Exploring overlooked non-extractable phenolics in pecan nut residues through an LC-MS-based approach.

Area of Science:

• Food Science
• Nutritional Biochemistry
• Agricultural Chemistry

Background:

• Pecan nut processing residue (PPR) contains bioactive compounds.
• Previous research focused on extractable phenolics (EP) in PPR.
• Bound (non-extractable) phenolic compounds (NEP) in PPR remain underexplored.

Purpose of the Study:

• To characterize NEP in PPR.
• To compare the phenolic profile of NEP with EP.
• To evaluate the antioxidant activity of NEP.

Main Methods:

• Liquid chromatography-tandem mass spectrometry (LC-MS/MS) for phenolic compound annotation.
• Quantification of phenolic compounds in PPR fractions.
• Assay of specific antioxidant activity.

Main Results:

• Identified 61 phenolic compounds in PPR, including novel tetramers and pentamers of condensed tannins.
• NEP constitutes 30% of total phenolics and is rich in condensed tannins (approx. 50%).
• NEP exhibits 2.8-fold higher specific antioxidant activity compared to EP.

Conclusions:

• NEP is a significant and bioactive component of PPR.
• Bound phenolics disproportionately contribute to PPR's antioxidant capacity.
• Findings support the valorization of PPR as a functional ingredient.