Quality characteristics of sand, pan and microwave roasted pigmented wheat (Triticum aestivum)

Holistic View of Starch Chemistry, Structure and Functionality in Dry Heat-Treated Whole Wheat Kernels and Flour

“…The temperature and time combinations of the wheat kernel roasting conditions in a study by Gujral et al [ 27 ] ranged from 250 to 350 °C for 15–100 s. Enhanced puffing and crispiness, due to mass transfer in the form of moisture diffusion ( Figure 2 ), was observed in the roasted kernel at these high temperatures. No puffing was observed in a more recent study by Dhua et al [ 28 ] when the wheat kernels were roasted at a lower temperature of 175 °C for 60 s. The water and oil absorption capacity of the milled flour increased, whereas the emulsifying, foaming capacity and pasting properties decreased. This method, however, produces non-uniformly roasted kernels with a high silica and acid-insoluble ash content due to sand contamination [ 10 ].…”

“…This method, however, produces non-uniformly roasted kernels with a high silica and acid-insoluble ash content due to sand contamination [ 10 ]. Furthermore, due to conduction heating with sand as the main heat transfer method, the outer areas of the sample can become over-roasted whilst the core remains untreated [ 28 ].…”

“…Dhua et al [ 28 ] noticed a decrease in the pasting properties as well as a significant reduction in the emulsifying capacity of the flour produced from the microwave-treated wheat kernels (5 min; 600 W). This may be ascribed to protein denaturation and surface hydrophobicity after the heat treatment.…”

“…This may be ascribed to the solitary presence of the starch in the latter study, whereas the weak gluten network formed in the first study allowed for the granules to expand and absorb more moisture. Rapid temperature increase during the microwave heating resulted in a weaker gluten protein configuration, increased starch granule rupturing, the absence of a continuous amylose network and a reduction in swelling power [ 28 , 29 ].…”

“…Water absorption is dependent on the presence of hydrophilic groups to bind water molecules [ 11 , 28 ]. Partial gelatinisation allows for strengthened interactions between the water and polar groups from the exposed starch granules, consequently enhancing the ability of the granules to bind and retain water [ 16 ].…”