The effect of osmotic dehydration pretreatment with sweeteners on the quality of dried aronia berries

Aronia (Aronia melanocarpa) berries are rich in polyphenols. However, they are extremely astringent, which reduces their commercial viability. This study suggests a treatment method to produce more commercial aronia products. In this method, the berries were pretreated with osmotic dehydration and then dried with hot air or lyophilized to reduce their astringency. Sucrose, glucose, and xylitol were used as the pretreatment solutions. The products were prepared and grouped as follows: raw aronia (CON), freeze-dried (FD), osmo-dehydrated using sucrose solution and freeze-dried (FDS), osmo-dehydrated using glucose solution and freeze-dried (FDG), osmo-dehydrated using xylitol solution and freeze-dried (FDX), hot-Air-dried (HD), osmo-dehydrated using sucrose solution and hot-Air-dried (HDS), osmo-dehydrated using glucose solution and hot-Air-dried (HDG), and osmo-dehydrated using xylitol solution and hot-Air-dried (HDX). Water loss was highest in aronia berries that were osmo-dehydrated using sucrose solution (16.36%), followed by berries that were dehydrated using glucose solution (14.26%), and those that were osmo-dehydrated using xylitol solution (12.83%). Moisture contents and total soluble solid contents of the FD products were 3.83-7.45% and 6,908.47 °Brix, respectively. FDS and FDX showed relatively high phenolic compound contents and antioxidant activities. FDG and FDS showed better texture and redness. FDS received the highest score for sweetness (5.07) and overall preference (5.13). Hence, FDS proved to be the most appropriate pretreatment, because it allows a better control of the moisture content and maintenance of their appearance and texture, with a relatively low reduction of their phenolic contents. Hence, it affords better preservation efficiency to aronia products.