https://doi.org/10.17113/ftb.57.04.19.6380

Influence of Gum Arabic Enriched with GABA Coating on Oxidative Damage of Walnut Kernels

Asghar Ebrahimzadeh¹*, Farhad Pirzad², Hamidreza Tahanian³ and Morteza Soleimani Aghdam⁴

¹Department of Horticultural Sciences, University of Maragheh, Madar Street, 8311155181 Maragheh, Iran
²Department of Horticultural Science, University College of Agriculture and Natural Resources, University of Tehran, Daneshkadeh Street, 3158777871 Karaj, Iran 
³Shahrood Agricultural and Natural Resources Research and Education, Bastam Street, 3615799811 Semnan, Iran 
⁴Department of Horticultural Science, Imam Khomeini International University, Imam Khomeini Street, 3414896818 Qazvin, Iran

Article history:
Received: 21 May 2019
Accepted: 4 December 2019

Key words:
DPPH scavenging capacity, γ-aminobutyric acid, gum arabic coating, postharvest nutritional quality, walnut kernel

Summary:
Because of the higher content of unsaturated fatty acids (UNSFA) and phenolics, walnut kernels are vulnerable to oxidative rancidity and browning due to unfavorable postharvest handling procedures. This study investigates the impact of gum arabic coating enriched with γ-aminobutyric acid (GABA) on oxidative rancidity and browning of kernels during storage at 20 °C. The results showed that the walnut kernels coated with gum arabic (5 %) enriched with GABA (0.1 mM) exhibited lower oxidative rancidity and browning, manifested by lower peroxide value and malondialdehyde accumulation along with higher whiteness index. Moreover, kernels had higher UNSFA/SFA ratio as a response to lower lipoxygenase activity and H₂O₂ accumulation. The reduced oxidative browning in coated kernels was accompanied with lower polyphenol oxidase and higher phenylalanine ammonia-lyase activity leading to higher accumulation of phenolics and increased DPPH• scavenging capacity. Based on our findings, gum arabic coating (5 %) enriched with GABA (0.1 mM) may have a commercial potential for maintaining nutritional quality of walnut kernels.

*Corresponding author:   +98 914 778 3936
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