Impact of room temperature storage on the pecan kernel color, carotenoids, polyphenols, and physicochemical properties

Authors: PHAM, THI - Texas Woman'S University; YUSUFALI, ZAHRA - Texas Woman'S University; Wang, Xinwang; Kubenka, Keith; DU, XIAOFEN - Texas Woman'S University

Submitted to: ACS Food Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/9/2023
Publication Date: 5/22/2023
Citation: Pham, T., Yusufali, Z., Wang, X., Kubenka, K.A., Du, X. 2023. Impact of room temperature storage on the pecan kernel color, carotenoids, polyphenols, and physicochemical properties. ACS Food Science and Technology. 3(6):1077-1089. https://doi.org/10.1021/acsfoodscitech.3c00087.
DOI: https://doi.org/10.1021/acsfoodscitech.3c00087

Interpretive Summary: The goal of the USDA ARS Pecan Breeding Program is to breed superior pecan cultivars. Over the last nine decades, the program has introduced 32 pecan cultivars that have been beneficial to pecan growers in the United States. These cultivars have helped to increase profits and competitiveness on the international market. The research heretofore conducted by the program has not included an evaluation of how storage affects kernel quality. A recent study has examined the impact of storage time on kernel quality, including color, chemical composition, and physical properties. This research offers valuable information to both pecan growers and consumers on how to properly store pecans.

Technical Abstract: The quality of pecans is crucial for consumer acceptability as well as the profitability of growers and manufacturers. During storage, pecan kernel quality, including color, flavor, and nutrient composition, may change. However, there are limited studies on the relevant kernel color and physicochemical changes that occur during storage. This study aimed to investigate the changes in pecan kernel color, carotenoids, polyphenols, and physicochemical properties during five months of storage at room temperature for five different pecan varieties. The results showed that during the storage, the pecan kernel color darkened (declining L* value), with a shift towards more red (inclining a* value) and less yellow (declining b* value), and there was genotypic variation observed in all five varieties. Additionally, the dorsal side of the kernel had lighter color than the ventral side. Total carotenoids deceased from 92.0 – 118.8 to 45.2 – 101.9 µg/100g whole kernel during storage, while total polyphenol had minor changes but without significant differences (18.1 – 27.0 mg GAE (gallic acid equivalent)/g whole kernel), except for one breeding line. Three phenolics (gallic acid, catechin, and ellagic acid) were 6.7 – 9.6, 31.4 – 46.7, and 11.7 – 16.2 mg/100g whole kernel, respectively, and increased during storage, with variety-specific changes. Pecan kernel moisture loss was significant, while total lipid content remained unchanged. Five texture parameters (hardness, toughness, slope, fracturability, and break) showed irregular changes. The study provides new insights into the changes in pecan kernel color, chemical compositions, and physical properties during storage at room temperature with the genotype variation.