Caballero B. (ed.) Encyclopaedia of Food Science, Food Technology and Nutrition. Ten-Volume Set

Подождите немного. Документ загружается.

0038 Similar Bacillus-fermented soy bean products are

Thai thua-nuo and kinema, made in eastern Nepal,

Darjeeling, Sikkim, and Bhutan, but in these cases,

the products are still made by traditional methods.

Consequently other Bacillus spp., as well as non-

bacilli, commonly occur in the fermentations, and

the products often develop strong ammoniacal

odors. Thua nuo is prepared either as a paste or as

dried disks, and kinema is sold in the markets as a

paste. Neither is eaten directly as a condiment but

they are used to flavor soups and stews, etc.

Other Cereal–Legume Fermentations

0039 Cereal–legume mixtures are commonly used as the

substrate for fermentations. Whereas, as explained

elsewhere, wheat is added in soy sauce manufacture,

rice is added in Japanese miso.

0040 In contrast to the above fungal fermentations, from

the Indian subcontinent come a number of rice-flour

and bean-flour bacterial fermentations. These include

two widely used products, idli and dosa.

0041 South Indian Products The beans most commonly

used for the Indian fermentations are Vigna spp., the

green and black grams: V. radiata (L.) Wilcek (for-

merly Phaseolus aureus Roxb.) and V. mungo (L.)

Hepper (formerly Phaseolus mungo L.). Vigna is an

Old World genus, and the two grams are closely

related to the cowpea or blackeye ‘peas’ (V. unguicu-

lata (L.) Walp., formerly V. sinensis (L.) Hassk.).

These beans may be confused in reports with beans

of the unrelated New World genus Phaseolus, beans

of which are not used. Any process development of

grain legumes should be preceded by careful study of

the correct identity of the raw material, as many

legumes, unlike cereals, are very poisonous when

incorrectly or inadequately processed.

0043 Idli The beans and rice are normally milled separ-

ately, and water is added to give a thin gruel, or they

may be soaked and wet milled, adding about 1% salt

to the final gruel. The bean–rice mixture, in which the

proportions vary widely from 10:1 to 1:10, is left

covered overnight at 28–32



C. The temperature is

ambient shade temperature, although the duration

of the fermentation is not as critical as for the tempe

fermentation. The mixture may be stirred from time

to time but should be kept anaerobic (microaerophi-

lic) to encourage the growth of the heterofermenta-

tive lactobacilli. At the end of the fermentation, the

slurry is poured on to an idli steamer surmounted by a

perforated plate, in which there are shallow, saucer-

shaped depressions some 10 cm in diameter and 2 cm

deep. A cotton cloth prevents the slurry oozing

through the depressions. The cloth also aids removal

of the steamed cakes. Cooking for 15–20 min pro-

duces the raised cakes of idli, which are then ready

to be consumed.

0043Dosa Similar fermented mixtures, in which lentils

(Ervum lens) may be used in place of the gram beans,

are prepared and poured on to a hot griddle pre-

greased with ghee, coconut, or other oil, according

to culture.

0044These products are to be found wherever Indian

communities have settled. They vary in flavor and in

the added spices, but they are all lactobacillic, rather

than yeast fermentations, possessing characteristics in

common with sour doughs.

Indigenous Products

0045In contrast to the panoriental group, the indigenous

products are a highly diverse group of foods and

beverages, springing from the gathering activities of

local people who have inherited, or even retained,

recognizable Neolithic or bamboo culture traits and

have made full use of their habitats rich in diversity of

biota.

Cereal–Legume Fermentations

0046Cereals, principally rice and maize, and various

legumes are involved (predominantly of the genera

Glycine, Vigna, and Arachis). However, tree legumes

are also used, as in Africa.

Starches of the Rainforest

0047Edible carbohydrate-containing plants are in short

supply in the rainforests. Many plant species are too

loaded with additives to be exploited by fauna other

than those with specialized guts, such as leaf

monkeys. This shortage limits the population carry-

ing capacity. Those that are ‘possible foods’ may

contain poisonous substances associated with their

storage organs, e.g., oxalates. The forest and swamp

starch-containing plants include the aroids (Araceae),

such as the taros (Colocasia), the endangered

elephant-foot yams (Amorphophallus), and the true

yams, Dioscorea spp.

Tape

(Tapai)

0048Cassava (Manihot esculenta Cranz.) tubers are the

most widely used material for the production of the

popular sweet and sour alcoholic tape

, but this

product is also made from glutinous rice, maize, or

millet.

0049Manufacture The peeled cassava (tapioca in South-

east Asia) tubers or rice grains are inoculated, after

boiling or steaming, by dusting with a microbial

2348 FERMENTED FOODS/Fermentations of the Far East

starter powder, ragi. This is a stabilized mixture of

yeasts and molds fermented as a dough and dried as

small, flat cakes. Many types of ragi cake can be

found in Southeast Asian markets, each type being

applicable to a particular substrate. The inoculated

cassava tubers are incubated in baskets, lined and

covered with banana leaves. The inoculated rice is

wrapped in small banana leaf or plastic packets.

After 2–3 days at ambient temperatures (25–30



C),

the products soften and develop a sweet/sour slightly

alcoholic flavor. The product may be sold for direct

consumption, or after air-drying. Alternatively, the

fermented mass is squeezed, and the paste and exud-

ate are consumed separately; the latter, after further

fermentation, is drunk as an alcoholic liquor.

Wines and Acidic or Alcoholic Beverages

0050 Based on the ragi fermentation are the rice wines, such

as tuak, of the peoples of Borneo. Some of the wines

found in Southeast Asia are derived from the influence

of migrating cultures, particularly those wines derived

from rice and the inflorescences of palms, such as the

coconut and talipot palm (Borassus flabelliformis), a

feature of the landscape of Sri Lanka and Indo-China.

Others, derived from regionally indigenous plants,

are considered below. Reference to these is more

often to be found in ethnographic and economic

botany texts than in books on food.

0051 Tropical forest people often ‘tap’ plants for a drink,

using xylem and phloem saps. The rattans, for

example, are a forest source of water. The evolution

of fermentation of saps may have followed almost

incidentally from the tapping of sugar-rich phloem

saps from emerging palm inflorescences.

0052 Products of the Vitaceae are occasionally found, but

the Rosaceae of temperate zones are not represented.

0053 Local fermented beverages are made from the saps

of a number of genera of palms, such as Arenga and

Nypa as well as from the talipot palm (Borassus spp.).

Unlike in West Africa, the oil palm (Elaeis guineensis)

is not tapped in Southeast Asia.

0054Other true rainforest trees, furnishing sugary and

starchy substrates, are the jack and bread fruits (Arto-

carpus) and the durian (Durio zibethinus). The local

Indo-Malay name for the fermented product of the

durian is tempoyak. Baccaurea grifithii is another

rainforest tree, producing an aromatic resinous fruit

that is fermented to a retsina-like product.

0055Strong-smelling, biologically active, heterocyclic

ring, sulfur-containing compounds (extending the

‘garlic range’ to many other families) are common in

rainforest biochemical systems, the above quoted

durian being but one example. Like the durian, they

are locally exploited but are increasingly rarely

encountered.

Fermented Sugar Cane Juice

0056Sugar cane (Saccharum officinarum L.) is indigenous

to Southeast Asia, and the juice is fermented by the

indigenous forest people, such as the Semelai of Ma-

laysia. The fermentation is controlled by filtering the

raw juice through a filter made of the inner bark of a

dipterocarp tree, Shorea curtisii. The bark is rich in

phenolic compounds, some of which are transferred

to the liquor.

Detoxification via Fermentation

0057The recipes for these true forest products, and the

plant species themselves, are in danger of being lost

as the forests are cleared. The diversity of these forest

products is reflected in the range of biochemicals that

are detoxified by fermentation. These include the

following: alkaloids and other heterocyclic, nitrogen-

containing poisons – the nitriles and cyanides (the

cause of optical and peripheral neuropathies), an un-

usual one being that of Cycas spp., or false sago, the

seeds of which furnish a source of starch; poisonous

amino acids, peptides and proteins; steroids; sap-

onins; anthocyanins and related phenolics and or-

ganic acids such as oxalic. In the plant, these

secondary compounds function as selective attract-

ants, antibiotics, and feeding deterrents. As has been

shown in the examples above, the bioactivity of some

of these compounds has been exploited to advantage

in the preparation of the fermented foods, but, as

with so many aspects of tropical plant study, much

remains to be recorded and analyzed.

Fermented Fish Products

0058Fermented, salted, or dried fish and crustaceae are

used ubiquitously in oriental cooking. The products

used range from solids and pastes to very salty liquids,

fig0007 Slide 5 (see color plate 56) Tape

in Bandung market, Indo-

nesia. Cooked cassava roots fermented with fungi to produce a

slightly soured, slightly alcoholic, and sweetened cassava.

FERMENTED FOODS/Fermentations of the Far East 2349

the salt being necessary for conservation, more than

for culinary purposes. There is clearly a major sub-

division into products in which the process solely

involves autolysis by fish-derived enzymes, and

those in which carbohydrate fermentations, employ-

ing microbial enzymes, also occur.

Salt-aided Fermentation

0059 Outstanding amongst the desiccated products is kat-

suobishi, a mold-fermented product made from tuna

in Japan. It is as hard as Parmesan cheese and is used

in a similar way.

0060 Belacan is a softer autolyzed shrimp paste from

Indonesia and Malaysia; similar intermediate-

moisture fish and shrimp pastes occur throughout

Southeast Asia.

0061 The salty fish sauces, such as the patis of the phil-

ippines, are autolytic products, relying on the

enzymes of the fish gut rather than the associated

microflora. These salt-aided autolytic products nor-

mally contain 14% or more of salt and are thus only

of value as relishes to the main dish.

Carbohydrate-aided Fermentation

0062 In some fish pastes and slurries of Southeast Asia,

rice, usually as tape

or koji, also plays a part in the

preservative process. The rice provides a carbohy-

drate source for a lactic acid fermentation and allows

the use of less salt in the product.

Acceptance

0063 Unlike soy sauce and, to a lesser extent, tofu, miso,

and nata (the jelly-like sweet mentioned later), the

acceptance of the fish products outside their home

markets is limited, possible exceptions being the fish

and shrimp pastes, such as belacan of Indonesia. Fur-

thermore, the fish products mentioned above are not

easily amenable to modification. Each depends on a

particular local fish species, or group of species, and

the taste for them is acquired, just as the predilection

to the Scandinavian fermented herrings is very much

an acquired taste, not even shared by the rest of

Europe.

0064 Nevertheless, in a world of increasing protein

shortage and with an increasing proportion of by-

catch and trash fish in the harvests, owing in part to

over-fishing, as well as fish waste from processing, the

opportunity to improve nutrition worldwide afforded

by some of these products and processes should not

be overlooked.

Pickled Fish

0065 Unlike the above-mentioned products, pickled prod-

ucts rely on the addition of acetic acid and sugar, or

acid fruit extracts, and do not play a significant role

in the regional food supply.

Fermented Meats

0066Fermented meats are not important in the diet of

the peoples of the Far East, in comparison with the

fish products, although they are to be found in Thai-

land, for example.

Microbes as Food

0067Finally, in this review, the traditional uses of the

microbial cultures themselves as the end product

are considered. This is quite different from the

development of industrial processes for the produc-

tion of microbial protein, a large-scale, capital-

intensive exercise requiring many more process steps

than the traditional processes. The traditional foods

are derived from bacteria or from fungal fruiting

bodies.

0068Bacteria The polysaccharide and amorphous cellu-

lose coat formed by Acetobacter xylinum is eaten in

the Philippines under the general name nata. This is

made by encouraging the growth of the aerophilic

Acetobacter on sugar and ammonium phosphate-

enriched acetic-acidified (pH 5) coconut water (nata

di coco), pineapple (nata di pina), or other fruit juice.

0069Manufacture The substrate (a nitrogen- or phos-

phate-enriched sugared juice) is inoculated with the

liquid phase of a previous culture (1:10 of substrate),

held in a covered (not airtight) container, preferably

undisturbed and in the dark. The liquor is maintained

at a temperature below 31



C, preferably about



C, for approximately 2 weeks. The product is a

surface cake of a bacterial embedded cellulosic gel,

which acquires a particular flavor according to the

substrate used. This gel, which can be up to 3 cm

thick and is composed of cells plus polysaccharide

coat, must be soaked to remove excess acetic acid

before use. It is cubed, marketed fresh in a syrup, or

marketed in cans, bottles, or plastic pouches.

0070Use of waste The bacterial process is a conven-

ient way of making a useful product from a range

of fruit-processing wastes, the character of which –

unlike many of the fermentations mentioned here – is

easily adjustable, appears internationally widely

acceptable, and is already exported in limited

quantities. However, it is a product that could be

produced locally without much hazard and is accept-

able to a wide range of palates.

0071Fungal Fruiting Bodies The fruiting bodies of basi-

diomycetes (and some ascomycetes) are mentioned

2350 FERMENTED FOODS/Fermentations of the Far East

here, as they are ubiquitous foods of Southeast Asia,

produced by fermentation and exploiting waste or

inedible material. The main differentiation is between

those fungi with ephemeral (autolysing) fruiting

bodies, such as the paddy straw mushroom (Volvar-

iella volvacea), and those with durable (dryable)

mushrooms, such as the highly prized shiitake (Len-

tinus edodes).

Future

New Applications of Oriental Fermented Foods

0072 The interest of food scientists in traditional fermenta-

tions arises not only from the fact that they furnish

novel foods and are challenging from the point of view

of the techniques needed to effect industrialization,

but also from the fact that the unit processes have a

wide industrial application. The enzyme, flavor en-

hancement, color, texture, gel stabilization, and anti-

oxidant properties have come under scrutiny for

the production of shelf-stable, intermediate-moisture

foods, flavoring agents such as monosodium glutam-

ate, flavor-enhancing nucleotides, and even coloring

matters, e.g., the red–purple of Monascus purpureus.

Health Hazards

0073 The products mentioned in this review have under-

gone millennia (to quote Hesseltine) of testing. Never-

theless, in spite of the advances in food hygiene and

the current emphasis on care in avoiding contamin-

ation at harvest, safe storage, sanitary processing and

marketing, the reported incidence of food poisoning

has been rising. There are several reasons for this

phenomenon, but, in the present context, the

following question arises: how have the people in

hot, humid countries circumvented microbial food

poisoning in the past?

0074 The answer lies in the fact that the traditional

techniques for raw material processing, described

here, are energy-economical lessons in living with

the microbial world; the appearance of mycotoxins

and the various bacterial poisons, mentioned else-

where in this work, are examples of the failure to

learn those lessons.

Conclusion

0075 Some of these oriental fermentations, such as soy

sauce and, to a lesser extent, tempe, have already

found acceptance in the industrial world. Others

have yet to be discovered. A further group will be

lost forever if steps are not taken to preserve the

diversity of the resource base and record the processes

of conversion of these resources to food or, better

still, to conserve the environmental conditions so

that the original inhabitants may continue to practice

their art.

See also: Bacillus: Occurrence; Detection; Food

Poisoning; Enzymes: Functions and Characteristics;

Uses in Food Processing; Uses in Analysis; Lactic Acid

Bacteria; Mycotoxins: Classifications; Occurrence and

Determination; Toxicology; Preservation of Food;

Probiotics; Starter Cultures; Toxins in Food –

Naturally Occurring

Further Reading

Bray F (1984) Agriculture. In: Needham J (ed.) Science

and Civilization in China, vol. 6, part II. Cambridge:

Cambridge University Press.

Burkhill HM (1935) The Economic Products of the Malay

Peninsula. London: Crown Agents.

Campbell-Platt G (1987) Fermented Foods of the World.

Oxford: Butterworth.

Caplice E and Fitzgerald GF (1999) Food fermentations:

role of microorganisms in food production and preser-

vation. International Journal of Food Microbiology

50: 131–149.

Cummings JH (1997) The Large Intestine in Nutrition and

Disease. Brussels: Institut Danone.

Fukushima D (1985) Fermented vegetable protein and

related foods of Japan and China. Food Reviews Inter-

national 1: 149–209.

Hachmeister KA and Fung DYC (1993) Tempe: a mold-

modified indigenous fermented food made from

soybeans and/or cereal grains. Critical Reviews in

Microbiology 19: 137–188.

Huang KT (2000) Fermentations and food science. In:

Needham J (ed.) Science and Civilization in China,

vol. 6, part V. Cambridge: Cambridge University Press.

Reddy NR, Pierson MD and Salunkhe DK (eds) (1986)

Legume-based Fermented Foods. Boca Raton, FL: CRC

Press.

Stanton WR (1969) Some domesticated lower plants in

Southeast Asian food technology. In: Ucko PJ and

Dimbleby GW (eds) The Domestication of Plants and

Animals, pp. 463–469. London: Duckworth.

Stanton WR (1985) Food fermentation in the tropics.

In: Wood BJB (ed.) Microbiology of Fermented Foods,

pp. 193–211. London: Elsevier.

Steinkraus KH (ed.) (1996) Handbook of Indigenous Fer-

mented Foods, 2nd edn. New York: Marcel Dekker.

Steinkraus KH (ed.) (1989) Industrialization of Indigenous

Fermented Foods. New York: Marcel Dekker.

Wood BJB (ed.) (1998) Microbiology of Fermented Foods.

London: Blackie.

Yokotsuka T (1991) Proteinaceous fermented foods and

condiments prepared with koji molds. In: Arora DK,

Mukerji KG and Marth EH (eds) Handbook of Applied

Mycology, vol. 3, Food and Feeds, pp. 329–373. New

York: Marcel Dekker.

FERMENTED FOODS/Fermentations of the Far East 2351

Beverages from Sorghum and

Millet

J R N Taylor, University of Pretoria, Pretoria, South

Africa

Introduction

0001 Throughout Africa, the indigenous tropical cereal

grains sorghum (Sorghum bicolor L. Moench), pearl

millet (Pennisetum glaucum L. R.Br.), and finger

millet (Eleucine coracana L. Gaertn.) have been

used since prehistoric times to prepare fermented

beverages (Figure 1). In general, these traditional

beverages are popular as ever, and in southern and

eastern Africa their industrial manufacture has

become increasingly common. Although the charac-

ter of the industrially produced beverages is

substantially the same as the traditional products,

high proportions of maize (corn), (Zea mays L.),

which is native to the USA, and even maize alone

are normally used in their manufacture.

0002The fermented beverages may be alcoholic, or sub-

stantially nonalcoholic. The alcoholic beverages have

many names, including sorghum beer (South Africa),

opaque beer (Zimbabwe), jwala (Tswana), utywala

(Zulu), Chibuku (southern and eastern Africa), and

pito (west Africa). Chibuku is a commerical brand

name; the word is from the African ‘mine’ language

Fanagalo and can be translated as ‘according to the

recipe book.’ In this article the term ‘sorghum beer’ is

used generically for the southern and eastern African

product. Traditional African beers are very different

from European lager-type beer, partially on account

of the particular properties of the tropical cereal

grains. Sorghum beer is characterized by its opacity

due to the presence of semisuspended particles of

starch, cereal, and yeast. The starch gives it a viscous

consistency. The beer is generally pinkish brown in

color due to anthocyanidin pigments from the

sorghum or millet. It is sour in taste owing to the

presence of lactic acid but, unlike lager beer, is not

hopped; and it is consumed while actively fermenting.

In contrast, pito is clear or somewhat cloudy and is

not particularly sour in taste, but like sorghum beer it

is consumed while it is actively fermenting. African

beers are generally rather lower in alcohol than lager

beer. This is related to the considerably lower b-

amylase (EC 3.2.1.2) activity of sorghum and millet

malts, in comparison to barley malt.

0003The substantially nonalcoholic fermented bever-

ages have been less well documented but all involve

some form of lactic acid fermentation. Products

include kunun-zaki (Nigeria), hulu mur (Sudan),

and motoho oa mabele (South Africa). These are

made from sorghum or pearl millet; the grain may

or may not be malted according to local preference.

The best-known nonalcoholic beverage is mageu

(mahewu or magou) from southern Africa, which is

a lactic acid-fermented gruel, widely produced indus-

trially using almost exclusively maize.

Traditional Methods of Making Sorghum

Beer

0004Sorghum beer is intrinsically linked with African

culture, traditionally being brewed by the female

members of the family for use at ceremonies including

weddings, funerals, and other social gatherings.

0005The basic sorghum beer process involves the

following steps: souring (lactic acid fermentation),

cooking (starch gelatinization), mashing (thinning

and conversion of gelatinized starch to sugars),

Pearl millet

Sorghum

fig0001 Figure 1 Sorghum and millet growing together in a field in the

Northern Province of South Africa. Courtesy of Beryl Fabian,

CSIR, South Africa. Reproduced from Fermenting Foods:

Beverages from Sorghum and Millet, Encyclopaedia of Food

Microbiology, Robinson RK, Batt CA and Patel PD (eds), 2000,

Academic Press, with permission.

2352 FERMENTED FOODS/Beverages from Sorghum and Millet

straining (grain separation), and alcoholic fermenta-

tion. It should be noted that under home brewing

conditions it is very difficult to maintain the brews

at the optimal temperatures for each of the steps. This

leads to an overlap of the processes across different

steps, so that two or more brewing steps may take

place at the same time.

0006 Malt is the vital ingredient in brewing. In essence,

malting involves germinating the grain for several

days to produce enzymes (most importantly, amylase

enzymes) not present in the grain, then drying and

milling it. In the brewing of sorghum beer, the malt

amylase enzymes hydrolyze grain starch to sugars.

The sugars are fermented to lactic acid by lactobacilli

and, during alcoholic fermentation, yeasts convert the

sugars to ethanol and carbon dioxide, producing beer.

0007 In traditional home brewing, the grain is malted by

first soaking it for about a day, either in water-filled,

clay vessels, or in woven grass baskets placed in a

stream. After soaking, the steep water is drained off

and the damp grain is allowed to germinate for 2–4

days, depending upon the ambient conditions. Ger-

mination is conducted in small baskets or in sacks,

allowing the circulation of air. At the end of germin-

ation, the germinated grain is spread out in a thin

layer on the ground and sun-dried. Once dry, the

malt is ground by hand between two stones.

0008 To brew beer, a small portion of ground malt is

mixed with hot water; either slurried with the water

and then cooked, or added to previously heated

water. The warm mixture is then covered and allowed

to stand overnight to sour. The following day, the

soured wort is diluted with additional water and

more milled grain is added. This starch-rich adjunct

material is either malt, or more commonly whole,

coarsely ground sorghum or millet grain. The entire

mixture is then boiled (2–6 h), and then allowed to

cool and thicken. The following day, a second batch

of malt is added to the now cooled brew. The amylase

enzymes in the malt liquefy the mash. Depending

upon the taste of the brew and the preference of the

brewer, it may be recooked, cooled, and more malt

added. As the wort cools, wild yeasts in the environ-

ment ferment the brew, giving a bubbling, effervesc-

ing liquid. A characteristic of traditionally brewed

sorghum beers is their fruity flavor, due to fermenta-

tion by wild yeasts. The brew is allowed to ferment

for a few days When it is considered to be acceptable,

it is strained, traditionally by passing it through a

braided grass strainer, or today more generally

through a perforated steel sheet. The beer is then

served in decorated clay drinking vessels. Figure 2

shows a woman serving out the beer with a ladle

made from a plant gourd; the latter may also serve

as drinking vessel.

0009Modern home brewers may make their own malt,

or more commonly they obtain it from large commer-

cial maltsters who produce malt of more consistent

quality. Over the years, milled maize or brown bread

has tended to replace malted or unmalted sorghum

or millet as the adjunct. However, the procedures

followed are essentially the same as those of ancient

times. Figure 3 shows a modern-day sorghum beer

home-brewing recipe.

Traditional Methods of Making

Nonalcoholic Beverages

0010The procedures are substantially the same as used for

making sorghum beer, but certain steps are ingeni-

ously optimized to result in a substantially nonalco-

holic product. Figure 4 shows a scheme for making

kunun-zaki. It is notable that the malt is simply mixed

(not mashed) with the cooked adjunct. Alternatively,

according to local preference, boiling water may be

added to the malt. Both processes limit the amount of

enzymic hydrolysis of starch to fermentable sugars

and hence favor a lactic acid, rather than an alcoholic

fermentation. Further, the high initial temperatures in

such processes (approx. 50



C) enable the growth of

thermophilic lactic acid bacteria but not yeast. Later,

when the temperature falls towards the range suitable

for alcoholic fermentation, mesophilic bacteria

take over. Kunun-zaki has a pH of below 5.0 and a

fig0002Figure 2 Serving traditionally made sorghum beer from clay

pots using a gourd ladle. Courtesy of Beryl Fabian, CSIR, South

Africa. Reproduced from Fermenting Foods: Beverages from

Sorghum and Millet, Encyclopaedia of Food Microbiology, Robinson

RK, Batt CA and Patel PD (eds), 2000, Academic Press, with

permission.

FERMENTED FOODS/Beverages from Sorghum and Millet 2353

titratable acidity around 0.1–0.2%. The predominant

microorganisms are the bacteria Lactobacillus plan-

tarum and Bacillus subtilis, whereas yeast numbers

are low. Zaki means sweet in Nigerian Hausa

language and the product is often spiced with ginger,

cloves, and pepper, then sweetened.

Industrial Sorghum Beer Brewing

0011Industrial sorghum beer brewing was initiated by

municipal governments in South Africa and

Zimbabwe in the early part of the 20th century.

However, the adaptation of the traditional craft to

factory scale was hampered by technical difficulties.

In 1954, the Council for Scientific and Industrial

Research (CSIR) in South Africa was commissioned

to undertake applied research on behalf of the

municipal sorghum beer brewers. This technical as-

sistance aided a spectacular increase in scale from

home brewing (approximately 50–200-l brews) to

factory brewing (approximately 15 000–27 000-l

brews), made possible largely by the development

and institution of carefully specified raw material

standards and the use of specialized equipment.

Modern sorghum beer brewing equipment allows

rapid heating and cooling, enabling the key brewing

steps to be split into separate unit operations and

conducted under optimal conditions of temperature

(Figure 5).

Malting

0012The first major problem encountered in scaling-up

sorghum beer production related to the quality of

the sorghum malt. At that time, virtually nothing

was known about the science and technology of

sorghum malting. Because sorghum and millet malt

contains substantially lower levels of b-amylase than

barley malt and amylase activity can be limiting

in sorghum beer brewing, the CSIR researchers

developed a sensitive method of determining the

Boiling

water

Maize

meal

Cooking

(5 min)

Cooking

(2 h)

Mashing and

fermentation

(24 h)

STRAINING

Souring

(12 h)

Cold

water

1 part

Cool (3 h)

Cool (12 h)

1 part2 parts

1 part3 parts

5 parts

Sorghum

malt

fig0003 Figure 3 Modern-day home-brewing recipe for sorghum beer.

Courtesy of Nola, Randfontein, South Africa. Reproduced from

Fermenting Foods: Beverages from Sorghum and Millet, En-

cyclopaedia of Food Microbiology, Robinson RK, Batt CA and

Patel PD (eds), 2000, Academic Press, with permission.

Red guinea sorghum

grain (1.6 parts)

Wet milling

Cooking

Mixing

(50−60 ⬚C)

Filtering

Fermentation

(12−18 h, 28−32 ⬚C)

Boiling water

Sorghum

and/or millet

malt (1 part)

fig0004 Figure 4 Scheme for preparing kunun-zaki (from a description

by Inyang CU, Dabot YA (1997) Storability and potability of

pasteurized and sterilized ‘‘kunun-zaki’’: a fermented sorghum

beverage. Journal of Food Preservation and Processing 21: 1–7.

fig0005Figure 5 Modern industrial sorghum beer brewery. Courtesy of

Traditional Beer Investments of Johannesburg, South Africa. Re-

produced from Fermenting Foods: Beverages from Sorghum and

Millet, Encyclopaedia of Food Microbiology, Robinson RK, Batt CA

and Patel PD (eds), 2000, Academic Press, with permission.

2354 FERMENTED FOODS/Beverages from Sorghum and Millet

diastatic power (i.e., the joint level of a- and b-amyl-

ase activity) of sorghum malts. The assay remains the

most important quality parameter for sorghum malt.

0013 The malting process is physically split into three

unit operations: steeping, germination, and drying.

Steeping is carried out in steel tanks of several thou-

sand liter capacity. The grain is soaked in water for a

period of normally between 6 and 24 h. The water is

aerated to assist the grain respiration and may be

changed at intervals to allow the grain to respire in

air and also to clean it.

0014 As sorghum malt of high and consistent quality is

required as an ingredient in industrial brewing, today

most is produced in modern pneumatic maltings and

is referred to as ‘conversion’ or ‘industrial’ malt. The

steeped grain is germinated indoors, under conditions

of controlled temperature, moisture, and aeration

to produce malt to a diastatic power specification of

28–35 sorghum diastatic units (SDU) per gram. The

principle of pneumatic malting is that air is blown

through the bed of grain by means of a powerful fan.

The air aerates the grain, removes carbon dioxide,

and maintains it at an even temperature. Another

type of malt used in industrial brewing, referred to

as ‘souring’ malt, serves as a source of lactobacilli and

as a substrate for lactic acid fermentation. Souring

malt is generally produced by germinating sorghum

grain outdoors on a concrete floor (floor malting) and

as a consequence is generally of lower diastatic power

than conversion malt.

0015 The malt is normally dried by blowing heated, dry

air through it, at temperatures no greater than 50



until the moisture content of the malt is approxi-

mately 10%. Drying at this low temperature helps

conserve the amylase activity of the malt. Alterna-

tively the malt can be sun-dried.

Modified Reef-Type Brewing Process

0016 Several different industrial brewing processes are

used in southern and eastern Africa, as a result of

differences in the taste preferences of the customers,

and differing levels of brewing skills and equipment in

the breweries. The most common is the Reef-type

process (Figure 6), originally developed in the gold-

mining region of South Africa known as the Reef, and

later modified to include a second cooking and mash-

ing stage.

0017 Souring In South Africa, the lactic acid fermenta-

tion (souring) is an essential part of the brewing pro-

cess. Souring is generally performed by incubating a

10% slurry of ‘souring’ sorghum malt at 48–50



This favors the growth of thermophilic, homofer-

mentative Lactobacillus delbreuckii (leichmannii).

The sour is normally inoculated with a portion of a

previous, successful sour containing high levels of

viable lactic acid bacteria – a process of backslopping.

Some breweries, however, use specially prepared

freeze-dried cultures. The lactic acid sour lowers the

pH of the beer to below 4.0, which helps to prevent

the complete hydrolysis of starch into sugars, slows

the rate of microbial spoilage, and inhibits the growth

of pathogenic organisms. The sour also contributes to

the beer’s characteristic flavor. Breweries in other

countries generally simply add industrially produced

lactic acid during the brewing process.

0018Cooking After the lactic acid fermentation the sour

is diluted with water, then maize and/or sorghum

meal is added as a starchy adjunct and the mixture

is boiled for approximately 1–2 h under atmospheric

conditions, or for less time under pressurized condi-

tions, to gelatinize the starch. Industrial brewers in

South Africa generally use highly refined maize grits

(low-fat endosperm meal) as adjunct. The use of

whole, unrefined grain has been largely abandoned

owing to the high fat content of the grain, which

causes rancidity problems when stored in a milled

Maize or

sorghum grits

(2 parts)

Cooking - 1

Cooking - 2

Mashing - 1

Boil for 1−2h

(16% solids)

(14% solids)

50−65 ⬚C, 2h

Mashing - 2

Straining

(14% solids)

(11−12% solids)

60 ⬚C, 20 min

28 ⬚C, 8−24 h

80−100 ⬚C, 20 min

60%

Fermentation

(11−12% solids)

Water

Sorghum malt

(1 part)

(30%)

Souring

48−50 ⬚C, 18 h

(1−2% lactic acid)

Spent grain

Packaging

Active

dried

yeast

(0.3 g l

−1

)

(61%)

(9%)

or commercial

amylase

fig0006Figure 6 Modified Reef-type sorghum beer brewing process.

Reproduced from Fermenting Foods: Beverages from Sorghum

and Millet, Encyclopaedia of Food Microbiology, Robinson RK, Batt

CA and Patel PD (eds), 2000, Academic Press, with permission.

FERMENTED FOODS/Beverages from Sorghum and Millet 2355

form. The high fat content also negatively affects the

beer foam. Outside South Africa, the use of less-

refined meal, or even whole milled grain is still the

norm.

0019 Mashing The mash is cooled to approximately



C with cold water. Conversion malt is then

added. As a consequence of the action of the malt

a-amylase (EC 3.2.1.1) converting the gelatinized

starch to dextrins, the mash is very rapidly liquefied.

The b-amylase in the malt hydrolyzes the dextrins to

maltose, a fermentable sugar. The low pH of the mash

(about 4.0) is below the optimum for sorghum a-and

b-amylase activity, which limits starch hydrolysis,

preventing the production of too thin a beer and

limiting the potential alcohol content of the beer.

Some industrial brewers supplement or substitute

costly conversion malt with less expensive commer-

cially produced amylase enzymes (a-amylase and/or

amyloglucosidase), to facilitate the thinning of the

mash and fermentable sugar production. Mashing

is carried out for about 2 h at constant temperature

(50–65



C).

0020 Second cooking and mashing The gelatinization

temperature of sorghum starch is 68–72



C. There-

fore under the conditions of mashing in the previous

step, the sorghum malt starch is not gelatinized. In the

modified Reef-type brewing process the mash is

recooked (80–100



C for approximately 20 min).

This second cooking stage pasteurizes the mash and

also gelatinizes the sorghum malt starch, leaving vir-

tually no ungelatinized starch in the mash. Thereafter,

the mash is cooled to 60



C and a second short mash-

ing period (approximately 20 min) is carried out

either with a small amount of conversion malt or

commercially produced amylase. The second cooking

and mashing steps effectively increase the amount

of beer that can be obtained from a given quantity

of malt.

0021 Straining Straining removes the coarse cereal par-

ticles from the wort, and is normally carried out

directly after mashing and prior to fermentation.

Industrial brewers strain the mash at elevated

temperature using centrifugal decanters and vibrating

screens. Before straining there are approximately

14% solids in the mash and after straining approxi-

mately 11–12% solids remain in the wort.

0022 Alcoholic fermentation Plate or tubular heat ex-

changers are used to cool the strained wort to 28



The wort is transferred to stainless-steel vessels and

alcoholic fermentation is brought about by pitching

with commercially produced yeast (0.3 g l

1

). For

convenience, active dried yeast is generally used.

This yeast is a strain of Saccharomyces cerevisiae,

specially selected for its ability to ferment sorghum

beer rapidly. It is a top-fermenting, nonflocculating

type. The pitched wort is then allowed to ferment for

8–24 h. Unlike clear lager beer, sorghum beer is not

filtered.

0023Serving Sorghum beer may be transported by road

in bulk (100–500 l) for sale in beer halls as draft beer.

Alternatively, the beer is packaged in milk-type card-

board cartons or plastic containers (0.5–25 l) for sale

in the retail market. The containers may be returnable

and reusable or one-trip, nonreturnable, depending

on the market. However, all are characterized by

having a small vent in the top to allow the escape of

the carbon dioxide produced by fermentation. When

ready for consumption, sorghum beer has an alcohol

content of approximately 3% by weight. The shelf-

life of the product is approximately 5–10 days after

straining. Beyond this time, the beer is ‘flat’ and has

settled out, and is frequently spoiled by microbial

infection.

Variations in Industrial Brewing Process

0024In central Africa, the sorghum beer brewing process is

much simpler than that described above. Commercial

enzymes only are used to convert the adjunct. Whole

milled maize is used as the cereal ingredient, although

a little sorghum or millet grain may be added for

color and flavor. There is no souring step and in

some cases no lactic acid addition either. The beer is

also often not strained.

Industrial Nonalcoholic Beverage

Production

0025In view of the commercial importance of mageu –

some 100 million liters are produced annually – its

industrial production will be described, despite the

fact that strictly speaking, mageu is an almost exclu-

sively maize beverage, although it can be made from

sorghum. Research by scientists of the CSIR and

private industry in South Africa in the 1960s led to

today’s manufacturing process (Figure 7). After the

maize meal has been cooked to gelatinize the starch,

wheat flour (a source of b-amylase to produce mal-

tose) and/or cane sugar is added to promote fermen-

tation. Fermentation is by a commercial thermophilic

lactic acid bacteria culture that only produces lactic

acid. An interesting development is the widespread

use of artificial flavoring in mageu – flavors such as

banana, cream, ginger, and guava are popular. The

mageu is either pasteurized and/or chemical-preserved

to extend its shelf-life and, like sorghum beer,

2356 FERMENTED FOODS/Beverages from Sorghum and Millet

packaged in milk-type cartons. An alternative mageu-

making process involves the use of pregelatinized

maize meal, produced by extrusion cooking or gun

puffing, which obviates the need for cooking equip-

ment. The use of this so-called powder mageu is ideal

for preparation in institutions such as mine hostels or

hospitals.

Nutritional Aspects

0026 The nutritional value of fermented beverages is

influenced to a great extent by two factors, neither

of which is associated with fermentation. These are

the concentration of cereal solids, and the degree to

which the cereal has been refined. The total solids

content of commercial mageu is between 5% and

8%, rather lower than the sugar content of many

carbonated soft drinks. Higher concentrations are

not possible, as the starch would increase the viscosity

of the product to that of a porridge. As stated, there is

a trend for industrially manufactured fermented bev-

erages to be made with maize endosperm meal rather

than partially processed or milled whole grain. Re-

search has shown that brewing sorghum beer with

maize grits (the common practice in South Africa) as

adjunct substantially reduces its vitamin B and

mineral content.

Advantages of Lactic Acid Fermentation

0027 Many nutritional advantages have been claimed for

the lactic acid fermentation of cereal beverages and

porridges. These include improved starch digestibility,

increased protein quantity, improved protein quality

and digestibility, increased vitamin levels, decreased

antinutritional factors such as tannins and phytate,

improved mineral availability, production of bacter-

iocins and prebiotics, source of probiotic microorgan-

isms, and improved palatability and acceptability.

Unfortunately, there are few firm data on the extent

of these nutritional improvements. Probably the most

unequivocal advantage of lactic acid fermentation is

the reduction in pH. Sorghum beer and mageu have a

pH of around 3.5. At this low pH, pathogenic bac-

teria such as Salmonella typhimurium are destroyed,

heat-resistant bacterial spores do not germinate, and

the rate of growth of spoilage bacteria is much re-

duced. Because many households in Africa still do not

have access to potable water and few have refriger-

ators, these beverages are a valuable safe source of

nutrition.

Sorghum Beer

0028Disregarding the question of whether the consump-

tion of any alcoholic beverage is nutritionally desir-

able, the nutritive value of sorghum beer is here

compared with that of lager beer. There is little evi-

dence, certainly with respect to commercial sorghum

beer, to support the often-quoted statement that sor-

ghum beer is more of a food than an alcoholic drink

(Table 1). However, sorghum beer has some obvious

and not so obvious nutritional advantages. Although

the energy content of the two beers is similar, sor-

ghum beer has less ethanol and substantially more

complex carbohydrates. The protein content of sor-

ghum beer is much higher, and much of this is yeast

protein, which has a better essential amino acid con-

tent than cereal protein. The higher thiamin and ribo-

flavin levels are also due to the presence of yeast. The

lower nicotinic acid level is due to the use of a high

proportion of maize in the grist. The high levels of

iron and some other minerals in sorghum beer are the

consequence of leaching-out of vessels, because of the

low pH of the beer. This can also be disadvantageous.

In small-scale brewing where mild steel (as opposed

to stainless-steel) vessels are commonly used, exces-

sively high levels of iron have been found in the beer.

A benefit of sorghum beer consumption not shown is

that, uniquely among beers, it contains measurable

quantities of both insoluble and soluble dietary fiber.

Future Directions

0029As mentioned, these traditional fermented beverages

remain popular on the African continent. However, in

South Africa there is clear evidence that their indus-

trial production is declining, apparently due to com-

petition from western products such as lager beer and

Maize meal

Cooking

Cooling

Fermentation

(approx. 1 day, 50 ⬚C)

Addition of flavorants

and preservatives

Pasteurization

Packaging

(cardboard milk-type

cartons)

Inoculum

(thermophilic

lactic acid

bacteria)

Water

Wheat flour

and/or cane sugar

fig0007 Figure 7 Process for the industrial manufacture of mageu.

Reproduced from Fermenting Foods: Beverages from Sorghum

and Millet, Encyclopaedia of Food Microbiology, Robinson RK, Batt

CA and Patel PD (eds), 2000, Academic Press, with permission.

FERMENTED FOODS/Beverages from Sorghum and Millet 2357