Study Of The Sprouting Inhibiton Of Plant Essential Oil On Potato And The Preparation And Application Of Its Hydrogel

Potato(Solanum tuberosum L.)is an important grain and vegetable crop in China.It begins to sprout after the dormant period,sprout leads to the decline of potato tuber quality and facilitates the accumulation of toxic compounds such as solanine.Excessive consumption can cause nausea,headache,coma and other symptoms,which seriously affects consumers’ purchase intention and restricts the development of potato storage and logistics industry.In order to explore the effect of plant volatile substances on inhibiting potato tubers sprouting,firstly,the sprout inhibition screening experiments were carried out at room temperature(25 °C)and low temperature(3 °C)with 15 kinds of plant essential oils.It was found that citronella essential oil(CEO)and wintergreen essential oil(WEO)had great sprout inhibition effect,and the sprout inhibition mechanism of of these two essential oils was studied.Furthermore,it was found that the sprout inhibition effect of WEO was mainly due to methyl salicylate(MeSA),so MeSA hydrogel and CEO hydrogel were prepared,and finally applied to inhibition test of potato sprouting,and evaluate its effect on tuber quality,odor and residue.The main results are as follows:(1)WEO and CEO can significantly inhibit potato tubers sprouting.Among the 15 kinds of plant essential oils,CEO,WEO,peppermint essential oil,spearmint essential oil,geraniol and nerol had better sprout inhibition effect on potato tubers,while raspberry ketone,eugenol and ionone had poor sprout inhibition effect on potato tubers.When stored at low temperature for 270 days,the tubers treated with 100 μL/L of WEO and CEO did not sprout.The sprouting rate of Isopropyl N-(3-chlorophenyl)carbamate(CIPC)treatment was 2.22 %,while that of CK was 73.33 %.The results showed that WEO and CEO treatment delayed potato sprouting for 270 d.When stored at room temperature for 12 days,the sprouting rate of tubers treated with 200 μL/L of WEO and CEO were 18.75% and 13.75%,respectively.The sprouting rate of tubers treated with CIPC treatment was 17.50 %,while that of CK was 100.00%.It shows that WEO and CEO can achieve the same sprout inhibition effect as the chemical sprout inhibitors CIPC,which provides a theoretical basis for the application of essential oil potato sprout inhibitors.(2)The sprout inhibition mechanism of WEO and CEO was studied.Potato tubers were treated with WEO and CEO at a concentration of 1.0 m L/kg,and the tuber bud eyes were black and necrotic.During storage period,WEO and CEO treatment affected potato respiratory intensity,slowed down the decrease of starch,inhibited the accumulation of reducing sugar,and accelerated the degradation rate of sucrose,however,little change in fructose and glucose was observed.ase activity,inhibited the increase of indole acetic acid content,delayed the peak of gibberellin content,slowed down the decrease of abscisic acid content,and delayed the sprouting time of tubers.It indicates that WEO and CEO may inhibit potato tubers sprouting by affecting carbohydrate metabolism and plant endogenous hormone metabolism,but its specific physiological,biochemical and molecular mechanisms need to be further studied.(3)The MeSA hydrogel prepared has a great sprout inhibition effect.The main component of wintergreen essential oil(MeSA)on tuber sprouting was evaluated,and MeSA hydrogel was prepared by using the ionic gel method to improve the sprout inhibition efficiency.Based on SEM,FT-IR,XRD,and DSC images,MeSA was encapsulated successfully in hydrogel,and the thermal stability of hydrogel was improved.MeSA direct fumigation released sharply on the first day,while MeSA in hydrogel released slowly and steadily;the release of MeSA content was 0.0085 mg/m L on the 7th day.The optimized formulations of MeSA hydrogel were as follows: 1.91%of sodium alginate,2.2% of calcium chloride,1.87:1 of core-wall ratio,and 0.15% of Tween-80.The inhibition effect of MeSA hydrogel was better than that of pure MeSA at16 d,the sprouting rates of the MeSA and MeSA hydrogel were 100.00% and 27.78%,and the sprouting indexes were 29.52% and 3.81%,respectively.After 180 days of low temperature storage,the spprouting rate of MeSA hydrogel treatment was 58.33%,while that of CK was 8.33%.MeSA was found to inhibit potato tuber sprouting for the first time in this thesis,MeSA hydrogel can enhance the inhibition effect of MeSA on potato sprouting.Potato tubers were treated with hydrogel at room temperature(25 ℃)and low temperature(3 ℃),respectively.It could significantly inhibit potato tubers sprouting,slow down the decline of starch content,reduce the accumulation of reducing sugar,inhibit browning,and increase the total phenol content at both storage temperatures.Therefore,MeSA hydrogel can maintain the good quality of potato,which provides a theoretical basis for the application and promotion of new sprout inhibition technology in potato storage industry.(4)The CEO hydrogel prepared has a great sprout inhibition effect.Through the response surface optimization experiment,the optimal preparation conditions of CEO hydrogel were as follows: 1.56% of sodium alginate,2.26% of calcium chloride,2.02:1of core-wall ratio,and 0.15% of Tween-80.According to the SEM,FT-IR,XRD and DSC images of the CEO hydrogel,it was concluded that the CEO had been successfully embedded in hydrogel,no new compound was formed,and the thermal stability of hydrogel was improved.Through the study of the release characteristics of CEO hydrogel,it was shown that the CEO in hydrogel could be slowly released within one week,which was beneficial to achieve sustained sprout inhibition effect.CEO hydrogel treatment of potato tubers at room temperature and low temperature can reduce the consumption of starch content in tubers during storage,maintain a low level of reducing sugar,reduce the degree of tuber browning,and maintain great processing quality.At 16 d of storage,the spprouting rate of CEO hydrogel treatment was 42.06%,while that of CK was 100.00% After 180 days of low temperature storage,the spprouting rate of CEO hydrogel treatment was 58.33%,while that of CK was 10.83%.It indicated that CEO hydrogel as a new type of potato sprout suppressants was widely used in potato storage industry.(5)Application comparison between MeSA hydrogel and CEO hydrogel.By comparing the odor,residue of MeSA hydrogel and CEO hydrogel and their effect on sprout and quality of potato tubers,it was found that the sprout inhibition effect of MeSA hydrogel was better than that of CEO hydrogel.MeSA hydrogel can be applied to both room temperature and low temperature storage,and the odor of MeSA is weaker than that of CEO.For the residual amount on potato tubers after use,the residual amount of MeSA hydrogel was also lower than that of CEO hydrogel,indicating that the comprehensive use value of MeSA hydrogel was higher than that of CEO hydrogel.