060: Determination of Antioxidant Capacity and Phenolic Content of Haskap Berries (Lonicera Caerulea L.) by Attenuated Total Reflectance-Fourier Transformed-Infrared Spectroscopy

Introduction

Haskap berry (Lonicera caerulea L.), commonly referred to as honeyberry or blue honeysuckle, is considered a new “superfruit” that could potentially rival or even replace blueberries, as it has been validated to possess comparable or even higher levels of total phenolic content (TPC) and antioxidant capacity (TAC) in several studies.

Methods

TPC and TAC of haskap berries cultivated in various locations across Alberta were analyzed using attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy. The Folin–Ciocalteu assay was used to determine TPC, while TAC was quantified by 2,2-diphenyl-1-picrylhydrazl radicals (DPPH) assay and oxygen radical absorbance capacity (ORAC) assay. Three tenfold cross-validated partial least-squares regression (PLSR) models and three fivefold cross-validated deep learning models were developed separately based on FT-IR spectra collected from 22 haskap berry samples and their corresponding reference values determined through Folin-Ciocalteu, DPPH, and ORAC assays.

Results

The deep learning models (R2 = 0.95, 0.93, and 0.90 for Folin-Ciocalteu, DPPH, and ORAC assays, respectively) demonstrated better prediction capability compared to the PLSR models (R2 = 0.74, 0.72, and 0.66 for Folin-Ciocalteu, DPPH, and ORAC assays, respectively). In addition, PLS loading plots indicated that phenolic contents and polysaccharides in haskap berries could contribute to their antioxidant capacity.

Significance

FT-IR spectroscopy integrated with chemometrics provides a high-throughput, low-cost, and rapid approach to estimate the TPC and TAC of fruits and has the potential to be applied in the agri-food industry for food analysis.

Authors: Yihan He, Jinxin Liu, Marti Z. Hua, Kiren Singh, Xiaonan Lu*