Trade in ferments and resale of the brewers' spent grains.
« Women and children shall collect sura-beer and kinva-ferment. » (Arthashastra, Book II, chapter 25)
By extension, surā refers to the ingredients needed to make fermented beverages, especially grains, cooked rice and spices for beer. This Sanskrit term also includes the brewers' spent grains (dregs), as we shall see.
The mention of the brewing starter (kinva) is interesting. It means that at that time, as in the Vedic period before, beer was brewed in India with the amylolytic ferment technique. Moulds and yeasts are cultivated on a substrate of cooked starch, loaves or cakes which are dried. These dehydrated ferments have a long shelf life. They will later be mixed in small quantities with the cooked cereal porridge to simultaneously trigger the conversion of starch into sugars (enzyme of the microorganisms) and the alcoholic fermentation of the sugars (yeasts).
The sensitive preparation of the ferments requires a real mastery of the culture of microorganisms and the help of plants carrying the right strains of fungii at the right season (leaves, spices, fruits, berries, flowers).
The Arthashastra provides its recipe : 1 drona of either boiled or unboiled paste of másha (Phraseolus Radiatus), 3 parts more of rice, and 1 karsha of morata (Alangium Hexapetalum) and the like form kinva (ferment) (see Inventory of beers).
This technique and complex recipe explains why the ferments are made by specialists, often women, and sold separately. This is why the Arthashastra specifies that women and children can trade in the kinva.
Once brewed and drunk, the beer leaves a variable proportion of residues: grain husks, sediment, fermentation lees and various wastes. These are called dregs (āsavya, after Pānini, Aṣṭādhyāyī of Pāṇini, translated by Śrīśa Candra Vāsu Book 3 - 1898 III.1.117). With the western malting technique (germination), the volume of spent grains in a brew is close to the volume of the raw grains used. With the amylolytic fermentation technique, this proportion depends on the cereal used (rice vs. other grains, or paddy rice vs. polished rice). These two techniques are known in India and were practised indiscriminately, at least until the beginning of our era, when the amylolytic fermentation technique predominated.
But whatever the brewing technology, the volume of spent grains to be recycled is significant. They are used as feed for livestock or poultry, sometimes as fertiliser. The Treaty addresses this issue, but from the point of view of sales tariffs. Let us not forget that the taxation of fermented beverages is calculated on the selling price. From the point of view of the empire, brewers' spent grains and rotten beer are one and the same thing: in both cases, they imply a loss of fees income for the imperial state in relation to the initial volume of grain consumed. The Treaty therefore prescribes in the same paragraph the rules which will give the right to recycle spoiled beer and dregs:
« No fresh sura-beer other than bad sura-beer shall be sold below its price. Bad sura-beer may be sold elsewhere or given to slaves or workmen in lieu of wages; or it may form the drink of beasts for draught or the subsistence of hogs. »
The Superintendent of livestock ensures that bulls are provided with :
« For bulls which are provided with nose-rings, and which equal horses in speed and in carrying loads, half a bhára of meadow grass (yavasa), twice the above quantity of ordinary grass (trina), one tulá (100 palas = 5.1 kg) of oil cakes, 10 ádhakas (33 kg) of bran, 5 palas (205 g) of salt (mukhalavanam), one kudumba (206 g) of oil for rubbing over the nose (nasya), 1 prastha (825 g) of drink (pána), one tulá of flesh, 1 ádhaka (3.3 kg) of curis, 1 drona (13.2 kg) of barley or cooked másha (Phraseolus Radiatus), 1 drona (13.2 kg) of milk; or ½ ádhaka (1.65 kg) of surá-beer, 1 prastha of oil or ghi (sneha) 10 palas of sugar or jaggery, 1 pala of the fruit of sringibera (ginger) may be substituted for milk (pratipána). » (Book II chapter 29, Superintendent of cows).
The value of one bhára (a load or a burden) of grass is not known. We are missing one piece of information. The Treaty does not say whether these rations/animals are daily or not. The use of oilcake as animal feed should also be noted. These are the residues from the pressing of oil plants (palm, coconut, etc.) or sugar plants (cane). But more importantly, the 13.2 kg of milk + fodder given to the cattle can be replaced by the following preparation which contains beer-surā :
« ½ ádhaka (1.65 kg) surá-beer, 1 prastha (825 g) oil or ghee (sneha), 10 palms (510 g) sugar or palm sap , 1 pala (51 g) de fruit of the sringibera (ginger) can be substituted for milk (pratipána) ».
The 1.65 kg de surá does not refer to the beer itself, which is difficult for cattle to drink, but to the semi-solid spent grains from the brewing of the beer (surá). Again, the generic term surā encompasses in India all ingredients and by-products of the brewing process.
« The same products minus ¼ each make up the feed for mules, cows and donkeys; twice the amount for buffaloes and camels. ».
The recycling of spent grain from the brewery is of great importance for an imperial administration. The village economy has long been able to reuse brewery residues. However, an imperial centralised management favours the medium-sized beer production and thus the production of brewery residues. The concentration of beer production in cities and forts controlled by provincial governments accumulates much spent grains in the same places. The imperial administration therefore has an interest in adding value to spent grains, controlling feed formulas and coupling these two activities: brewing ⇔ cattle breeding.
For horses, the feed formula is improved :
« For the best horse (the diet shall be) 2 dronas (13,2 kg) of any one of the grains, rice (sáli, vríhi,) barley, panic seeds (priyangu) soaked or cooked, cooked mudga (Phraseolus Munga) or másha (Phraseolus Radiatus); one prastha (825 g) of oil, 5 palas 255 g) of salt, 50 palas (2,5 kg) of flesh, 1 ádhaka (3,3 kg) of broth (rasa) or 2 ádhakas (6,6 kg) of curd, 5 palas (255 g) of sugar (kshára), to make their diet relishing, 1 prastha (825 g) of súrá-beer, or 2 prasthas (1,65 kg) of milk. » (Book II chapter 30, Superintendent of Horses).
Here again, the 825 g of surā refers to the fermented residue of the beer.
The rations of the elephants also contain brewers' grains. War elephants were pampered by the empire. Their capture and training were a major concern. They were used to transport the imperial court, dignitaries and their families from camp to camp, from town to town. They were also armoured and trained for war. Chandragupta Maurya, father of Ashoka and founder of the empire of the Maurya, fought and defeated with his formidable "war elephants" the troops left on the Indus by Alexander the Great after the battle of the Hydaspe (326 B.C.).
The amounts of spent grain from beer (among all products intended for them) fit the size of the animal, that is to say 3.3 kg per elephant instead of 0.825 kg for a good horse :
« The rations for an elephant (of seven aratnis in height) shall be 1 drona of rice, ½ ádhaka of oil, 3 prasthas of ghi, 10 palas of salt, 50 palas of flesh, 1 ádhaka of broth (rasa) or twice the quantity (i.e., 2 ádhakas) of curd; in order to render the dish tasteful, 10 palas of sugar (kshára), 1 ádhaka (3,3 kg) of sura-beer, or twice the quantity of milk (payah); 1 prastha of oil for smearing over the body, 1/8 prastha (of the same) for the head and for keeping a light in the stables; 2 bháras of meadow grass, 2¼ bháras of ordinary grass (sashpa), and 2½ bháras of dry grass and any quantity of stalks of various pulses (kadankara). » (Livre II chap. 31, Surintendant des Eléphants)
Greek sources say that war elephants are made to drink rice beer :
« The elephant when feeding at large ordinarily drinks water, but when undergoing the fatigues of war is allowed wine,--not that sort, however, which comes from the grape, but another which is prepared from rice.. » (Aelian, On Animals. XII. 8). This rice wine is obviously beer!
It is doubtful whether a Greek, familiar with the wine culture, would have understood the difference between rice beer proper and spent grain (grain residue after the alcoholic fermentation of the beer) issued from one and same beer brew. Nevertheless, the Indian text of the Arthashastra (1 ádhaka (3.3 kg) from surā) corroborates the Greek testimony about the general custom in India of giving brewed products (beer or dregs) to be consumed by elephants.
 It cannot be the bhara = 20 tulas mentioned by the Treaty (1 tula = 1 drona/256 = 51 g). The bhara would be worth 1.02 kg, too little in relation to the quantities of grain needed by the animals.
 There are several reasons to believe that surā refers here to brewers' spent grains as much as to beer itself. 1) Its use for feeding cattle, from donkeys to horses and oxen to elephants. 2) The fact that Arthashastra deals in chapters 29, 30 and 31 of Book II with the economic issue of grain for cattle, not of fermented beverages (chapter 25). 3) the recycling of brewery residues for livestock is attested to the earliest times in all regions of the world which have brewed beer (Mesopotamia, Egypt, China, Africa, Europe, Andean America).