Phenolic compounds in different fruit parts of crab apple: Dihydrochalcones as promising quality markers of industrial apple pomace by-products

Detailed composition of phenolic compounds in the stems, seeds and flesh (including peel and core) recovered from crab apple pomace (seven single-varieties) was studied. The flesh constituted of 95.8-98.6%, whereas, the seeds and stems accounted for the remaining 1.0-3.7% and 0.4-0.7%, respectively, of the total apple pomace expressed in dry weight basis (dwb). The highest content of polyphenols was detected in seeds and stems 3592.6-23606.8 and 6747.2-59335.4 mg/kg dwb, respectively. In the flesh, the concentration of polyphenols was between 1654.8-5314.1 mg/kg dwb. Chlorogenic acid (405.3-2298.8 mg/kg dwb) was the main polyphenol detected in the flesh. For the seeds and stems - phloridzin was the main identyfied phenolic compound (2899.0-19600.3 and 3017.7-40488.3 mg/kg dwb, respectively). A dihydrochalcone - phloretin dihexoside was detected only in the seeds, and 3-hydroxyphloridzin was mainly identified in the stems, hence, these two dihydrochalcones may play an important role as quality markers of the apple pomace. (C) 2015 Elsevier B.V. All rights reserved.