Have you ever tasted these famous tropical fruits from Thailand: rambutan, mangosteen, or longkong? These fruits have unique shapes and flavors and are packed with abundant vitamins. They are a main source of income for local fruit farmers in Nakhon Si Thammarat, a southern province of Thailand, where Walailak University is located. Each day, during their seasons, thousands of tons of these fruits in the province are exported to fruit lovers worldwide, especially in the US, China, and European countries.
Although these fruits have a unique and marvelous taste, they have a short shelf life. Their skins quickly turn brown, even during the exporting process and before reaching supermarkets. As a result, their market value decreases while the interior flesh remains fresh and retains its delicious flavor. Let's take rambutan (Nephelium lappaceum) as an example: this fruit, with its hairy exterior, conceals luscious white flesh that encloses a seed. After the post-harvest stage within 7-10 days, rambutan naturally undergoes enzymatic browning due to the induction of Polyphenol oxidase (PPO) activity, resulting in the formation of undesirable brown pigmentation on the peel.
In an effort to mitigate enzymatic activity and delay the browning process, a novel technique utilizing Cardamom oil vapor has been investigated. This technique offers a cost-effective approach to reducing browning in a diverse range of tropical fruits. Importantly, its implementation facilitates the extension of transportation duration, thereby enabling the exportation of local fruit produce to foreign markets. Furthermore, this innovative method serves to enhance market competitiveness, as it has been observed that the treated rambutans not only retain their characteristic red color but also maintain sensory attributes, notably an extended duration of tactile sensation.
“Situated in the province of Nakhon Si Thammarat, Walailak University finds itself amidst a cornucopia of tropical fruits. This propitious location has sparked our research initiatives, aligning with the institution's commitment to community service and agricultural advancement. With a dual purpose in mind, our endeavors not only cater to academic pursuits but also strive to augment the market worth of our luscious fruits, especially during pivotal seasons when extending the post-harvest storage of fruits is crucial.” said Associate Professor Dr. Narumol Matan, a lecturer from the School of Agricultural Technology and Food Industry, and the director of Research Center of Excellence in Innovation of Essential Oil at Walailak University.
This technique, developed by Dr. Narumol and her Ph.D. student in Agro-Industry and Biotechnology, Ms. Pailin Chaidech, at the College of Graduate Studies, effectively slows down the browning process, extending it from 7-10 days to up to 21 days. Not only does it leave the fruit with no harmful residue, but it also provides a longer time for the fruit to reach the shelves fresh and helps improve the fruit grade and price, which benefits both consumers and farmers.
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Pailin Chaidech, Narumol Matan. 2023. Relatively low concentration of cardamon oil vapour for controlling enzymatic browning and maintaining the quality of rambutans. LWT, 182, 114832. (Q1) https://doi.org/10.1016/j.lwt.2023.114832
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Photos by Associate Professor Dr. Narumol Matan
Banner by Bunpoht Baimiden, article by Settaboot Onphakdee, Division of Corporate Communication