From time to time we have noticed a white discoloration on the surface of our allbutter shortbread Why does this occur

The discoloration that you have observed is the phenomenon commonly referred to as 'fat bloom'. It is the formation of small crystals of fat on the surface of the biscuit and occurs mainly as the result of temperature cycling during storage, that is periods of warmth and cold such as may occur in unheated locations subject to the effects of ambient temperature fluctuation.

Fat crystals may exist in a number of different forms (see 3.1). Since their size may be as small as 5 ^m only agglomerates of fat crystals can be seen with the naked eye. The formation of crystal agglomerates is encouraged by rapid cooling, such as might be experienced when the products are quickly chilled after baking. Similar conditions may occur if a warm product is placed into a chilled environment. A similar problem may be seen with chocolates that have become too warm in periods of hot weather and then placed in a refrigerator to cool.

To minimise the problem you should examine your cooling technique and try to cool more slowly, or eliminate forced air cooling. Also consider whether you can pack in a warmer environment. You should record the typical storage temperature history of the product, looking for any fluctuating periods of warmth and cold and eliminate, or at least minimise, these.

If none of these considerations is relevant you might tackle the problem by introducing a small portion (say about 5%) of a low melting point butterfat fraction or oil into the product. This will help to reduce the tendency for the fat to recrystallise.

11.3 We produce biscuits containing powdered fructose which we cream with the fat and sucrose before adding the other ingredients. Recently we have seen the appearance of brown spots on the product. What causes this effect?

The most likely cause of your problem is associated with the creaming of the fat and the sugars. It is likely that some of the fructose that you are adding has become so coated with fat that it cannot dissolve in the limited amount of water that is available in the biscuit dough. This leads to excessive browning during baking.

To avoid the problem you could dissolve the powdered fructose in the dough water before mixing. Or you could change to a fructose syrup, remembering to re-balance the sugar solids and water content of the recipe.

Similar brown or dark spots may arise if you are using very large crystals of sucrose which do not dissolve completely and lead to the problem sometimes described as 'sugar burn'.

Dark spots may also originate from undissolved aerating acids in the mix. For example, acid calcium phosphate is sparingly soluble and can hydrolyse on the surface of baked goods to give free phosphoric acid. The acid can carbonise carbohydrates during baking, giving rise to dark spots where the phosphate is concentrated. Often the problem is alleviated by changing to a finer form of the acid concerned so that there is better dispersion. Should the dark spots still form they are usually too small to be detected by eye.

Continue reading here: Our chocolatecoated wafer biscuits are prone to cracking Why does this happen and how can we avoid the problem

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