外源乙烯處理對(duì)甘薯裂果及細(xì)胞壁代謝的影響

程圣，靳苗苗，何欣遙，劉錦，張敏

(西南大學(xué) 食品科學(xué)學(xué)院，西南大學(xué)食品貯藏與物流研究中心，農(nóng)業(yè)部農(nóng)產(chǎn)品貯藏保鮮安全風(fēng)險(xiǎn)評(píng)估實(shí)驗(yàn)室(重慶)，重慶，400715)

Effectsofexogenousethyleneonthecrackingandcellwallmetabolismofsweetpotato

CHENG Sheng,JIN Miaomiao,HE Xinyao,LIU Jin,ZHANG Min*

(College of Food Science, Food Storage and Logistics Research Center, Southwest University,Laboratory of Quality (Safety Risk Assessment for Argo-products on Storage and Preservation(Chongqing)，Mimnistry of Agriculture, Chongqing 400715, China)

ABSTRACTSweet potato is easy to sprout under high temperature environment, it has been found that exogenous ethylene treatment could effectively inhibit the sweet potato germination. But sweet potato would crack under high concentration of ethylene which reduces its commercial value. In this paper, sweet potatoes were treated with exogenous ethylene at the concentrations of 0,0.5,1 and 2 g/L. And based on the result, it analyzed the changes of germination rate, root cracking rate, raw pectin content, soluble pectin content, polygalacturonase (PG), cellulase (Cx), β-gluosidase (β-Glu), polyphenol oxidase (PPO), peroxidase (POD) of sweet potato and explored. The effects of different concentrations of exogenous ethylene on cracking and cell wall metabolism of sweet potato were analyzed. The results indicated that all ethylene treatment groups could inhibit the germination of sweet potato, and the higher ethylene concentration, the better the germination effect. However, the high concentration of 2 g/L ethylene caused the sweet potato to crack while the other groups had no cracking phenomenon. As the ethylene concentration increased, the activities of PPO and POD would increase, which led to hardening of cell wall and reduced extensibility. In addition, 0.5 g/L and 1 g/L ethylene could delay the increase of PG, Cx activities and the original pectin content in the middle and late stages. And 2 g/L exogenous ethylene treatment significantly increased the activities of sweet potato cell wall hydrolase (PG, Cx and β-glucosidase), and also promoted the decline of sweet potato pectin content and water-soluble pectin content, which eventually led to the increase of cracking.

Keywordssweet potato;exogenous ethylene;fruit cracking;cell wall metabolism

新鮮甘薯口味甜美，富含淀粉、維生素和糖類等營養(yǎng)物質(zhì)，具有抗癌活血，止血消炎，舒腸通便等功效[1]。然而甘薯在16～35 ℃的貯運(yùn)環(huán)境下極易發(fā)芽[2]，嚴(yán)重影響其商品價(jià)值。目前國內(nèi)外關(guān)于甘薯的抑芽技術(shù)有輻照處理[3]、熱處理[4]、植物提取物處理[5]等。但由于技術(shù)及成本問題限制，這些技術(shù)均不適用于我國甘薯貯運(yùn)抑芽。

乙烯是迄今發(fā)現(xiàn)五大類植物激素之一，與器官休眠和植物成熟衰老等生理現(xiàn)象密切相關(guān)，GEBHARO等[6]研究了乙烯在洋蔥休眠和發(fā)芽期間的作用，發(fā)現(xiàn)用5～10 μL/L外源乙烯連續(xù)處理洋蔥18周，發(fā)芽率從100%降低至7.5%。同時(shí)，本實(shí)驗(yàn)室前期研究發(fā)現(xiàn)，外源乙烯能抑制甘薯發(fā)芽且效果顯著，是一項(xiàng)操作方便、成本低廉的有效抑芽技術(shù)。但過高濃度乙烯處理會(huì)導(dǎo)致甘薯塊莖開裂，使其失去商品價(jià)值。如能明確開裂機(jī)理，避免開裂的出現(xiàn)，乙烯抑芽技術(shù)就值得推廣應(yīng)用。然而目前乙烯甘薯抑芽技術(shù)研究匱乏，乙烯引起甘薯塊莖開裂的機(jī)制更是缺乏文獻(xiàn)基礎(chǔ)。有研究表明，裂果現(xiàn)象本質(zhì)為果皮和果肉組織生長速度不一而表現(xiàn)為果皮表面開裂現(xiàn)象[7]，臍橙[8]、明棗[9]、荔枝[10]、蘋果[11]、鱷梨[12]等果蔬的裂果現(xiàn)象與細(xì)胞壁組分及酶活性存在密切關(guān)系。本試驗(yàn)采用不同質(zhì)量濃度的外源乙烯對(duì)甘薯進(jìn)行處理，研究甘薯塊莖開裂及細(xì)胞壁代謝情況，探尋裂果機(jī)理，為甘薯實(shí)際儲(chǔ)運(yùn)抑芽保鮮提供科學(xué)依據(jù)。……