Nitric Oxide Treatment Preserves Fresh Walnuts, Reduces Decay, and Maintains Quality

Newswise — The research revealed that SNP treatment significantly reduced decay and maintained the walnuts’ appearance, enhancing both disease resistance and overall quality. This breakthrough offered a practical solution for extending the shelf life of fresh walnuts.

Fresh walnuts are highly valued for their rich nutritional content and crispness taste, but their high water content makes them prone to rapid decay and browning during storage. Traditional preservation methods, including irradiation and modified atmosphere packaging, have shown some effectiveness but are often too complex for large-scale application. Nitric oxide, a signaling molecule, has previously been proven to enhance stress tolerance in various fruits and vegetables. This study is the first to explore SNP as a preservation technique specifically for fresh walnuts.

A study (DOI: 10.48130/fia-0024-0006) published in Food Innovation and Advances on 28 March 2024 , helps walnut producers minimize decay/waste, improve storage conditions, and maintain product quality.

The study examined the effects of SNP treatment on the appearance, decay resistance, and physiological properties of fresh walnuts during storage. Researchers applied different SNP concentrations to the walnuts and monitored changes in their appearance, color, and decay over 20 days. The results showed that walnuts treated with 0.5 mmol/L SNP maintained the closest appearance to fresh walnuts with less decay (59.7 %), reduced browning (31.3 %) and minimized skin shrinkage compared to the control group. This concentration was optimal for retaining the green color and smoothness of the walnuts. And it also enhanced the activity of disease-related enzymes, such as chitinase (CHI) and β-1,3-glucanase (GLU), which help prevent fungal infections. Additionally, walnuts treated with 0.1 and 0.5 mmol/L SNP exhibited lower decay rates. The study also found that SNP treatment suppressed ethylene production and respiratory metabolism, which slowed fruit ripening and aging. At 0.5 mmol/L, the respiratory rate was reduced by 14 %, significantly delaying spoilage. Furthermore, SNP reduced O₂•^- and H₂O₂ content and improved antioxidant enzyme activities (SOD, CAT, POD), which helped regulate reactive oxygen species (ROS) metabolic homeostasis and maintain walnut quality. The sensory evaluation also showed that walnuts treated with 0.5 mmol/L SNP had higher consumer acceptance, with better taste, odor, and crispness, and reduced rancidity. These findings indicate that SNP treatment at optimal concentrations can effectively preserve the post-harvest quality of fresh walnuts.

According to the study's researcher, Dr. Liping Qiao,“Our research shows that SNP treatment, particularly at a concentration of 0.5 mmol/L, significantly diminishes decay, regulates oxidative damage, and improves walnut quality during storage. This is a highly promising method that is both cost-effective and environmentally friendly.”

 This innovative approach using nitric oxide may transform how walnuts and similar perishable crops are stored, reducing resource waste and contributing to sustainable agriculture practices. While the study highlights SNP’s potential, further research is needed to optimize its use for different walnut varieties and storage conditions. Future studies could also explore combining SNP with other preservation techniques to maximize efficacy. There may also be challenges in scaling this method for industrial use, but its low cost and ease of application make it a promising avenue for the food industry.

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References

DOI

10.48130/fia-0024-0006

Original Source URL

https://maxapress.com/article/doi/10.48130/fia-0024-0006

Funding information

the National Natural Science Foundation of China (No. 32001765. No. 32272395);

Postdoctoral Research Foundation of China (No. 2022M712375);

Open Project Program of State Key Laboratory of Food Nutrition and Safety (No. SKLFNS-KF-202316).

About Food Innovation and Advances

Food is essential to life and relevant to human health. The rapidly increasing global population presents a major challenge to supply abundant, safe, and healthy food into the future. The open access journal Food Innovation and Advances (e-ISSN 2836-774X), published by Maximum Academic Press in association with China Agricultural University, Zhejiang University and Shenyang Agricultural University, publishes high-quality research results related to innovations and advances in food science and technology. The journal will strive to contribute to food sustainability in the present and future.