Rheology and structure of heat-treated pasta dough : Influence of water content and heating rate

• The migration of water and the influence of water content and heating rate on the rheological and structural formation of pasta dough were investigated. The dough used in the study had two different water contents, 39.5 and 41.0%, and was made using water and wheat flour. The samples, 15 x 15 x 2 cm in size, were heated from 25 to 80°C in a conventional oven at two different temperatures, 100 and 150°C, to achieve two different heating rates. During the heating the local water content was measured in the centre of the samples with a fibre-optic NIR instrument. The temperature was measured in the centre, halfway to the centre and at the surface. The rheology of the heat-treated samples was studied by means of tensile tests. Young's modulus, stress at maximum load and energy to break point were calculated. The micro structure of the samples was characterised by CLSM, confocal laser scanning microscopy, and the microstructural parameters were quantified using image analysis. The changes in rheological properties during heating were studied by means of DMA. Untreated dough samples were heated from 25 to 90°C with a heating rate of 5° C/min and a compressing oscillation of 1 Hz. The changes in phase angle δ and storage modulus E' were measured. The most important results were that no migration of water inside the pasta dough could be found. Both the water content and the heating rate affected the structural and rhelogical properties of the pasta dough. There was a maximum in E' vs. temperature, which shifted towards higher temperatures with decreasing water content. Young's modulus was affected by both the heating rate and the water content. Energy to break point and stress at maximum load were affected by the heating rate. The pore size was affected by the water content. The swelling temperature seemed to increase as the heating rate increased

Ämnesord

LANTBRUKSVETENSKAPER  -- Lantbruksvetenskap, skogsbruk och fiske (hsv//swe)

AGRICULTURAL SCIENCES  -- Agriculture, Forestry and Fisheries (hsv//eng)

Nyckelord

Heating rate

Migration

Rheology

Structure

Water content

Triticum aestivum

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