ABSTRACT
Acrylamide is a carcinogen element which is formed at temperatures higher than 120°C in the foods rich in carbohydrates, such as Sangak bread. At first, a series of confirmed mechanisms effective on the formation of acrylamide was determined: Free asparagine, glucose, fructose, maltose, and sucrose sugars in two kinds of dough made from two kinds of flour with the extraction rate of%82 and%93. Then, the effect of flour extration rate, enzyme asparaginase, temperature and time needed for baking, and interactions of effectual factors was studied on the formation of acrylamide in Sangak bread. The amount of acrylamide was determined by liquid chromatography tandem mass spectrometry [LC/MS/MS]. The data analysis was performed using Spss16, Minitab15, and Factorial test. A significant differenc was seen between average sugars other than sucrose in the two kinds of flour. Also, average acrylamid formed by principal factors affecting [flour extration rate, asparaginase enzyme, baking time and temperature] and reciprocal impact of the 2, 3, 4 factors showed a significant difference [p< 0/001]. The maximum of acrylamide formation from 72 treatments caused by the reciprocal impacts of the four factors was seen at the temperature of 352oC, baking time of 10 minutes, and flour with 93% extraction rate [without enzyme] of 60/30 [mg/kg] and the minimum of acrylamide formation was observed at the temperature of 241oC, baking time of 5 minutes and the flour with 82% extraction rate [with enzyme] of 13/07 mg/kg Sangak bread. The decrease of free asparagine by asparaginase enzyme indicated that glucose and fructose were the major sources of acrylamide formation in Sangak bread. The rate of acrylamide formation increased with the increase in flour extraction rate. This rate has direct relationship with baking time and temperature. Acrylamide formation can be minimized in the presence of asparaginase enzyme. Training the bakers not to toast the bread will result in the production of healthy Sangak bread
ABSTRACT
Annual production of Doogh [a yoghurt drink] in Iran exceeds 120000 metric tons. Iran is probably a leading producer and consumer of this type of dairy-based product in the world. Separation of Doogh into 2 phases [serum separation] during storage is a major problem which affects its market share. The present study was undertaken to investigate the stabilizing effects of salep and tragantin gums [as local gums] and guar gum [as a commercial gum], added individually or in combination, to Doogh [containing 40% yoghurt]. Various gums [salep, tragacantin and guar], individually [concentrations 0.1 - 0.5%] and in combination [at ratios 50:50, 20:80 and 80:20] over a range of 0.1 to 0.2%, were added to samples of Doogh [composed of 40% stirred yoghurt, 59.3% tap water, 0.7% NaCl], and their physical stability [serum separation percent] were monitored over a period of 30 days at various storage temperatures [5 and 25 °C]. In addition, some mechanical parameters, namely homogenization [up to 200 bars] and agitation speed [9000 and 11000 rpm for up to 2 min] of the samples, as well as their biphasic separation and rheological properties were determined. Sensory evaluation was also performed using semi-trained panelists and the 9-point hedonic scale procedure. Our findings revealed that the individual gums could significantly reduce phase separation during storage [p <0.01]. Gum tragacantin was the most effective, resulting in full stability of Doogh at a concentration of about 0.3%. Generally speaking, increasing the concentration of gums caused changes in the rheological behavior of the Doogh samples. Samples containing salep, tragacantin and guar gums showed a pseudo-plastic flow behavior, whereas in their absence, the Dooghs behaved as a Newtonian fluid. Mechanical operations, particularly agitation speed, led to a considerable reduction in the apparent viscosity of Doogh and, consequently, a significant increase in serum biphasic separation [p <0.01]. In the organoleptic tests, the Doogh samples containing tragacantin and tragacantin-guar combinations received the highest scores. It is probable that the stabilizing effects of the gums, being non-absorbent hydrocolloids, were due to their viscosity-raising and water-holding properties. Moreover, mechanical operations [stirring and homogenization] could have disrupted the colloidal structure, leading to a decrease in viscosity and an increase in the biphasic separation