Dehydration Kinetics and Changes of Bioactive Compounds of Tulip and Poppy Petals as a Natural Colorant under Vacuum and Oven Conditions

Abstract

The aim of this study was to investigate the drying kinetics and thermal degradation of anthocyanin and other phenolic compounds of tulip and poppy petals, as potential source of natural colorant, under both oven and vacuum drying processes at 45, 55 and 65C. The novelty of the study is to be the first attempt on the anthocyanin degradation and drying characteristic of tulip and poppy petals during drying process. Drying rate in vacuum drying was greater than that of oven drying. Drying characteristic of the petals was described by selected six thin layer models. Midilli-Kucuk model was found to be the best model (R 2 > 0.99). Vacuum drying at 55C was the best suitable drying condition for the preservation of anthocyanin content. Total color differences (ΔE) significantly changed, depending on the drying temperature. Lowest ΔE values were obtained in samples dried at 45C for tulip petals and at 65C for poppy petals. PRACTICAL APPLICATIONSColor is one of the most important food quality parameters in the food industry, and both natural and synthetic food colorants are used in the food industry. In recent years, trend for use of natural food colorant has increased due to the negative effects of synthetic colorants on health. Because tulip and poppy flowers are rich in anthocyanin and antioxidant compounds, they have potential use as a natural food colorant. However, these plants are perishable and should be dried immediately in order to prevent fungal deterioration. The stability of anthocyanin and the color of these plants are affected by several factors such as temperature, oxygen, and enzymatic and nonenzymatic reactions during the drying process. Therefore, selection of the most favorable drying condition may be crucial in terms of decreasing loss of the anthocyanin during the drying process.

Dehydration of green beans using ultrasound-assisted vacuum drying as a novel technique: drying kinetics and quality parameters

“…The D eff values of green beans dried with USV were measured as 2.65 × 10 −10 −4.13 × 10 −10 m 2 /s and calculated as 2.00 × 10 −10 −3.23 × 10 −10 m 2 /s. These D eff values were in agreement with previously published data on the drying kinetics of agricultural products (Başlar, Karasu, Kilicli, Us, & Sagdiç, ; Karasu et al, ). The D eff (m 2 /s) values of green beans were higher with USV than for the USV control, indicating that moisture in the samples was transferred rapidly by the ultrasound.…”

Effect of vacuum drying and pulsed vacuum drying on drying kinetics and quality of bitter orange ( Citrus aurantium L.) slices

“…The difference of D eff between 15.0 kPa and 20.0 kPa at the same drying temperature was not significant. These results closely agreed with those for Asian white radish slices, pumpkin slices and some agricultural products (Doymaz, 2007;Jun & Hui, 2009;Karasu et al, 2015).…”

The effect of press temperature on the total tocopherols, sterol, fatty acid, phenolic profile, in-vitro cytotoxicity assay, and anti-inflammatory activity

“…The total protein contents were determined by multiplying the obtained nitrogen values by 6.25. The oil contents were determined by the Soxhlet extraction system, and hexane was used as a solvent (Karasu et al, 2015). The free fatty acidity (FFA) and peroxide values (PV) of the samples were determined according to the method described by IUPAC 2.201 and 2.501, respectively (International Union of Pure and Applied Chemistry, 1992).…”