A batch of our biscuits containing oatmeal has developed a soapy aftertaste which makes them unpalatable Why is this

The soapy taste that you observe is almost certainly the result of lipase enzyme activity in either the dough before baking or in the baked product during storage. Oats are prone to this problem because of the high level of lipase enzyme activity which is naturally present. Lipase splits fats into fatty acids which react with the sodium bicarbonate to yield the soapy flavour. The most common way of avoiding this problem is to use only oat products in which the lipase activity has been eliminated. This is achieved by steaming the oats and you should specify this to your supplier. Steaming should not have any adverse effects on the functionality of the oats, which is limited in biscuit making.

You should also examine your dough mixing and processing to ensure that there has been no incorporation of scraps of old dough or dough that have become heavily contaminated with microorganisms, which also have the potential for considerable lipase activity.

As commented above the lipase activity can have a microbial origin and so could also come from post-baking contamination. In normal circumstances the water activity of an oatmeal biscuit is too low to support microbial activity because of its low moisture content. However, if there has been any condensation on the surface of the biscuit then the water activity might have become high enough to initiate the necessary microbial activity. You should consider whether there have been any opportunities for warming and cooling that may lead to condensation in the pack.

Oat-based products may also develop off-odours and bitter tastes because of oxidative rancidity. In this case the low water activity in the product encourages the problem, along with exposure to light and traces of certain metals, e.g. iron and copper. Oxidative rancidity is normally a lengthy process, taking many weeks or months to become manifest. The inclusion of a suitable anti-oxidant in the fat is usually helpful in avoiding this problem.

Continue reading here: How do biscuits and crackers get broken during storage even if they are not disturbed

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