Ayib, Adugna

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Adugna Melkie W/ Medhin

Instructor- Ketema Bacha (PhD)

July 2010



1. Introduction

2. Objectives

3. Description of Ayib, Unripened traditional cottage

cheese and Ripened cheese

4. Microbiological quality of««««

5. Nutritional constituents of«««

6. Safety of ««««««..

7. Summery and conclusion

8. References



Cheese

Fermented product of milk, Lactic acid fermentation.

Fermentation is a chemical process by which changes are broughtabout in an organic substrate through the action of enzymeselaborated by micro organisms.

Casein in milk , has functional properties, for coagulation in tocheese product.

The curdling of milk is done by enzyme rennin (casein coagulase) andlactic acid bacterial (LAB) starter culture.

Cheese can be unripened cheese if they are produced by single stepfermentation.

Ripened cheese if additional growth is required during maturation of cheese to achieve the desired taste, texture, and aroma.

Ripening involves additional enzymatic transformations after theformation of cheese curd. .

Cheese may be consumed as fresh curd or it may undergo ripeningby means of enzymes from the milk, from the rennet, and frommicroorganisms in the cheese or on the surface.



To describe the process how Ayib, traditional Ethiopian cottage

cheese, is produced.

To describe What ripened cheese is and the major cheese groups.

To Identify the microbial quality of Ayib and Ripened cheese.

To describe the effect of curd cooking temperature on the microbial

quality of Ayib.

To assess the safety and nutritional quality of Ayib and ripened

cheeses.



How is Ayib, Produced in Ethiopia?

Fumigating the clay pot with leaves or stem of Olea spp. (woyira) Raw milk is collected in a clay pot and kept in a warm place, about

30oc for 1-3 days to sour (to form sour milk)

Churning of sour milk is carried out by slowly shaking the contents of the pot until the fat is separated

The fat is removed then defatted milk (Arrera) is formed

The defatted milk is heated to about 50

o

c-70

o

c until a distinct curdmass forms and floats over the whey (aguat)

After gradual cooling, the curd is recovered from the whey



Kibe (traditional

Butter)

Fresh Cows· Milk

Keep in warm place

(30oc)

Churning

Ayib (traditional

cottage cheese)

Arrera (defatted

Butter milk)

Whey (Aguat)

Ergo (Sour milk)

Cooking

(heat about 50oc-70oc)



Clay pot

Muslin cloth

Wood stick



Ripening is the process of allowing change of cheese by enzymes and

microorganisms which is important for development of characteristic

flavor, consistency, and appearance.

The effects of the enzymes and the microorganisms depend

On pH and temperature

On the content of moisture and of salt

on the surface treatment.

Ripening period varies from a few weeks up to several years



Cheeses can be classified as

Soft cheeses (high, 50-80%, water content)

Unripened (fresh cheeses)= Cottage, Quark, Cream, Mozzarella

Ripened= Camembert, Brie, caciota

Pickled or salt-cured= Eeta, Domiati Semisoft cheeses (39-50%, water content)=Pressed cheeses

Ripened principally by internal mould growth= Danish Blue

Ripened by bacteria and surface micro-organisms= Limburger

Ripened primarily by bacteria= Edam, Gouda, Brick, pasta filata

Hard cheeses (low water content, less than 39%) =Pressed cheeses

Ripened by bacteria , with out eyes= Cheddar,Caciocavallo

Ripened by bacteria, with eyes= Emmental , Gruyere

Very hard cheeses (water content less than 34%)= Pressed cheeses

Asiago old, Romano, Grana, Parmesan



Ayib [ 100 samples from open market in Awassa, Ethiopia]

The counts of mesophilic bacteria, yeasts and entrococci of 108, 107,

and 107 cfu/gm respectively .

Bacillus cereus, and Staphylococcus aureus were isolated at varying

frequencies built at low temperature (102 _103cfu/gm).

The PH values of the samples varied between 3.3 and 4.6 with about

40% having PH lower than 3.7.

The high microbial in the Ayib would come from handlers and plant

parts used for packaging and for importing flavor.



The effect of curd cooking temperature on themicrobial quality of Ayib

Ayib is made by cooking defatted sour milk at 40oc-70oc

Cooking at 40

OCdid not decrease the microbial load in general .

At 50OC, counts of Entrococci, Entrobacteriacea and Staphylococcidecrease to102 cfu/gm. However substantial number of yeasts, moldsand lactic acid bacteria still remained in the product.

Cooking at 60OC markedly decreased number of most bacteriagroups, yeasts and molds.

Heat treatment at 70 OC required a relatively shorter time for curd

formation and achieved maximum reduction in number of variousmicrobial groups .

Temperature higher than 800C are reported to give the product acooked flavor.

heat precipitation of curd at 700C (PH, 4.0) was recommended as it is

resulted in a less contaminated and more wholesome Ayib .



Ripened Cheese

The combined effects of moderately low pH and low Eh provide a

barrier against some microorganisms, there are others, including

spoilage organisms, and in rare cases, pathogens, that can grow

in the cheese environment.

Microorganisms can cause several general types of spoilage in

cheese. these include appearance defects, texture defects, and

flavor and aroma defects.

Spoilage of cheese by microorganisms is a constant concern, the

presence of pathogens in cheese occurs only infrequently, and

rarely does food borne disease result.

Just a single positive test for L. monocytogenes or E . coli

O157:H7 may initiate a product recall.



Type of nutrient in Ayib Percentage composition

Water««««««««««««««««««..79

Protein«««««««««««««««««..14.7

Fat««««««««««««««..««««««.1.8

Ash«««««««««««««««««««««.0.9

Soluble milk constituents«««««.««.3.1



Milk Cheese Whey

(100kg) (10.8 kg) (89.2kg)

Water 87 3.9 83.1

Fat 4 3.6 0.4

Total Protein 3.3 2.5 0.8 Casein 2.5 2.4 0.1

Whey protein 0.8 0.1 0.7

Lactose 5 0.2 4.8

Minerals 0.7 0.6 0.1



Why cheese Making is important ?

The fresh curd contains valuable nutrients and can therefore quickly

be spoiled by bacteria, Yeasts and molds if not preserved

Cheese making is the means of conserving many of the nutrients in

milk

The main factors contributing to preservation are low Moisture

content (concentration), acidification by adventitious or added lactic

acid bacteria, and salting.



Ayib

Listeria monocytogenes was not encountered in any of the samples.

Salmonella typhimurium, Salmonella enteritidis and Salmonella

infantis were able to grow when added to raw cheese milk, but none

was able to survive the heating process at the prevailing low pH.

The count of E. coli 0157:H7 increased during milk souring for Ayib

processing, but the count immediately after curd-cooking was below

detectable limits.

LAB suppresses the growth of other micro-organisms.



Ripened cheese

more focus on emerging pathogens such as Listeria and E. coli

H7:O157

the larger batch sizes increase risk to larger numbers of consumers,

if pathogens are present

Because of the large batches, economic losses will be substantial if

the quality is not acceptable

An unacceptable quality in just a few batches from a producer may

lead to loss of market shares.



In order to control the presence and growth of pathogenic

microorganisms, it is important to do whatever is possible to prevent

their occurrence from farm to cheese product.

Implementation of HACCP is an excellent tool to control the

pathogens or spoilage microorganism.

Raw milk should be of good quality, and its storage should be at lowtemperatures, especially if storage times are long..

The activity of the starter must be high; this will lead to a fast drop in

pH, helping to control pathogens. If possible, the temperature should

be kept as low as possible and the salt content as high as possible.

To make the cheese is a well-conserved system, creating a protective

chain of hurdles against pathogenic and spoilage microorganisms. Cheese is the wise use nutrients found in milk.

Ayib is a fermented traditional milk product in Ethiopia.



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Ayib, Adugna