Apricot is one of the fruits dried by using different methods, such as sun, convective or microwave drying. The effects of drying methods on the components of this fruit differ depending upon the temperature or time parameters. In this research, the impacts of convective, microwave and microwave–convective drying techniques on color, β-carotene, minerals and antioxidant activity of apricots were investigated. The color values (L*, b*,ΔEab, h° and C*ab) of dried fruit were decreased, while the a* values increased. Compared with a fresh sample, the dried apricots showed a 1.4-3.9-fold proportional increase in β-carotene based on the increment of dry matter. The samples dried at high temperature and microwave levels, at 75 °C+90 watt and 75 °C+160 watt, showed lower antioxidant activity. Of the different drying treatments, the microwave-convective method (50 °C+160 watt) obtained a higher β-carotene content while maintaining antioxidant activity with a short drying time.
30 May 2018 in Quality Assurance and Safety of Crops & Foods
In this research, the effects of microwave (190, 375, and 680 W) vacuum (500, 600, and 700 mbar) and oven (70, 85, and 100 °C) drying methods on the total phenolics, antioxidant capacity, colour and drying characteristics of celery slices were studied. For the selection of the most suitable thin layer drying model, five mathematical models (Page, Modified Page, Logarithmic, Lewis, and Henderson and Pabis) have been applied to the treatments. In light of the statistical tests, Page and Modified Page models were considered the best to describe drying characteristics. Regarding the colour value changes during drying, L*, ΔEab and h° decreased, and a* increased. Additionally, both b* and C*ab increased with microwave and oven drying but decreased with vacuum drying. Dried celery had 38.51-75.34% less total phenolic content than fresh samples, while its antioxidant capacities was greater. The highest ferric-reducing ability of plasma (FRAP; 49.35±3.10 μmol TE/g dw) and cupric-reducing antioxidant capacity (CUP...
22 May 2019 in Journal of Food Processing and Preservation
The aim of the present work was to design new beverages using lemonade and some herbal extracts (linden, heather, green tea, lemon verbena, clove, peppermint, ginger and mate) rich in vitamin C and flavonoids. The linden-added lemonade showed the highest value (597.9 mg/kg) for ascorbic acid content, whereas the lemon verbena-added lemonade showed the lowest value (486.04 mg/kg). The amount of saccharose was changed by 11.07-11.58%, the glucose by 1.11-1.62% and the fructose between 11.07-11.58% in the beverages. K, Na, Mg and P values in the lemonades were determined in the range of 178.83-210.98 mg/kg, 33.75-39.13 mg/kg, 22.37-27.89 mg/kg and 7.22-10.04 mg/kg, respectively. The total phenolic content in the samples changed between 315.11-397.57 mg GAE/100 g. When the samples were analyzed for antioxidant activity, FRAP (17.13-26.79 µmol trolox/mL) and ABTS (16.91-25.38 µmol trolox/mL) methods gave higher results than the DPPH (14.88-17.72 µmol trolox/mL) method. Linden-, ginger- and peppermint-added lemonades, which had been found to be rich in total phenolic compounds and ascorbic acid, showed higher antioxidant activity than the control sample. Overall, the most preferred lemonades were heather- and ginger-added beverages and the control sample. Mate-added lemonade was the least preferred.
15 May 2021 in Journal of Food Processing and Preservation