Effective zein-based germination inhibitor for potatoes

To address the problem of potato germination during postharvest storage, we prepared a series of zein-based germination inhibitors and tested their inhibitory effects on germination. The germination inhibitors were characterized by scanning electron microscopy (SEM), hydrophobicity, Fourier-transform infrared (FTIR) spectroscopy, and thermal gravimetric analysis (TGA). The results demonstrate that the germination inhibitors can form a hydrophobic film on the surface of potatoes, thereby reducing contact with, and absorption of, water. The application of an optimal germination inhibitor at a final zein concentration of 1.25 g/L was shown to reduce the germination rate of potatoes by 54% after 30 d of storage compared with the control group. In addition, the plant germination rate, height, and stem diameter of potatoes treated with the germination inhibitor were similar to those of the control group in the subsequent planting process, indicating that the germination inhibitor had no effect on potato cultivation. This study provides a safe and effective method for the post-harvest storage of potatoes, which has broad commercial applications. The text before is the Abstract of the paper; the references in the Introduction can be find in the original paper (see below). IntroductionPotatoes are an important food crop worldwide. They are rich in nutrients and contain protein, fat, crude fiber, vitamins and starch (Decker and Ferruzzi, 2013; King and Slavin, 2013; Ierna and Parisi, 2014). Moreover, they are very popular with both consumers and food processors. However, potatoes tend to germinate during storage after harvesting, which reduces their quality and results in the production of solanine (?eng?l et al., 2004; Hoerger et al., 2009; Jianquan Kan, 2018; Romanucci et al., 2018). Humans and animals experience acute poisoning symptoms, such as gastrointestinal muscle spasms, after ingesting a certain amount of solanine (Friedman, 2006; Mandimika et al., 2007; Ginzberg et al., 2009; Nakayasu et al., 2018). Research has shown that the lethal dose of solanine in humans ranges between 3 and 6 mg/kg body weight, and may be related to human nutritional status and sensitivity to solanine (Slanina, 1990). With continuous expansion of the potato industry, the problem of sprouting during the harvest period has become a bottleneck, restricting development of the industry. Therefore, improving the storage conditions and quality of potatoes is an urgent problem that needs to be addressed for further development of the potato industry. The storage temperature and humidity of potatoes are important factors that affect their storage time (Boivin et al., 2020; Gong et al., 2021; Gumbo et al., 2021; Thoma and Zheljazkov, 2022). It has been reported that potatoes can achieve better storage results when the relative humidity is approximately 90% and the temperature is in the range 2?4 ?C; however, long-term low-temperature storage affects the quality of potatoes, such as their taste and color. The use of low-temperature storage significantly increases the cost, which is inconvenient for wholesalers and individual merchants. Physical methods such as ultraviolet, gamma, and microwave irradiation can inhibit potato sprouts to a certain extent, but the equipment is expensive. Additionally, certain compounds have been designed as germination inhibitors and have achieved good results (Silva et al., 2007; Gomez-Castillo et al., 2013; Arnon-Rips et al., 2020; Daniels-Lake et al., 2011). Currently, chlorpropham (CIPC) (*) is commonly used to prevent potato sprouting, and its validity period is approximately five months, resulting from its long lifetime after application to the potatoes (Vijay et al., 2018; Visse-Mansiaux et al., 2021). However, this compound has been proven to be harmful to humans and the environment, and is not suitable for small-scale production. The degradation products of CIPC also have highly toxic effects on humans; therefore, side effects of CIPC use can continue after it has degraded. The risk of using CIPC requires exploration and development of a safer and more environmentally friendly potato germination inhibitor. S-carvone, purified from natural materials such as caraway and spearmint, is a volatile monoterpene compound that has been reported to be a commercial potato germination inhibitor (Sanli and Karadogan, 2019). S-carvone also has an antifungal effect that maintains the quality of potatoes during the postharvest storage. Other active molecules, such as 1, 4-dimethylnaphthalene (1, 4-DMN) and eugenol, have also been shown to inhibit sprouting (Boivin et al., 2020). In recent years, biopolymers such as proteins and polysaccharides have been used to prepare functional materials with good results (Zollfrank et al., 2012; Bondalapati et al., 2014; Le et al., 2017; Muxika et al., 2017; Elschner et al., 2018; Wei et al., 2022). Zein is a storage protein derived from corn with high biosafety, good film-forming ability, and degradability, and is regarded as a high-quality food-grade raw material (Li and Yu, 2020; Luo et al., 2011). Therefore, the application of zein has a high economic and practical significance. Zein contains a large amount of hydrophobic amino acids, which provides an opportunity for the preparation of antisprouting agents for agricultural production. Studies have revealed that zein can form a film with strong water retention, and when applied to the surface of fruits and vegetables, it may inhibit gas exchange, effectively maintaining moisture in food and thus play a role in preservation (Kasaai, 2018; Zhang et al., 2019). To the best of our knowledge, there are no relevant reports on potato sprout inhibition using zein, which may be because the surface properties of the film formed by pure zein cannot meet the production requirements. To this end, researchers have prepared multicomponent composite materials based on zein, and the hydrophobicity and ductility have been significantly improved (Liu et al., 2019; Huang et al., 2020). Similarly, if we apply a zein composite membrane to the surface of potatoes, it could aid in the post-harvest storage of potatoes. Zein composite membranes have potential applications owing to their high safety and operability. In this study, we prepared a potato germination inhibitor based on zein, studied the solution ratio, hydrophobicity, and other properties of the material, and investigated its effect on the germination rate of potatoes during storage and subsequent cultivation. The value of the material used in production applications is also explained. This study provides new insights into the preparation of potato germination inhibitors. Contents- Materials- Preparation of germination inhibitors- Evaluation of the effect of germination inhibitors- Conclusions (*) Not allowed in some countries, like Spain. SourcesApplication of zein-based germination inhibitors in potato postharvest storageWenfeng Ni, Yulong Xu, Aifang Zheng, Zhenling Zhang & Huilan ZhangScientia Horticulturae, Volume 312, 15 March 2023, 111854https://www.sciencedirect.com/science/article/abs/pii/S0304423823000304https://doi.org/10.1016/j.scienta.2023.111854Picture,?Stop throwing them away! Scientists chastise shoppers for binning sprouted potatoes as they confirm they ARE edible (and they're definitely not poisonous)https://www.dailymail.co.uk/femail/food/article-5190405/Scientists-reveal-sprouted-potatoes-EDIBLE.html