Effects of hot air, microwave and vacuum drying on drying characteristics and in vitro bioaccessibility of medlar fruit leather (pestil)

Abstract

The effects of microwave (90 W and 180 W), hot air (60 and 70 degrees C) and vacuum (60 and 70 degrees C with 200 and 300 mbar) drying methods on drying characteristics, total phenolic content, antioxidant capacity, color and in vitro gastrointestinal digestion of medlar pestil were investigated. Medlar showed a good potential for pestil production while being the most applicable in microwave treatments. For drying kinetics, five thin-layer drying models were applied and the Page and Modified Page were the best fitted models. L*, b*, chroma and hue angle decreased while a* generally increased in dried pestils. Dried samples showed a general decrement in phenolics and antioxidant capacity. According to in vitro gastrointestinal digestion, intestinal phase of all the samples resulted with an increment in phenolics, FRAP and DPPH compared to undigested extracts. In conclusion, different drying methods may affect the release of phenolics and antioxidant capacity, while leading to increased bioaccessibility during intestinal digestion.