A new drying technique for producing healthy and attractive dried apricot: Reducing atmosphere drying

In this study, a new and alternative technique called Reducing Atmosphere Drying (RAD) was developed for producing healthy and attractive dried apricot. An Hacıhaliloğlu apricot variety fruit was dried using different methods: Reducing Atmosphere Drying System (RAD) with 3 different drying atmospheres [air, nitrogen and reducing gas mixture (4% H2, 5% CO2, 91% N2)], lyophilizator, vacuum and hot air. The color and antioxidant capacity (DPPH, ABTS, and total phenolic content) of dried apricots were evaluated. Color analysis showed that the closest color values to the fresh sample were observed for RAD MIX and RAD NITROGEN samples. In the preliminary experiment performed on Şalak variety, results showed that the RAD MIX dried apricot had the lowest ΔΕ value (4.08) and exhibited the highly effective method in preserving apricot color. According to results of the antioxidant activity determinated by DPPH inhibition activity method, it was observed that the difference between fresh (freeze drying), RAD MIX, oven (hot air) and vacuum dried apricot samples was not significant and RAD MIX samples had the highest antioxidant activity with 76.3% value after fresh samples. The lowest value of DPPH inhibition activity (40.25%) was observed for the RAD NITROGEN samples. The total phenolic content assays showed that the difference between fresh, RAD MIX, RAD AIR, oven and vacuum samples was not significant (p<0.05) and RAD NITROGEN samples had the lowest value 161.8 mg GAE.100 g-1 (dm)] as in DPPH inhibition activity results. The ABTS method, unlike DPPH and total phenolic results, showed that the difference between fresh, RAD MIX, RAD NITROGEN and RAD AIR was not significant and RAD MIX exhibited the highest antioxidant activity with 68.74 mol TE. g-1 (dm). The results of total flavonoid content show that the difference between fresh (or freeze drying), vacuum, hot air and RAD MIX samples with range of 27.38, 24.25, 19.41 and 18.81 mg QE.100g-1 (dm) weren't significant (p<0.05). Reducing Atmosphere Drying, for the first time, has been designed as an alternative and novel drying technique. It was concluded that the sensorial and nutritional values (total antioxidant and total phenolic) of foods could be maintained by this new drying technique, which is found to be highly effective and suitable for drying the food products a.