Influence of Pretreatment Combinations on Drying Time and Quality of Melon Chips Produced by Vacuum-Assisted Two-Way Infrared Drying
Abstract
Research background. Infrared technology, which has become widespread in recent years due to its rapid drying effect, also causes some negative changes in the products. To eliminate the negative effects that occur during the drying process in dried products, different pretreatments such as dipping, blanching, freezing, and ultrasonic treatment are applied. Experimental approach. This study aimed to determine the effect of different pretreatments (citric acid, ethanol, ultrasound, blanching, and freezing) and their combinations on drying time and quality characteristics of melon chips produced by a novel vacuum-assisted two-way infrared dryer. Results and conclusions. The samples produced with the combination of citric acid/ethanol/ultrasound/freezing had the highest rehydration ratio (6.07 %), shortest drying time (72.5 min), lowest specific energy requirement (2.59 kWh/kg), and shrinkage ratio (85.7 %). The best result in terms of color values was obtained from the samples treated with the citric acid/ethanol combination. 5-hydroxymethylfurfural (HMF) contents in melon chips produced with pretreatments including ultrasound application were higher (74.92–117.98 mg/kg DM) than other pretreatments. Multiple pretreatment applications caused a decrease in total phenolic content and antioxidant activity. The highest total phenolic content (2565.34 mg GAE/kg DM) and DPPH value (7.47 mmol TE/g DM) were found in samples immersed in citric acid. The most liked melon chips were the samples in which citric acid/blanching combination was used. Novelty and scientific contribution. Infrared drying is emerging as an increasingly widespread drying technology. The primary innovation of this study is the investigation of how two-way vacuum-assisted infrared technology can mitigate or eliminate the disadvantages of infrared drying by leveraging the benefits provided by various pretreatment processes used in chips production. As a result, it was found that a combination of citric acid and blanching pretreatments can be used to reduce the negative effects of the vacuum-assisted infrared drying, which provides rapid drying, on the product and to produce more flavorful and appealing melon chips.