Low-temperature vacuum drying as novel process to improve papaya (Vasconcellea pubescens) nutritional-functional properties

Authors: VEGA-GALVEZ, ANTONIO - University Of La Serena; URIBE, ELSA - University Of La Serena; PASTEN, ALEXIS - University Of La Serena; VEGA, MACARENA - University Of La Serena; POBLETE, JACQUELINE - University Of La Serena; Bilbao-Sainz, Cristina; Chiou, Bor-Sen

Submitted to: Future Foods
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/17/2022
Publication Date: 1/21/2022
Citation: Vega-Galvez, A., Uribe, E., Pasten, A., Vega, M., Poblete, J., Bilbao-Sainz, C., Chiou, B. 2022. Low-temperature vacuum drying as novel process to improve papaya (Vasconcellea pubescens) nutritional-functional properties. Future Foods. 5. Article 100117. https://doi.org/10.1016/j.fufo.2022.100117.
DOI: https://doi.org/10.1016/j.fufo.2022.100117

Interpretive Summary: Papaya fruit contains high amounts of nutrients and water, which make them susceptible to attack by microorganisms. Drying is one common way to remove water from these fruits and to prevent the microorganisms from multiplying. In this study, we evaluate the potential of low-temperature vacuum drying to preserve Chilean papaya (vasconcellea pubescens) by examining drying kinetics and the physical and nutritional-functional properties of the final dried product. The use of low temperature vacuum drying at 10, 20, 30 and 40 ºC required 77.6, 36.0, 22.0 and 437 19.5 hours, respectively, to complete drying. At this point, the water activity of all dried samples were below 0.60, indicating the samples were safe from microbial growth. The dried papayas had lighter color than the fresh papaya, with the papaya dried at 10 ºC being most similar in color to the fresh sample. The samples dried at higher temperatures had higher total phenolic contents than those dried at lower temperatures due to possible inactivation of oxidative enzymes. However, samples dried at lower temperatures had higher ß-carotene contents due to ß-carotene’s low thermal stability. Also, dried papaya inhibited a-glucosidase activity better than fresh papaya. In addition, the dried samples had retention values of total phenolic, total flavonoid, ß carotene and ascorbic acid contents that were comparable to those of freeze-dried samples. These results indicated that low temperature vacuum drying can be a cheaper and faster alternative to vacuum freeze-drying.

Technical Abstract: A novel dryer operating at low temperature and vacuum conditions was used to examine the drying kinetics and resulting physical and nutritional-functional properties of papaya (Vasconcellea pubescens) slices. Drying experiments were carried out at 10, 20, 30 and 40 °C under a constant vacuum (1 Kpa). Proximate, dietary fiber content, sugar content, color, and non-enzymatic browning changes were determined for fresh and dried papayas. The drying time of the fruit was significantly influenced by the temperatures. Sugar content increased considerably after drying, whereas proximate and dietary fiber compositions varied in value. Dried samples were brighter and exhibited low Maillard potential. Phenolic compounds, ß-carotene, vitamin C and flavonoids retention values of dried samples ranged from 71.8 to 131.3%, 73.7 to 137%, 76.1 to 85.5% and 48.7 to 86.9%, respectively. Finally, antioxidant properties of papaya decreased significantly after drying. The resulted indicated that the properties of the final dried products are comparable to those of freeze-dried products reported in the literature.