The Effect of Microwave-Vacuum Pretreatment on the Drying Kinetics, Color and the Content of Bioactive Compounds in Osmo-Microwave-Vacuum Dried Cranberries (Vaccinium macrocarpon)

Abstract

The aim of this study was to compare the effectiveness of microwave-vacuum pretreatment conducted at 100, 500 and 800 W on the drying kinetics of whole cranberries (Vaccinium macrocarpon) during hybrid osmotic and microwave-vacuum drying. Additionally, the effect of microwave-vacuum pretreatment and subsequent osmo-microwave-vacuum drying on selected quality indicators of dried cranberries, including phenolic content, antioxidant activity and color, was studied, and the quality of samples was compared with freeze dried, microwave-vacuum dried and osmo-microwave-vacuum dried samples. Irrespective of microwave power, the initial pretreatment accelerated mass transfer during osmotic dehydration of cranberries, and the Weibull model well fitted the experimental data. Final microwave-vacuum drying of cranberries was a two-stage process involving a relatively long phase with a constant drying rate, followed by a short period with a decreasing drying rate. Microwave-vacuum and osmomicrowave-vacuum drying resulted in similar retention of polyphenols and similar antioxidant activity, both of which were relatively higher than in freeze-dried cranberries. However, microwave-vacuum pretreatment at low microwave power (100 W) before dehydration also resulted in high retention of phenolic compounds, high antioxidant activity and attractive color, which were consistent with the high content of total anthocyanins and flavonoids. Microwave-vacuum, osmo-microwave-vacuum and osmo-microwave-vacuum drying combined with microwave-vacuum pretreatment at low microwave power (100 W) were the most suitable methods for the production of high-quality dried whole cranberries.

Determination of drying kinetics, some physical, and antioxidant properties of papaya seeds undergoing microwave vacuum drying

“…Several studies have been carried out on the use of MVD of agricultural materials. Recently, Zielinska, Zielinska, and Markowski () studied the effectiveness of microwave vacuum pretreatment before drying under a microwave vacuum. They found that the retention of both polyphenols and antioxidant activity in microwave vacuum‐dried cranberries was higher than in freeze‐dried cranberries.…”

Influence of Pretreatments on Microwave Vacuum Drying Kinetics, Physicochemical Properties and Sensory Quality of Apple Slices

“…Due to chemical residues in the fi nal product, which may cause asthmatic reactions in some sensitive individuals and other health problems, there is an increasing demand to produce sulfur-free dried fruits [Igual et al, 2012;Krokida et al, 2000]. Some novel pretreatments including ultrasound [Rodríg uez et al, 2015;Nowacka et al, 2012;Mothibe et al, 2014], microwave [Zielinska et al, 2018;Mothibe et al, 2014;Liu et al, 2015], vacuum [Blanda et al, 2008], have been developed to satisfy the growing health-conscious consumers. Ultrasonic wave has been used to enhance mass transfer since it can create microscopic channels in solid material by unique mechanical fl uctuation and cavitation effect [Rodríguez et al, 2015;Nowacka et al, 2012].…”

Drying kinetics and selected physico - chemical properties of fresh cranberries preserved with microwave – vacuum process

“…Sadly, cutting the fruit also leads to several negative consequences, such as a higher leakage of sap or an increase in nutrient oxidation during the final drying. Available literature documents numerous attempts to intensify the osmotic dehydration of cranberries through various pre-treatments [2][3], as well as attempts to accelerate the drying process by applying new drying techniques [4][5][6]. Among the new techniques, a hybrid technique including microwave technology has been intensively investigated [7].…”

“…Among the new techniques, a hybrid technique including microwave technology has been intensively investigated [7]. According to the latest reports the drying time can be reduced to less than 100 min [3]. The other problem associated with dried sweetened cranberry production is the time needed to infuse sugar, which can take up to 24 hours [8].…”

“…The other problem associated with dried sweetened cranberry production is the time needed to infuse sugar, which can take up to 24 hours [8]. Despite the introduction of some new ideas to reduce the osmotic dehydration process [3,5], the waste sucrose syrup collected after the process, remains a serious technological and environmental problem.…”