Use of volatile organic compounds and physicochemical parameters for monitoring the post-harvest ripening of imported tropical fruits

The trade of fresh fruits from tropical countries has steadily increased over the past decades, but limited familiarity of consumers with these products has limited their introduction in worldwide markets. The increasing competition in European and international fruit markets is generating the need for improved ripeness evaluation techniques to assess fruit quality standards. As tropical fruits produce a wide range of volatile organic compounds (VOCs), PTR-ToF-MS was used to fingerprint the volatile profile of four tropical fruits (avocado, banana, mango and mangosteen) and determine whether this instrument could be used to assess fruit ripening stages, which was measured with traditional methods. Data were subsequently subjected to partial least squares discriminant analysis. By pooling the entire dataset together, it emerges that VOCs and chemical analyses enabled the separation of the two different ripening stages of all fruits, while skin color and fruit firmness did not always enable that separation. For avocado, banana and mangosteen, it was possible to observe the process of maturation during the shelf life, via physicochemical parameters and VOC analysis, whereas for mango, the constant production of methanol and acetaldehyde detected at both stages, together with the unchanged of evolution of the physicochemical parameters (TSS, pH and color), indicated a lack of maturation. Given the rapidity and the potential to use this analysis method on a large scale, the PTR-ToF-MS has a high potential to become a commercial standard tool for monitoring food quality from entering the storage chain up to the ‘ready to eat’ labeling.