The effects of ultrasound‐assisted glycation with 1 m glycine at room temperature in comparison with thermal glycation on the colour and radical scavenging activity of nipa palm (Nypa fruticans Wurmb.) syrup were investigated. The pH of both treatments decreased with increasing reaction time. The browning development occurred after induction period of 10 min for thermal glycation and 60 min for ultrasound‐assisted glycation. A shorter time of ultrasound rendered the syrup light brown to amber in colour with some green. With long‐term ultrasound, the syrup turned brighter, yellower and greener. The increased DPPH^· scavenging activity of the thermal syrup was due to the brown pigments as shown by a marked increase in the A₄₂₀ and a* value. The scavenging activity of ultrasound‐treated syrup was improved by 53–57% due to the accumulation of UV‐intermediate products as shown by a higher A₂₉₄/A₄₂₀. Thus, ultrasonication for 30–60 min was recommended in order to prevent dark colour development of the final syrup.

中文翻译：

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超声辅助甘氨酸糖基化后，改善了自由基清除活性并稳定了尼帕棕榈糖浆的颜色

研究了室温下用1 m甘氨酸超声辅助糖基化与 热糖基化对尼帕棕榈糖浆的颜色和自由基清除活性的影响。两种处理的pH均随着反应时间的增加而降低。诱导期为热糖化10分钟，超声辅助糖化为60分钟后发生褐变。较短的超声时间使糖浆的颜色从浅棕色变成琥珀色，并带有绿色。通过长期超声检查，糖浆变亮，变黄和变绿。热糖浆清除DPPH ^·的活性增加是由于褐色颜料所致，如A ₄₂₀和一个*值。超声处理的糖浆的清除活性提高了53–57％，这是由于较高的A ₂₉₄ / A ₄₂₀可以显示出紫外线中间产物的积累。因此，建议超声处理30-60分钟，以防止最终糖浆出现深色。