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Showing posts with label biscuit manufacturing. Show all posts
Showing posts with label biscuit manufacturing. Show all posts

Types of Industrial Biscuit Ovens

Various  types of biscuit ovens  are used in biscuit industry  for production of   varieties of biscuit .  Selection  parameter  for   any biscuit  oven are capacity ( which covers length ,width  and speed ) , products , baking time  and type of fuel  .Normally in bakery parlance  ovens are defined as per  width and no of  baking zones .

Biscuit Oven , Industrial  Biscuit oven , Tunnel Oven , Direct fired oven , Indirect oven Biscuit ovens are mainly  classified  under  following  types

Direct gas fired

 The gas fired  oven is used  for those product  that require  great heating power . They can burn natural gas  or LPG . The gas  is mixed  with air  in a special  mixing pipe  based on  the Venturi tube  principle . In each zone  the heat at  top and bottom  can be  independently set by regulating  the two combustion  air fans which controls  the volume of gas  fed  to the  burners . A bar graph potentiometer  set by operator  can be  used to select the heat ratio between  top and bottom . Each zone is equipped with a suitable humidity  extraction system .

Indirect   radiating  cyclotherm oven

 The Indirect Gas / Diesel fired ovens  also known as  cyclotherm  oven - transfer heat  to the product   by radiation . Each zone consists of  set of tubes  at the top and bottom  of the baking  wire band  through which  the hot air  which has been previously heated  by burner flows .

At the end  of each baking  zone the hot gasses are collected  by a plenum and returned  by blowing  fan to the burner  where they  are heated  up again  to the working  temperature  and sent back  to the tube circuit . The heating  system  is there for  completely  independent  and the products  of combustion   does not  comes in contact with dough being baked . Each zone  has  extraction fan to remove humidity from  baking chambers .

Convection oven 
The convection  oven  is suitable  for baking delicate products  like cookies , wire cut  or sponge . Its baking chamber  is constituted  by a plenum  duct positioned  on the top and bottom  of the baking wire band  where hot air is  gently  blown out of  properly  designed  slats  and comes  in  contact  with the dough . The heat transfer  is mainly by convection . The convection  type of oven can be  direct  or indirect . In those cases  where the available fuel  is natural gas or lpg  and the reduction  of baking time is a necessity the direct convection  is the  correct choice .  In the  In direct   convection type of  oven  the  air is heated  up by passing through  a dedicated  heat exchanger  hence  baking  never comes into contact  with the dough .Humidity  is removed through extraction fans in each zone .


Hybrid  Oven

Hybrid ovens are those  ovens which have combination of any of the above types of ovens.  Sections are divided  into different type of heating  systems , depending upon  product and its baking  requirement .

Electric  Oven

Electric ovens  are  not so popular with  manufacturers due to low cost of lpg,cng or diesel as compared to  electricity . Oven  consist of electric heater s  which  en capsuled into radiating pipes  . These are then set  for set temperatures by thermostats .

How to control dough temperature during bread/biscuit manufacturing process

Temperature plays a vital role in dough consistency which in turn impact the quality of bread or biscuit . Bakers have to maintain the dough temperature after mixing for better results after baking . Ambient temperature varies as per the season s a expert bakers has to arrange various method to maintain dough temperature . Average temperature maintained could be different in different locations .However temperature ranging from 28 –32 deg c provides better results at this part of the world .

Following factors effects dough temperature

  • Mixing duration

  • Water temperature

  • Ingredients temperature

Jacketed Mixers

All Mixers Manufacturers have Mixers with jackets around the mixer body . Operators can feed this jackets with cold or hot water as per requirement . Cold water is circulated through chilling plants .Hot water generally circulated by boilers or hot water generators .

Ingredient Temperature

Dough temperatures get impacted by ingredients temperatures.Ingredients with low temperature can be fed into mixers to maintain dough temperatures . Areas where ambient temperature reached 45 – 40 deg c its important to store this ingredients in cold storages or air conditioned places.

Ice Addition

Some places Ice is added manually to maintain dough temperatures or for certain varieties like choco chips ice is added to maintain the dough temperatures so as chips does not starts melting during the process.

Other methods used in most advanced bakeries are

  • CO2 Injection in mixing bowl

  • Flour cooling

  • Breaker bars and Agitator in mixers

RADIO FREQUENCY - Post baking drying technique

Biscuit manufacturers all across world have following options to increase capacity in existing plant . They have been trying various method to achieve this .

  • Increase the oven length hence increasing moulder /cutting speed .Not all ovens has this advantage you have to check whether another zone can be added to existing biscuit oven or not .

  • Run plant at maximum speed with increased temperatures in different biscuit oven zones resulting in reduced baking time .This has disadvantage that the quality of biscuit gets affected.

  • Using Radio frequency dryers at the delivery end of biscuit ovens ,this helps in reducing moisture further by 10 - 11% hence we can increase the speed of moulder/cutter resulting higher output .

Principle on which radio frequency dryer work s is that as water has As product exiting the baking oven enters the RF post-baking dryer, it passes through an electrode array having an alternating electric field which reverses its polarity at a rate of 40.68 million times per second.
Water is comprised of "polar molecules" which can be likened to each molecule having a north and south pole. When passing through an alternating electric field, polar molecules react similar to the way bar magnets behave in an alternating magnetic field, constantly realigning themselves to face the opposite pole. At a frequency of 40MHz, friction caused by this rapid movement causes the polar molecules of water to quickly heat, wherever moisture is present, throughout the entire thickness of the product.

Nonpolar materials such as fat, oil, and dry ingredients do not react and, therefore, are not directly heated by RF energy. In the case of bakery products, this means an RF dryer will preferentially heat and dry the wettest area of a product without heating the areas already dry. Typically, there is greater moisture in the interior of a product as it exits a conventional oven. Therefore, this moist area will preferentially absorb more of the RF energy.

Developed for high-volume cookie production Post-Baking Dryers quickly and efficiently remove residual moisture trapped within the center of the product, permitting conventional ovens to run at the maximum speed that a product can be produced with the correct loft, crumb structure, and color. These RF dryers are available in different band widths

Advantages of RF heating
Increased Throughput - Up to 30% increase for crackers and often up to 40% for cookies.

Elimination of Checking - By greatly reducing the moisture variation throughout the thickness of the product, checking caused by differential shrinkage is eliminated.

Excellent Control of Final Moisture Content - Final moisture is controlled to approximately +/-0.25%.

Independent Color Control - Since moisture is controlled in the RF dryer, color development in the oven can be done without concern for final moisture content
Refer radiofrequency.com for more details on RF technology

Are hybrid oven better than any other type of biscuit ovens

I had opportunity to work with different type ovens in biscuit factory . They have direct fired ovens and indirect fired ovens . Basically Oven types are selected with following parameters .

Type of Product

Hybrid oven , direct fired ovens , indirect fired ovens , biscuit ovensBoth direct and indirect ovens have few disadvantages and advantages as far as biscuit production is concerned .Direct ovens are generally used with cracker variety
As greater heating is required during baking stage . It has got numerous burners at bottom and top of the oven band .Direct fired operates generally on gas . Controls are less in direct oven .Less energy is consumed in direct oven .

Indirect ovens uses circulating fans to heat pipes or plenum in different zones . Used generally for moulding variety of biscuit as gradual heating is preferred for such type of oven . Control are more in indirect ovens . Energy is consumed more in Indirect oven .

Hybrid Oven combines benefits of direct as well as indirect ovens . Hybrid ovens are most versatile ovens for multi product usage you can have moulded variety as well as cutting variety with higher speed hence with more production .Ratio of direct part to Indirect part are generally 20-30% ( direct ) to 70%-80% ( indirect ).

Main  advantage  of Hybrid ovens  are

  • Flexibility  of the baking process - different  products  requiring  different  baking profiles  can easily  and successfully  be processed  in the same oven .
  • Much better  fine tuned  control  of the final  moisture  content  of the products  with  consequent  reduced risk  of  checking effects  on biscuit .
  • Improved crispness  and improved  general  texture  of  the product
  • More uniform  colour  of all  the baked products  across the width 
  • Higher output can  be obtained

Why MNC have failed in Indian Bakery Industry

Indian bakery today stands for Rs 6000 Crore Industry . Since opening of our markets for Overseas companies Bakery Industry is the Industry which these Multinationals have not able to crack where as in other industries they have remarkable presence like Pepsi , Coke , Unilever , Samsung , LG , Panasonic , Nike , Adidas , Citi , Hsbc , Procter and Gamble ,Colgate List goes on ---- . Companies like Excelsia , Unilever , Kellogg's ,Kraft ,United Biscuits ,Ceylon Biscuits , Unibic are either launched / trying to launch their products/ or have very negligible presence .

The reasons which can be attributed to failure of MNC in bakery Industries can be attributed to .

1. Jv These companies have tried to enter Indian market through partners .

2. Indian Competition was stiff from very much entrenched players like Britannia and Parle

3. Pricing done by these companies was on the on the premium side hence didn't get mass market slice .

4. Recipes which were not palatable to Indian tastes . Even Macdonalds and KFC have got Indian variants.

What makes bakery product popular

bakery product are becoming more popular now days because of varieties available due to technological advancement and packaging certain categories of bakery product has distinct advantage of shelf life , it has been found that baked goods have shelf life of minimum of six months .
Long Shelf of bakery product like biscuits and cookies had made them popular to armed forces /sailors in earlier days .

Other advantages are that it can be fortified and other ingredients can be topped or mixed it with it . Cakes and breads can easily be prepared in homes in micro oven . The basic raw material the flour is easily available in grocery also the other products like sugar , salts ,baking soda etc .

Bakery products are all weather , all gender , all classes and any time snacks .
Thus its makes them best food category in entire range

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