Protein-phenolic interactions in lentil and wheat crackers with onion skin phenolics: effects of processing and in vitro gastrointestinal digestion

Günal-Köroğlu D., Turan S., Çapanoğlu Güven E.

Food and Function, vol.14, 2023 (SCI-Expanded) identifier identifier identifier

  • Publication Type: Article / Article
  • Volume: 14
  • Publication Date: 2023
  • Doi Number: 10.1039/d2fo02885a
  • Journal Name: Food and Function
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, CAB Abstracts, Chemical Abstracts Core, Compendex, EMBASE, Food Science & Technology Abstracts, MEDLINE
  • Istanbul Technical University Affiliated: Yes


This study aimed to evaluate the protein-phenolic interaction in functional crackers made of wheat/lentil flour with onion skin phenolics (onion skin powder: OSP, onion skin phenolic extract: OSE, or quercetin: Q) after in vitro gastrointestinal digestion. Phenolic/antioxidant recovery in crackers was lower with higher levels of phenolic addition. In vitro gastrointestinal digestion procedure was applied for crackers prepared/cooked with onion skin phenolics (functional crackers) or crackers consumed with onion skin phenolics (co-digestion). Functional crackers had similar nutritional attributes (p > 0.05), however they had lower L* values, and higher a* values. A higher concentration of OSP/OSE caused a decrease in the b* value while it was increased with the quercetin addition. Phenolic/antioxidant recovery in functional crackers was decreased by increasing the ratio of phenolic supplements. The amount of quercetin 7,4-diglucoside was lower than the theoretical value whereas the amount of quercetin was higher in functional crackers. The phenolic bioavailability index (BIP) of co-digested crackers was higher than that of functional crackers, whereas antioxidant bioavailability index (BIA) was mostly similar. Quercetin was only identified in functional wheat/lentil crackers with OSE. After digestion (1) TCA-precipitated peptides of the wheat crackers could not be identified, whereas that of co-digested lentil crackers was more abundant, (2) level of free amino groups of co-digested/functional crackers were lower than the control except for the co-digested sample of lentil cracker with quercetin.