EVALUATION OF INTERNAL QUALITY OF FRESH-CUT POMELO USING VIS/NIR TRANSMITTANCE

Modeling and De-Noising for Nondestructive Detection of Total Soluble Solid Content of Pomelo by Using Visible/Near Infrared Spectroscopy

The flavor of Pomelo is highly variable and difficult to determine without peeling the fruit. The quality of pomelo flavor is due largely to the total soluble solid content (TSSC) in the fruit and there is a commercial need for a quick but nondestructive TSSC detection method for the industrial grading of pomelo. Due to the large size and thick mesocarp of pomelo, determining the internal quality of a pomelo fruit in a nondestructive manner is difficult, and the detection accuracy is further complicated by the noise typically generated by the common methods for the internal quality detection of other fruits. Thus, the aim of this study was to determine the optimal method to accurately detect pomelo TSSC and find a de-noising model which reduces the influence of noise on the optimal method's results. After developing a full-transmission visible/near infrared (VIS/NIR) spectroscopy sampling method, the confirming experimental results showed that the optimal pomelo TSSC detection model was Savitzky Golay + standard normal variate + competitive adaptive reweighted sampling + partial least squares regression. The R2 and RMSE of the calibration set for pomelo TSSC detection were 0.8097 and 0.8508, respectively, and the R2 and RMSE of the validation set for pomelo TSSC detection were 0.8053 and 0.8888, respectively. Both reference and dark de-noising are important for pomelo internal quality detection and should be calibrated frequently to compensate for time drift. This study found that large sensor response translation noise can be reduced with an artificial horizontal shift. Data supplementation is efficient for improving the adaption of the detection model for batch differences in pomelo samples. Using this optimized de-noising model to compensate for time drift, sensor response translation, and batch differences, the developed detection method is capable of satisfying the requirements of the industry (TSSC detection R2 was equal or larger than 0.9, RMSE was less than 1). These results indicate that full-transmission VIS/NIR spectroscopy can be exploited to realize the nondestructive detection of pomelo TSSC on an industrial scale, and that the methodologies used in this study can be immediately implemented in real-world production.

Supporting young researchers in food texture studies

I learned about food texture by reading many articles in the Journal of Texture Studies (JTS) and Prof. Bourne's textbook Food Texture and Viscosity, Concept and Measurement. I present here his great contributions as both the Editor-in-Chief of JTS and as the author of a superior textbook in the cultivation of future food texture researchers. Prof. Bourne has provided significant guidance to those in the industry using his textbook to suggest appropriate approaches to measure, evaluate, and alter the textures of agro-products and processed foods. I began my career in food rheology, learned the physiological techniques necessary for measuring mastication, and developed relationships with good sensory scientists along the way. I am happy to offer advice to agriculture and food scientists, researchers, and engineers in the food industry regarding food texture. I would like to be a follower of Prof. Bourne and support young food texture scientists in the 21st century.

PRACTICAL APPLICATIONS

Food texture studies conducted during the last century are beginning to evolve. Based on previous publications in the Journal of Texture Studies, I believe that several areas can be further examined in this century. First, methods to evaluate the textures of heterogeneous materials, such as fruits and vegetables, require improvements. Second, the monitoring of rapid changes in food texture during oral processing should be considered during the design of food products. Third, a new instrumental method that mimics the movement and breakdown of soft foods by the tongue is being developed. The optimization of food processing to reduce the loss of agro-products and production of high-quality foods both require more attention according to the Sustainable Development Goals adopted by the United Nations in 2015.