CHEMICAL AND MICROBIOLOGICAL CHANGES IN BLUEBERRIES AND IN HYPERTONIC SOLUTION DURING OSMOTIC DEHYDRATION EMPLOYING REUSED CONCENTRATE

摘要

Dehydration was carried out in 65°Brix sucrose solution at 40C for 120 min. Thensolution was used 15 times, each time a new batch of fruits was processed. Prior tondehydration, the fruits were subjected to pretreatment by immersion in solutionsncontaining pectinolytic and lipolytic enzymes. Following dehydration, the dehydratednmaterial and osmotic solution were tested for the content of dry mattern(36.6 u0002 3.3% [w/w] and 58–61°Brix, respectively), total polyphenols (1,738 u0002n289 mg/100 g initial dry matter [IDM]), anthocyanins (606 u0002 58 mg/100 g IDM)nand flavan-3-ols (695 u0002 139 mg/100 g IDM). The highest retention of anthocyaninsnwas observed for cyanidin-3-O-glucoside (over 81%), petunidin-3-Oglucoside,nmalvidin-3-O-arabinoside and malvidin-3-O-glucoside (over 74%).nThe average retention of procyanidins in fruits was 77%. The pH value of thenhypertonic solution remained at the level of 3.4–3.7. The syrup used for osmoticndehydration was characterized by a relatively low quantity of mesophilic bacterian(<103 cfu/mL) but a higher contamination with osmotolerant yeasts and moldsn(from 1 ￥ 103 to 2.5 ￥ 104 cfu/mL).