Paper Information

Journal:   ELECTRONIC JOURNAL OF FOOD PROCESSING AND PRESERVATION   2017 , Volume 8 , Number 2 #G0058; Page(s) 1 To 24.
 
Paper: 

INVESTIGATION OF COLOR CHANGES IN SOUR ORANGE JUICE DURING THERMAL PROCESSING

 
 
Author(s):  AGHAJANZADEH SURAKI S.*, ZIAIIFAR AMAN MOHAMMAD, KASHANINEJAD M., MAGHSOUDLOU Y., ESMAILZADEH E.
 
* DEPARTMENT OF FOOD SCIENCE AND TECHNOLOGY, GORGAN UNIVERSITY OF AGRICULTURAL SCIENCES AND NATURAL RESOURCES, BASIJ SQUARE, GORGAN, IRAN
 
Abstract: 

Background and objectives: Sour orange juice is used as a seasoning in preparation of different foods because of its sour taste. Although thermal processing is a common method to improve safety of sour orange juice, it induces the nutritional loss and undesirable compounds formation. Generally, chemical changes in food products influence the product color. By considering the relation between product color and its chemical changes, the objective of this work is to investigate the effect of thermal processing (temperature and time) on the color parameters including the browning index (BI) of sour orange juice.
Materials and methods: In this study, the BI of product was measured using two different methods, the image processing method and the spectral analysis. The color changes were investigated using L*, a* and b* color parameters. In addition, the ascorbic acid content was measured using iodine titration method.
Results: The results showed that the luminance (L*) of sour orange juice decreased as processing temperature and times increased, while a* (redness) and b* (yellowness) increased. An increase in the color intensity during thermal processing was shown by investigating the Chroma index. Total color changes (TCD), as an appropriate index in product color change, increased during processing. The reaction constant rate (k) of TCDincreased about 1.66 times as temperature increases, representing the color temperature affinity. The high activation energy (Ea) revealed the high temperature tolerance of components colo. Sour orange juice browning was found to be dependent upon the ascorbic acid content. A good correlation was also found between both of the applied methods to investigate the browning index.
Conclusion: By considering the effect of thermal processing on the nutritional content of the sour orange juice, it could be reported that the color intensity of the product changed during thermal processing at different temperature and time; as the temperature increased, the rate of changes of different color parameters raised. Also it was observed that there was a high correlation between BI and ascorbic acid content in sour orange juice. By comparing the changes in BI and that of ascorbic acid content, it could be stated that the both methods (image processing and spectroscopy) were effective in analysis of BI. The image processing method is suggested in BI measurement due to its more simplicity, lower cost and not destructive effects.

 
Keyword(s): SOUR ORANGE JUICE, THERMAL PROCESSING, COLOR CHANGES, IMAGE PROCESSING, SPECTROSCOPY
 
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