Studies On Non-Enzymatic Browning Of Litchi Juice

Litchi is one of the subtropical and tropical fruit with special flavor and high nutrtion, and is widely accepted by customers all over the world. Litchi is so dependent on the season that people should process it promptly after the harvest to prevent it from being rottened by the microbes and its enzymes reaction. The development of litchi fruit juice industry can extend friut industry chain and reduce post-natal consumption, which is the way to solve the problems such as overproduction and low profits for the farmers. The primary problem for the development of Litchi juice is the non-enzymatic browning. In this paper, using chemical and instrumental analysis methods, the Litchi's browning change in the different heating conditions and storage period was studied, and through the research on the browning change of Litchi in the model system, the non-enzymatic browning mechanism of Litchi juice was expect fully revealed, and it provided references for the Litchi juice processing technology.1 The result of the comparison of the processing characteristics of thirteen varieties litchi showed that Feizixiao was the most suitable variety for Litchi juice processing because of its excellent color and lustre, typical litchi flavor, appropriate sugar acid ratio, and low browning level during thermal treatment.2 The change of non-enzymatic browning of litchi juice was studied during the heat treatment. It was found that the A420 change of Litchi juice at 60,70,80℃can be described by the zero order kinetic model, while its change at 90 and 100℃could be described by the first kinetic model. The results showed that the change of 5-HMF and A420 had good correlation and Maillard reaction and ascorbic acid degradation mutually effected Litchi juice's browning with the heat treatment.3 The change of non-enzymatic browning of litchi juice was studied during the storage period. It was showed that during Litchi juice stroage, A420 had a little change at 4℃, while at 25,37 and 50℃, the change of A420 can be described by both the zero and first order kinetic model, but more tended to the first order kinetic model. At 25 and 37℃the change of 5-HMF and A420 had remarkable correlation, but at 50℃their correlation.was not significant. It was considered that Maillard reaction and ascorbic acid degradation mutually effected Litchi juice's browning during the storage.4 The change of non-enzymatic browning in simulation system of litchi juice was studied. The change of A420 can be described by the zero and first order kinetic model, but more tended to the zero order kinetic model. It was considered that Maillard reaction and ascorbic acid degradation mutually effected Litchi juice's browning in litchi juice simulation system.