Combined Hot Air, Microwave, and Infrared Drying of Hawthorn Fruit: Effects of Ultrasonic Pretreatment on Drying Time, Energy, Qualitative, and Bioactive Compounds’ Properties

Abstract

The present study aimed to examine the effect of ultrasonic pretreatment and hot air, microwave–hot-air, infrared–hot air, and freeze-drying on the drying time, specific energy (SE), qualitative properties (i.e., color, shrinkage, and rehydration ratio), and bioactive compounds’ properties (i.e., antioxidant activity, phenolic, and flavonoid contents) of hawthorn fruit. Drying of hawthorn was conducted from 45 min for the ultrasonic + microwave–hot-air drying to 1280 min for the freeze-drying method. The lowest amount of SE was obtained using the ultrasonic-microwave–hot-air drying method, which was 47.57 MJ/kg. The lowest values in color changes (12.25) and shrinkage (17.21%) were recorded for the freeze-drying method, while the highest amounts for these traits were 45.57% and 66.75% in the HA drying, respectively. In general, the use of different drying methods reduces the antioxidant capacity (AC), total phenolic content (TPC), and total flavonoid content (TFC) during processing compared to fresh samples. The highest values for AC, TPC, TFC, and the rehydration ratio were 30.69%, 73.07 mg-GAE/gdw, 65.93 mg-QE/gdw, and 2.02 for the freeze-drying method, respectively.

Influence of three drying methods on physicochemical properties of okra (Abelmoschus esculentusL.) powder

“…Denaturation of polyphenols was occurred during the heating process, inhibiting its activity by the increasing activity of polyphenol oxidase that was enhanced by the increasing temperature (Zhang et al, 2017). However, freeze‐dried okra exhibited the highest TFC compared to other drying method, which were similar to the study on the drying of hawthorn (Abbaspour‐Gilandeh et al, 2021), persimmon (Kayacan et al, 2020), and broccoli (Xu et al, 2020). Low temperature used during the process of freeze‐drying decreased the degradation rate of the heat‐sensitive phenolic compounds (Xu et al, 2021).…”

Process Efficiency and Energy Consumption during the Ultrasound-Assisted Extraction of Bioactive Substances from Hawthorn Berries

“…Based on the literature review, it can be concluded that the TPC values may range from 2.9 mg GAE/g d.w. [40] to 96.9 mg GAE/g d.w. depending on the species [41]. Abbaspour-Gilandeh et al [42] showed that the TPC value was 79.82 ± 2.42 mg GAE/g d.w. in fresh hawthorn fruits. Żurek et al [16] extracted shredded and previously freeze-dried berries from hawthorn with ethanol in two concentrations (50 and 70% v/v).…”

Aloe vera Gel Drying by Refractance Window®: Drying Kinetics and High-Quality Retention

“…When drying foods, a very important factor is to achieve good quality indicators such as color, flavor, texture, nutrient availability, among others; all of which determine the food’s value and consumer acceptance on dehydrated food products [ 7 ]. However, in most cases, these conventional drying methods produce inferior quality products and require higher drying times [ 7 , 15 , 16 ].…”