Impact of Drying Processes on Bioactive Phenolics, Vitamin C and Antioxidant Capacity of Red-Fleshed Apple Slices

Abstract

The impact of drying (air‐, oven‐ and vacuum‐drying) on bioactive polyphenolics, vitamin C and antioxidant capacity of slices of “Redfield” apple, a red‐fleshed apple cultivar, was investigated. The drying process significantly impacted the concentration of specific phenolic compounds and vitamin C concentration in dried slices. The loss of epicatechin, cyanidin‐3‐O‐galactoside, phloridzin and quercetin glycosides occurred during oven‐drying. The concentration of all the phenolic compounds in vacuum‐dried apple slices at 20C for 24 h was comparable to that of fresh apple slices. Antioxidant capacity measured by oxygen radical absorption capacity was significantly reduced by the oven‐drying as compared to other drying methods. PRACTICAL APPLICATIONS These results suggested that vacuum‐drying offers a great potential for preserving bioactive compounds during dehydration process for obtaining nonfried apple chips. Red‐fleshed apples have potential for use in value‐added snack product manufacturing because of the presence of anthocyanins in the flesh. However, nonuniform color distribution in red‐fleshed apples is an issue for quality measurement.

Comparison of three drying processes to obtain an apple peel food ingredient

“…These results demonstrate that oven drying causes the maximal reduction of the total antioxidant capacity of the apple peel ingredient. These results are in agreement with Joshi, Rupasinghe, and Khanizadeh (2011), who observed that the antioxidant capacity red-fleshed apple slices was significantly reduced by oven drying as compared to other drying methods (air and vacuum drying).…”

Effect of Preparation and Extraction Parameters of Banana (Musa balbisiana cv. Saba) Inflorescence on their Antibacterial Activities

“…However, no significant difference (p<0.05) was found between these method of preparations. Joshi et al (2009) reported similar retention of epigallocatechin, chlorogenic acid and quercetin glycosides in both freeze-dried and oven-dried 'Redfield' apple which could probably due to the stability of those phenolics in the sample. On the other hand, sun dried buds extract showed a significant lower antibacterial activity.…”

“…On the other hand, sun dried buds extract showed a significant lower antibacterial activity. Direct exposure of bioactive compounds to sunlight could facilitate oxidation process which correlated with the reduction of bioactivity (Joshi et al 2009). Besides, sun drying is commonly associated with prolonged drying times allow degradation of bioactive compounds by enzymatic reaction (polyphenol oxidase and glycosidase) (Shahidi & Naczk 2004).…”

“…However, the success in determination of plant bioactive compounds are largely dependent on the extraction parameters used which include the plant maturity (Mokbel & Hashinaga 2005), geographical origin (Jordan et al 2013), handling and preparation of plant materials (Joshi et al 2009), choice of solvents (Ao et al 2008) and extraction conditions (Koh et al 2009). Unfortunately, none of these is proven superior in isolating and separating biological active compounds from the broad diversity of structures and massive functionalities of molecules found in natural products.…”

The use of convective-thermoradiative method of energy supply in the apple snack technology

“…They used traditional convective [5], microwave [6], vacuum [7], sublimation [8], and combined vacuum [9] drying and the combination of these techniques [10]. But such drying methods are quite expensive and energy-consuming.…”