The Effect of Pre-Drying Treatment and Drying Conditions on Quality and Energy Consumption of Hot Air-Dried Celeriac Slices: Optimisation

Abstract

Celeriac is a good source of fibre, trace minerals, and phenolic compounds; it has a pleasant aroma but is a perishable material, prone to discolouration. This research investigated the optimisation of the quality and energy demand in hot-air dried celeriac slices. The experiment utilised the I-optimal design of response surface methodology with 30 experiment runs. Pre-drying treatments (blanching at 85 °C, three minutes; dipping in 1% citric acid solution, three minutes; no pre-drying treatment), drying temperatures (50, 60, and 70 °C), air velocities (1.5, 2.2, and 2.9 m/s), and thickness (three-, five, and seven-mm) were applied. The drying conditions affected drying time significantly (p < 0.0001). The model by Midilli and others and the logarithmic model fitted best with celeriac slices drying kinetics. Blanched samples had a higher ΔE*ab (total colour difference) and BI (browning index) but lower WI (whiteness index) than samples with other pre-drying treatments. The rehydration ratio decreased with the increase of sample thickness and blanching (p < 0.0001). A quadratic model described the specific energy consumption (Es) best. The dried samples compared with fresh samples had increased antioxidant activity but decreased total phenolic compound value. The optimisation solution chosen was 58 °C drying temperature, 2.9 m/s air velocity, and 4.6 mm sample thickness with acid pre-drying treatment.

Effect of gum Arabic and ethanol pretreatments on drying kinetics and quality attributes of dried carrot slices

“…The dried carrot slices' total phenolic content was determined using the Folin–Ciocalteau reagent, according to Nurkhoeriyati et al. (2021) .…”

Celery Root Phenols Content, Antioxidant Capacities and Their Correlations after Osmotic Dehydration in Molasses

“…Additionally, the AOC value determined by FRAP, ABTS, and MRAP and the FRAP and TPC value were increased after OD in molasses for all observed experimental conditions (Table 2). Nurkhoeriyati et al ( 2021) reported that hot-air dried celery root slices compared with fresh samples had increased antioxidant activity but decreased total phenolic compound value [30].…”

Statistical approach to investigate the effect of vibro‐fluidized bed drying on bioactive compounds of muskmelon ( Cucumis melo ) seeds

“…Results show that TPC was increased with the increase of temperature, which might be attributes to the increase of TAA. The vibration effect reduces the polyphenol, but it might be possible that extractability of other antioxidants increased due to increasing of reducing sugar and Maillard reaction product formation at higher temperature (Nurkhoeriyati et al., 2021). On the other hand, the drying temperature might be triggered by the nonenzymatic browning that extracts partially oxidized polyphenol with higher antioxidant activity than nonoxidized phenols.…”