Effect of traditional sun-drying and oven-drying on carotenoids and phenolic compounds of apricot (Prunus armeniaca L.)

Background: The indubitable role of phytochemicals such as carotenoids and phenolic compounds in human health has prompted the researchers to study the factors affecting the stability and the availability of these compounds. Aims: This study investigates the effect of two drying processes; oven-drying (OD) and traditional sun-drying (TSD) on carotenoids and phenolic compounds of apricots. Methods and Material:   OD was performed at 65°C, and TSD was performed by direct exposure of apricot to sunlight at daytime temperatures around 40°C and relative humidity between 25 and 35%, following an Algerian traditional method of drying. Carotenoids and phenolic compounds were extracted, and then total carotenoids (TC), total phenolic compounds (TPC), total flavonoids (TF) and total tannins (TT) were spectrophotometrically quantified. The free radical scavenging activity (FRSA) of the phenolic extracts was measured by the DPPH method. Results: Carotenoids and phenolic compounds were significantly affected by both drying methods. OD decreased TC and TT by 44% and 12%, respectively, and increased TPC and TF by 4%. TDS affected negatively all the measured components, where TC, TPC, TF, and TT decreased by 67%, 15%, 43%, and 36%, respectively. However, the highest FRSA was reported for the TSD apricots (40%) followed by OD apricots (36%), and fresh apricots (32%). Conclusions: The effect of drying on apricot antioxidants depends on the applied drying method and the studied component. The direct sunlight exposure and the duration of drying condemned TSD to be more harmful on carotenoids and phenolic compounds compared to OD, where carotenoids where more fragile during TSD. In addition, OD improved the content of phenolic compounds by improving their extractability. However, TSD apricots seem to be a better source of free radical scavenging compounds.