Recent Developments in Methods and Techniques for Rapid Monitoring of Sugar Metabolism in Fruits

The major sugars in fruits, including glucose, fructose, and sucrose, play a critical role in fruit quality control and maturity evaluation. Many novel methods and techniques such as enzymatic and nonenzymatic biosensors, nuclear magnetic resonance, and near-infrared spectroscopy have been developed to provide the rapid estimation of sugar inversion under different storage conditions. This review provides a description of recent advancements in these technologies for the determination of sugar contents in fruits. The prospects of emerging spectroscopic technologies such as Raman spectroscopy, hyperspectral imaging, and terahertz imaging, for assessing sugars in intact fruits are discussed. The challenges for further developments of these methods and technologies to meet the increasing demand for rapid and on-line quality control are also presented.