Microwave conditioning of durum wheat. 1. Effects of wide power range on semolina and spaghetti quality

Abstract

Crosby durum wheat was conditioned with microwave energy at 2450 MHz before experimental milling and processing. Randomly selected duplicate samples were irradiated at 625 W up to 600 s, in 120-s increments. The temperature of conditioned samples ranged from 22 "C (0 s) to 110 "C (600 8 ) . Physicochemically important semolina and spaghetti quality parameters were adversely affected after 360 s (+25.9 cal/g) of microwave conditioning. Milling behavior and physical dough characteristics were reduced after prolonged irradiation. Most notable among the adverse biochemical effects were (1) increased dough strength, (2) increased starch damage during milling, (3) increased rate of starch retrogradation, (4) decreased a-amylase activity, (5) decreased &amylase activity, and (6) loss of only 25% of total lipoxygenase activity after 600 s. Spaghetti color and cooked weight decreased, while cooking loss and firmness increased. In general, there were minimal effects on overall quality after 240 s (+17.3 cal/g) or less of microwave conditioning, Wheat is conditioned before milling to improve product yield and quality. Conditioning involves a change in grain temperature and is performed with or without the removal or addition of water. As a result, the amount and distribution of moisture within the kernel are altered. Bradbury et al. (1960) have reviewed the literature on wheat conditioning.Warm conditioning techniques shorten the time required for moisture redistribution. In general, product quality is not adversely affected after warm conditioning up to 46 "C (Wichser and Schellenberger, 1949; Bradbury et al.

Effect of Microwaves on Technological and Rheological Properties of Suni-Bug (Eurygaster spp) Damaged and Undamaged Wheat Flour

“…The total protein contents was not affected significantly (p<0.05) by heating with microwave treatment. The ranges of moisture value and protein content in samples are similar to the results obtained from previously studies (Doty and Baker 1977;Campaña et al, 1986Campaña et al, , 1993Lupano and Anón 1987;Türker and Elgün 1998;Walde et al, 2002;Vadimbal and Jayas 2007).…”

“…This finding indicated that thermal denaturation of glutens in sound and damaged samples might be with different microwave times owing to having different levels of proteolytic activity in flours. The changes in WG content are similar to the findings previously reported by many authours (Doty and Baker 1977;MacArthur, 1981;Campaña et al, 1986Campaña et al, , 1993Lupano and Anón, 1987;Koksel et al, 1993;Türker and Elgün, 1998;Kaasov et al, 2002;Walde et al, 2002).…”

“…The wet gluten (WG) contents of sound and damaged Baker 1977;MacArthur 1981;Campaña et al, 1986Campaña et al, , 1993Kaasov et al, 2002;Walde et al, 2002;Vadimbal and Jayas 2007), limited information is available about the effects of microwave application on quality parameters such as some technological and rheological aspects of the flour milled from suni-damaged wheat (Sivri and Köksel 1996;Türker and Elgün 1998). Our main objective in this investigation was to examine the effects of microwave energy on some specific technological and rheological properties of flours produced from undamaged and damaged wheat by suni-bug and to describe the effects of microwave treatment on excessive proteolytic enzymes in flours.…”

“…1993). The PGI values significantly (p<0.05) increased with higher microwave energy doses and higher end temperature of samples because of the thermal denaturation of gluten proteins and excessive proteolytic activity from insect (sunibug) enzyme (Doty and Baker 1977). In addition, it was observed that gluten harshed along with increasing PGI values for sound and damaged samples due to effect of microwave application what is compatible with Kent's (1983) statement that heat treatment of wheat tends to make the gluten harsher and tougher.…”

“…Microwaves, nonionizing energy, have been increasingly used as novel technology in drying, baking fields of cereal industry since 1980's due to effective advantages (Bouraoui et al, 1993;Fito et al, 2004). Although some studies on using in cereal industry of microwave application (MW) appear in the literature (Aref et al,1972;Doty and Gluten index (GI) value was determined according to the method of Perten (Perten Instruments, 1993). After washing off from flour gluten is put on a special sieve and centrifuged under standard conditions.…”