Wednesday, April 30, 2008



The use of two stage or two phase fermentation usually involves the the use of a two tank system or two fermentors in sequence and physically connected. These two tanks are usually in a series with the process starting in tank A and flowing and continued into tank B.

The two stage or two phase fermentation system is usually applied in a mixed fermentation system involving at least two groups pf microorganisms. The separation into two groups of microorganisms into two tanks are not really exclisive whereby tank A contain a particular species and tank B contain another species. The physical separation of the tanks into two dominant groups of microorganisms are really more physiological than physical. The two tanks still usually contain similar types of microorganisms but the conditions applied differently to each tank resulted in the enrichment of certain groups of microorganisms in each tank

For example, the first tank might be fukky aerobic or have shorter retention time or exposed to rapid sugars. The second tank might be anaeobic or might have a different composion of substrate and even longer retention time

We could view the two stage or two phase fermentation more as a 'plug flow' fermentation system too as the flow is one way! passing through the two tanks

The two stage or two phase fermentation system allows the optimization and finer control of the fermentation process

While admittedly the optimization of a two stage or two phase fermentation system depends on the two reactors providing two separate optimal conditions, the important point is that the flow of the mixed liquor or fermentation broth from one reactor to the other should be a smooth flow. This is made possible by adjusting the hydraulic retention time of the second reactor. Usually the second reactor is larger to accomodate the longer retention time. Of course there are various reactor configurations that can accomodate the flow

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Tuesday, April 29, 2008



Cleaning and sterilizing are one of the most important activities carried out in the fermentation process. A good cleaning and sterilization ensures not only the removal of residues from previously operated fermentation but also reduces or removed the probability of microbial contamination. If fermentors or its ancillaries equipments and processes are not cleaned, the remaining organic residues not only provide nutrients for the growth of unwanted microorganisms and allow the proliferation of the microbial populations, it also protects the microorganisms from the full effect of sterilizations.

Sometimes the process of cleaning the fermentors and its ancillary equipments are often confused with the sterilization process. In the cleaning process the activity centred on washing the equipments and removal of organic matters or soiled components. Sterilization is more in the killing and the removal of the microorganisms. This explains why CIP is often confused with SIP.

In most fermentation industries both SIP and CIP are carried out concurrently.

There are two kinds of cleaning often carried out in the fermentation industries; COP and CIP. COP refers to cleaning of the fermentors by removing and dismantling the fermentor components before cleaning it. The fermentor components are then reassembled after the cleaning process

CIP is the kind of cleaning carried out in situation where there is no dismantling or reassembling of the fermentor components. Cleaning is carried out with the fermentor component in tact. CIP is only carried out where the scale of the fermentor is too large and complex and the industry does not have the time, expertise to carry the COP

In both CIP and COP the basic principles of cleaning are the same. Both CIP and COP usually follow standard cleaning and sanitizing procedures such preliminary rinsing, draining, washing, rinsing and drying. However in CIP this procedure is a bit more complex as there is no ready access for cleaning and dismantling and require special procedures and methods of executing CIP.

It is strange that when the topic of CIP for fermentors are carried out, two common views are often held:

1 The first view is the picture of a worker scrapping or brushing the inner walls of the fermentor
2 A brief comment of passing hot steam through the pipes leading to and from the fermentor

CIP is more than the above standard views. CIP is a standard procedure or a system which are attached to and form part of the fermentation system.

The first CIP cleaning was rather quite primitive and manual in approach. The CIP involves the use of vessels as the solution tank, portable pumps, and hoses to connect the equipment and piping into circuits for recirculation of flush, wash and rinse solutions.

Temperature in CIP was accomplished by inserting a low-pressure steam hose into the solution tank and the “finger test”, or a thermometer reading.

The early CIP practises is a mixture of CIP and COP. CIP were quite restricted to the few long pipelines such as the receiving line or a supply line to the process plant. All other shorter pipelines, connections to equipment, and fittings and valves were manually cleaned, as in COP

Its only lately that CIP have become independent of COP and are fully automated to improve the efficiency of the process.

Modern CIP and SIP are systems designed for automatic cleaning and disinfecting without major disassembly and assembly work. Additionally, a well designed CIP system using a double seat block and bleed valve technology and process integration will allow cleaning of one part of the plant while other areas continue to function.

Modern CIP system saves money in terms of higher plant utilization and savings in CIP liquid through recycling of cleaning solutions, water reuse and conservation and man-hours.

In any CIP the most important components are the manipulation and control of the three parameters:

1 Time

2 Temperature

3 Concentration

In the application of CIP is also the interplay of hydraulics such as flow velocity and flow rate, number and volume of tanks, number of CIP circuits, type of detergent and sanitizing chemicals among others. Each CIP is custom made for the particular system

The design of a specific automatic CIP requires the integration of the design into the process. Such system usually have:

1 the addition of spray systems, tank cleaners, nozzles, and seals into the cleaning process.

2 advanced wash liquid preparation unit handling all filtering, preheating, mixing, and pumping of water, detergents, and demineralized water.

3 continuous monitoring and control of cleaning parameters, including flow rate, detergent concentration, temperature, and wash time.

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Thursday, April 24, 2008


The use of hot and pressurized steam to clean and sterilize fermentors is one of the most crucial steps in the fermentation process. Yet how much do we really know about the hot steam and its effects and limitations on the fermentation process?

Steam is the gas phase of water. Steam is produced when water passes its boiling point. Thus the temperature of steam is always very hot. It is possible to increase the temperature of the steam by generating steam under pressure such as those produced during autoclaving. By manipulating the pressure and controlling the temperature of the steam produced it enhances the value of steam as a sterilizing agent. This makes steam as a very useful method or technology in cleaning and sterilizing fermentors.

As a very hot gas phase, steam is most suitable in cleansing and sterilizing various components of the fermentors as well as in CIP and COP operations. Its power to sterilize and clean can even go beyond the fermentors but the plant environment such as other utensils and even floorings and processing machineries

The advantage of using steam is that it has the ability to penetrate the most hidden and inaccessible places


Using steam to sterilize the fermentor depends more on the size of the fermentors

For small size fermentors the normal autoclave and the standard operating sterilization parameters apply. But for larger fermentors at the level of pilot or industrial fermentors there need to be adjustments in the sterilizing parameters

Steam sterilization of pilot and industrial fermentors is a bit more complicated as CIP needs to be applied. The fermentor and feed-system piping must be steam sterilized.

The accepted procedure involves heating the entire system with steam to a minimum of 121°C for 60 minutes or more. In case of very large fermentor installations large industrial fermentation systems often prove more difficult to sterilize. Steam heating to temperatures approaching 150°C for sterilization periods approaching 4 hours are often needed to insure that all hard-to-reach internal areas have been brought to minimum sterilization temperatures.

The efficacy of the operating regimes for steam sterilization has to be individually determined and validated for each type of fermentation

In fermentation technology we are often faced with the choice of two kinds of steam; the saturated or wet steam and the dry steam. The "dry steam" describes a system that produces a high temperature with "low moisture vapor". This vapor contains only 5-6% water and is much less dense than the air we breathe.
The trick to get a dry can of steam is to know the volume of your can and the amount of H20 in the can. Assuming the can to be a constant volume and that the H2O cannot escape, you pick the temperature and pressure needed to get "dry" steam
Not many using the autoclaves know the difference between the terms psi and psig. Find out….!

We can use pressurized hot steam to sterilize the vessels without using autoclaves. However the temperature of the steam would not be as high as in the autoclaving process. There are a number of mobile steamers in the market that can provide in situ hot steam. This method of sterilizing would be ideal in cottage fermentation industries

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Monday, April 21, 2008


(PICTURE TAKEN FROM WWW.LSL.COM.MY)Most of the traditional food fermentation industries could be considered as small household or backyard industries with small capacity production and inefficient in the application of the fermentation technology process and know how. It is not that difficult to improve or upgrade the traditional fermentation industries with little capital input and application of GMP

The characteristics of traditional fermentation industries in Malaysia are:
1 They are small scale or small volume industries
2 There are a diversity of fermentation products produced mre towards the geographical location and the type of food substrate available in the area. Coastal areas may produce fermentation products from cincaluk, belacan, budu. Other more inland areas might be producing tempe, tapai and kicap fermentation
3 Level of technology utilized is very low and do not really changed with time and regarded as passive fermentation. Use of automation and mechanization is low
4 GMP is rarely applied. Lack of quality control and sanitary standards
5 Very low level of research or scientific input
6 Government industries supposed to support and upgrade these small and scattered industries are quite passive and do not really enter the playground to participate
7 Shelf life for some of the fermentation products are really short in case of tempe and tapai
8 Marketting of the traditional fermentation products considered poor
9 These industries do not really have professional consultants in fermentation who can advise them how to improve and standardize the quality of fermentations
10 Most of the traditional fermentations are Batch or fed batch fermentations
11 Operators of the traditional fermentation have poor or lack of understanding of the science of fermentation that be applied to their process
12 The fermentation industry is a mix of Solid substrate and liquid fermentation

In this blog we will only try to discuss one or two aspects of the traditional fermentation industries

1 Increasing the volume of fermentation production
2 Improving the efficiency of the traditional fermentation industries with simple cheaper and alternative modes of fermentation


One of the most common characteristics of traditional fermentation here is that the fermentation process are often carried out in a large number of small fermentation vats ( or earthen jars). This limiting step can be avoided by carrying the fermentation process in a large fermentation vessel. The most ideal container for the fermentation now would be adapting or modifying the new stainless steel water tanks. These tanks are easily available from hardwate shops. These tanks are sanitary and are easily cleaned and sterilize

Adding a simple motor to the top of the fermentor or stainless steel water tank will help improve the mixings and the fermentation process

Improvement of the traditional fermentation process has always been the rate limiting steps in the fermentation process. To improve the fermentation process must be carried out in terms of time, quality and volume of the fermentation process.

When we talk about shortening the fermentation time by optimizing the various physical, chemical and microbiological as well as the engineering aspects of the fermentor operation. This initially requires some laboratory scale fermentation studies to optimize the various parameters

The product of the fermentation should be of the highest quality and consistency. Standard operating procedures and good GMP or the basics of GMP should be adapted or modified for use at the level of cottage industries fermentation. The HAACP procedures should also be adapted in its essence to be applied at the small scale fermentation

The main problem of traditional fermentation industries in this country it has always been so successful in maintaining the traditional way of thinking and making fermentations. There is lack of tendency to understand the process, to increase the input of science and technology to the fermentation production system. Days of fermenting in plastic pails and porcelain vats are numbered.......

Imn my observations the fermentation entrepreneurs still practise the art of fermentation handed down from the fathers and refusing to optimise or even experiment to improve their fermentation process. There is poor monitoring of the fermentation process in terms of temperature, ph , sugar in the traditional fermentation industries. This has led to inconsistency in the fermentation products produced. A little investment in these instruments would increase the efficiency of their fermentation

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Saturday, April 19, 2008


Say, we have a fermentation process which we would like to commercialize. In order to commercialize it at the level of industrial manufacturing we have to build an industrial scale fermentation plant so that we can manufacture enough volume to be economically viable.

To build a large industrial scale manufacturing plant is not without risks. It involves huge capital investments in terms of millions of dollars. It would be risky to build such huge fermentation plants only to find out later that it could not operate efficiently as expected.

True! We do have some small laboratory scale fermentation studies to guide us. But it would still be risky. As fermentation behaviour at small laboratory scale often differ compared to those that occur in the huge industrial vats.

So we have a choice. Take a heavy risk and build the huge industrial fermentation plants based on data obtained from laboratory studies and PRAY to God that nothing disastrous would occur. Alternatively we could reduce the risks of building the huge industrial scale fermentation plants by doing extra studies on scaling up by using pilot scale fermentation plants. At least the data obtained would provide us further confidence to invest or abort the project.



A fermentation pilot plant is a small fermentation processing system which is operated to generate information about the behavior of the fermentation system for use in design of larger industrial facilities

In fact fermentation pilot plant ‘mimic’ the industrial scale fermentation process by carrying out the industrial process on a smaller scale. Thus mimicking the industrial process and size is the main characteristics of pilot plant. However, the only difference pilot plant fermentation is still considered a research stage and not the final industrial production.

In trying to mimic the industrial scale fermentation the pilot plant show similar activities and equipments at mid stream and downstream facilities


We carry out fermentation plant studies based on ‘uncertainties’ of what will the industrial scale fermentation plant will be like in reality.

How will the processes be similar or different from the smaller lab scale studies and how much changes will need to be executed at the various processes.

There are few crucial studies which will only be answered by carrying it out on the pilot plant such as:

1 Determining the various operational parameters for optimized oxygen supply to the fermentation process.

2 Selection of optimum operative modes of the fermentor

3 Determining the changes in rheological properties and its effect on the fermentation process.

4 Modeling and formulation of process controls

5 Sensors and controls



If a system is well defined and the engineering parameters are known, pilot plants are not used. For instance, a business that wants to expand production capacity by building a new plant that does the same thing as an existing plant may choose to not use a pilot plant.



Adding the pilot plant studies would probably add up further costs but we would decrease the risks of huge financial disaster many times over if we do not carry out further pilot plant studies. Fermentation pilot plants are cheaper to build compared to building industrial scale plants. So even if we failed in the project it does not involve much capital loss. Using fermentation pilot plants we can tweak the design and work out any problems that arise before the design of the large industrial fermentors. Pilot fermentation plants will be able to provide additional useful data that is anticipated at the level of industrial scale such as reactions, corrosiveness and material properties among others

At the end of pilot plant studies, the pilot plant can still be used as additional manufacturing fermentors or for carrying out other tests and operating conditions



Many industries developing a product might find it too costly and uneconomically viable financially to set up pilot plant fermentation for one or two products. So they would rather invest in contractual work being carried out by commercial pilot plant facilities. They would get the services of experts, advance equipments and fermentors for a minimum investment.

Once this choice has been decided it would make more sense economically to hire or rent such pilot plant facilities. Pilot plants are very expensive to invest as it not only include a number of various sizes fermentors but also expensive down stream processing equipments and sophisticated analytical facilities

There are however advantages if we build our own pilot fermentation plants even though it is costly

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Friday, April 18, 2008


Now Saddam Hussein is gone. Gone are also his threats of unleashing the powers of pathogenic microorganisms which the West previously ' believed' and tried so hard to ' convince' the world. It even went as far as the US state secretary providing 'proofs' of Iraqi capabilities in cultivating large volumes of the pathogenic microbes with a 'demonstration' of a capsule to indicate the potency of a disaster if such volumes of anthrax are released.

One of the 'solid proofs' provided by their secret agency is the mobile unit for cultivating the microbes as shown.

What a laugh it provided me! While in the West such as Britain's famous Porton Down laboratory and the advanced sophisticated laboratories in US have a more complex structure, function and operations to cultivate it, Saddam Hussein's bioreactor is far worst than those carried out in the era of the two world wars

Let us look in depth the problem of producing high volumes of pathogenic microorganisms using fermentation technology

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We are in the twenty first century where biotechnology run supreme and we have big or mega fermentation industries. Yet despite the scientific understanding and the fermentation technology at our disposal, a significant number of us still believes in the taboos and myths associated with the fermentation process. Breaking or going against the taboo or making the 'spirits' angry will not lead to a successful fermentation process.

In this blog we will discuss some of the common taboos and the rationality why some of the taboos really got a rational scientific explanation behind it

One of the most popular beliefs in this country is in tapai making. It is believed that:
1 Women who are in their menstruation should not prepare the fermented food
2 The fermentation food preparers must not be in an angry mood

There have been many cases when this taboo is broken it will result in the poor fermentation of the tapai.

If one rationalize the situation, there might be some truth of these superstitions or taboo from a scientific angle

When women are in menstruation, they are undergoing strong hormonal changes which affect their metabolism and state of health. It is most possible that these ladies may have changes in their body ph or acidity which allows either different contaminants to proliferate on their normal human flora. This additional flora will be 'accidentally' introduced into the fermenting process.

It is also possible that during the mixing of the substrate by the ladies the ph of the substate will be changed when in contact with the ladies acidity thus allowing other type of yeasts to proliferate instead of the usual yeasts

As regard to the fact that ladies who are angry will make lousy tapai is because in their anger they lost the mood to be extra careful in preparing the tapai and the fermentation improperly carried out allowing ease of entry for the contaminants

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Thursday, April 17, 2008


I remembered during my teaching days at the university that the lecturer in microbial genetics used to claim that it is possible to create a microbial super strain that is genetically designed to produce high concentration of fermentation products.

In a way this is true or can be even proven in the laboratory at small conical flask level and where the growth conditions are closely monitored and control. However in translating the research into industrial scale or using large fermentors is another issue. It is generally not possible to retain the efficiency of the super strains achieved at the small scale laboratory in large fermentors.

The problem is more than just engineering scale up procedures but involve on the stability of the selected strain. The conditions or the environment of large fermentors are very different from those in the laboratory. Let us get one correct point of view here.

Even though we develop the super strain cultures and use that as inocula of the large fermentors, the culture will have to reproduce into a large population and at the same time adapt to the new internal environment of the the fermentors. As the microorganisms reproduce and build up into a large population in the fermentor it will be busy genetically mutating itself with progenies which are adapted to the new environment. Over the long time period the original cultures have probably 'mutated' into new strains far different from the original strain studied in the laboratory. It might no longer be able to produce the same composition and quality of the desired fermentation products

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One of the hallmarks of fermentation industries is the rich diversity of fermentation products produced. The rich variety of fermented foods and drinks are often the pride of many countries and civilizations throughout history of mankind. If the Japanese are proud of their sake, and the Indonesians with their tempeh and the Thais with their fish sauce or Malaysians with their pungent belacan, the British are proud of their beers and the Irish with their stouts.

The rich diversity of fermentation products are attributed to two main factors:
1 Rich diversity of fermenting microorganisms and their varied metabolism
2 Rich diversity of substrates used in the various fermentation process

We will discuss in detail the two factors.

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Wednesday, April 16, 2008


The success of many food and beverage based fermentation industries depends heavily on the availability of the microorganisms which drive the fermentation process. The type or types of microorganisms used, the quality and volume of inocula used in the fermentation process is crucial in the fermentation industries. In reality, most of the food or beverage based fermentation industries use pure or mix cultures for their fermentation depending on the type of fermentation carried out. Some fermentation requires the use of mono cultures while there are food or beverage fermentations that require the contribution of a number of species of microorganisms for the fermentation to be successful.

The microorganisms used in the various food and beverage fermentations were in fact historically isolated from the ' natural contaminants' which occur on the decomposing or naturally fermented foods!

The use of starter cultures is not new. In traditional fermentations traditional starter cultures have always been used in the fermentation though many do not realize it. Some of these starter cultures used are obtained from:

1 Remnants or residuals of past fermented food and beverage
2 Original flora that existed naturally on wrappings used in the fermentation such as banana leaves
3 Inocula that occur naturally in the substrate of the fermentation such as grapes used in wine making
4 Traditionally made 'kojis' used in many soy sauce or tuak fermentation

It is only now in the modern, sanitary, stainless steel fermentors of modern fermentation industries are ' starter cultures' used to start the desired fermentation process. Starter cultures are specially isolated and selected strains of microorganisms used in the fermentation which are massively cultivated under strict and scientific control to give the best and optimized fermentation which are not often seen in traditional food fermentations

Before the first cultures entered the market,traditional fermented food producers tended to rely on their own cultures. However, inadequately characterised cultures and inadequately defined compositions generally variability in the quality of the fermented products which is regarded not satisfactory in the market.

The development of such cultures requires the expertise and experience of specialists microbiologists, biochemists and food technologists as not all combinations are suitable for all products. The use of different strains in the same microbial starters must not result negative influence on each other. Usually in any microbial starters it is not wise mix more than four different species in a culture,”

The advantages of using industrially prepared starter cultures for food and beverage fermentation are:
1 Use only the microorganisms responsible for the fermentation
2 No other microbial contaminants that can cause diversion from the optimal fermentation
3 Can use the best strains specifically designed for the particular fermentation
4 Use of large inocula of starter cultures will result in better and faster fermentation
5 Quality and stability of the fermentation will be maintained
6 Taste, texture, colour stability and shelf life are mainly determined by microorganisms involved in the maturation, i.e. fermentation, of the product.

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Monday, April 14, 2008


I have often wondered what our life would be without the exotic lactic acid bacteria? Would we still have our fermented foods such as soy sauce, yogurt, pickled cabbage and fermented fish sauce? Our life must be quite bland without these bacteria, with
nothing in our food and drinks to tingle our taste buds. Thanks to the lactic acid bacteria for giving us so much benefits right from providing tastier foods, preserving our foods and even increasing the nutritional values of the food. I don't think there is no human civilization on earth not humbled by these simple lactic acid bacteria

The Lactic acid bacteria refers to a group of different types of bacteria which show the common characteristic of being able to produce lactic acid from their carbohydrate or sugar metabolism. These bacteria are Gram positive. The types of bacteria forming the Lactic acid bacteria includes Streptococcus spp., Lactobacillus spp.Lactococcus spp,Leuconostoc spp.)

These lactic acid bacteria are heterotrophic and generally have complex nutritional requirements because they lack many biosynthetic capabilities. Most lactic acid bacteria have multiple requirements for amino acids and vitamins. This explains why they are easily found in habitats rich in nutrients

Lactic acid bacteria are used in the food industry due to:

1)Their growth lowers both the carbohydrate content of the foods that they ferment,

2)the pH due to lactic acid production is one of the most desirable side-effects of their growth. Their low ph to as low as 4.0 inhibit the growth of most other microorganisms including the most common human pathogens. This will allow the foods to have prolonged shelf life.
3)The acidity also changes the texture and improve the flavour of the foods.

The lowering of the ph also will ultimately control the growth and fermentation process of the lactic acid bacteria.

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The kitchen or the 'dapur' is one of the best place to learn about fermentation and making fermented foods.The best thing about doing fermentation in the kitchen is that you don't need to have a PhD in fermentation, neither do you need sophisticated laboratory fermentors. Everything is there just around you in the kitchen.

You need not order expensive cultures from Culture Collection; you can get those cultures easily from your surroundings or even from the common corner shops.

Kitchen fermentation boils down to 'GREAT FUN!' for all and might even make you more interested in the fermentation process later

In this blog we will discuss the various kitchen utensils which are commonly found in the average kitchen and how to use them in preparing fermented foods. We will also discuss the various physical, chemical and microbiological process that can be handled by the 'kitchen laboratory fermentation'

In carrying out home fermentation in the kitchen, we are often faced with the limitation of fermentation resources that are often found in laboratories or industries. That does not mean that we cannot carry out fermentations succesfully in the kitchen. To be honest most fermentations started in the homes or cottage industries before they turn into multi million industries.

Before we start discussing further on this topic it must be stressed here that in most home fermentations the conditions are:
1 Not really sterile or aseptic environment
2 Both solid substrate and liquid fermentations are often carried out
3 Most of the fermentations are natural or mixed culture fermentations
4 The fermentation substrate are common food materials commonly used by the family
5 The common utensils and ingredients are often used for various other cooking
6 The fermentation recipes are traditional and hand me downs
7 Most involved in the fermentation are not trained in the fermentation techniques
and microbiology of the process
8 Home fermentation is still considered more an art and craft rather than science.
Taboos are still aplenty in the 'do's and don't s' of successful fermentation

There are many kitchen utensils or tools which can be exploited to carry out the fermentations.

There are many common kitchen utensils which can be used to carry out or hold the fermentation vessels such as bottles, kilner jars, earthen wares such as vases. The best bet is kilner jars as these jars are equipped with air tight lids to carry out fermentation

In this modern times it is very easy to sterilize or kill the microorganisms. There are the modern microwaves to the ancient and tested steamers. Electric rice cookers are easily adapted to become steamers for sterilizations

The inocula can be obtained by natural inoculation or stater kits such as yeasts and koji easily obtained from supermarkets

There are simple ovens which are easily temperature controlled for making bread dough and home made yogurt


We have all sorts of electrical mixers and blenders in the market for the purpose


We have simple weighing machines and balances easily available. Good thermometer and probes are easily obtained too. Volumes of liquids can be easily measured by various calibrated or measured vessels

For cooler fermentation or slow down fermentations are available

The success and failures of kitchen fermentations are often dictated by the techniques used by the operators/ It is most important in most kitchen fermentations the operators and utensils and even the substrate materials be cleaned to minimize the introduction of unwanted microorganisms. Certain procedures that might introduce microbial contaminants should be examined

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Saturday, April 12, 2008


News is in the air now that the Selangor State Government is proposing a centralized pig rearing industry somewhere in Sepang and that there will be a centralized pig wastewater treatment estimated to cost about RM100 million dollars. There must be excitements among contractors and vendors trying to secure the project! After 100 million 0.1 billion worth of money. Its a lot of money and the cost of building such mega anaerobic digestors would probably look easy on paper than in reality. It is very easy to build very large anaerobic digesters but it would not be easy to operate and maintain the process efficiently as the anaerobic digestion process is known for its sensitivity, process fluctuations and lack of stability. I wonder if the marketting people promises the moon in order to get the contract or will the State government will end up with a white elephant project? And the people surrounding the rearing site will still face air and water pollution from the pig generation activities?

Rearing pigs is a dirty business! Everybody knows that pigs generate a lot of wastes mainly through their faeces and urine. It is further compounded by the volume of wasted feed that end up in the wastewaters, Pig slurry is often characterised by very high BOD, COD, Solids and high ammonia and phosphates. It is the Armageddon of wastewater treatment

I feel concerned over the wastewater project being offered to the successful companies just based on a few visits by state representatives who probably knows next to nothing about wastewater treatment of pig slurry and bowled over by the platinum services given throughout their stay and site visits to these holiday spots. It makes me wonder how much they really see or understand the process. Secondly, the data or slide shows being generated to show to the invited guests from from our countries are perhaps too idealistic and does not reflect the reality.

I do hope our state counselors who endorse this project will learn from examples of failed projects almost similar nature.
My suggestion to the state government is that:

1 They must select their own experts who understand and foresee the problems of such ventures and be accountable for failure if any
2 The company being awarded the contract must provide real proof or carry out feasibility studies including scale ups to show that the proposed process is working in reality and not just on paper
3 Such studies should use our own pig wastes and under real conditions

Do not award the tender if these conditions are not fulfilled as it can be a source of embarrassment in the next general elections
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Thursday, April 10, 2008


(The picture is taken from
If you go to a modern supermarket or a hypermarket, you are bound to see stacks and stacks of yogurt cream and drinks in the dairy section. Yogurt is now a very popular and nutritious food drink which most of the health conscious population will vow to its nutritional goodness and even to anti cancer properties.

For the general information, yogurt is not a new food product. It is a fermented milk derived from cows and goats and have a long history stretching hundreds or thousands of years ago.

The remarkable thing is that yogurt was not that well or popularly known in Malaysia. This is probably attributed to its sour taste, boring whitish curd appearance and are taken only by very few people. Nowadays with the advent of powerful marketing, food technology and re branding and repackaging yogurt is becoming very popular indeed.

Now we have yogurt in all sorts of beautiful containers and in various fruity and sweet flavours. The old yogurt now is spiced up with all kinds of goodies making it so appealing to all. Even children love yogurt now!!

In this blog we will be discussing in detail about yogurt fermentation and how it is made or manufactured

Yogurt is actually a fermented milk product. The milk are fermented using bacteria such as Lactobacillus bulgaricus. In some yogurt production it might involved more than one type of bacteria such as Streptococcus thermophilus.

The Lactobacillus bacteria are fermentative bacteria which convert sugar into lactic acids. They can tolerate the presence of oxygen

The milk sugar or lactose is fermented by these bacteria to lactic acid which causes the characteristic curd to form. The acid also restricts the growth of food poisoning bacteria.

During the yogurt fermentation some flavours are produced, which give yogurt its characteristic acetaldehyde flavour.

Yogurt is a fermented food derived from the fermentation of milk. A commercially produced yogurt is made up of milk, sugars, stabilizers, fruits and flavors, and a bacterial culture Lactobacillus bulgaricus.

The fermentation of yogurt is approximately about 4 hours. A completely fermented yogurt has about ph 4.4 value of acid range

The most important component in controlling the quality of yogurt fermentation is temperature. Temperature affects the yogurt fermentation by:
1 Controlling the growth rate of the microorganisms
If the temperature is too low, the culture grows too slowly to adequately acidify milk and to achieve a good texture. The commercial starter is a mixed culture of thermophilus and L. bulgaricus.
If the temperature is too high it might end up killing the cultures

Temperature will affect the taste of the yogurt produced a the formation and secretion of metabolites which contribute to the overall taste are dependent on the growth rate.

The temperature range of proper yogurt fermentation is quite small, i.e. from 42 ºC to 44 ºC.
Higher temperature tends to give a sweeter yogurt as the rate of metabolism is higher. It will also makes the yogurt set faster.

It is very important that once the desired acidity is reached the fermentation is halted by low temperature. This cooling step is of most importance in the industrial production of yogurt, if not the taste of yogurt will be affected

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It seems nowadays, there are various universities and colleges offering 'fermentation workshops' for all kinds of individuals ranging from students to even researchers and scientists. I have been following the sylabbus for all these fermentation workshops offered by the various universities and colleges and I have my doubts to the real objectives of the workshops as to whether the participants really gained anything significant from these workshops or is it just another ' paid holidays' for the attendees

The common things that I have observed in these fermentation workshops is that they have various types of fermentors being offered or presented, and that the participants will only learn what the basic lessons offered by the manual, or how to operate the fermentors as according to the operating manuals

In most of these workshops either the participants are too few and from a diverse background and/or the time allocated to learn to operate the fermentor is indeed to short so as to really obtain significant gain from the courses. As far as I can see these courses are just for peopple who are curious how fermentors look and how they are operated!

These workshops have never really go in depth in the theory of the fermentors, nor the finer side of exploiting the fermentors for research. They do not teach you how to design a good fermentation experiment or how to optimize the conditions or how to trouble shoot the process. Such course would be a full time courses requiring in depth understanding of the fermentor and fermentation process from both the engineering and microbiological point of view

The organizers of such fermentation workshops must make real efforts to improve the courses to the public not showing bits and pieces of the fermentor

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Wednesday, April 9, 2008


These are some pictures of the fermentation technology workshop held at Sultan Abdul Samad Secondary school in Petaling Jaya.
The workshop ran over 4 days covering two weekends

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Sunday, April 6, 2008


In all my years learning and teaching fermentation technology, I have come across many many books on the subject. In my opinion the best book for fermentation technology is still the first edition of Stanbury & Whitaker's "Principles of Fermentation Technology published by Pergamon Press. It is still the classic undergraduate text for the subject

The book covers the field of fermentation technology from upstream , midstream to downstream activities. Mind you it even covers the economics of fermentation and treatment of fermentation effluent. Due to the range of the topics covered it does suffer the lack of depth of information required and thus it tends to give a light hearted and sketch treatment

Sometimes certain chapters are sort of irrelevant or not that important to the student of fermentation technology such as too comprehensive survey of the different valves and impellers in the fermentor

On the application of microbiology in the fermentation technology it has a good coverage but the authors failed to discuss in depth the theory and application of such microbiology information

Sometimes I feel that perusing through the book is like perusing through an advertisers catalogues or yellow pages in areas of downstream processing such as different type of homogenizers for cell disruption

There should be more worked out examples especially with regard to sterilization and holding times.
Topics like scaling ups and scalinh downs should be well covered
On the whole it is still the best book in fermentation technology in the market! Buy it! Especially the first edition copy

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Thursday, April 3, 2008


The objective in most fermentation industries are:
1 To produce the desired fermentation product using the microbes
2 Produce the products in high concentration and volume

The ability of the microorganisms to produce the fermentation product is ultimately determined by its genetic set up. Within the genetic make up or the genes are all the instructions needed to produce the enzymes which transform the substrate through a series of metabolic pathways to form the products

Trouble is the formation of a particular fermentation product is not exclusively held or controlled by one particular metabolic pathway, Although we often simplify the picture of product formation as:

[A]--> B--> C--> D--> E -->[F]

Where A is the initial substrate to be converted to F the final fermentation product.

From the above simple hypothetical pathway we know for the substrate to be converted to the final fermentation product, it has to pass through a number of enzyme mediated transformations

The problem of the above is seen from two main views:
1 The metabolic pathway is not independent by itself and form part of the intricate metabolic maze with other pathways,substrates, products and intermediates capable of influencing the metabolic pathway forming the fermentation product
2 Each metabolic pathway forming the fermentation product is controlled by the various steps of metabolic reactions which can affect the ultimate fate of the formation of the fermentation product. The activity of each step of enzymatic conversion are affected by the incoming substrate, concentration of the intermediate product formed

We must note that in analyzing the metabolic pathway, in terms of substrate and product formed controlling the metabolic pathway, there are other kinds of substrate and product contributing to the efficiency of the fermentation product formation

A -----------------------> B

H2O, OH- and H+

These 'other products and intermediates' do influence the metabolic fermentation pathway.

Some of the most significant changes that may occur during the fermentation process from these side products are:
1 Affecting the ph of the reaction
2 Affecting the dissociation of NADH2 to NAD+ vice versa
3 High hydrostatic pressure built up in the fermentor will affect the release of gaseous products of the metabolism thus preventing the gas from escaping from the metabolism of the cell. This might cause diversion in the pathway resulting in the formation of unwanted fermentation side products

The ph could be explained as the measure of acidity or the concentration of hydrogen ions in the media. If the fermentation broth contains a lot of [H+] then the broth will be acidic. The contribution of the [H*] in the fermentation media could be initially caused by the acid components of the nutrients in the media or by the addition of chemicals that changes the ph of the media or it sould be the resultant changes to the media brought about by the microbial actions such as the formation of strongly acidic fermentation products.

In whatever the case the high acidity produced is the reflection of high [H+] in the fermentation media.
The impact of high ph could result in:

1 Changes in the optimal of of the fermentation reactions making it no longer optimal for the reactions to occur
2 It might affect the growth and behaviour of the microorganisms in the fermentor
3 It might affect the toxicity of certain acids by favouring ionizations or dissociations of certain molecules
4 It might affect precipitations of nutrients

In a normal metabolic reaction in the generation of energy, the redox carrier NADH2 is a very important electron carrier. It functions in the metabolic redox reactions by receiving and donating electrons

The simple equation could be seen as follows:

NADH2---------> NAD+ + H2
<--------- It is a two way reaction in which H+ is liberated During very acidic conditions, if there are too much H+ then the overall reaction might favour the formation of NADH2. This would lead to a condition where there would not be enough NAD+ for the metabolism to function HIGH HYDROSTATIC PRESSURE ------------------------- This is the situation which often occurs in very large fermentors where the hydrostatic pressure could be very significant affecting microorganisms at the bottom of the fermentor. Under very high hydrostatic pressure it could lead to the diversion of the metabolism of the microorganism resulting in the formation of other products. Gases could be one of the products released during the metabolism of the cells. The high hydrostatic pressure on the microorganisms could prevent the release of the gases produced during the metabolism
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Tuesday, April 1, 2008


One of the most important parameters monitored during a fermentation process is determining the number or concentration of microorganisms .The problem is microorganisms as bacteria are too small to be seen with our naked eyes. In the case of fungal fermentations, it is difficult to differentiate the whole organism as a hyphae or unit cells

There are many methods of counting microorganisms, both direct and indirect methods. All the methods have its advantages and limitations.

In most fermentation studies it is most crucial that a very rapid method of establishing the number or concentration of microorganisms be carried out immediately. It is of no point during the fermentation process to know or estimate the number of microorganisms days later when the fermentation process has completed

The most simplest methods is of course using dry weight or the biomass which gives the amount of microorganisms in terms of total biomass weight. A simple calibration curve is made with optical density versus dry weight of microorganisms are plotted out. Once the calibration curve is made it is only a matter of determining the optical density of the sample using spectrometer to know the equivalent value of biomass concentrations

There are other methods of estimating the number of microorganisms using advanced fluorescent and even DNA methods. The price could be a factor to consider...
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