History of food microbiology

As a discipline, Food Microbiology does not have a precise beginning.  Events which stretched over several centuries ultimately led to the recognition of the significance and role of microorganisms in foods.  Food borne disease and food spoilage have been part of the human experience since the dawn of our race.  Although the actual cause of these problems would remain a mystery for thousands of years, many early civilizations discovered and applied effective methods to preserve and protect their food:


7000 BC – Evidence that the Babylonians manufactured beer (fermentation).  Wine appeared in about 3500 BC.  In early civilizations (and even today in underdeveloped countries where modern sanitation is lacking), alcoholic beverages like beer and wine were much safer to consume than the local water supply, because the water was often contaminated with intestinal microorganisms that caused cholera, dysentery and other serious diseases.


6000 BC – The first apparent reference to food spoilage in recorded history.


3000 BC – Egyptians manufactured cheese (fermentation) and butter (fermentation, low aw).  Again, fermented foods such as cheese and sour milk (yogurt) were safer to eat and resisted spoilage better than their raw agricultural counterparts.  Several cultures also learned to use salt (low aw) to preserve meat and other foods around this time.


1000 BC – Romans used snow to preserve shrimp (low temp), records of smoked and fermented meats also appear.


Even though early human cultures discovered effective ways to preserve food (fermentation, salt, ice, drying and smoking), they did not understood how these practices inhibited food spoilage or food borne disease.  Their ignorance was compounded by a belief that living things formed spontaneously from nonliving matter (Theory of Spontaneous Generation).


1665 – An Italian physician by the name of Francesco Redi demonstrated that maggots on putrefying meat did not arise spontaneously but were instead the larval stages of flies (put meat in container capped with fine gauze so that flies couldn’t get access to deposit eggs).  This was the first step away from the doctrine of spontaneous generation.


1683 – Anton van Leeuwenhoek from the Netherlands examined and described bacteria through a microscope.  At about the same time, the Royal Society was established in England to communicate and publish scientific work, and they invited Leeuwenhoek to communicate his observations.  He did so for nearly 50 years until his death in 1723.  As a result, Leeuwenhoek’s reports were widely disseminated and he is justifiably regarded as the person who discovered the microbial world.


1765 – Italian named Spallanzani tried to disprove the theory of spontaneous generation of life by demonstrating that beef broth which was boiled and then sealed remained sterile.  Supporters of the theory discounted his work because they believed his treatment excluded O2, which they thought was vital to spontaneous generation.


1795 – The French government offered 12,000 francs to anyone who could develop a practical way to preserve food.  A French confectioner named Nicholas Appert was issued the patent after showing that meat could be preserved when it was placed in glass bottles and boiled.  This was the beginning of food preservation by canning.


1837 – Schwann demonstrates that healed infusions remain sterile in the presence of air (which he passed in through heated coils), again to disprove spontaneous generation.  It is interesting to note that although Spallanzani and Schwann each used heat to preserve food, neither man apparently realized the value of turning these observations into a commercial method for food preservation.  (Critics suggest heating somehow changed the effect of air as it was needed for spontaneous generation.)


The first person to really appreciate and understand the causal relationship between microorganisms in infusions and the chemical changes that took place in those infusions was Louis Pasteur.  Through his experiments, Pasteur convinced the scientific world that all fermentative processes were caused by microorganisms and that specific types of fermentations (e.g. alcoholic, lactic or butyric) were the result of specific types of microorganisms.


In 1857 he showed that souring milk was caused by microbes and in 1860 he demonstrated that heat destroyed undesirable microbes in wine and beer.  The latter process is now used for a variety of foods and is called pasteurization.  Because of the importance of his work, Pasteur is known as the founder of food microbiology and microbiological science.  He demonstrated that air doesn’t have to be heated to remain sterile using his famous swan-necked flasks that finally disproved spontaneous generation.


Some of Pasteur’s most notable achievements include:

       Demonstrated that fermentation was a product of microbial activity and that different types of fermentation (i.e. lactic, butyric, etc.) were caused by different types of microorganisms.  The knowledge that microbes were responsible for fermentation and putrefaction led Pasteur to argue that microbes were also causative agents in disease.  These arguments eventually reached an English surgeon named Joseph Lister who used them to develop the first aseptic surgical procedures.


       he developed the pasteurization process used to preserve wine


       He developed a vaccine to protect sheep from anthrax by isolating an attenuated (avirulent) strain of the causative bacterium, Bacillus anthracis.  Pasteur isolated the attenuated organisms by growing them at elevated temperature (42oC).  Sheep exposed to the attenuated bacterium became immune to virulent strains.   Although Pasteur did not understand the basis for attenuation, we now know that virulence in this bacterium depends on the presence of a plasmid that cannot replicate at 42oC.


       Pasteur also developed a method to make chickens immune to cholera caused by Pasteurella septica, again using an attenuated bacterium that he had isolated in his laboratory.


–     He developed the method for treating rabies still in use today.


From the time of Pasteur, microbiological discoveries and developments began to proceed more rapidly.  Microbes were implicated in several diseases, heat-resistant spores were discovered, toxins were identified, and by the late 1800s, governments began to enact legislation to protect the quality of food.


In the U.S. many food industries hesitated to adopt industry wide microbiological standards until they were economically threatened by the publicity which surrounded outbreaks of food borne disease.  Several nasty outbreaks of botulism in the early 1920s finally prompted the U.S. canning industry to adopt a very conservative heat treatment, known as the 12D process, that reduces the probability of survival of the most heat resistant C. botulinum spores to one in a billion (10-12).  This practice continues today, and since 1925, the canning industry has produced more than a trillion containers with only 5-6 known incidents of botulism.  Most of these incidents involved faulty containers, not under processing.


At about the same time, the dairy industry was driven to implement microbiological control over milk because of several notorious outbreaks of milk-borne typhoid fever, diphtheria, tuberculosis and brucellosis.  Public health authorities established requirements that addressed animal health, sanitation, pasteurization (which had an immediate and very effective impact on the problems), and refrigeration, with all of these steps reinforced by bacterial standards.  As a result, pasteurized milk was one of our safest foods by the mid-1900s.


In one of the more unusual episodes of early food microbiology, the New York state government institutionalized a woman who came to be known as “Typhoid Mary.”  Mary was an asymptomatic typhoid carrier that worked as a cook for several families near the turn of the century.  Over ten years, 7 outbreaks of typhoid were directly traced to her and estimates suggest she may have been responsible for 51 cases of typhoid fever.  New York authorities arrested her and sought to have her gall bladder removed but eventually released her when she agreed never to work as a cook again.  When another outbreak was traced to her a few years later, she was arrested as a threat to public safety and institutionalized until her death in 1938.


Take home message:


       We have come to expect government protection in food safety, yet still outbreaks occur despite our efforts to develop the cleanest food supply in the world.  Why?


Jay “….it is not inconceivable that E. coliO157:H7 and L. monocytogenes have emerged as food-borne pathogens because our foods are so clean.”  [Statement to USDA FSIS public hearing on proposed changes to meat and poultry inspection].


As we eliminate microbes from food we create an environment free of competition which may allow opportunities for other microorganisms to grow and cause disease.  For this reason, there is considerable interest in identifying safe bacteria (e.g. lactic acid bacteria) which, when deliberately added to food, would inhibit growth of pathogens but would not rapidly spoil the product themselves (though some lost shelf life seems inevitable).

Jai Hind vande matram 👦


Slaughtering process of goat and sheeps

1. Introduction

Sheep and goat skins are one of the most important foreign exchange earners to the Ethiopian

economy. There is, however, substantial loss due to rejection and downgrading of sheep/goat

skins. This has resulted in substantial losses to producers, traders, tanneries and also to the

country’s economy. Most people in Ethiopia slaughter sheep and goats in their backyards due to

traditional norms and lack of legislation. Inadequate attention is paid to maintaining quality as a

result of the by-product status accorded to skins. Farmers and butchers in rural areas get a very

low price for the skins that are no incentive for proper handling and drying. Tanning of damaged

skins require more chemicals and effort to repair them. This means extra cost and extra pollution.

Estimates of the loss to the Ethiopian economy due to poor handling and other problems reach

US $ 14 million per year.

Care during slaughter and flaying of sheep/goats has a profound impact on the quality of skin

produced and in the reduction of associated losses. Even though slaughter practices in Ethiopia

differ according to local culture, customs and religious practices, the following general

procedures of slaughter and flaying will help to substantially reduce the rate of defective skins


2. Slaughter/flaying steps and proper care

2.1. Stunning

Stunning is the practice of rendering animals unconscious just before slaughter. Proper stunning

procedures reduce the chance of stained carcasses and blood splash. Currently, stunning is,

generally, not practiced for sheep and goats in most abattoirs in Ethiopia. The following stunning

options are available for use in abattoirs:

• Mechanical instrument like a sharp knife that traumatizes the brain so that the animal loses

consciousness instantaneously can be used. The correct location of using the instrument for

sheep and goats .

Electrical stunning: This method of stunning is well suited

for sheep or goats. Electrical stunning induces electric

shock or epileptic state in the brain. This state should last

for long enough for bleeding to be carried out. Since the

brain of sheep and goats is small, the electrodes should be

accurately and firmly placed high up on the sides of the Head.

2.2. Bleeding

Bleeding is best performed with the carcass hoisted by the hind legs

while leaving the forelegs to kick in the usual reflex action (Figure

3). It is advisable to stun the animals prior to hoisting. For sheep and

goats, some flayers prefer to complete most of the bleeding on the

floor adjacent to a drain. When

sheep and goats possess long hair,

much more care must be taken to

avoid contamination with blood

and dung, and bleeding on a

definite slope is to be preferred.

In either case, final bleeding is

best carried out after suspension

of the carcass.

In the simplest case, the bleeding is done on the ground (Figure 4) on a cover of banana leaves,

on a table or something similar. Then a rack with standard hooks or gambrels (hanger-like

hooks) is used to keep the carcass in a vertical position off the ground for skinning and

eviscerating. The branch of a tree may be sufficient for slaughtering on a farm premise.

The slaughter needs to be performed within 30 seconds. The knife must be properly sharpened to

minimize pain during the cut. Excessive bending of the neck is unnecessary.

2.3. Ripping

• Ripping is the process of tearing the skin to start the skinning process. Figure 5 shows the

proper ripping lines during slaughter of sheep and goats. The following are the steps in the

ripping of sheep and goats to start the skinning process:

• One long and straight incision from the jaw to the anus along the center line of the belly.

• Four circular cuts around the shanks at the level of the knee and hock joint.

• Two cuts on the inside of the forelegs, knees to the breast bone.

• Two cuts on the back of each hock joint to a point mid-way between the anus and scrotum.

2.4. Flaying/Skinning

Flaying/skinning should be done within a few hours of the animal’s death as the skin will peel off

especially easily. Make sure the knives used are sharp. Proceed as follows:

Flaying/ skinning of sheep and goats can be started by making a small incision on the inside of

one of the hind legs. The hind legs, including a small portion of the skin covering the abdomen

and edges of the butt round the rump, can be flayed with a knife and fist while on the floor. The

carcass should then be hoisted. Hoisting the animal makes it easy to use one’s body weight to

pull the skin off

. It also assures that the meat will stay clean. The slaughtered animal

can either be hanging from the neck or from the legs. Strong ropes should be used for the


To hang a sheep/goat by its back legs, find the large tendon that connects the lowest leg segment

with the rest of the leg. Poke a hole in between that tendon and the leg bone. Use your fingers to

feel the lump that is created by the double jointed bone. Then sever the lower leg at the lower of

the two joints .Cut skin and tendons around the joint, and then snap it over

your leg.

Skinning is a straight forward activity if one follows the body’s built in guidelines. This is

because the skin and muscle tissue are naturally separated from one another by protective

membranes. The skin easily separates from the meat along these membranes when you pull it.

After getting a clean start, there is little risk of tearing the skin or the meat. Sometimes, the belly

skin is removed using a knife leaving the surface of the carcass with close serrated scores.

When you use a knife to slice the skin from the animal you inevitably violate these layers and

make the whole job harder. Once you cut into the meat, you are no longer working with the

natural division between meat and skin. You usually end up removing large chunks of meat, as

well as putting cuts and holes in the skin. These cuts (also called scores) and holes open up and

enlarge easily, increasing the amount of work at every stage of the tanning process later on.

There are absolutely no advantages to knifing a skin off. It is not faster! Thus, it often requires

the butcher to punch his fist forcefully between the skin and the carcass surface to detach the

skin referred to as fisting.Fisting is hygienically critical. The butcher must take care

to frequently wash his hands and arms and not touch the dirty outside of the animal’s skin while

removing the skin this way.

An alternative to fisting is the use of compressed air. If facilities are available, a compressed air

pipe is introduced between the skin and carcass surface and the air pressure gradually detaches

the skin. The air must pass through a filter in order to reduce the micro-organisms present in the

air, which otherwise can constitute a source of contamination. Blowing air into the cut in the

hind leg is a traditional practice in many areas when the skin, usually goat skin, is required as a

water bag.

A knife should not be used in the final phase. The flayer uses his weight with downward pressure

to remove the skin especially from the tail area, the neck and forelegs.

After the skin is separated, remove any meat and/or fat from the skin. Wash flesh side if

contaminated with blood and/or gut contents. Then immediately cure with common salt or by air

drying to prevent putrefaction.

3. Glossary

Abattoir: A slaughterhouse having proper facilities for all aspects of slaughter with the necessary

equipment for proper handling of meat, skins and other animal by-products in an appropriate manner.

Correct pattern: A standard pattern for a flayed skin when laid out flat, which is adopted by the trade,

and which enables the tanner to cut maximum area of good leather from a hide/skin.

Curing: The treatment of skins with common salt or by air drying to prevent putrefaction.

Defatting: The removal of unwanted fatty (adipose) tissue from the flesh side of a fresh skin during


Flay cuts: Damage caused by careless use of a knife during flaying, sometimes cutting through the skin.

Flaying (skinning): The removal of a skin from a carcass.

Flaying knife: The knife used to sever the subcutaneous tissues when removing the skin from the


Flesh side: The inner side of a skin next to the body of an animal in life.

Fleshing: The removal of the residual connective and adipose tissues from the flesh side of a skin after


Gouges: Knife damage to the skin during flaying, taking out scooped portions of the corium.

Grain layer: The top portion of the dermis.

Pattern: The pattern of skin when laid out flat.

Putrefaction: Bacterial and enzymatic breakdown, rotting.

Ripping: Opening of a skin on a carcass, following an accepted pattern of cutting, before flaying.

Ripping knife: Knife designed to make the opening cuts on a skin before flaying. It can also be used for

slaughtering, bleeding and other operations. N.B: Is similar to a flaying knife but has a straighter

cutting edge.

Scores: Knife damage to skins during flaying by cuts that do not fully penetrate through the skin.

Trimming: Removal of unwanted portion of a skin.

Jai Hind vande matram 👦

The Biggest Memory Problem Solved!!!!! why we get 29.8GB from 32GB pendrive, memory card ? where that memory goes ? Explained!!!!!!!

Hello guys , Today I will come with new interesting topic i think so most important topic that is about the memory in hard drive memory cards pen drive  let’s start this interesting topic

 Guys you will buy different type of storage device for ex. you buy a 32gb pendrive you have notice the storage of that device in mobile phones and computer that 29.8 gb or you get 64gb pendrive you will get  less storage  if talk about the mobile phone ram that is also show less memory moreover if we talk about the hard drive if it is 500gb you will get 460,470 gb is available to use the question is arises that where was the that storage go?

Guys you will listen from your friends ,teacher or any expert that, that storage is for system driver or for any important files or any type of computer software but you will absorb that you cannot get satisfactory answer today i will give knowledge about this topic so tune with topic.

Guys we will study in school that ,

8bit=1 byte

1024 bytes=1kb




and so on…

guys you notice that 24,24 come repeatedly if we should multiply 24×24 you get random number. Manufacture will do that they will ignore the 24,24 series  and according to them storage units are

8bit=1 Byte

1000 Bytes=1Kb




and so on….

Guys you will notice that they not consider 24 series but in first case OS operation is performed or whole world will follow and in second case it show how the manufacturing is performed ,lets us we check the difference between both cases .

let us consider a 32 gb pendrive you will get 29.8 gb in it .



In above photo i shall solve the 32GB storage by mathematically to show you that how the manufacturers manufacture any memory card pen drive ram etc .

I think you will get idea upon this topic if you like my article dono forget like share and comment column .

Jai Hind Vande Matram

More RAM or better RAM ?Are we thinking right?? # Explained

Hello guys, I will come with new topic that is more RAM or better RAM?Stay tune with me .

Guys in today world we shall talk about the smart phones computers it’s battery backup features apps software and RAM etc. RAM is a thing which is easily understandable like 1GB,2Gb,3GB etc and we take decisions on basis of their numbers for example RAM we should think that more will be the ram better will be the performances normally people take decisions on this number.

Guys take time and think whether be will need more RAM means in your practical work whether you need the more RAM for example you want to build the computer for gaming and almost all games will played in 8GB RAM but no we need the best we need 32Gb RAM etc but guys take a time to think whether the 8GB RAM or 32gb RAM will create any type of differences answer is no for example

You will sitting around desk and consider as you will the processor and desk consider as RAM and the almira which in the front of you consider as the hard drive now you want to process the data  but your hand range to inough to reach at the corner of the desk , agreed now the object which is located at the table consider as data now guys data which is near to processor which easily access as compare data at the corner because it take time to come into processor and then access

So that this explains that if 8 GB ram will perform better why we should go for 32gb

Yes I will consider that due to mordenisation you will update your gadgets but think little that in what case we will get better performances

I think you will get my idea upon this topic think quiet logical before to take step

If like my topic like it share it comment it

Jai Hind vande matram 👦

How to track the lost phone ?How to track IMEI number ?what to do:-

Hello guys,you guys are very much confused the that to track your stolen phone ? what is IMEI number ?how to track it ?etc Today we shall talk about this topic …first of all guy I will tell you that IMEI number  is not only for the mobile,the device which is connected to any network will have own identity number eg.tablet,mobile,dongle etc. This number will give you identity of your device and you can it on the box, in the box, in the bill ,and you can find under the battery or,you can dial *#06# can get your IMEI number. Now guys think that you have lost your mobile in that case we should decided into two cases i.e firstly you have featured phone second you have smart phone .

Let us talk about first featured phone those which you can use as primary phone like Samsung guru Nokia 3310 etc,in that case you can’t do so much you just go to police station write fir and take duplicate Sim card or you get sim card without fir and all case it only depend upon the police efficiency.

In second case if you have Android device or ios device if you lost these type of  device what will you do?go to police station 👮 no guys just login in  Android device manager .

In this you got a three option :-

  1. Play sound :- IN this option your device will ring at max level no matter if your phone is on silent mood it will at max level and same in the ios device .
  2. Lock :- this option will help you to lock your device even if you have pattern or other security password .IT just lock your device as same in ios device .
  3.     Erase:- it will delete all your personal data from the phone in one click same in ios device .

If you guys get your phone go to the police with your IMEI number same step as featured phone if you don’t have IMEI number go to the Google dashbord and get your IMEI number and in ios device if you take BACKUP for iOS device from itune you get simple options to achieve your data  and IMEI number.

Now you guys think what is the purpose of IMEI number guys role of this number is just provide identity to your your we can’t track it ,every phone have different IMEI number .
I hope you got idea how to track your Android and iOS device if you like it don’t forget to like it share it comment it

Jai Hind vande matram

What Is Cell Phone Jammer? EXPLAINED

Computer related

Moto G Play, 4th Gen (Black)

Hello guys you will listen about cell phone jammer, but you will still confuse that how  the cell jammers is work .Today  we should discuss about this topic , lets start guys .when ever you guys listen about jammers you will think about that this device can block the various type of signals and

you will notice guys that jammers normally used in military for various security purposes  so we should think this is very high tech device and their making is too difficult  and their technology is very incredible device but reality is totally different, it is very simple to make if you want your own jammer it is not so difficult .

Now we guy what is the working of jammers let us talk about it ,it will create interference in radio signals for ex. any mobile phone or any toy car or any type of woky talky etc.the main work is to just become the handicapped the electronic devices . Signal  jammer is of different type of different  ranges different power  but the concept will be the same for ex. you have an phone which can give signal to the tower and the tower will give the answer of the signals this is how mobiles phones basically works so that mobile phone are called duplex devices because both mobile phones signal and tower signal will work simultaneously ,that is why speak or heard in your phone but in woky talky we should speak and wait until the signal is received, this is one way signal type .
But in mobile phone jammer for ex. you have a mobile which can give signal to tower for communicate for ex. you have another device which can give strong type of frequencies to tower  that will causes the inference in the signals of mobile phones and your device would not be connected to the mobile tower at that time your phone increases the their power to connect the tower that time jammers also increase their own power at that time your phone become the handicapped  more over jammer normally used in VVIPS or bomb porne area so that any type of destruction will not be occurs .

Normally jammer will stop any type of frequencies for example blue have very low frequency and mobile have  very large frequency jammer will create noise in their frequencies ….
I hope you will get my idea about the Mobile Phone jammers , thanks for reading. like it, share it, comment it.

jai hind vande mataram