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Rice (Oryza sativa L.), a major cereal crop, is the staple food source for half of the world population. Rice is an excellent source of energy, in the form of starch, and it gives the benefit of providing proteins with a higher nutritional quality than those of other cereal grains (M���������� et al. 1998). At present, many possible applications of microwave (MW) energy in the food industry are known. MW drying was demonstrated to be an alternative means for the rice drying (W�������� & K����� 1986). Major components and the enzymic system of rice can be influenced during MW treatment. Since starch comprises approximately 90% of the dry matter of the rice endosperm, the research on rice cooking behaviour has focused on this fraction. W�������� and K����� (1986) used two long-grain cultivars and one medium-grain cultivar of rice for drying under vacuum by means of MW energy to determine the effects on the physicochemical properties and eating characteristics. Amylographic characteristics were used to obtain more information on the influence of the starch fraction of rice on its cooking behaviour. No significant differences were found in both maximum viscosity and setback viscosity between the air-dried controls and MW dried rice. M������ and T������ (1993) reported the effect of MW treatment on the contents of total and enzyme resistant starch in white and brown rice (three Australian cultivars -Calrose, Doongara and Waxy). The starch content was maintained or increased by cooking in a MW oven except with cv. Waxy. The increase was consistent with starch gelatinisation and therefore, with greater susceptibility to enzymic attack. Cooked rice had a higher content of resistant starch than the corresponding raw product, possibly because of the production of retrograded starch. It can be concluded that although the content of the resistant starch in rice increased by the techniques known to increase the resistant starch in other foods (heating, cooking, cooling and freezing), the impact was not as great. Z���� et al. (1996) treated two japanase cultivars of rice (700 W, 3 min, 500 g batches) with MW and determined physicochemical properties, cooking quality and enzyme activities. It was found that both cultivars of rice had debranching enzymes, and that α-amylase activities were significantly lower than those of the untreated controls. Cooking qualities, such as water absorption capacity, pH, and iodine blue value of cooking water, β-amy- The properties of rice after microwave irradiation were evaluated by means of amylograph and enzymic determination of the total and the damaged starch. The content of the total starch was not affected by the immediate energy output used for irradiation but that of the damaged starch increased with microwave energy absorbed and the temperature of treatment, mainly at the moisture of 30% and the temperature of 100°C. The results of damaged starch determination are in accordance with the amylographic readings of changes at maximum viscosity. Amylographic characteristics suggest mini...

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Currently attention is paid to a possible use of microwave (MW) heating for the drying of cereal grain, rice or pulses. Heat from the kernel surface is transferred by conduction to the inner endosperm if the usual convention drying of grain with hot air is used. This method of drying is time consuming with low economic effectiveness since heat conductivity of wheat kernel is rather low, similarly to insulating materials. MW heating allows drying grains to a permitted limit moisture without deteriorating effects on its composition or properties (CAMPANA et al. 1986). MACARTHUR and D'APPOLONIA (1982) studied the influence of MW heating and grain moisture on wheat conditioning prior to milling and optimisation of semolina yield as well. Some deteriorating changes can occur as a result of high doses of MW treatment. MATERIALS AND METHODSTechnique of microwave treatment: Parameters of a MW oven Whirlpool MT 243/UKM 347 (Norrköpping, Sweden) were as follows: frequency 2450 MHz, pulsed variable MW rated values of power output -90, 160, 350, 500, 750, 850 and 1000 W, inner space volume 25.4 l, without sample rotation during measurement. Before the samples are treated, pre-heating of the oven has to be done to achieve a heating process standard. For this purpose a volume 2 l of water was heated in the oven, using a maximum power output for 5 min. The absorbed power according to BSEN 60705 test (International Standard BSEN 60705 -Methods for measuring the performance of microwave ovens for household and similar purposes) was determined every day as well. Load of water for this test is 350 ± 5 g, initial water temperature 10 ± 2°C. The mean value of absorbed power (n = 22) corresponding to the rated power output 350 W was 298.42 W; standard deviation 8.5 and coefficient of variation (relative standard deviation) 2.85% (SKULINOVÁ et al. 2002).A special polyethylene container with bottom dimensions 100 × 150 mm was used for MW treatment. Weight of single sample was 200 g, height of sample layer in the container was 20 mm. The container with sample was put in the middle of the oven, MW power output was set and the sample let heat until the desired end temperature of heated sample was reached. Then the power output of the oven was switched out and the sample was left in the oven for 1 min more to homogenise the temperature in The effect of microwave (MW) heating on the changes in wet gluten content, Gluten Index, Falling Number and amylographic characteristics was studied in sprouted wheat grain. Different moistures of wheat in two ranges of 10-11% and 15-17% and two end temperatures of MW heated samples (60 and 80°C) were applied to wheat samples. Falling Number and Gluten Index increased with increasing absorbed energy during MW heating, whereas gluten content decreased. Amylographic maximum increased due to α-amylase inactivation progressively with increasing absorbed energy as well. The greatest relative changes occurred when the end temperature of MW heated samples 80°C and moisture 15% were used. An improvement effect on...