A Review on the Sudanese Traditional Dairy Products and Technology
A.M. Mohammed Salih,
S.M. El Sanousi
I.E.M. El Zubeir
Sudanese traditional fermented foods represent the main source of nutrition for rural and urban communities. Dairy products participated in enhancement of the economy, finance and business of local societies. Although, many dairy product studies have been conducted in Sudan, information on the microbiology and technology is still sparse. Most of the research conducted has relevance to organisms associated with fermentation and those considered spoilage. Diverse strains of Lactic Acid Bacteria (LAB) were documented as part of many traditional fermented milk products. But knowledge about their specific health benefits and strains properties needs to be revealed. Moreover, publishing is not having much concern compared to the flow of the Sudanese studies. The aim of this review was to figure out the traditional dairy technology used, identity of the isolates as well as presentation of the Sudanese research to the world abroad.
Received: July 02, 2011;
Accepted: September 14, 2011;
Published: November 16, 2011
No other group of bacteria took a considerable attention than Lactic Acid Bacteria
(LAB). Its fermentative properties revolutionize the dairy products industry.
Its uses as probiotic pave the way of bacteriotherapy era. Its use as natural
preservative remains safe for many centuries (Ali, 2011).
Milk represents the most important diet for human from infancy to elderly (Elmagli
and El-Zubeir, 2006). Milk is fermented by LAB to produce other products
varied in their tastes, constitutions and shapes. Dairy products are major source
of nutrition and consumed daily throughout the world. In some countries, addition
of traditional spices enhances the fermentation process and suppresses the growth
of pathogenic organisms (Abdalla and El-Zubeir, 2006).
The chemical composition, the hygienic quality and determination of food borne
diseases were widely studied in Sudan. But researches issued to laboratory work
not actively contribute to industry manufacturing (Warsama
et al., 2006). Governments are asked to strength their efforts to
advance the measurements of food quality and safety (Yagoub
et al., 2006). Many factors are indigenously attributed to the fermentation
processes such as the form of the inocula, type of vessels used and the micro
flora from the starter/s or from the surrounding environment (Osuntoki
et al., 2008).
|| Map of Sudan
Sudan in glance: Sudan (Fig. 1) is laid in the heart
of Africa between latitude 4° and 22.5°N and extends from longitude
22° to 38°E. It is the largest country in Africa covers area of 2.505.813
km2 and ranked as the tenth world largest country. River Nile, the
worlds longest river, divided Sudan into east and west sides (Collins,
2007). Sudan is bordered by Egypt from north, Libya from northwest, Chad
from west, Republic of Central Africa and Congo from southwest, Kenya and Uganda
from southeast, Eritrea and Ethiopia from east and the Red Sea from the northeast.
Sudan is among the wealthiest countries in Africa in terms of the natural resources
(Ibnouf, 2009). It is the second largest livestock in
Africa. The nomadic pastoral sector accounts more than 90% of the huge animal
population (FAO, 2001). Recent census estimates the Sudanese
population about 35 million person. Federal Ministry of Animal Resources and
Fisheries in 2006 estimated that there were 39.67 million head of cattle, 48.44
million sheep, 42.03 million Goats, 3.50 camel, 7.00 million equines and 50.00
million poultry. The total rate of fresh milk production (Fig.
2) from different animals sources is 7.095 thousand ton. The consumption
as dietary food is 3.969 thousand ton. Cattle, sheep and goats provide an important
investment property in terms of meat, milk and leather (FAO,
Historical background: The introduction of fermented milk products to
Human civilization date back many thousands of years (Campbell-Platt,
1994). They may originated in the Middle East and dated back long before
the phoenician era. It was proved that Laban Rayeb and Laban Khad (traditional
Egyptian fermented milk products) were consumed as early as 7000 Before Christ
(Kosikowski and Mistry, 1997).
The Sudanese history of using milk dated back to 5000 years ago. Strong evidence
proved that people of Meroe Kingdom (690 BC-D 323) may know how to ferment cow
milk (Abdel Gadir et al., 1998).
||Production versus consumption for meat, milk and eggs with
the year 2002. Source: FAO (2005)
Milk fermentations provide a way for long-term preservation, enhance the nutritional
value, improve the appearance of various products, give the desirable taste,
prevent the spoilage and reduce the effort and time required for cooking (Tamime,
2002; Motarjemi, 2002; Floros
et al., 2010). The souring of milk into a product or into certain
dairy products is a widespread practice. These products are art specific of
certain country whereas others are confined to specific geographical locations
(Abdel Gadir et al., 1998).
SUDANESE TRADITIONAL DAIRY FOODS
The various sources of fresh milk in Sudan shaped the different traditional
dairy products (Fig. 3). Dirar (1993)
divided the Sudanese fermented dairy products into two major groups: the truly
indigenous which include Rob, Gariss, Biruni and Mish and the quasi-indigenous
which include Zabadi and Gibna beida. Methods of preparation are different slightly
from one part of the country to another. The most important traditional products
are Rob (fermented milk product mainly of cows), Zabadi (local name of
yogurt), Gariss (fermented camel's milk product), Gibna Bayda (white cheese),
Gibna Mudaffra (White pickled cheese) and Mish (fermented milk product with
spices) (Dirar, 1993; Abdel Gadir
et al., 1998).
Rob: Rob is produced (Fig. 4) in the rural areas mainly
on household levels. It is the popularly known way for surplus milk preservation.
There are many spelling Rob, Roub and Robe. The name is varying according to
the area produced. For instance, in Butana area called kit, Darfur Berkib and
laben-rayeb in urban areas. Rob is made from fermentation of cow, sheep and
goats milk. The bulk is made from cows milk while a smaller proportion
is prepared from either goats or sheeps milk or a mixture of these
two milks (Abdel Gadir et al., 1998; Dirar,
1993). Milk surplus is collected in a container, inoculated with a starter
from the previous day and left to ferment overnight. The fermentation process
usually starts in the evening when the animals return from grazing and the sour
product is churned in the morning when the herd leaves for grazing. Freshly
produced Rob has a pleasant taste with a pH of about 4.5.
||Flow scheme for processing of various traditional fermented
milk products. *Bukhs and Siin Local churner gourd
are used for churning fermented milk, mainly in Darfur State
|| Rob production in the rural area in Sudan
In some parts of the country, churning is done in a leather container called
Siin made of tanned goatskin (Girrba) and in other parts it is
done in a container called Bukhsa. Bukhsa is a gourd made from the dried fruit
of the plant Lagenaria leucantha. In hot climatic conditions, Rob is
diluted with 2 or 3 volumes of water to give Gubasha, a thirst quencher (Abdelgadir
et al., 2001; Dirar, 1993).
In urban, Rob is usually refrigerated and consumed with sugar as a desert or
eats with wheat bread. Sometimes it is fed to babies and often turned into sauce
for Aceda (porridge) or given to young animals as a milk replacer (Dirar,
1993). Most of the developing countries started to search in their indigenous
homemade yoghurt for effective antibacterial agents against enteric pathogens
(Salih et al., 2011; Osuntoki
et al., 2008; Yesillik et al., 2011).
Gibna: Ginba (cheese) production in Sudan has been started in the early
eighteenths by the Greek families who migrated to Sudan. They settled mainly
at El Dueium in the White Nile State, El Obeid in North Kordofan state and other
localities in the country (El-Tayeb, 1986). Gibna making
is the major preservation method for surplus milk in rural areas. The highest
production is during the rainy season (Hamid and El Owni,
2007). The major types of cheese are Gibna Bayda and Gibna Mudaffara (El-Sheikh,
1997; Hamid and El Owni, 2007). They are varying
in composition, texture, color, taste and flavor. The variation is due to composition
of milk, methods of production, microbial flora, type of package, microbial
activity during ripening and ripening conditions. Cheese manufacturing is influenced
by product composition, processing, packaging and storage conditions. Control
of temperature and humidity and transportation are dynamic aspect of health
hazards (Nour El-Diam and El-Zubeir, 2006).
Gibna bayda: Sudanese Gibna Bayda is unique in containing high concentrations
of salt (Sodium Chloride) which is added to the milk before processing. High
salting preserve cheese from rapid deteriorating before ripens (Taormina,
2010; Osman, 1987). The procedure (Fig.
5) for making Gibna Bayda includes heating of the fresh milk to 35°C
followed by salt addition to give 6-10% solution in milk. The lactic acid bacteria
naturally present in the raw milk carry out the fermentation process, no starter
is used (Abdel Gadir et al., 1998; El-Owni
and Hamid, 2008).
Gibna mudaffara: Gibna Mudaffara is similar to Gibna bayda but high
percentage of salt is added to milk (Fig. 5). Rennet or rennet
extract is added to obtain a firm coagulum which develops in 4 to 6 h. Ripening
takes place while the cheese is submerged in whey. The purpose of coagulant
is the conversion of liquid milk into a gel catalyzed by different proteases
(Green, 1984). There are two main phases in the mechanism
of milk clotting: the primary (enzymatic) phase and the secondary (coagulation)
phase (Dalgleish, 1993; Payne et
al., 1993). The coagulum is then transferred to wooden moulds lined
with cheese cloth muslin and the whey is allowed to drain overnight. The drained
whey collected into a clean pan, boiled for 15 min, followed by removal of the
fats and coagulated whey proteins, then starter from previous fermented milk
is added and left overnight to ferment. Next day the cheese is removed from
the molds and the curd is cut into 10 cm cubes. Gibna Mudaffara preserved for
long time by immersion in the whey. For marketing it packed in tins or other
suitable sealed containers (Dirar, 1993; Abdel
Gadir et al., 1998; El-Tayeb, 1986).
Gariss: Gariss is unique Sudanese traditionally fermented camel's milk
product. It made by a semi-continuous fermentation process. The word Gariss
means pinching or stinging, denoting a high degree of sourness (Dirar,
|| Cheese production in Sudan
Fermentation is carried out in two leather bags of tanned goat skin embedded
in green or wet grass carried on the back of camels. Milk is subjected to continuous
shaking by the jerky walk inherent to camels. Whenever part of the product is
withdrawn for consumption, a part of fresh camels milk is added to make
up the volume and this continues for months (Dirar, 1993;
Abdel Gadir et al., 1998). Camel milk is the
main dietary of nomadic tribes in the East and West of Sudan. It also consumed
by pastoralists living in the arid and semi-arid regions. Pasteurization reduces
the chemical composition (total solids, fat, protein, ash and acidity) of Gariss.
Pasteurized and non pasteurized Gariss equally withstand the storage conditions
(Hassan et al., 2007).
Suusac is similar to Garris and widely consumed by the pastoralist communities
living in Kenya and Somalia. It is prepared by fermenting fresh camel milk in
a pre-smoked gourd at ambient temperature (26-29°C) for 1-2 days (Lore
et al., 2005).
Mish: Mish is famous fermented milk product recently introduced from
Egypt (El-Mardi, 1988). Mish is produced by boiling milk,
cooling and inoculation with small quantity of the previous batch or Rob. After
souring, seeds of black cumin (Nigella sativa), seeds of fenugreek (Trigonella
foenum graecum) and perhaps a few pods of green or red pepper are added.
The product is fermented for 2 or more days before consumption (Dirar,
1993). Black cumin played a remarkable inhibitory effect on the growth of
Staph aureus. This may be due to the fact that volatile oil inhibits
the growth of some pathogenic bacteria (Abdalla and El-Zubeir,
2006). The intensity of spicing may differ from region to another and from
family to family within the same district. Variation depends on spices availability
and the taste of the people (El-Mardi, 1988).
Other Sudanese dairy products
Biruni: Biruni is similar to Mish. Its manufacturing was limited to Nuba
Mountains area but recently spread into the area inhabited by pastoralists who
named it Laban-gadim (aged milk). Biruni is stored at least for one year and
may extend to more than ten years. The main purpose of making Biruni remain
secret as it consumed years after fermentation (Dirar, 1993).
Samin: Samin (ghee) like in many African countries is produced from
butter (Sserunjogi et al., 1998). The process
involves a gradual heating of butter, during which water is driven off and protein
is dehydrated and precipitated. Then oil is extracted in a closed tight container.
Samin is home-made product and mainly add to Rob sauce and for bakery.
MICROBIOLOGICAL OVERVIEW OF THE DAIRY PRODUCTS
Milk fermentation process depended on the microbial biological activity to
produce a range of metabolites. These metabolites have preservative and antagonistic
effects so prevent the spoilage and/or pathogenic food microbes. Fermentation
produces aromatic compounds such as diacetyle and acetaldehyde which flavor
the foods, as well as vitamins and antioxidants (Ross et
al., 2002; Ray and Daeschel, 1992). The nature
of fermented products is different from one region to another. Differences depend
on the local indigenous microflora and the climatic condition of the area. Thus,
traditional fermented milk in cold region contained mesophilic bacteria such
as Lactococcus and Leuconostoc spp while thermophilic bacteria
which include mostly Lactobacillus and Sterptococcus prevailed
in subtropical or tropical regions (Savadogo et al.,
2004). The metabolic pathways of each strain ended with different byproducts
as organic acids, alcohol and carbon dioxide. The microorganisms present in
milk may originate from the animal itself, milking equipment and environment,
personnel or from the previous batch if back-slopping is used (Narvhus
and Gadaga, 2003). It is clear that the microbiology of these products is
so variable. The variation is due to the method of processing, salting time
and method of whey treatment. It is of great value to carry out extensive and
comprehensive studies to elucidate and identify the Sudanese normal dairy flora.
Research must focus on which is which microbe and/or its products is predominated
or confined in each country part.
LACTIC ACID BACTERIA (LAB)
Lactic Acid Bacteria (LAB) are widespread in most ecosystems. They are famous
starter cultures for food fermentation, as well as commonly found in non-fermented
foods such as fruits, vegetables, cereals, sewage. LAB also inhibits the genital,
intestinal and respiratory tracts of humans and animals. LAB has an excellent
employment in foods industry, due to their contributions to flavor, aroma and
increase shelf life of fermented products (Stiles and Holzapfel,
1997; Leisner et al., 1999). It bears many
responsibilities as in dairy to make yoghurt and cheese, in meat to produce
sausages, in fish to manufacturing tuna, in cereals for bread bakery and beverages
to make beer, in fruit (malolactic fermentation processes in wine production),
and in vegetables to prepare sauerkraut, kimchi and silage (Calo-Mata
et al., 2008).
LAB are Gram-positive microorganisms, non-sporulating, cocci or rods, negative
to catalase test, devoid of cytochromes, preferring anaerobic conditions but
are aerotolerant, fastidious, acid-tolerant and strictly fermentative. LAB produces
lactic acid as main product of glucose degradation (Stiles
and Holzapfel, 1997). The most important genera are Lactobacillus, Lactococcus,
Enterococcus, Streptococcus, Pediococcus, Leuconostoc and Bifidobacterium.
The isolation and characterization of LAB aimed to provide starters that allow
standardization without changing the fundamental properties of the product (Herero
et al., 1996). Tentative identification of new strains may attract
the attention of the dairy industry for development of starter cultures, new
products and tastes. Great efforts were made to investigate and manipulate its
role in these symbiotic processes (Reid, 2008). Current
researches focused on the use of LAB as probiotic (Ouwehand
et al., 2002). Sudanese researchers still want to know the starters,
the common microbes present and the chemical composition of the fermented dairy
products. Little research (Abdullah and Osman, 2010;
Ali, 2011; Salih et al.,
2011) intended to constitute a bank of LAB strains isolated from Khartoum
state. They aimed to use the selected strains, one hand, in manufacturing fermented
dairy products suitable to local conditions and on the other hand, to introduce
national functional products into the Sudanese and international markets.
In general practice, although the method used for characterization and identification of LAB species was still traditional phenotypic characterization, few studies used the recently advanced molecular techniques.
RESEARCHES AREA REVIEW
The capital city (Khartoum) is the most studied area and nomads in the surrounding
(Saeed, 1981; Mahjoub, 1998; Abdelgadir
et al., 2001; El-Mardi, 1988). Few studies
were conducted in White Nile State, central of Sudan (Abdalla
and Ahmed, 2010), Darfur (Abdel Moneim et al.,
2006; Hamid and El Owni, 2007) and Gezira states
(Sulieman et al., 2009) west and center of Sudan,
respectively. The researches were either for microbial screening or for isolating
the common types of bacteria in the samples. Samples studied were varied according
to the dairy products.
The microflora of Sudanese dairy products: The microbiology of the spontaneous
souring of milk in Sudan is complex and diverse (Table 1).
Most of the dairy products are prepared by spontaneous fermentation, either
using the previous fermented batch back slop or using the same instrument (Gonfa
et al., 2001). The predominant microbiota in animals milk (cows,
goats, camels and ewes) contains variable strains of different genera and species
(Elgadi et al., 2008). Homofermentative lactobacilli
from cows and camel milk were tentatively identified as Lactobacillus plantarum
and Lb. acidophilus, whereas the Heterofermentative ones from cows, goats
and ewes milk were found to be Lactobacillus fermentum. The Homofermentative
Streptococci isolated from all milk were tentatively Streptococcus
cremoris and Streptococcus lactis, whereas the only Heterofermentative
strain isolated from camel milk is Leuconostoc lactis (Elgadi
et al., 2008).
Dirar (1975) noticed that milk soured by Enterobacter
aerogenes to produce a frothy product or by Lactococcus sp. to produce
a smooth-set product. Coliform bacteria and LAB are both involved in
the souring of milk, especially in the hot summer.
The early studies of Saeed (1981) and El-Mardi
(1988) revealed Streptococcus thermophilus, Lactobacillus bulgaricus
(or the closely related L. jugurti), Lactobacillus helveticus,
Lactobacillus fermentum and Lactococcus lactis as the common
microbial species in Rob.
|| Frequency of the common isolates in Sudanese dairy products
All studies used the conventional methods of identification. In the new millennium
recent advanced methods were used for bacterial identification. Hamza
et al. (2009) identified Lactobacillus delbreuckii sub sp.
bulgaricus, Lactobacillus rhamnosus, Lactobacillus plantarum,
Lactobacillus casei, Lactobacillus pentosus using API 50 CHL.
Aerococcus viridians, Enterococcus faecium, Enterococcus gallinarum,
Lactococcus lactis sub sp. lactis, Leuconostoc sp. Streptococcus
acidominimus and Streptococcus bovis were added to the list by API
20 STREP identification. Random Amplified Polymorphic DNA (RAPD) was used as
molecular identification technique to confirm the results (Hamza
et al., 2009). Gram negative bacteria may not associate with the
aerobic bacteria in Rob. This may due to the acidity of the product (Mahjoub,
1998). Some of the bacterial species were not frequency reported in dairy
products such as Corynebacteria pseudodiptherium isolated from Rob (Mahjoub,
1998). Other unfavorable bacterial species may present in high amount such
as Staphylococcus saprophyticus, Staph. epidermidus, Staph. arlettae, Staph.hyicus,
Streptococcus uberis, Micrococcus luteus, M. kristinae and Coliform
(Mahjoub, 1998). It seems that some pathogenic bacteria
may be a part of the normal dairy biota such as Streptococcus infantarius
sub sp. infantarius in Gariss (Abdelgadir et
Studies on Gariss revealed that the most dominant LAB were Lactobacillus
paracasei sub sp. paracasei, Lactobacillus fermentum, Lactobacillus
plantarum and Lactococcus raffinolactis. The dominant were Lactococcus
lactis, Enterococcus spp., Leuconostoc spp., Lactobacillus
animalis, Lactobacillus gasseri, Lactobacillus brevis, Lactobacillus
divergens, Lactobacillus rhamnosus and Lactococcus alimentarium.
Whereas the less frequently isolates from Gariss were Streptococcus lactis
sub spp diacetylactis, Lactobacillus brevis, Lactobacillus
casei, Lactobacillus leichmanii, Lactobacillus acidophilus
(Sulieman et al., 2006; Abdel
Moneim et al., 2006; Hassan et al., 2008;
Ashmaig et al., 2009).
The presence of Salmonella spp. and Clostridia spp. is not documented
in Gibna Bayda collected in Zalingei Area, west Darfur State (Hamid
and El Owni, 2007) but Salmonella spp. present in considerable amount
in Gibna from Khartoum State (Yagoub et al., 2006).
There are significant variations between color, texture, flavor and saltiness
in Gibna from Zalingei. The common microorganisms in Gibna bayda were Streptococcus
mutans, Lactobacillus bulgaricus, Lactobacillus casei and
Lactococcus plantarum (Ahmed, 1997).
There is no significant difference in the microbial counts of Gariss from transhumance
and nomadic camel. But Streptococcus lactis is the most predominant in
the Nomadic herders, while Str.lactis sub sp diactylactis is predominate
in transhumance herders (Hassan et al., 2008).
The microbiota of Gariss is different from area to another. In Butana area high
count of Lactobacilli (8.22±0.28 log10 cfu mL-1),
Kordufan area higher counts (7.85±0.45 log10 cfu mL-1)
of yeasts than Butana (Sulieman et al., 2007).
|| Chemical composition of fresh milk in %
|TSS: Total soluble solids, TS: Titrable acidity. Modified
from Sulieman et al. (2007)
|| Amino acid composition of Fresh Milk (FM) and Rob samples
|Bql: Below quantifiable limit of 0.11 m mole amino acid/100
g, ND: Not detected with the procedure utilized.. Sucrose: Sulieman
et al. (2009)
Lactobacillus plantarum, Lactobacillus paracasei are major
bacteria in Kordufan, whereas the major in Butana is Lactobacillus paracasei
sub sp. paracasei (Sulieman et al., 2007).
Changes in fermentation of the dairy products: The development of food
industry depends entirely on the use of defined strain starters. The mixed undefined
starters used traditionally require more efforts to be elucidated. The quality
of culture performance, product quality and consistency need more improvement.
Unsatisfactory strain performance in manufacturing can results from intensively
use of specific starters (Klaenhammer and Fitzgerald, 1994).
Moreover, Change in sensory is critical to the overall quality of the product.
Deterioration of sensory is indicated by rapid end of shelf life (Gacula,
2004). The direct antimicrobial effects of lactic and acetic acids (present
in the fermented products) play a significant role in improving the shelf-life
(Davidson, 1997). Their antagonistic action on the bacterial
cytoplasmic membrane, interfere with the maintenance of membrane potential and
inhibit the active transport (Blom and Mortvedt, 1991).
Proximate chemical composition of fresh milk was profiled to study the changes
due to fermentation (Table 2). Changes following Rob fermentation
increased the availability of some free amino acids, particularly Methionine,
Histidine and Isoleucine (Sulieman et al.,
2009). There is doubling in the concentrations of most amino acids of Rob
than that of fresh milk (Table 3). Fermentation also increases
the contents of most macro-and micro elements with decreased in sodium and manganese
|| Comparison of chemical composition of Gariss samples collected
from transhumance and nomadic herders
|Values are Means±SD. *Significant differences at (p<0.05).
**Significant at (p<0.01)
Minerals analysis revealed that the concentration of most macro- and micro
elements is increased. However, in general, the concentrations of micro-elements
are very low and hardly detectable in the analyzed sample (Sulieman
et al., 2009). Rob present in the Sudanese market regardless of the
source i.e., from powder or fresh milk showed variable chemical composition.
But it contains high amount of coliform, yeast and mould (Mohammad
and El-Zubeir, 2011). Sudan standards should establish strict sanitary standards
to control milk production and marketing and to improve the hygienic processing
Sulieman et al. (2006) suggested the relatively
high amounts of ethanol detected in Gariss (average 1.40±0.03%) together
with the high yeasts counts (6.0±0.53 log10cfu mL-1)
indicated that the fermentation process is a yeast-lactic fermentation. Gariss
from transhumance and nomadic camel Herds in Sudan showed differences in mean
levels of total solids, ash and protein content (Table 4).
In an experiment (El Hadi Sulieman and Tsenkova, 2007)
to prepare fermented milk products in High Temperature Short Time (HTST) pasteurized
cows milk was used. The LAB strains were already isolated from Gariss
and yeast strains were isolated from Rob. LAB included Lactobacillus plantarum,
Lactobacillus paracasei sub sp paracasei and Lactobacillus
fermentum while the yeast strains were Pichia membranefaciens and
Candida famata. The strains were inoculated into HSTS milk and incubated
at 25°C. Mixture of LAB and yeast showed sufficient growth at 25°C for
24 h. Therefore, resulted in stable fermented milk with high nutritive value.
At the end of the experiment, the chemical profile of organic acids during fermentation
was studied (Table 5). The organic acids concentrations increased
in all fermented milk samples but were more or less similar I n all fermented
milk products. Other experiment (Abdel Rahman et al.,
2009) combined two bacteria (Lactobacillus bulgaricus plus Streptococcus
thermophilus) as starters for Garris. The mixture gave most acceptable sensory
than Gariss fermented by one strain e.g., Lactococcus lactis. It also
showed increase in the total viable count, acidity and proteolytic activity.
According to El-Owni and Hamid (2007) Gibna bayda was
affected by the period of storage. But usually affect by some of the microbial
hazards such as E. coli, Salmonella spp. and Staph. aureus
(Warsama et al., 2006). The weight loss, crude
proteins, total solids and ash contents significantly increased in the beginning
of storage then decreased after 120 days. The total bacterial count, Coliform,
E. coli, Staph. aureus and psychrotrophic bacterial count decreased
during storage while yeasts and mould increased with improvement in the texture,
flavor and colour of the cheese (El-Owni and Hamid, 2008).
Mish has less shelf-life and could be up to 21 days (Table 6)
(Abdalla and Ahmed, 2010). Traditionally added spices
may be have a good role in extending to this period (Abdalla
and El-Zubeir, 2006).
|| Microbiological quality of Mish from each plant during storage
(Log10 cfu g-1) (Mean±SE) (Abdellah
and Ahmed, 2010)
Molecular characterization of the isolates: Enumeration of LAB species
in the dairy products is important to study their dynamics role. The Culture-dependent
technique widely used is still problematic (Dave and Shah,
1996). The appropriate rapid quantification approaches are dot blot rRNA
hybridization and whole-cell in situ fluorescent hybridization techniques (Furet
et al., 2004). They are much suitable tools for the rapid identification
and quantification of LAB species in complex microbial ecosystems without their
prior isolation (Matsuki et al., 1999, 2002).
But when the threshold of the target population is lower than 1%, Polymerase
Chain Reaction (PCR) is much more suitable means (Furet
et al., 2004).
Currently, there is a wide variety of molecular techniques used for microbial
identification such as PCR with specific primers, DGGE, RAPD, PFGE, FISH, RFLP
and PCR-ARDRA (Morris et al., 2002). In Sudanese
dairy products literature there are few studies applied PCR and RAPD for housekeeping
genes (rpoB, sodA), 16S rRNA and gtf (Abdelgadir et al.,
2001; Hamza et al., 2009; Ashmaig
et al., 2009). Strains genes sequencing is not far from application
in Sudan (Abdelgadir et al., 2001, 2008).
But traditional PCR for genus species of LAB is the most common application.
Some research used multiplex PCR for group and species specification of Lactobacillus,
other designed primers form nucleotide sequence of the 16S-23S rRNA intergenic
spacer region (Sulieman et al., 2007; Abdelgadir
et al., 2008).
FAO/WHO (2002) defined probiotic as live microorganisms
which when administered in adequate amounts confer a health benefit on the host.
A wide variety of species and genera of bacteria could be considered potential
probiotics, the most potential strains are LAB. Industrial applications are
relying on six main beneficial and nonpathogenic species isolated from natural
sources: Lactococcus (milk), Lactobacillus (milk, meat, vegetables,
cereal), Leuconostoc (vegetables, milk), Pediococcus (vegetables,
meat), Oenococcus oeni (wine) and Streptococcus thermophilus (milk).
Lactobacilli, occupy important niches in the gastrointestinal tracts
of humans and animals and offer a number of probiotic benefits to general health.
These benefits include a positive influence on the normal microflora, competitive
exclusion of pathogens and stimulation/modulation of mucosal immunity (Klaenhammer
et al., 2005). The use of probiotic bacteria is not documented in
the Sudanese literature. There is no published study carried out in Sudan to
isolate this type of bacteria, study the therapeutic or functional role. However,
Salih et al. (2011) studied the antibacterial
activity of selected probiotic bacteria isolated from Rob. The results paved
a way to use those strains as therapeutic agents. A delightful study used Gariss
(G) and Gariss supplemented with Bifidobacterium lactis Bb-12 (G+Bb-12)
to investigate their hypocholesterolaemic effect in rats. Rats were fed on a
cholesterol enriched diet for one week. Then the levels of cholesterol and triglyceride
were measured in rats plasma. Rats fed on (G) and (G+Bb-12) diet showed
significant low levels of plasma VLDL+LDL-cholesterol. The (G+Bb-12) diets were
more effective in lowering plasma VLDL+LDL-cholesterol levels than (G). Also,
both of the diets (G) and (G+Bb-12) were remarkably lower the levels of plasma
triglycerides in rats (Elayan et al., 2008).
Outside of dairy products, probiotic of Malaysian origin, Bifidobacterium
longum, was used to ferment malted brown rice flour to produce a nutritious
Medida (Sudanese cereal thin porridge) (Kabeir et al.,
Sudanese dairy products were used traditionally for therapy. In Butana area
Kit (ferment product from goats milk) is used to cure patients complaining
from some enteric ailments (Abdel Gadir et al., 1998).
Gariss is used to cure Leishmaniasis or kala-azar (Dirar,
1993). The addition of spices (Black cumin, fenugreek and garlic) and salt
to Rob and Mish acted as antimicrobial agents against Enteropathogens
and Staph. aureus (Abdalla and El-Zubeir, 2006).
Human progression has been catalyzed by evolution of food industry. Food manufacturing
promotes the populations health and helps the societies to prosper and
flourish. There is a pressing need for a re-evaluation of livestock policy in
Sudan. Many problems hinder the development of the dairy industry. To be overcome;
comprehensive plans, regulations and economical policy must be introduced. Most
of the animal wealth owned by the nomads and represent a part of their own traditions
and customs which are handed down throughout generations. This shed negative
effect on the quality of the animals breeding and dairy products. Although,
the government developed several policies and projects to promote the crop production;
it had quantatively bordered the livestock and pastoralism. Despite the merit
reproductivity of Sudanese cattle, research is influential to increase the awareness
of the role of livestock, their genetic diversity and for the implementation
of sustainable breeding programmes (Lutfi et al.,
2005). Most of the dairy products are traditionally made, either part of
their livelihood, daily dietary needs, or as part of a small enterprise scale.
Modern, large-scale production of fermented foods is dependent entirely on the
use of defined strain starters which have replaced the undefined strain mixture
traditionally used for the manufacture of the products. This switch to defined
strains has meant that both culture performance and product quality and consistency
have been dramatically improved.
The first dairy factory is established in the early 19th in Khartoum North by the British colonization. The main purpose of the factory is to supply the governmental employees with dairy needs. In 1963 the first equipped milk factory established in Hela-Koko (Khartoum North). Since then only few small factories are added into the industrial sector.
Civil wars in Sudan have great negative effects on Sudan economy. The past efforts devoted to develop the dairy products are apparent in todays violent conflicts, massive population displacements and extensive food insecurity. In the natural pastures and throughout the last centuries, the style of the grazing depends on two things; continuous searching for water sources and landing on the seasonal green pastures. Environmental and social conflicts are raised from desert encroachment and utilization of the animal welfare. All these factors led to civil wars, tribes conflicts and scarcity of resources. The issues of overgrazing and desertification have been inadequately studied. Because episodic drought, the southward drift of isohyets, fires and deforestation are cited as causes but pastoralism is often singled out for blame.
Sudan has one of the largest and most species diverse livestock populations
in Africa. It greatly contributes to national economy and export revenue. The
importance of traditional dairy products is not of economical only but also
represents a cultural heritage for the production area. The knowledge of microbial
communities may improve the understanding of specification and characterization
of these products. Only little research was carried out on the Sudanese dairy
food. Most of the researchers focused on the isolation of the LAB presented
in the traditional dairy products. Conventional methods used for microbial detection
are based on samples dilution and pour-plating or spreading the highest dilution
on selective media. However, this method might not isolate the species present
in small number. Gap exists in our knowledge of the mechanisms of fermentation,
role of the different isolates and characterization of probiotic bacteria. More
additional studies on isolation, classification and molecular characterization
of the strain in milk and dairy products are particularly needed. For the hygienic
quality of market raw milk in Khartoum State during the two seasons (summer
and winter) some important procedures must be considered (Mohamed
and El-Zubeir, 2007):
||Immediate cooling of milk after milking [in the absence of
cooling facilities, Lactoperoxidase System (LPS) is efficient means for
preservation (El Zubeir et al., 2006)
||Heat treatment to control bacteriological quality (it was noticed that
Brucella is more common in winter than in summer)
||Milk commission must staff the production, distribution and marketing
||Sanitary inspector and veterinarian have to implement the standards methods
||Screening laboratory tests to the entire employees from farms to shops
must be inspecting periodically
||More studies are needed to identify bacterial toxins produced by harmful
The authors would like to thanks Prof. Abdelrahim M.E., for his contribution in establishing the Probiotic project and guiding. Gratitude to Prof. A.El-Shalali for his continuous support and Prof. I. Elgaali for their kind fund, assistance and providing me with some articles. Sincere thanks to Prof. Mohammed Salih ElGabalabe for his kind contribution in correction and editing this manuscript.
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