Improving the color of bulgur: new industrial applications of tempering and UV/sun-light treatments

Abstract

Color (CIE b*; yellowness) is an important parameter for bulgur quality. Color of bulgur is mainly due to natural pigments (carotenoids) that are present at different levels in wheat. In order to increase the customer acceptability, the producers try to obtain yellowish color in bulgur. In this study, two different tempering methods (spray and steam) were used before sun and UV-light polishing applications. Sun and UVlight were applied to tempered bulgur for 12, 24, 36, 48, 60 and 72 h. Moisture content (%, d.b.), ash content (%, d.b.), protein content (%, d.b.), total carotenoid content in terms of lutein equivalent (TCC) and color values (CIE L*; lightness, CIE b*; yellowness, CIE a*; redness and CIE YI; yellowness index) were determined. It was found that UV-light was more effective (P<0.05) on the CIE L* and CIE b* values compared to sunlight. Both tempering methods were significantly (P<0.05) increased the CIE L*, CIE b* and CIE YI values. Steam tempering has a significant effect (P<0.05) on the CIE b* values as well as UVand time of UVexposure. The highest value of TCC i.e. 6.31 μg/g was obtained by using spray tempering and UV-light exposure. As a conclusion, as proposed methods steam tempering and UV-light have an obvious positive effect on the color of bulgur.

Effects of different cooking and drying methods on phenolic acids, carotenoids, and antioxidant activity of emmer (Triticum turgidum ssp. dicoccum) bulgur

“…Although there are many studies related to color of bulgur in the literature (Bayram & Oner, 2006;Hayta, 2002;Kahyaoglu, Sahin, & Sumnu, 2010), the lack of studies on carotenoid content, which has the greatest effect on color, draws attention. In one of the existing studies, Balci and Bayram (2015) investigated the effect of different tempering processes (spray steam) and polishing methods (sun light-UV light) with 0-72 hr on the TCC of the bulgur. They reported that the TCC of the samples was between 3.65 and 6.31 µg/g and the best method in terms of TCC was provided in the combination of spray tempering and UV light polishing.…”

Characterization of Volatile Compounds of Bulgur (Antep Type) Produced from Durum Wheat

“…During spraying, the wheat kernels were mixed. After the tempering [11], the samples were left for 15 min (tempering time).…”

“…According to Balci and Bayram [11], a mechanical polishing system was used (Lab. Scale Mechanical/Kneading/ polisher, Biltek Eng., Gaziantep/Turkey).…”

Processing and quality aspects of bulgur from Triticum durum

“…After milling, an additional polishing step of tempered (~17%) bulgur can be added in order to increase the bright yellow color of the bulgur and therefore its market competiveness (Balcı & Bayram, 2015). A mechanical polisher kneads, or squeezes, the bulgur making it smoother and heat is generated through friction aided by the electrical heater of the polisher (Balcı & Bayram, 2015). The bulgur can be steam tempered or spray tempered before polishing although steam tempering has been shown to be more effective at increasing the b* color values.…”