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ARS Home » Pacific West Area » Davis, California » Crops Pathology and Genetics Research » Research » Publications at this Location » Publication #347211
Title: Ethanol fumigation combined with and without nitrogen gas delays potato greening and inhibits glycoalkaloid generation under light

Author
item DONG, TIANTIAN - Shandong Agricultural University
item MENG, WEIQIN - Shandong Agricultural University
item SHI, JINGYING - Shandong Agricultural University
item Jiang, Cai-Zhong
item WANG, QINGGUO - Shangdong Agricultural University

Submitted to: Postharvest Biology and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/29/2017
Publication Date: 8/18/2017
Citation: Dong, T., Meng, W., Shi, J., Jiang, C., Wang, Q. 2017. Ethanol fumigation combined with and without nitrogen gas delays potato greening and inhibits glycoalkaloid generation under light. Postharvest Biology and Technology. 134:31-37. https://doi.org/10.1016/j.postharvbio.2017.07.013.
DOI: https://doi.org/10.1016/j.postharvbio.2017.07.013

Interpretive Summary: Potato is the third most important crop in the world. Postharvest potato greening is associated closely with generation of toxic glycoalkaloids under the light, resulting in a potential serious health risk and great postharvest losses. Glycoalkaloid accumulation and chlorophyll biosynthesis are often concurrent processes in response to illumination. Glycoalkaloids mainly include bitter and toxic a-solanine and a-chaconine. Glycoalkaloid concentration above 200 mg kg-l fresh weight of potato tissue is considered to exceed the limits recommended for food safety. Consuming beyond the upper limits of glycoalkaloids can cause gastroenteric symptoms, coma and even death. A common practice to inhibit greening is to keep potatoes away from light by using opaque packaging materials, but avoiding all traces of greening during storage or at the market before potatoes reach consumers is seemingly impossible. Other practices or techniques including endogenous carbon dioxide, controlled atmosphere storage, calcium infiltration, detergents and other surfactants have been shown to inhibit potato greening to some extent under light. To date, however, there is no report that any of these techniques have been used commercially. Endogenous and exogenous acetaldehyde and ethanol could prevent potato greening as the toxicity of acetaldehyde and ethanol could cause cell membrane fluidization. Ethanol, a liposoluble substance, possibly causes the destruction of thylakoid membranes of chloroplasts and thus influences photosynthesis. Previous studies have also demonstrated that ethanol treatment could inhibit potato greening, but high concentrations induced tuber decay. In addition, a high concentration of nitrogen gas (N2) treatment delayed potato greening, but treatment for only a short time could not achieve ideal effects. The objectives of this study were to determine the proper ethanol fumigation concentration that would effectively inhibit potato greening and cause less potato decay, and to investigate the effects of ethanol fumigation combined with N2 on potato greening and glycoalkaloid generation under light at a storage temperature of 20o C. Our goals were to develop a practical way to delay potato greening and to prevent glycoalkaloid accumulation for prolonging the shelf-life of potatoes. We found that ethanol fumigation with concentrations of 400, 600, and 1000 µL L-1 inhibited potato greening but caused decay when the concentration exceeded 600 µL L-1. Ethanol fumigation with 600 µL L-1 combined with nitrogen gas (N2) treatment (600 ET+N2) enhanced the effect of inhibiting greening and delayed potato greening for 6 ~7 d compared with the control. The treatment of 600 ET+N2 significantly inhibited glycoalkaloids generation in potato peel and flesh and effectively improved the overall visual quality and flavor of potatoes during storage under light. Our results suggested that the ethanol fumigation could provide a useful way to delay potato greening and to prevent glycoalkaloids accumulation for prolonging the shelf-life of potatoes.

Technical Abstract: Postharvest potato greening under light accompanied by the generation of toxic glycoalkaloids results in a potential serious health risk and great postharvest losses. This study examined the inhibiting effects of ethanol fumigation and ethanol fumigation combined with N2 treatment on potato greening and glycoalkaloids generation in potato peel and flesh under light. The results showed that ethanol fumigation with concentrations of 400, 600, and 1000 µL L-1 inhibited potato greening but caused decay when the concentration exceeded 600 µL L-1. Ethanol fumigation with 600 µL L-1 combined with nitrogen gas (N2) treatment (600 ET+N2) enhanced the effect of inhibiting greening and delayed potato greening for 6 ~7 d compared with the control. The treatment of 600 ET+N2 significantly inhibited glycoalkaloids generation in potato peel and flesh and effectively improved the overall visual quality and flavor of potatoes during storage under light. Our results suggested that the ethanol fumigation could provide a useful way to delay potato greening and to prevent glycoalkaloids accumulation for prolonging the shelf-life of potatoes.