Studies on the antioxidant capacity of caramel and their relationship with browning intensity

• Main Authors: Tzu-Yu Yu, 余子瑜
• Other Authors: Pi-Jen Tsai
• Format: Others
• Language: zh-TW
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/39611799826368136050

碩士 === 國立屏東科技大學 === 食品科學系所 === 96 === Caramelization is one of nonenzymatic browning, which produces the substances called caramelization products (CPs). Reports showed that, CPs could inhibit lipid oxidation in fish mince during storage, and the inhibition effectively increased as the amount of CPs increased. However, the CPs varied when the kind and concentration of sugars are different, so is their corresponding antioxidant capacity. The aim of this study is to elucidate the effect of sugars (sucrose, fructose, glucose, xylose), sugar concentration (1%, 10%, 20%) and pH (pH 3, pH 7, pH 10) on the color and antioxidant properties of CPs. Analyses include optical characteristics (UVλmax, A420 and RUV/brown), color qualities (Hunter L a b value, chroma, △E) and antioxidant capacities (FRAP reducing power and DPPH scavenging ability).To elucidate the relation of caramelization products browning intensity or degree of pH decrease and antioxidant capacity. Results showed that the caramels from monosaccharides seemed to provide better FRAP reducing power and DPPH scavenging ability at neutral or alkaline condition. In addition, while sucrose at acidic condition was to show the better antioxidant capacity. The browning intensity and antioxidant capacity also increased as the sugar concentration was increased from 1% to 10 % and 20%. Under the pH 3 acidic system with three sugar concentration, four sugar kinds were heated after 42 hours, the leveling of browning intensity and antioxidant capacity, in order were fructose, sucrose, xylose and glucrose. And at neutral condition, xylose was greater, and fructose was the posterior one. Xylose was to show much better, next was fructose in 1% and 10% sugar concentration, and glucrose was to show better at 20% sugar concentration under the alkaline condition. Correlation analysis results showed that the browning intensity, Hunter a, Hunter b, chroma, △E, UV-absorbing substance, FRAP reducing power, and DPPH scavenging ability showed highly positive correlation coefficient, while Hunter L and RUV/brown value showed negative correlation. Caramel intermediate or brown products increased as heating time increased. Which are also connected with the formation rate of caramel. Besides the browning intensity, △pH was also found to linearly correlate with the initial rate of FRAP increase. Consequently, we found that the correlation coefficient between browning intensity and FRAP reducing power or DPPH scavenging ability were among 0.78-0.94 and 0.55-0.96, respectively. And the initial rate of browning and △pH also linearly correlated with the increase rate of FRAP (correlation coefficient were 0.81-0.89 and 0.89-0.94, in 1% and 20% sugar system, respectively). In conclusion, on the caramelization process, under neutrality or alkaline condition, the antioxidant capacity, browning intensity, color change increased which caramels from monosaccharides increased as heating time increased. It can be concluded that, intensity and rate of brown caramel formation depend on pH and may decide the antioxidant capacity of caramel, which can also be easily detected by the measurement of △pH or browning intermediate during the caramelization process.