Kamis, 26 Juni 2008

From time to time we experience problems with the sheeting of our short paste; in particular it cracks or fails to remain cohesive. Why does this happ

Gluten formation in short pastry is not normally considered necessary. Traditional multistage methods of dough mixing were evolves to try minimize the potential for gluten formation required in the manufacture of pastry the paste units or sheets remain intact during the forming and sheeting processes otherwise crack may form on the surface of the pastry. In extreme case the crack may extend through the pastry sheet, cousing it to break into two separate pieces.

Too much gluten formation in short pastry commonly leads to problems associated with shrinkage during sheeting, blocking, forming and during baking. Getting the balance between too little–lack of cohesion–and too much–excessive shrinkage–requires careful control of recipe and mixing conditions.

As might be expected the level of water used in the recipe plays a major role in determining the rheological properties of the final paste (Cauvain and Young, 2000). Too little and the paste will not form a cohesive sheet, too mush and the on paste firmness: more fat inhibiting gluten formation and water promoting it.

Taylor (1984) studied the effect of mixing method for the manufacture of puff pastry and found that the mixing method used. Short pastes mixing on a high-speed mixing time tended to be more friable and prone to cracking because of the short mixing times employed. These findings confirm the need to develop a limited degree of gluten in the paste in order to minimize cracking of the sheets.

We suggest that you first investigate the effects of increasing mixing time. You may notice a small increase in paste temperature which can be readily compensated for by lowering the water temperature. If you still have the problem when you have optimized mixing time then we suggest you raising the added water level.

Jumat, 30 Mei 2008

When we cut open bread rolls and hamburger buns that have been stored in the deep freeze for a period of time we observe a white ring just inside the


The phenomenon that you have observed is commonly referred to as ‘freezer burn’ and arises from the movement of water within and from the product while still in the deep freeze. It was reported by Pence et al. (1958) who examined the whitened areas of products exhibiting the phenomenon and observed that they had a greater number of tiny voids associed with starch granules. These voids were linked with ice cristls that had sublimated from whitin the starch granules, causing a greater opacity of th crumb and the whitened appearance. The change in the crumb texture fro, this effect also couses the crumb to have a harsh, dry eating quality arising from the lower moisture content. However, the effect does not come exclusively from the loss of moisture since the attempts to restore the crumb properties are unsuccessful enless substaintial ‘re-wetting’ of the crumb is applied.

Even thoung the product has been stored in a deep freeze running at about –20ºC not all of the aqueus phase in the product is ‘frozen’. This aries because of freeze-concentration effects and presence of consentration of the remaining aqueous phase increades and its ‘freezing point’ becomes lower (Cauvain and Young, 2000). Eventually the consentration may become so low that the solution will not freeze even at –20ºC.

Any increase in the product temperature during storage will enable some of the ‘unfrozen’ water present to diffuse from the product into the surrounding atmosphere. This clearly happens with may frozen products since it is not product is held in the storage freezer then the greater is the accumulation of snow as the product progressively dehydrates.

After the product has warmed in the storage freezer any subsequent refreezing will take place very slowly from the surface inwards. This creates an interesting effect because the center of the surface begins to freeze quite quickly, while a few millimeters under the surface freezes slowly. The end resuld is the formation of the while areas of freezer burn which commonly reflect the outer shape of the product.

The problem can be ninimised by paying attention to a few simple ‘housekeeping’ rules:

  • Do not store the product for very long periods of time.

  • Check the actual storage temperature over a period of running time. The set temperature in the deep freeze is nominal and the thermostat will allow some degree of fluctuation around the set point.

  • Ensure that your storage freezer is regularly serviced and have the conditions of any automatic defrost cycles checked.

  • As much as possible avoid actions that allow the freezer temperature to rise excessively. For example, keep doors closed as much as possible and minimize loading and unloading times as much as possible.



What steps couls be taken to prevent round doughnuts shirking or collapsing within a few minutes of leaving the fryer?


What steps couls be taken to prevent round doughnuts shirking or collapsing within a few minutes of leaving the fryer?

The collapse of doughnuts after they the fryer is associated with the transition of the dough from a ‘foam’ to a ‘sponge’ (in the genetic not specific cakemaking sence). In foams the gas bubnles or cells are sparated from one another by a stabilizing film of one form of another, e.g. protein, fat, emulsifier, while in sponge the cells are interconnected and gases and liquids can readily pass though the matrix.

In the oven most baked products undergo the form foam to sponge and the gas contained withing the individual cells difuses out of the product into the surrounding atmosphere. The transition occurs at different parts of the dough piece at different times, depending on the head transfer rate. Before conversion the pressure inside the air bubbles is greater then that of the product. At the moment of conversion from foam to sponge there is equalization of gas pressure with that in the surrounding atmosphere and is seen as a slight shrinking of the volume of the baked product just before the end of baking.

Addition of some ingredients can delay the convertion of the foam to sponge to a leter time during the wheat starch and subsequeantly the temperature at which the foam to sponge conversion is made. In some formulations the transition may not take place within the center of the product before baking is compled. As a consequence the internal pressure. At some point the externl pressure on the product becomes greater than the internal pressure of the cells and the product shrinks. This is the collapse and wrinkling of the product that you see.

To avoid the problem you should reduce the sugar level in the formulation or reduce the ability of the dough to remain gas. It is well known that a mechanical shock delivered to many such products can be used to eliminate the problem, so simply banging the trays as you remove them from the fryer can reduce or even eliminate this problem.


What is the Falling Number of a flaur and how is it measured? What values shold we specify for our flour miller?

The Falling Number of s flour related to the level of cereal α-amylase whict is persent. The production of cereal α-amylase is encouraged within the wheat grains if their moisture content is sufficiently high in the last few weeks before harvesting. Such conditions are most likely to happen if the period concerned is particularly wet.

The full name for test is the Hagberg Falling Number test and it was originally developed in Sweden. It takes its name from the basis of test. A flour-water suspention is heated within a tube held in a boiling water bath. The mixture is stirred for 60 s to ensure uniformity of the mixture. At the top of the tube, released and the time taken stirrer to fall down the tube is known as the Fallin Number.

The test is based on the action of the cereal α-amylase on the starch present in the flour. The temperature in the test is designed to give maximum enzymic activity in the flour-water ixture and quickly changes according to the level of cereal α-amylase present; the faster the stirrer falls and therefore the lower the Falling Number.

The higher the cereal α-amylase level, the greater the formation of dextrin during bread making and so the more likely that there could be problems with bread slicing. In bulk fermentation high cereal α-amylase levels will lead to dough softening.

The Falling Number includes the 60s strirringf time so that the lowest theoretical number is 60. in practice Falling Numbers over 250 ae suitable for most breadmaking processes. As well ad Falling Numbers above 350 indicate suggest you specify that your Falling Number lies between 250 and 280, though the actual level you require will be specific to your products and processes.



What are bread improvers and why are they used?

What are bread improvers and why are they used?

The term ‘bread improver’ is used to embrace a wide range of materials that can be added to wheat flour and dough in order to improve some aspect of dough behaviour and final bread quality. The use of the term is common and most often applied to the addition of several ingredients at low levels blended with a ‘carier’ a material that may or may not have functional properties but that aids dispersion and provides a more conveniently handled composite material. The formulation of bread improvers will be influenced by legislative control over the list of permitted ingredients that may be used in breadmaking.

  • Alternative names for bread improvers that may be encountered

  • In the baking industry include ;

  • Dough conditioners, a specific reference to that the material addition changes dought rhealogy.

  • Procesing aids, that imples a similar function to dought conditioners.

  • Oxidizing agents, that implies a more specific role concerned with the formation of the gluten network in the dought.

  • Additives, more commonly applied to specific ingredients.

  • Concentroes, similar to an improver but with a greater range of ingredients present (e.g fat, sugar and salt) and commonly used at higher rates of addition.

Almost any material added to a flour and water dough will have some improving effect. For example, the addition of east improves the lightness and palatability of bread, while salt changes the handling properties of wheat flour dough and the flour of the baked bread. However, the term bread improver is now commonly restricted to materials that are typically added at much lower levels of addition than yeast or salt with the intention of improving gas production or gas retention in the dough, retaining bread crumb softness and obtaining a whiter crumb colour.

Some of the more common ingredients used in bread improvers are noted bellow. The classification used is arbitrary since the complex action of most materials in breadmaking means that they might be classified in more that one group. For examples, addition of many enzyme preparations brings about chanes in dought rheology that makes it easier to process dought but also results in improved oven spring, a manifestation of improved gas restention.

  • Aids to dough processing: enzyme-active preparation, e.g. malt flour, fungal α-amylase.

  • Aids to gas production: yeast foods, such as ammonium chloride.

  • Aids gas retention: oxidizing agents, such as ascorbic acid and potassium bromate.

  • Aids to bread softness: e.g. glycerol monostearate (GMS).

  • Aids to improving crumb colour: soya (soy) flour.


Chocolate Wafers









Preparation time : 40 minutes

Cooking time : 12 minutes

Makes about : 12 minutes

¼ cup sugar

3 egg whites

2 tablespoons plain flour, sifted

1 tablespoon cocoa

2 tablespoon thickened cream

60 g butte, melted

½ cup sliveres almonds


  1. beat sugars and egg whites in a small bowl with an electronic mixer until frothy. Beat in sifted flour and cocoa, then cream and butter. Leave mixture to stand for 10 minutes.

  2. spoon about two teaspoonfuls of mixture onto each end of paper-lined baking sheets. Allow room for spreading. Spread out mixture to form 12 cm cirles. Arrange almond slivers on top.

  3. bake at 160ºC for 10-12 minutes or until edges begin to darken. Cool on tray for 2-3 minutes. Transfer to a wire rack. Store in an airtight container.