Assessment of browning index of maillard reaction for differentiation of fish, bovine and porcine gelatin with Principal Component Analysis (PCA)

Abstract

Gelatin is commonly used as the ingredients in food, beverages, pharmaceutical, personal care and many more. It can be extracted from animal’s bones and hides. However, Halal and Haram issues on the source of gelatin are widely debates among Muslim scholars. Scientists have made a lot of effort to detect the origin of gelatin sources by using various methods. Therefore, the assessment of browning index from Maillard reaction of different sources of gelatin have been performed with Principal Component Analysis (PCA) as the latest reliable chemical approach in gelatin authentication. The objectives of this study are to optimize the factors affecting the browning index of Maillard reaction of fish, bovine and porcine gelatin by one-factorat- a-time and Response Surface Methodology, to differentiate the browning index of Maillard reaction using UV-Vis spectroscopy combined with PCA and to characterize the browning compound from Maillard reaction of different sources of gelatin with FTIR and GC-TOF/MS. All factors affecting Maillard reaction such as pH, type and concentration of reducing sugar, type and concentration of metal ions, reaction temperature and time were investigated based on one-factor-at-a-time experiment. Response Surface Methodology was also used to optimize the Maillard reaction. The absorbance of browning compound of each sample was obtained by using UV-Vis spectroscopy in the range of 200 nm to 600 nm and converted into browning index. Next, the browning compound was characterized by using FTIR and GC-TOF/MS to compare the gelatin sample before and after subjected to Maillard reaction. Finally, the differentiation of browning index from fish, bovine and porcine gelatin were established through PCA. In general, the result showed high browning index can be obtained from 0.5 M of xylose at high temperature and long reaction time with the presence of metal ions Cu2+. However, the effect of pH was insignificant and can be ignored in Maillard reaction of gelatin. From optimisation experiment, reaction temperature at 95°C for 9 hours were suitable for all types of gelatin but 5 mM of metal ions Cu2+ only required for bovine gelatin. In comparison with the raw gelatin standard, the browning compound in Maillard reaction of gelatin was successfully characterized by FTIR and GC-TOF/MS. In conclusion, the result from PCA revealed a notable differentiation between the browning index of fish, bovine and porcine gelatins after undergoing Maillard reaction. All the results demonstrated the success of the proposed combination methods of browning index and PCA analysis in achieving the objectives of this study.