The dietary fibre contents of row and cooked wheat products are highly correlated with their total pentose contents. A colorimetric method for rapid estimation of pentosans in while flour has been adapted for use with products of a wide range of dietary fibre contents, by introducing a prehysrolysis with 0.5m sulphuric acid for 0.5h.

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Flours milled from English ('weak'), Canadian ('strong') and mixed English and Canadian wheats ('medium') had different rates of lipolysis (weak > medium > strong) during prolonged storage at ambient temperatures (average about 12°C). Lipolysis was more rapid in the medium flour at 25"C, but was very slow in 'control' flours kept at -20°C in an inert atmosphere. Loss of baking quality in stored flours was assessed using the Chorleywood Bread Process (CBP), a long fermentation process (LFP) and the Activated Dough Development process (ADD). The loaf volume changes varied with the flour type and test method, especially depending on whether or not fat was included in the recipes. In tests with fat, the CBP was the most sensitive to deteriorative changes (strong= medium > weak); with the medium and strong flours, loaf volumes were nearly constant for 24 months before decreasing rapidly. Deterioration became apparent more gradually when using LFP and ADD tests with fat. When fat was omitted, short-term improvement (weak > medium > strong) occurred with all three baking methods, but there was subsequent loss of volume. To account for these changes in baking behaviour, it is suggested that the tests differ in their sensitivity to flour type and variations in dough composition, especially to the level of bakery fat, the level of fatty acids (generally deleterious), and to protein changes which were also detectable by rheological tests on stored flour doughs (flour 'maturation' ; generally beneficial).

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When a fresh flour dough containing a model fat prepared from pure saturated and unsaturated triglycerides was supplemented with pure oleic or linoleic acids in amounts sufficient to raise the level of unesterified fatty acids to that obtained with a flour badly deteriorated by age, the acids were equally detrimental to loaf volume. Margaric acid added at the same level was not deleterious. Lipid binding studies showed that both unsaturated fatty acids behaved similarly during doughmixing, not only becoming largely 'bound' themselves, but also causing increased binding of glyceryl trioleate and flour lipids. Conversely, margaric acid remained largely 'free' and did not affect the binding of other dough lipid constituents.