Semi‐sweet biscuits: 1. The influence of sodium metabisulphite on dough rheology and baking performance

Abstract

The influence of sodium metabisulphite (SMS) on the performance of single wheat varieties in the production of semi-sweet biscuits has been studied. In general doughs produced with SMS required a shorter mixing time, produced shorter dough extrusion times and lower elastic and viscous moduli than doughs produced at the same water level without SMS. Doughs were also produced at a higher water level in the absence of SMS to give similar rheological properties to the corresponding doughs containing SMS. However, dough pieces from doughs containing SMS showed less contraction on processing than dough pieces from all doughs without SMS, including those with similar rheological characteristics to doughs containing SMS. It is believed that this is due to the rheological properties of the dough being achieved through different mechanisms. In the presence of SMS the gluten proteins undergo chemical modification whereas the increased water in the absence of SMS causes a reduction in the magnitude of the rheological parameters through a dilution process. The inclusion of SMS, or increasing water content, caused a reduction in the hardness of biscuits from the varieties Galahad and Riband. The hardness of biscuits from other varieties studied was not affected by a reduction in dough strength. Measurements of flour protein quality were able to rank varieties in order of their likelihood to exhibit dough contraction on processing. However, the measurement of the rheological parameters of dough gave a better prediction of the dimensions of the baked biscuit.

Effect of baking improvers on the quality of whole cassava biscuits

“…However, this is not in agreement with findings of Olive et al (1995). The reason is that the raw material used for the biscuit production is not the same because cassava flour completely lacks gluten which is the unique functional characteristics of wheat flour.…”

“…35oc) during the dough development. The variations in mixing time between dough developed from improvers and the one developed without improver was also observed by Olive et al (1995). Although, they reported longer mixing time for dough prepared from wheat flour.…”

“…The initial dough piece length (65 mm), width (42 mm) and thickness (4 mm) were altered by the inclusion of improving agents. Olive et al (1995) in their finding reported similar contraction in dough piece length on processing, which results in a small increase in width and increase in dough piece thickness. They also confirmed that an increase in dough piece thickness occurs more readily than increase in dough piece width.…”

“…After 10 min a plunger with a weight (2,370 g) was placed on top of the dough piece. The time taken for the plunger to travel 1 cm was recorded with stop watch (Olive et al 1995). The mixing time during dough development was determined by using stop clock.…”

“…Today, small amount of oxidising agents (improvers) are added to flour to accomplish the maturing process, and these oxidising agents are called flour improvers or sulfhydryl oxidising agents. The influence of improver on dough rheology and baking performance for the production of semi-sweet biscuits have been studied by Olive et al (1995). The use of soy-flour as an improver in the baking industry is well known in improving dough handling characteristics particularly in products such as cookies.…”