing flour with water to form a dough) and subsequently incubated in a warm, humid environment during a favorable season, typically spring or autumn. No inocula are used, but often herbs are added. To keep the grains or dough relatively moist and warm, they are housed in closed straw-roofed huts and typically kept in straw baskets, stacked on wooden shelves, or simply placed on the floor. Leaves of various plants, often straw, mulberry leaves or Artemisia, are used to wrap or cover the qu to promote a beneficial condition. The presses and molds used to shape the dough are made of wood. All of these elements unknowingly provided access to the microbes. The cakes are deemed ready when a colored coating forms on the outside. They are then dried and stored until used. The control of moisture and temperature levels and a lack of atmospheric access was recognized as vital to making consistently good qu as early as the Qimin Yaoshu.
One aspect that has changed is the method of re-culturing for later preparation. Traditionally, microbes indigenous to the raw material, the process, and the locale simply grew upon the grains or dough. At some stage in history, it was discovered that using small amounts (2–8% mass) of a previous successful batch to inoculate the current one gave more consistent results. The starter cultures are often handed down from generation to generation in a continuous cycle of serial re-culturing. The most important functional organisms in qu have been recognized as the filamentous molds Aspergillus and Rhizopus, which reproduce only asexually through spores called conidia, so an important step in manufacturing is to allow some of the cultured substrate to mature and sporulate to inoculate the next batch. Most of the other microbes present are capable of vegetative budding (yeasts) or binary fission (bacteria) and propagate without intervention.
The incubation and maturation phase is a typical biomolecule manufacturing process using solid-state fermentation. Yeasts and bacteria are often used in industrial submerged fermentation because they thrive at high water activity and reduced oxygen levels. Molds, however, prefer the lower water content and increased oxygen found in solid-state fermentation. The steaming of grain or making of dough creates a solid substrate with reduced water activity. Thus, the actual technique passed down through history unknowingly favored the growth and reproduction of the mold genera, organisms capable of excreting large amounts of functional enzymes onto their substrate. The qu itself became a dried product carrying both microbes and their enzymes (the biomolecules). Most yeast and bacteria do not find the conditions of qu optimal, but still grow effectively in solid-state fermentation. Their relationships to qū are not well understood.
Qu processing can be carried out synchronously in the factory or workplace that produces a fermented end-product (such as a brewery or soy sauce factory) or it can be produced independently for sale. Traditionally, breweries did not make qu, but later often specialized in the preparation. Qu manufacturing techniques still vary widely, with each brewery or factory using a slightly different process and locally indigenous microflora, which in turn have generated diverse strains across China.
The process of making industrialized qu is inherently more complex as the two end products are sought to be manufactured by the factory: qu for use in alcohol production and so-called 'seed' qu for continued culturing of the microbiota. Seed qu is a pre-production process tailored to suit the growth and subsequent reproductive cycle of select microbes.
As such, qu practices have evolved from: Non-inoculum, spontaneous growth of microbiota from the natural surroundings through to Inoculation with a previous batch to improve consistency, culminating in Industrial culturing in a special process
A fourth step was introduced in 21st century China, where aseptic laboratory conditions are used to mono-culture specific favorable strains of mold, yeast, and bacteria grown on independent, fortified substrates. Such isolates now find usage in biotechnology applications such as fuel ethanol or enzyme production. An important objective is continued research into the biotechnological domestication of such microbes and as such, standardization of qu preparation.
Functions The advantage of using qū for alcohol production is its two-fold effect. The enzymes and microorganisms break down the starches and sugars, reducing the process of making grain spirits to one step. The use of microbial cultured starches for fermentation has a long history in East Asian countries, as evidenced by the diversity of foods and beverages produced. Brewing alcoholic beverages from grains typically involves the use of sprouted cereal grains that supply natural enzymes to break down carbohydrates, proteins, and lipids.
Traditional East Asian alcoholic fermentations use raw and unsprouted (unmalted) grains. Such grains lack the enzymes responsible for the conversion of carbohydrates to fermentable sugars and thus fermentation cannot proceed. Culturing microbes on cereal grains is a time-honored tradition in East Asia and the necessary way to solve this limitation, as they exude the enzymes that allow liquefaction and saccharification to occur (up to fifty different enzymes have been isolated from Aspergillus oryzae starters). Their mutualistic symbiosis with fermentative yeast and bacteria initiates the complex saccharification-liquefaction-fermentation process to produce the final alcoholic beverage.