Effect of Convective and Vacuum–Microwave Drying on the Bioactive Compounds, Color, and Antioxidant Capacity of Sour Cherries

Abstract

The aim of this study was to determine the effect of microwave power during the vacuum-microwave drying (VMD) on sour cherries in terms of drying kinetics, including the temperature profile of dried material, as well as on some quality factors of the finished product including phenolic compounds, antioxidant capacity, and color. The content of phenolic compounds, antioxidant activity, and color change were used as quality indicators of dried sour cherries. Sour cherries were dehydrated by convective drying (CD) at temperatures of 50°C, 60°C, and 70°C and by VMD at the initial microwave power of 240 W, 360 W, and 480 W reduced to 240 W and 120 W in order to avoid a rapid increase in temperature at the critical moisture content of ca. 1 kg/kg dry mass. Control samples were prepared by freeze drying (FD). The increase in air temperature during CD as well as the increase in material temperature during VMD deteriorated dried product quality in terms of the content of phenolic compounds, antioxidant activity, and color, which was consistent with anthocyanins content. However, VMD turned out to be much better than CD and competitive to FD. The best quality of the dried product and its more attractive color were achieved at VMD at 480 W followed by drying at microwave power reduced to 120 W, which corresponds to anthocyanins content. In addition, the drying process had a positive impact on contents of quercetin and keampferol derivatives. Dried sour cherries have a long shelf life and therefore may be a fine alternative to fresh fruit all year round.

Effect of Sun, Oven and Freeze-Drying on Anthocyanins, Phenolic Compounds and Antioxidant Activity of Black Grape (Ekşikara) (Vitis vinifera L.)

“…Our results are consistent with previous studies evaluating the effect of hot air-, oven-and sun-drying methods on individual anthocyanins in fruit (Slatnar et al, 2011;Nora et al, 2014;Wojdyło et al, 2014;Kamiloglu & Capanoglu, 2015). For instance, the drying of guabiju and red guava at 70 o C resulted in losses of cyanidin-3-O-glucoside and malvidin-3-O-glucoside (48% to 100%) (Nora et al, 2014).…”

“…For instance, the drying of guabiju and red guava at 70 o C resulted in losses of cyanidin-3-O-glucoside and malvidin-3-O-glucoside (48% to 100%) (Nora et al, 2014). Similarly, as reported by Wojdyło et al (2014), sour cherry dried at 50 o C, 60 o C and 70 o C had 13% to 38% less cyanidin-3-O-glucoside compared to fresh ones. According to the results of Kamiloglu and Capanoglu (2015), sun drying of yellow and purple figs led to a drastic reduction in the amounts of cyanidin-3-glucoside and cyanidin-3-rutinoside (98%).…”

1-Methylcyclopropene postharvest treatment and their effect on apple quality during long-term storage time

“…For example, the content of (−)-epicatechin and (+)-catechin may decrease during storage due to polymerization and re-arrangement of procyanidins during storage. Similar effect was observed previously for strawberry jams [36] and drying sour cherries [37].…”

Optimization of microwave vacuum drying parameters for germinated lentils based on starch digestibility, antioxidant activity and total phenolic content

“…With the combination of vacuum with the microwave drying system, the materials can be dried in a shorter time and at low temperatures allowing better retention of sensory attributes such as colour, texture and essential nutrients (Mitra & Meda, 2009). Vacuum assisted microwave drying has been applied to reduce the moisture content of various plant materials, such as cranberries (Sunjka, Rennie, Beaudry, & Raghavan, 2004), tomatoes (Durance & Wang, 2002), garlic (Figiel, 2009), rosemary (Szumny, Figiel, Gutierrez-Ortiz, & Carbonell-Barrachina, 2010;Calin-Sanchez et al, 2011) Saskatoon berries (Mitra & Meda, 2009) and sour cherries (Wojdyo, Figiel, Lech, Nowicka, & Oszmianski, 2014). Hence, microwave assisted drying shows a potential method for drying of germinated seeds as the operation is rapid, more uniform and energy efficient as compared to conventional hot air drying.…”