【作者】 杨力；

【导师】 马惠玲；

【作者基本信息】 西北农林科技大学 ， 野生动植物保护与利用， 2009， 硕士

【摘要】 我国是苹果（M. pumila Mill.）生产与加工大国,并且加工数量呈逐年上升趋势[1]。苹果加工工艺的完善与改进及其残渣的综合利用是关系到苹果加工业生存与可持续发展的关键举措和有力保证。为了寻求新的高效、经济、简便的果汁加工工艺,本试验用乙烯利和加热处理苹果果实以期加速苹果果实细胞壁降解,利于出汁,并对其作用效应和机理进行了研究。首先以晚熟的‘秦冠’苹果果实为试材,研究了不同处理方式:乙烯利溶液(10 mg·L^-1,100 mg·L^-1,500 mg·L^-1,1000 mg·L^-1)浸泡处理10min,低浓度乙烯利处理配合加热(100 mg·L^-1乙烯利溶液浸泡后自然风干,分别在30℃,45℃,60℃水浴中加热30min)双重处理下果实细胞壁组分降解的规律,从而选出两类处理方式下对苹果果实细胞壁组分降解的优化工艺条件;再用优化工艺处理“秦冠”和“富士”苹果,分析不同种类苹果经处理后细胞壁组分降解效应的差异,阐明乙烯对苹果果实细胞壁组分降解的效应和机理;最后通过两种优化工艺条件下苹果果实品质及出汁率的变化,揭示外源乙烯利处理以及低浓度乙烯利配合加热双重处理作为苹果加工预处理手段的可行性,结果得出:1.‘秦冠’苹果果实经乙烯利溶液处理后,随乙烯利浓度由10 mg·L^-1增至1000 mg·L^-1,果胶甲酯酶（PME）和多聚半乳糖醛酸酶（PG）的活性先逐渐增强而后下降;纤维素酶（CS）活性先得到促进,而后被抑制;木聚糖（Xyl）却没有受到明显影响。加热增进了乙烯的作用,60℃下,PME、PG、CS、Xyl活性分别增加到对照的1.5、2.7、1.1、1.5倍。PG活性的显著增加也同时引起了果实可溶性糖的显著升高,其它酶活性变化与可溶性糖含量之间未显示直接相关。综合各处理结果,选取500mg·L^-1的乙烯利处理（Eth-tr）和100mg·L^-1的乙烯利配合60℃加热处理（Eth-he-tr）为优选处理。2.两种优选处理对不同品种苹果果实细胞壁酶的影响有所不同,其中500mg·L^-1的乙烯利对‘富士’苹果影响较大,使‘富士’苹果的PME、CS活性高峰分别提前6天和3天出现,并使PG活性在前十五天均明显高于对照（CK）;100 mg·L^-1乙烯利配合60℃辅助加热对‘秦冠’苹果影响较大,使‘秦冠’苹果的Xyl活性在前15天持续高于CK,而使PME、PG、CS活性在前12天明显高于CK;同时两种优选处理对原生质膜酶LOX产生一定影响,在两个品种一致表现为乙烯利处理后LOX活性升高。加热辅助处理反而对LOX活性产生抑制作用。3.两种优选处理对不同品种苹果果实细胞壁多糖的降解影响不同。处理12天后,500mg·L^-1乙烯利处理对‘富士’苹果细胞壁多糖影响较大,使果胶类多糖、半纤维素类果糖和细胞壁残渣多糖含量分别下降到CK的80.1%、70.4%和75.7%,而100 mg·L^-1乙烯利配合60℃辅助加热对‘秦冠’苹果细胞壁多糖影响较大,使果胶类多糖、半纤维素类果糖和细胞壁残渣多糖（CWM-residue polysaccharide）含量非别下降到CK的83.8%、92.0%和82.5%。同时经两种优选处理后苹果果实可溶性糖含量在贮存前期（0～9d）明显增加。4.乙烯利处理及加热辅助处理对苹果果实的电学指标产生了不同影响。乙烯利处理后果实电学指标Z、ε,σ和LP在不同时间段随频率变化的线形基本与对照（CK）相同,与果实外观品质未发生明显改变的结果一致;乙烯利和加热双重处理后Z的线形在果实贮存后期脱离了CK的变化规律,而且随贮存时间延长脱离越明显,与加热辅助处理使果实发生品质劣变有关一致,显示了Z作为果实品质无损检测指标的可行性。5. 500mg·L^-1乙烯利处理后9天到12天,‘富士’和‘秦冠’苹果的出汁率分别较对照（富士75.5%～78.0%、秦冠75.5%～78.0%）高2.3～4.0、1.3～4.7个百分点,是一种简便适用的提高出汁出的果实加工预处理方法;用100mg·L^-1乙烯利浸泡后后再经30min加热处理后,可以在第9天使‘富士’和‘秦冠’苹果出汁率分别较对照高3.2～7.5、7.5个百分点,但是对苹果果肉品质有一定影响,果实处理后发生表层轻微褐变,所以需经过后续检验其是否会产生对果汁品质的不良影响后才能确定其可行性。更多还原

【Abstract】 Our country is powerful in the production and processing of apple fruit, moreover, a increasing trend presents in the processing industry year by year.The improvement of processing techniques in apple fruit and the integral utilization of pomace has become an important measurement as well as a guarantee for the survival and sustainable development in apple processing industry. In order to search for more efficient, economical and convenient processing techniques of apple juice, treating apple fruit with ethrel and heating were performed to promote the degradation of cell wall and enhance juice yield . Effects and mechanism of the treatments were studied.Firstly, late-mature variety‘Qinguan’apple fruit was employed to investigate the regularity of cell wall composition degradation under the influence of different treatments as: soaking for 10 min with ethrel solutions（10mg?L-1,100 mg?L-1,500mg?L-1,1000mg?L-1）, soaking in low concentration （100 mg?L-1）ethrel then heating with waterbath （30℃、45℃and 60℃for 30 min respectively）, so that the best conditions for the two processes to promote the degradation of the cell wall compositions of apple fruit were screened. Second,‘Fuji’and‘Qinguan’apples were treated each under the two sets of best conditions,then the difference of the degradation effects of cell wall components of the two kind of treated apple fruit were analyzed to elucidated the degradation effects and mechanism of apple fruit affected by ethrel; Finally, the feasibility of taking exogenous ethrel treatment and low concentration treatment of ethrel combining with heating as pretreatment ways in apple processing was illustrated according to the results of the apple fruit quality changes and the juicy yield. All results present as following:1.After "Qingguan" apple fruits were treated with different concentrations of ethrel, some physiological changes occurred. The activity of pectin methylesterase（PME）and polygalacturonase（PG）first increased gradually and then declined with ethrel changed from 10mg·L^-1 to 1000mg·L^-1;The activity of Cellulose （CS） was promoted first and then inhibited; 500mg·L^-1 ethrel showed most obvious role. Xylan （Xyl） had not been significantly affected. Heating had increased the role of ethrel, the activity of PME、PG、CS、Xyl had increased ,respectively were 1.5、2.7、1.1、1.5 folders of the comparison samples in the temperature of 60℃.The significant increase of PG activity caused the increase of soluble sugar content from fruit significantly, the changes in other enzymatic activity did not show a direct correlation to the soluble sugar content. 500mg·L^-1 ethrel （Eth-tr） and 100 mg?L-1 ethrel soaking then heating at 60℃（Eth-he-tr） were screened the two selected treatment.2.The two selected treatments affected the cell wall enzymes in different ways on the two varities of apple. Eth-tr had stronger effect on‘Fuji’apple,whick made the activities peak of PME and CS from‘Fuji’appl come 6d and 3d earlier than control, respectively, and the activity of PG increased obviously than control till 15th day. Eth-he-tr had stronger effect on‘Qinguan’apples,whick made the activity of Xyl increase obviously than control till 15th day, and the activities of PME、PG and CS be stronger than control till 12th day. The protoplastic membrane enzyme LOX was also affected as its activity rised in some degree in Eth-he-tr ethrel treated fruit, whereas the activity of LOX was inhibited instead in the Eth-he-tr treatment.3.The treatments of ethrel and assistant heating affected the degradation of cell wall polysaccharides in different ways on the two varities of apple.The cell wall polysaccharides of‘Fuji’apple was affected more stronger by Eth-tr of 500mg·L^-1 ethrel after 12d later, the contents of pectin polysaccharides,hemicellulose polysaccharides and cell wall material residue（CWM-residue） polysaccharides decreased to 80.1%、70.4% and 75.7% that of control, whereas, Eth-he-tr affected more stronger on the cell wall polysaccharides of‘Qinguan’apple, the contents of pectin polysaccharides, hemicellulose polysaccharides and CWM-residue polysaccharides decreased to 83.8%、92.0% and 82.5% that of control. At the same time, the content of soluble sugar increased obviously at prior period（0～9d）.4. Eth-tr and Eth-he-tr showed different effects on the electricity indexes. The curve shape of the electricity indexes of Z、ε,σand LP from Eth-tr fruit at different day interval were almost the same as control, showing the same result as appearance quality of fruits between control and treatments; The curve shape of Z from Eth-he-tr fruit showed difference from control at later stage, even the difference became more and more obvious with day proceeding, correlated with the decline of appearance quality,indicating that Z is a suitable index for non-damage check of apple fruit .5.The rates of juice yield of‘Fuji’and‘Qinguan’apples were 2.3～4.0 and 1.3～4.7 percentage points higher than control respectively in Eth-tr fruit 9～12 days after,which could be screened the pretreating way for promoting juice yield of apple fruit; Eth-he-tr could rised the rate of juice yield for 3.2～7.5 and 7.5 percentage points higher than control respectively , too, 9～12 days after, but the quality of the apple was affected definitely indicating by the occurring of slight browning, thus whether it was a feasible pretreating way or not will be be decided by the result of futher juice check.更多还原