【作者】 石磊；

【导师】 李诚；

【作者基本信息】 四川农业大学 ， 农产品加工及贮藏工程， 2008， 硕士

【摘要】 ε-聚赖氨酸（ε-Polylysine简写ε-PL）是一种天然的微生物代谢产物,具有优良的抑菌作用,满足添加剂天然、安全的要求。鉴于ε-聚赖氨酸（ε-Polylysine）普遍公认的安全性（GRAS）和抑菌特性,本文对ε-聚赖氨酸的抑菌特性进行了研究,并将其应用到畜产品的防腐保鲜中。本文的主要研究结果如下:（1）采用分光光度法、菌体重量法以及打孔扩散法等方法来研究ε-PL对食品中常见菌的抑制作用,探讨了浓度、温度、pH值、复配等对其抑菌效果的影响。结果显示:ε-PL对金黄色葡萄球菌、大肠杆菌、黄曲霉、枯草芽孢杆菌、酿酒酵母、保加利亚乳杆菌等六种供试菌种均有一定的抑制作用。ε-PL对大肠杆菌、金黄色葡萄球菌、保加利亚乳杆菌抑菌效果较好,对黄曲霉较差;对各种菌的最小抑菌浓度（MIC）为大肠杆菌、金黄色葡萄球菌、保加利亚乳杆菌6.25mg/L～12.5mg/L;枯草芽孢杆菌12.5mg/L～25mg/L;酿酒酵母400mg/L～800mg/L;黄曲霉800mg/L～1600mg/L。ε-PL的抑菌活性随着其浓度的增加而增强。ε-PL热稳定性非常好,能耐100℃的高温。在pH为5～8范围下,ε-PL抑菌活性最强。同时,ε-PL与甘氨酸、Nisin复配都有协同增效的作用。（2）把ε-PL用于冷却猪肉保鲜中,与在食品保鲜中应用比较广泛的天然保鲜剂Nisin作对比,并与甘氨酸配合使用。在4±0.5℃冷却保藏条件下对保鲜效果和食用品质进行了评定。评定指标选用了感官指标、pH值、H₂S试验、TVB-N值、TBA、球蛋白沉淀试验、细菌总数、汁液流失率、蒸煮损失率、持水力、肉色泽。结果表明:ε-PL和Nisin分别用于冷却猪肉保鲜时,浓度为400mg/L的ε-PL的保鲜效果明显地优于对照组（蒸馏水）,差异达到极显著水平（P＜0.01）;优于200mg/L Nisin组,差异达到显著水平（P＜0.05）。400mg/Lε-PL、20mg/L甘氨酸、200mg/L Nisin复配组和200mg/Lε-PL、20mg/L甘氨酸、200mg/L Nisin复配组一级鲜度货架期可达21天;400mg/Lε-PL和20mg/L甘氨酸复配时,一级鲜度货架期可达18天;400mg/Lε-PL组,一级鲜度货架期可达15天;200mg/L的Nisin组,一级鲜度货架期可达12天;对照组一级鲜度货架期只有3天。400mg/Lε-PL、20mg/L甘氨酸和200mg/L Nisin复配组保鲜效果最好,同时对冷却猪肉的食用品质没有很大影响。（3）在凝固型酸奶发酵前,将不同的防腐剂随同发酵剂一起加入到凝固型酸奶,研究ε-PL用于凝固型酸奶在4±0.5℃冷却贮藏过程中的保藏效果。评定指标选用了感官指标、酸度和活菌数。结果表明:添加防腐剂的凝固型酸奶第三天的主要指标达不到酸奶国家标准的要求,同时凝固的时间也比对照组（蒸馏水）长了。因此,通过添加ε-PL来延长凝固型酸奶保藏时间的方法不可行。（4）在搅拌型酸奶搅拌后迅速加入不同的防腐剂,研究ε-PL用于搅拌型酸奶在4±0.5℃冷却贮藏过程中的保藏效果。结果表明:ε-PL、甘氨酸和Nisin复配组对搅拌型的保藏效果最好。进一步确定以ε-PL、甘氨酸、Nisin为试验因子。根据三因素三水平正交试验的结果,对酸度值影响的主次顺序为:ε-PL＞甘氨酸＞Nisin;对乳酸菌活菌数影响的主次顺序为:Nisin＞ε-PL＞甘氨酸;对感官指标影响的主次顺序为:Nisin＞ε-PL＞甘氨酸。最后确定防腐剂较优水平组合为ε-PL为200 mg/L、甘氨酸20mg/L和Nisin50 mg/L。更多还原

【Abstract】 ε-Polylysine is a natural metabolic product by microbes.It has a superordinary bacteriostatic action,that meets the demand of natural and safety.Considering the antibacterial properties and generally recognized as safe（GRAS） status ofε-Polylysine,some study ofε-Polylysine were conducted in this paper.Firstly proceeded to its antimicrobial characteristic, and on the basis of this experiment,applied it to fresh preservation of livestock products. The main results were as follows:（1） The antibacterial action ofε-Polylysine was studied by spectrophotometric method, aperture pervasion method,and dry cell weight method in this paper.The antimicrobial property included concentration,temperature,pH and matching preservative influenced toε-Polylysine by investigating.The result showed thatε-Polylysine had a notable restrainable function on six species of food common bacteria（Staphylococcus aureus、Escherichia coli、Aspergillus flavus、Bacillus subtilis、Saccharomyces cerevisiae and Lactobacillus bulgaricus）.Andε-Polylysine had obvious antimicrobial actions especially to on Escherichia coli,Staphylococcus aureus and LactobacilIus buIgaricus.It is not very effective on Aspergillus flavus.The minimal inhibition concentration（MIC）was as follows: Escherichia coli,Staphylococcus aureus and Lactobacillus bulgaricus 6.25mg/L～12.5mg/L,Bacillus subtilis12.5mg/L～25 mg/L,Saccharomyces cerevisiae 400 mg/L～800mg/L,Aspergillus flavus 800 mg/L～1600mg/L.And it was proved that the more the concentration ofε-PL,the more the antimicrobialactivity it has.It was also proved thatε-PL had super stability by 100℃temperature changing and it can be effective from pH5～8. Besides,the addition of glycine or Nisin can improve antimicrobial activity.（2） Researching the application ofε-Polylysine on chilled pork preservation. Compared with Nisin which is one of natural preservative to be used widely in chilled pork preservation,ε-PL used with glycine or not in pork preservation.In this paper,the effect of preservation and quality of chilled pork was evaluated by differerent preservative solutions at 4±0.5℃during storage.All dectecing items for these samples processed covered sensory assessment,pH,H₂S test,TVB-N,TBA,protein sediment test,coliform bacteria,holding water capacity,steaming loss rate,sap run off rate,color.The results showed:ε-PL of 400mg/L showed a better preservative effect than control group（P＜0.01）,ε-PL of 400mg/L had significant difference on preservative than Nisin of 200mg/L（P＜0.05）,ifε-PL and Nisin were used on chilled pork preservation separately.Chilled pork by using 400mg/Lε-PL,20mg/L glycine with200mg/L Nisin or 200mg/Lε-PL,20mg/L glycine with 200mg/L Nisin could be preserved 21d in the first class of shelf life.Chilled pork by using 400mg/Lε-PL with 20mg/L glycine could be preserved 18d in the first class of shelf life.Chilled pork by using 400mg/Lε-PL could be preserved 15d in the first class of shelf life.Chilled pork by using 200mg/L Nisin could be preserved 12d,and control group（water） could only be preserved 3d in the first class of shelf life.We got a better preservative effect when matched 400mg/Lε-PL,20mg/L glycine with200mg/L Nisin,and the group didn’t effect quality of chilled pork.（3）Differerent preservative solutions were added to concretionary yogurt with starter culture before yogurt fermenting.The effect of preservation of concretionary yogurt was researched at 4±0.5℃during storage.All dectecing items for these samples processed covered sensory assessment,acidity and viable count.The results showed:the main index of concretionary yogurt added different preservative solutions can not reach standard on the third day,and the time of concreting will delay than control group（water）.Maybe the preservative solutions restrained lactobacillus breeding so that the main index of them can not reach standard.Therefore,the application ofε-PL on concretionary yogurt preservation was unfeasible in theory.（4） Different preservative solutions were added to stirred yogurt after yogurt stirring. The effect of preservation of stirred yogurt was researched at 4±0.5℃during storage.All dectecing items for these samples processed covered sensory assessment,acidity and viable count.The results showed:We got a better preservative effect when matchedε-PL,glycine with Nisin.Use the influential factor ofε-PL,glycine and Nisin to carry out orthogonal experiment.Through on the orthogonal design of L₉（3³ ）,the best effect of acidity followed byε-PL＞glycine＞Nisin,the best effect of viable count followed by Nisin＞ε-PL＞glycine,the best effect of sensory assessment by Nisin＞ε-PL＞glycine.The results showed that the optimum formulation wasε-PL 200 mg/L,glycine 20 mg/L and Nisin 50 mg/L.更多还原