Use of 2-furoylmethyl derivatives of GABA and arginine as indicators of the initial steps of Maillard reaction in orange juice

The formation of 2-furoylmethyl derivatives of GABA (2-FM-GABA) and arginin e (2-FM-Arg) as early indicators of nonenzymatic browning in different type s of orange juice was studied. In dehydrated orange juice, the presence of 2-FM-GABA and 2-FM-Arg was detected from the first day of storage at 30 deg rees C. In this type of juice, the content of these two compounds increased with temperature (30, 50 degrees C) and time (1-7 days) of storage. A noti ceable increase in 5-hydroxymethylfurfural was only observed after 4 days o f storage at 50 degrees C. No formation of 2-FM-GABA and 2-FM-Arg was detec ted in liquid orange juice heated under conditions similar to those used in the industry. These furoylmethyl derivatives were also found in commercial orange juice made from concentrates. A slight increase in their concentrat ion was observed in the two samples stored during 8 months at room temperat ure. According to the results obtained, 2-FM-GABA and 2-FM-Arg contents cou ld be suitable indicators to assess the main modifications due to Maillard reaction produced during the manufacture and/or storage of orange juice con centrates.