Optimization Of Ammonia Caramel Color Quality And Control Of The Content Of4-Methylimidazole

Caramel color was widely used in food as a kind of colorants. However, the security ofcaramel color was always concerned due to the4-methylimidazole formation in caramelcolor preparation. Thus, the content of4-methylimidazole must be restricted. In this paper,glucose and ammonium chloride were used to prepare caramel color which had both highercolor intensity and red index. An optimized technology was detailed to prepare caramelcolor with a high quality, and removing the4-methylimidazole using ultrafiltration was alsostudied. At last, the structure, antioxidant and anti-tumor activity of melanoidins(10kDa~50kDa,50kDa~300kDa and300kDa~0.22μm) were discussed. Main results weredetailed as follows:Firstly, orthogonal array design means was used to optimize the technologicalparameter during ammonia caramel color preparation. An optimized product, prepared at135°C for60min using50%(w/v) glucose-water solution with6%ammonium chloride(calculated by NH4+) as reactant, was obtained with the color intensity43632EBC and redindex5.34.After testing the physicochemical properties, i.e. color intensity, red index, charge, pHvalue, irradiation stability and salt tolerance, of caramel color samples after ultrafiltration,the characteristics of the products(i.e.10kDa~50kDa,50kDa~300kDa and300kDa~0.22μm)were evaluated. Results showed that all the products contained positive charge which couldbe used in fermented food. On the other hand, the caramel color50kDa~300kDa showed thehighest quality with the color intensity102370EBC and red index5.30. Their salt toleranceand irradiation stabilit of concentrate (i.e.300kDa~0.22μm) was significantly decreased asthe molecular mass300kDa of cut-off membrane was used.Reducing or even removing4-methylimidazole in caramel color using ultrafiltrationtechnology was detailed. Results showed that no4-methylimidazole in the retentate ofhigher molecular mass cut-off membrane (above1kDa) such as10kDa~50kDa,50kDa~300kDa and300kDa~0.22μm was tested, which proposed that ultrafiltration was aneffective means to remove4-methylimidazole in caramel color production. The molecular characteristic of three caramel melanoidins (10kDa~50kDa,50kDa~300kDa and300kDa~0.22μm) was analyzed using elemental analysis, infraredspectrum and scanning electron microscope. While the antioxidant and anti-tumor activitieswere also detailed. Results showed that all molecular of melanoidins might contain alkane,amide and hydroxyl. On the other hand, all melanoidins had significant DPPH radicalscavenging activity, and nearly no significant multiplication on MDA-MB-231cells afterincubated48h was observed.