• Journal of the Korean Society of Food Science and Nutrition
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• v.30 no.6
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• pp.1041-1046
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• 2001

Solutions of fructose, glucose and sucrose were heated without catalyst at various temperature for different length of time. Changes in the formation of early caramelization product and browning intensity as well as pH of heated sugar solutions were determined. Reducing powers of caramelization products (CP) and their inhibitory effects on polyphenol oxidase (PPO) were also determined and their correlations were discussed. The early CP and browning intensity increased with temperature and time, in the order of heated fructose>sucrose>glucose solutions (p<0.005), while pH decreased. pHs of sugar solutions heated at 20$0^{\circ}C$ showed in the range of 3.32 ~ 3.50. Reducing power of CP as well as their inhibitory effect on PPO also increased with temperature and time, respectively. Among sugar solutions, reducing power showed the same trends as above at both 15$0^{\circ}C$ and 17$0^{\circ}C$ (p<0.001). However, those of heated fructose solutions were the highest in the early stage, while those of heated sucrose solutions were the highest in the final stage at 20$0^{\circ}C$. This is due to the difference in CP formed. Sucrose solution heated at 20$0^{\circ}C$ showed the highest inhibitory effect, reducing PPO activity by 34.6%. From these results, it is considered that the inhibitory effect of CP on PPO is partly related to their reducing power.

• Korean journal of food and cookery science
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• v.21 no.1 s.85
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• pp.24-32
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• 2005

Changes in apple slices during cold storage were investigated by evaluating the physical properties such as degree of browning and compression force. Chemical properties such as PPO activity and total phenol contents were also determined and sensory evaluation was carried out. The correlation analysis between browning parameters was conducted. Degree of browning was increased in the order of fresh apple slice, water-dipped apple slice, $0.5\%$ ascorbic acid solution-dipped apple slice and CP(caramelization product) from sucrose-dipped apple slice. PPO activity was increased in the order of fresh apple slice, water-dipped apple slice, $0.5\%$ ascorbic acid solution-dipped apple slice and CP(caramelization product) from sucrose-dipped apple slice. Amongst several treatments, CP from sucrose-dipped apple slice showed the lowest degree of browning and PPO activity. Total phenol contents were decreased from 60 to 56.2 mg and from 59.6 to 56.0 mg in fresh apple slice and water-dipped apple slice, respectively, but CP from sucrose-dipped apple slice and $0.5\%$ ascorbic acid solution-dipped apple slice were increased from 51.9 to 52.8 mg and from 54.1 to 54.4 mg, respectively, showing the smallest changes when compared with fresh apple slice and water-dipped apple slice. Compression forces of apple slices during cold storage were decreased in the order of fresh apple slice, water-dipped apple slice, $0.5\%$ ascorbic acid solution-dipped apple slice and CP from sucrose-dipped apple slice. In sensory evaluation of apple slices during cold storage, CP from sucrose-dipped apple slice had higher score than the other treatments. In addition, a significant correlation was observed among degree of browning, PPO activity and phenol content. Therefore, CP from sucrose-dipped apple slice seems to be effective in controlling of enzymatic browning during cold storage. In addition, CP from sucrose-dipped apple slice seems to be effective on other several factors. These results suggest that CP from sucrose should be a potential source for controlling enzymatic browning during storage of vegetables and fruits.