Real-time temperature estimation and non-destructive quality monitoring in packaged fresh produce

Fresh-cut vegetables are increasingly welcomed by consumers for its convenience. However, processing of fresh-cut vegetables results in wounding tissues and makes them more vulnerable to shelf life changes. Shelf life of fresh-cut vegetable is affected by several factors like temperature, humidity and light in storage and transportation. The whole process, from vegetables being harvested, transporting to retailer and ending up in domestic refrigerator, is called cold chain. An efficient and uninterrupted cold chain can help maintain vegetable quality and retard deterioration. However, temperature abuse occurred frequently in distribution which cause unpredictable shelf life changes to packaged fresh produce. Therefore, a real-time temperature estimation and non-destructive quality monitoring method need to be established to help control and manage cold chain for packaged fresh produce. A simplified heat transfer model is proposed to estimate temperature inside packages and the efficiency of the model is verified by applying to primary and secondary spinach packages. Besides, an on-package miniature RGB sensor is used to monitor spinach leaf color change and the results are correlated with corresponding spectrometry and texture analysis. The heat transfer model has yielded very good estimation comparing with actual package temperature change with total variation less than 3% in primary package and 7% in secondary package. The RGB sensor has successfully monitored spinach leaf color change in 25 ℃ and 2 ℃ storage temperature. The change of red, green and blue values from RGB sensor provide good correlation with spectrometry and texture with R2 of 0.99 and 0.92 respectively. Results of the study suggests that temperature inside fresh produce package can be efficiently estimated by using the proposed model and the real-time quality of spinach can be monitored by the RGB sensor.M.S.Includes bibliographical reference