The processing of Flat Wafers (6/7): Post Baking Procedures

This is the sixth of seven installments covering all the facets of flat wafer processing, which continues discussing details regarding post-baking procedures.

Creaming/Book building – Naked wafers 

The sheets automatically pass directly in line from the arch cooler to the creaming unit, or alternatively are automatically fed to one or more magazine feeders. The unit consists of a cream hopper and three rolls through which the cream passes for laying onto the wafer sheet which pass beneath. Cream depositing or layering can be completed in two different ways:

1. Contact creaming where the wafer is delivered and raised by means of a roller beneath the carrying conveyor. The wafer is raised to make contact with the cream on the bottom roller of the hopper. Following creaming, the wafer drops and proceeds to the book builder. This system is considered by some manufactures to be more suitable for cream layers up to approx. 250 g of filling per sheet. I.e. thinner layers.

2. Ribbon or film creaming is more suitable for cream layers say over 250 g., i.e. thicker layers. In this situation, the cream is deposited as a continuous sheet onto “butt joined” wafers that are fed beneath the hopper in a continuous flow. Film depositing can accommodate warped sheets better than contact and is more flexible.

The rolls within the hopper of both systems can be heated to aid depositing. As well as having speed and roller gap controls for weight adjustment, a strip knife across the second lower roller aids depositing and prevents pick up. A deposited layer does not cover the total width of a sheet but comes to within approx. 1.5 mm of the edge to allow for bulk sizing and trimming. The book builder which stacks the creamed sheets to the required number usually covers the range from 2 -7 sheets separated with cream filling, although the average amount is usually 3 wafers and 2 cream giving due consideration to size, weight and price point constraints.

The creaming unit is designed to be flexible and depending on model or supplier can be programmed to “miss” a sheet. This is done usually on short footprint models using the contact principle to provide an uncreamed sheet for the top of the sandwiched book or block. Long footprint models usually incorporate two or three magazine feeders linked to as many creaming stations. As sheets come from the arch cooler they are programmed to be delivered to the respective magazine feeders. Having two or more creaming stations allows for more than one color or flavor of filling to be used with a common wafer sheet resulting in more novel possibilities which may also include caramel or jam with cream, etc.

As mentioned previously some wafer sheets are produced with different engravings on either side. In such cases using the long footprint unit the top sheet can be programmed to turn over as it travels on the overhead conveyor to its depositing station. This gives the flexibility to produce an alternative visual aspect to the product. A deep engraving or reeding can provide a 2X1 wafer: cream with a slight waffle type appearance on both sides yet can be lean in filling for some popularly priced products.

In situations where a book builder is not incorporated (this is not so uncommon in some small operations or where older equipment is used) the job can be done manually by stacking the creamed sheets back. The disadvantage here of course is that misalignment is very common resulting in the need for excessive trimming leading to increased rework.

Following book building, the book of creamed wafers passes beneath a press that lightly adjusts the height to size. Too much pressure here can cause shelling of the top sheet and for this reason flat presses have become more popular than the roller presses of old. The latter tend to create a nip point on entry and exit from the roll allowing the top sheet or wafer to spring encouraging or resulting in surface shelling. The normal cream to wafer ratio is accepted at 70:30 using standard size wafer sheets of 50-56g weight. However, it is possible to find ratios of 80:20 for very good quality count lines or conversely 60:40 for less expensive or popularly priced products in some areas. A check weigher in line is a worthwhile investment and will often pay for itself within a few months. It usually takes the average of say ten weighings and is programmed to adjust the cream deposit accordingly.

Cream mixing 

The cream is usually made from a 50:50 blend of milled sugar and fat, although less expensive blends of 60:40 are common. The traditional ideal fat would always have been of Lauric origin, preferably coconut or palm kernel with characteristics to suit the climatic conditions in which the product was to be manufactured and marketed. Eating characteristics obviously are also important and a fat with a slip melting point above 37°C (98.6°F) will leave its effect on the palate. Likewise, the fat should have a sharp melting curve over a narrow range between 20-40°C (68-104°F). For this reason, H.C.N.O. or blends of H.C.N.O. and C.N.O. traditionally have been used or alternatively H.P.K.O. or blends of H.P.K.O. and P.K.O.

Adding no more than 2.0% of a very high melting point fat (50-60°C/122-140°F) to a normal fat of 37-38°C (98.6-100.4°F) will “hold” the fat without ill effects for use in hot climates. Most shortening manufacturers these days also supply proprietary blends to achieve the above characteristics. These blends needless to say will conform to local legislation and are tailored to a price to suit the client and market.

Given concerns regarding hydrogenated fats and Trans Fatty Acids (TFA) it is worthwhile to ensure that the fat supply is able to cover fully the needs of the biscuit manufacturer. Some enterprising suppliers will provide readymade blends of fat and sugar that will guarantee consistency and can be particularly useful if the plant in question does not have sugar milling facilities and wants to avoid problems sometimes experienced with bought in milled or icing sugar. Boxed fats can be aerated or texturized and this is usually done to approx. 15-20% although how much air remains in the filling at the sandwiching stage is debatable due to mixing, pumping and depositing.

The cream filling on mixing can be at a temperature of approx. 28°C (82.4°F) or more and may increase on depositing particularly when using heated rollers. Consideration should be given to the “advantages” of aeration compared to price against standard fat. Bulk fats purchased in oil form can be votated and texturized in situ as required by the user factory assuming that the appropriate equipment is available and that volume or throughput justifies it. It is obviously also fair to say that a fluid deposit of cream filling will set up with a denser texture than one deposited ” dryer”, although of course it does aid in “keying” cream to wafer, avoiding delamination of one from the other. Sugar for cream fillings is often overlooked in terms of particle size. If too course one can experience an excessive grittiness to the palette and if too fine it tends to “absorb” too much fat, creating a “dry” filling.

As the filling will blend with the wafer, which in itself has a crisp textured crumb when eaten, it needn’t be too fine. A good rule of thumb is to consider that a milled sugar of about 40 microns will be acceptable. In some North American locations milled sugar was supplied with the designation of 4X, 6X or 10X the higher the number the finer the sugar. 6X was considered ideal for cream fillings, although from one supplier to another the X designation could be different, so knowledge of the micron size could be an advantage.

Some wafer manufacturers who have chocolate making facilities don’t necessarily mill their sugar but use it in crystal form and make a basic fat sugar mix then pass this through a 3 or 5 roll chocolate refiner. This gives a very smooth cream. This is mainly for convenience as the smooth texture is reduced to some extent when eaten with the crisp dry wafer. Many believe that passing through a chocolate refiner also avoids the metallic taste often created in some hammer mills when sugar is milled or pulverized. When crystal sugar is milled or pulverized it has quite a high temperature and may need to be cooled before mixing into cream. Some in house sugar mills incorporate a facility to accommodate this but many do not.

Often sugar is milled on demand above the cream mixer and dropped by gravity into the vessel when required. Blowing milled sugar to its point of usage is not recommended and should be avoided as the sugar dust can ignite causing an explosion. Frequently the sugar is milled and bagged or dropped into a suitable container before transfer to the point of usage where it is later weighed and dispensed into the mixer. If produced too far in advance the milled sugar can become compacted and at worst solid, being difficult or impossible to use. A balance has to be considered between the need for cooling the sugar and its rate of uptake in production. It is not uncommon when milling the crystal sugar to add about 1.5% tri-calcium phosphate as an anti caking agent to help avoid compacting.

As the cream filling is about 70 % of the product it is as important to texture, as is the wafer, which often draws more attention. Colors, flavors, cocoa powder, coconut, salt, etc. are added to the basic cream of sugar and fat at the mixing stage. With modern cream mixers employed for wafers, an all-in method is often used, the objective being to obtain a homogeneous smooth mix. If inclusions such as nuts or other aggregates are added consideration has to be given to particle size so as not to impede cream layering or depositing. If added after the sheet is creamed from a separate hopper care has to be taken to ensure sufficient fluidity remains in the cream or filling to maintain cream and wafer adhesion with no likelihood of delamination. Cream mixing should take about 4-5 minutes depending on equipment and depending on whether or not air is used to improve or lighten the filling bearing in mind the influence and effect of heated depositing rollers, etc.

Details of specific gravity of various cream fillings could be described as follows: wafer fillings usually fall in the 0.7-0.95. range, the latter in particular if the cream needs to be fluid to aid wafer adhesion. Factories with a significant cream filled wafer business may prefer to produce cream filling on a continuous rather than batch basis. In such situations slurry is produced from milled sugar and liquid fat or oil along with other small or minor ingredients. This slurry is then passed through a scraped surface heat exchanger that results in a plastic textured filling or basic cream that can be stored in a holding bin and drawn off directly to the hopper of the cream application unit. If colors and flavors are used these can be added just prior to entry into the hopper of the cream application unit. This is done by injecting into the pipe work and blending into the filling using an in line screw mixer.  Frequent check weighing of the creamed block should be made following book building.

Specific gravity: heavy

This can be done manually at random or preferably automatically. Equipment exists capable of weighing books in line up to 1000 g to a claimed accuracy of +/- 0.5 g. As previously mentioned, such a unit can be a worthwhile investment.

The processing of flat wafers (1/7): Wafer Ingredients

The processing of flat wafers (2/7): Pre-baking processses

The processing of flat wafers (3/7): Baking specifications

The processing of flat wafers (4/7): Baking plates I.

The processing of flat wafers (5/7): Baking plates II.

The processing of flat wafers (6/7): Post baking procedures

The processing of flat wafers (7/7): Cooling, cutting and conditioning

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References:

• M.B.R.A. Reports
• Technology of Biscuits Crackers and Cookies – D.J.R. Manley
• Biscuits Crackers & Cookies – Bill Smith