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Torbed Services

Limitedtsltsltsltsl

U n i t 2 5 , Y o u n g s I n d u s t r i a l E s t a t eA l d e r m a s t o n , R e a d i n g , B e r k s h i r eR G 7 4 P W , E n g l a n d . Tel:

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+44 (0)118 981 1255

+44 (0)118 981 0117www.torbedservices.co.uksales@torbedservices.co.uk

Factsheet No. 16

Title:

Equipment: Torbed 400, 750 & 1000 Processors

Title: BAKED SNACK PRODUCTS

Equipment: Torbed 400, 750 & 1000 Processors

Revised Date: August 2001

General Introduction - Torbed Services are a licensed manufacturer for the manufacture andsupply of TORBED hot air processing equipment for applications within the food and mineralindustries in general.

The following comments and notes are supplied for general information only and are based onobservations and experience gained with regard to processing a variety of extruded, farinaceous snackproducts on the TORBED processing equipment.

Types of Snack Pellets - Originally, all snack pellets were formulated for frying. However, pelletmanufacturers around the world have and continue to introduce new pellets (second generation halfpellets) that have been specifically formulated for expansion by frying and by hot air to meet the needfor the growing baked snacks market. TORBED processed snacks are Oil Free and hence ahealthy snack product becomes the result.

There are many factors that can have an effect on the degree of expansion, taste, texture and colourof baked snacks as described below:

Moisture Content - The moisture content within the pellet is critical. The rapid heat transfercapabilities of the TORBED system will quickly transform the moisture to steam creating a pressurewithin the pellet that will cook and expand the pellet before the steam migrates to the outeratmosphere. Too little moisture will create a finished product with a reduced degree of expansion andtoo much moisture will result in a very hard product with little or no expansion. Snack pellets for HotAir processing require a moisture content of between 10 to 12% by weight that is fairly typical for mostextruded half products.

Salt Content - The salt content, in conjunction with the moisture and starch content, appears tohave a significant effect in order to achieve a good expansion and hence low bulk density results. Asalt content of 1.5 to 2% seems to be required for successful processing. With 4% and above, theproduct still expands well but the finished product may have a salty taste. However, with only 0.5%

salt content, poor expansion appears to be the result when processing some types of pellets.

Pellet Formulation - The base material ingredients for farinaceous snack pellets is mainly acombination of starches, flakes or granules produced from a variety of cereal and vegetable productssuch as Potato, Maize, Wheat, Corn, Rice, Semolina, Soya and Tapioca etc. In addition,combinations of different ingredients and/or products, such as those used in multi-grain snack pellets,together with varying moisture, salt and even sugar contents can create a world of combinations.

Understanding and quantifying the complex reactions that take place within the pellet during theprocessing treatment is a science on its own and best left to the pellet manufacturers knowledge, skillsand expertise.

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Pellet Shape and Size - The TORBED process is very tolerant to a variety of shapes and sizesof pellets. They all tend to have their own individual characteristics and will create different bed orflying formations within the process chamber. The majority of these varying bed formations can bekept under strict control within the TORBED process chamber by using the variable configurations,processing and parameter settings that are all available.

Snack pellets must be free flowing by nature with no tendency for pellets to stick or interlock together.The quality of the pellets relates directly to the quality of the expanded product that is true for allprocessing techniques.

a) Shape

To achieve an evenly expanded product in a hot air system, pellets should have a uniformcross sectional area and this is probably true when frying them. This allows for an even anduniform heat transfer throughout the pellet during the processing stage and will eliminate theproblem of hard or burnt sections within the expanded product.

Pellet shapes can be and should be unlimited but basically they can be defined into twodistinct categories:

1) Two dimensionalFlat pellets with a uniform thickness of less than 0.5mm will first go through a plasticstage on initial heating and may well remain reasonably flat and thus tend to act likean aeroplane wing and can fly in an unpredictable manner in the process air stream.

Flat pellets with a uniform thickness greater than 0.5mm appear to have somestressing within the pellet that is produced during the extrusion, stamping and/orslicing stage. This type of pellet will quickly start to curl making it into a threedimensional shape that will fly in a very predictable manner within the process

chamber.

Flat pellets of any thickness that incorporate holes or apertures within the pellet actjust like three dimensional shapes and provide for an even expansion throughout theproduct due to the cross sectional area at any point within the pellet being similar.

The free flowing characteristics of flat pellets can be poor and should be avoidedalthough the TORBED processors can be configured to accommodate them.

2) Three dimensionalProducts with a three dimensional and uniform section expand very evenly and areunder total control within the process chamber. They also tend to handle well within

the feed and batch weighing system with little or no problems incurred.

b) Size

The physical size of pellets that can be processed is related simply to the size of the TORBEDprocessor being used. The TORBED 400 unit, being the smallest processor in the range, willhandle pellets from 2mm up to 30mm in diameter or length. However, the TORBED 750 and1000 will handle all known pellet sizes.

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Pellets - Potato starch pellets, such as Pasta Foods (UK) Airlite Spirals, have been specificallyformulated for hot air processing and an eight times increase in volume is easily obtainable with atypical finished bulk density of 37g/1.

Torbed Services have undertaken many successful product trials in conjunction with individual clientswho extrude and manufacture their own formulated pellets and with pellet manufactures whose

products are freely available such as:

* Quality Pellets S/A - Denmark* Valin S.r.l. - Italy* Pellsnack Products GmbH - Germany* Pasta Foods Limited - UK* General Mills Inc. - USA* Liven S.A. - Spain* Le Caselle S.r.l. - Italy* Maffin S.r.l. - Italy* M C Technologies - France* Pellfoods S.r.l. - Italy

TORBED product trials of new pellets and pellets from other pellet manufacturers are continually ongoing.

Addition of Oil and Flavours - All snack products processed in theTORBED system are OilFree apart from any natural oils contained within the base ingredients. With virtually no oil present,compared to up to 37% by weight in oil fried snacks, the natural taste of the base ingredient is clearlyevident. Basically they are now a cereal product and many can be directly packaged as a natural,healthy snack or breakfast cereal product.

Oil Free snacks no longer have to be flavoured with strong flavours in order to mask the taste of theoil such as when fried. Less of the costly flavouring needs to be applied and the use of more delicateflavours, even sweet flavours are now an option all of which help to create new and unique product

variations.

For savoury products, the addition of a small percentage of oil, typically up to 5 to 7% by weight,depending on individual requirements, can be sprayed onto the processed product. The oil canenhance the expected taste or texture in the mouth and at the same time provide a medium for theflavouring to adhere.

Oil Free or Low Fat snacks are healthy food products and have an extended shelf life due to theabsence or low oil content and is advantageous for markets in hot climates.

Pre-flavoured Pellets - There are some pellets that are available that have flavouring

incorporated within the extruded pellets. This obviously eliminates the capital expense andcomplication of additional processing equipment and makes processing with the TORBED Technologya single process operation apart from packaging.

Several pellet manufacturers are showing a keen interest to introduce pre-flavoured and/or pre-coloured pellet technology and this area is growing in popularity. Watch this space !

Note: The above information is for general release and does not form any part of a specification

and/or performance guarantee.

1997 Torbed Services Limited TORBED is a registered Trademark of Mortimer Technology Holdings Limited