反丁烯二酸蔗糖甲酯合成及抗菌特性研究

利用固体超强酸SO2-4/TiO2催化合成反丁烯二酸蔗糖甲酯(SMF),反应分为3步:马来酸酐先和蔗糖反应生成顺丁烯二酸单蔗糖酯、顺丁烯二酸单蔗糖酯异构化和反丁烯二酸单蔗糖酯与甲醇酯化反应生成SMF。用单因素法确定了"一锅法"合成SMF的工艺。研究了酯化度为5.5的SMF的最低抑菌浓度和生长抑制曲线,并与山梨酸及富马酸二甲酯进行了对比。结果表明:SMF具有较广的抗菌谱系,对细菌、酵母和霉菌的生长具有较强的抑制能力。添加0.12%的SMF可使大肠杆菌和苏云金杆菌的生长适应期分别由对照的3h延长至30h和35h;添加0.10%的SMF能使酵母的生长适应期延长至对照(5h)的6倍,添加0.06%SMF,液体培养96h后才有黑曲霉菌丝球出现,而对照样20h即可见到。反丁烯二酸蔗糖甲酯的抑菌效果好于山梨酸而与富马酸二甲酯接近。     

反丁烯二酸蔗糖甲酯合成及乳化特性研究

以固体超强酸SO42-/TiO2为催化剂,一锅法合成了反丁烯二酸蔗糖甲酯。乳化特性研究表明:酯化度为5.5的反丁烯二酸蔗糖甲酯的HLB值为6.8、临界胶束浓度为0.7g/L、浓度为0.3%溶液的表面张力为28.5mN/m,说明反丁烯二酸蔗糖甲酯具有一定的表面活性。反丁烯二酸蔗糖甲酯的乳化活性介于蔗糖酯和Span-80之间,比蔗糖酯要好。大于临界胶束浓度时,反丁烯二酸蔗糖甲酯、蔗糖酯和Span-80均有较高的乳液稳定性。有关反丁烯二酸蔗糖甲酯与其它乳化剂的复配性能及其在日用化学工业及食品等领域的应用有待于进一步研究。     

富马酸酯类防腐剂改性方法研究现状

富马酸酯类具有良好的抗茵活性,广泛用做食品防腐剂.近年来人们通过对富马酸酯类进行结构改造,合成具有防腐及其它综合性能的新型食品添加荆.介绍富马酸单酯、溴代富马酸二甲酯、反丁烯二酸蔗糖甲酯等富马酸酯衍生物的改性方法及改性效果的研究现状.     

三种新型防座剂抗菌性能的研究

对山梨酸及本实验室最新合成的三种防腐剂的抗菌性能进行了研究，发现溴代山梨酸比山梨酸具有更强的抗菌强度和抗代谢能力，反丁烯二酸桂醇甲酯的抑菌强度最强，而且几乎不受介质pH的影响，二者均有很好的应用前景，反丁烯二酸桂醇酯则由于溶解性等方面的原因，抑菌强度较低，但其半衰期较长，下一步可从增强其水溶性角度对其进行分子改造以提高其抗菌性能。     

三种新型防腐剂抗菌性能的研究

对山梨酸及本实验室最新合成的三种防腐剂的抗菌性能进行了研究，发现溴代山梨酸比山梨酸具有更强的抗菌强度和抗代谢能力，反丁烯二酸桂醇甲酯的抑菌强度最强，而且几乎不受介质ｐＨ的影响，工者均有很好的应用前景。反丁烯二酸桂醇酯则由于溶解性等方面的原因，抑菌强度较低，但其半衰期较长。下一步可从增强其水溶性角度对其进行分子改造以提高其抗菌性能。     

新型防腐剂富马酸半乳糖甲酯的合成及抗菌特性研究

基于食品防腐防霉剂的结构-活性关系研究结果,以马来酸酐和甲醇为原料,经酯化及异构化得到富马酸单甲酯,再经酰氯化得到富马酸单甲酯单酰氯。富马酸单甲酯单酰氯与半乳糖反应,在相转移催化剂四丁基溴化铵的作用下,得到具有α、β-不饱和羰基结构的富马酸半乳糖甲酯。抑菌活性试验结果表明:富马酸半乳糖甲酯对混合菌具有良好的抑菌能力,抑菌效果优于富马酸单甲酯,接近苯甲酸。     

2种富马酸糖酯的相转移催化合成及抑菌活性研究

以马来酸酐和甲醇为原料,经酯化及异构化得到富马酸单甲酯,再经酰氯化得到富马酸单甲酯单酰氯.富马酸单甲酯单酰氯与葡萄糖或乳糖反应,在相转移催化剂四丁基溴化铵的作用下,得到具有α、β-不饱和羰基结构的富马酸葡萄糖甲酯及富马酸乳糖甲酯.抑菌活性试验结果表明:富马酸葡萄糖甲酯及富马酸乳糖甲酯对混合菌群的生长具有良好的抑制能力,其中富马酸葡萄糖甲酯的抑菌活性与富马酸单甲酯接近.     

α-溴代富马酸二甲酯的合成及抗菌特性研究

为了消除富马酸二甲酯(DMF)的升华性及过敏性并保留其良好的抗菌特性,合成了新型防腐剂α-溴代富马酸二甲酯(α-BrDMF),研究了α-BrDMF对不同种类微生物的抗菌性能,并与山梨酸及DMF进行了对比。α-BrDMF的合成分为两步:以冰乙酸为溶剂,DMF与溴发生亲电加成反应生成富马酸二甲酯二溴化物(d-BrDMF);d-BrDMF与氢氧化钠的乙醇溶液共热,发生消除反应可得α-BrDMF。经IR和MS确证产物结构。抗菌作用实验结果表明:α-BrDMF对细菌、酵母和霉菌的生长具有较强的抑制能力。添加0.1%的α-BrDMF可使大肠杆菌和枯草芽孢杆菌的生长适应期由对照3h延长至40h和44h;添加0.04%的α-BrDMF能使酵母的生长适应期延长至对照(4h)的13倍;霉菌菌落形成数减少,抑菌效果优于山梨酸和DMF;经高温处理其抑菌能力无明显降低。皮肤过敏性测试表明α-BrDMF无明显致敏性。     

新型食品防腐剂富马酸海藻糖甲酯的抗菌特性研究

合成一种具有α,β-不饱和羰基结构的新型食品防腐荆--富马酸海藻糖甲酯(TMF),并对其进行抗菌活性研究.结果表明,TMF抑菌谱广,对大肠杆菌、枯草芽孢杆菌、苏云金芽孢杆菌、牛奶酸败混合菌、啤酒酵母和面包酵母等常见微生物的生长有良好的抑制作用,其最低抑菌浓度(MIC%)分别为0.08、0.07、0.07、0.06、0.04和0.03.添加0.12%的TMF可使大肠杆菌、枯草芽孢杆菌、苏云金芽孢杆菌的生长适应期分别延长至空白对照的11、8、10倍;添加0.08%的TMF可使酿酒酵母和面包酵母的生长适应期可延长至空白对照的9倍左右.TMF可在pH 3-9范围内保持良好的抗菌活性.TMF对供试微生物生长的抑制效果优于苯甲酸、山梨酸及山梨酸钾而与富马酸二甲酯接近,具有广阔的开发前景.     

三种天然食品防腐剂抗菌活性通过分子结构改造而增强的研究

对天然抗菌化合物肉桂醛、肉桂酸和富马酸进行了分子结构改造和活性预测，合成得到了α，β－二溴代肉桂醛、α，β－二溴代肉桂酸酯和α，β－二溴代富马酸二甲酯三种新化合物。对三种新化合物最低抑菌浓度值进行了理论上的计算，并通过实际测定以及与母系其它化合物抗菌活性进行比较加以验证。结果表明，随着α，β－二溴代和酯化，最低抑菌浓度值降低，抗活性增强。α，β－二溴代肉桂醛、α，β－二溴代肉桂酯甲酯，α，β－二溴     

低粘度辛烯基琥珀酸淀粉酯的物化性质研究

以原淀粉为原料用湿法工艺制备的辛烯基琥珀酸淀粉酯,糊的粘度较高,采用洳淀粉酶进行水解得到低粘度的酶解产物,类似于纯胶的变性淀粉产品。本文采用X射线衍射、红外光谱、紫外-可见光谱、HPLC等方法,测定研究辛烯基琥珀酸淀粉酯酶解产物（OSA-SH）的结构、组成、DE值、粘度、表面张力、乳化性参数等理化特性。结果表明,试验的OSA-SH的DE值为3．06,无定形结构,分子中含有C=C、COOR官能团,具有较好的水溶性、高浓低粘性、表面活性和乳化性。     

小麦糊精低脂蛋黄酱研究

采用响应面实验设计方法,研究小麦糊精DE值、替代脂肪率及全蛋添加量等因素对蛋黄酱粘度、质构及感官特性影响,目的是探讨小麦糊精作为脂肪替代品制备低脂蛋黄酱应用效果。实验结果表明,小麦糊精DE值8.0%、替代脂肪率27.7%、全蛋添加量15.8%时,可制备得到感官特性及质构优良的低脂蛋黄酱。     

Food preservative content reduction by controlling sorbic acid release from a superficial coating

In the aim to reduce the total amount of preservatives added in food, edible coating is used in the present study as surface retention of active agents to maintain a local high effective preservative concentration where microorganisms are intended to contaminate and/or grow, i.e. on coating surface. A food/anti-microbial coating system with sorbic acid as the active compound, agar gel as model food and wheat gluten (WG) or beeswax (BW) film as edible coatings was studied. A mathematical model able to describe the release kinetics of the anti-microbial agents from the edible coating into food products was developed and validated. It was used for estimating the local surface concentration in sorbic acid of coated model food. This surface concentration is an essential value for predicting microorganism growth but cannot be evaluated by experiments. In the case of WG coating, the surface concentration drops below 10% of the initial value after 1 h whereas in the case of the BW coating, the surface concentration remains above 75% even after one week of contact. Simulation realized using the estimated surface concentration and a simplified equation for the growth inhibition kinetics of Saccharomyces cerevisiae were compared to microbiological efficacy assessment. The calculated amount of sorbic acid required to maintain a 0.2% surface concentration during 23 days was 100 times lower when introducing the additive in a beeswax thin layer than directly in the core of the high moisture food or in a hydrophilic film such as wheat gluten.Industrial relevanceThe methodology presented in this study based on experimental measurements and mathematical predictions is of great interest for the rational design of anti-microbial coatings and could be used in industrial applications. Edible coatings are already used in commercial practice for their barrier properties (water barrier property for example to avoid remoistening or drying of cereal-based products, gas barrier properties for the coating of fresh fruits and vegetable, etc) or for food appearance improvement (brilliance of apples for examples could be improved using polysaccharide-based film). Edible coatings have proved to be suitable as vector of preservatives such as anti-microbial or anti-oxidants. By using such retention matrices, very small amount of additives is required since the preservative is concentrated at the product surface. The benefit of using anti-microbial edible coating for consumer health is consequently non-negligible and this aspect is more and more taken into account by food manufacturers. The use of active edible coatings at an industrial scale is expected to grow, in Europe, due to the European framework regulation (EC 2004/1935) which authorizes the concept of active packaging with intentional active agents' release.The efficacy of anti-microbial edible coating could be assessed through time-consuming experimental tests. But most of the time, the couple edible matrix/active compound suitable for one applicable won't be anymore suitable for another food product and empirical tests should be undertaken once more by the food manufacturer. By using an integrated approach such as the one presented in this work, based on mathematical model for predicting additive release kinetics, numerous experiments may be avoided, since once the preservative diffusivity values in the coating and the food are known, the numerical tool could be used to optimize the initial quantity of preservative to add in the coating, to predict the food shelf life as a function of coating thickness or coating concentration in preservative, etc. The data shown in this paper concerning wheat gluten- and beeswax-based films could be also added in data bases of industrial relevance for further commercial applications.The approach used in this study could be considered as an assistant and prediction tool that should (i) optimize food preservation and (ii) help manufacturers in elaboration of new food product and packaging.     

天水大红袍花椒籽黑色素的提取工艺优化及体外抗氧化活性分析

采用单因素实验结合响应面法优化天水大红袍花椒籽黑色素提取工艺,并对其抗氧化性进行评价。结果表明,最佳提取工艺为:NaOH浓度1.11 mol/L、提取温度59 ℃、料液比1:23 g/mL、提取时间2 h,在此条件下,天水大红袍花椒籽黑色素得率为7.60%±0.05%,与模型预测值（7.75%）接近,且其相对误差为0.66%,说明该模型回归项良好,拟合度好,优化后的工艺条件可行。体外抗氧化实验结果显示,质量浓度为1.0 mg/mL时,花椒籽黑色素对羟基自由基（·OH）、1,1-二苯基-2-三硝基苯肼自由基（DPPH·）以及2,2'-联氮-双-3-乙基苯并噻唑啉-6-磺酸自由基(ABTS+·)的清除率分别为66.07%±0.96%、61.27%±0.97%、62.19%±0.83%,说明天水大红袍花椒籽黑色素对·OH、DPPH·和ABTS+·均具有良好的清除活性。     

In vitro antifungal effect of black cumin seed quinones against dairy spoilage yeasts at different acidity levels

The antiyeast activity of the black cumin seed (Nigella sativa) quinones dithymoquinone, thymohydroquinone (THQ), and thymoquinone (TQ) were evaluated in vitro with a broth microdilution method against six dairy spoilage yeast species. Antifungal effects of the quinones were compared with those of preservatives commonly used in milk products (calcium propionate, natamycin, and potassium sorbate) at two pH levels (4.0 and 5.5). THQ and TQ possessed significant antiyeast activity and affected the growth of all strains tested at both pH levels, with MICs ranging from 8 to 128 μg/ml. With the exception of the antibiotic natamycin, the inhibitory effects of all food preservatives against the yeast strains tested in this study were strongly affected by differences in pH, with MICs of ≥16 and ≥512 μg/ml at pH 4.0 and 5.5, respectively. These findings suggest that HQ and TQ are effective antiyeast agents that could be used in the dairy industry as chemical preservatives of natural origin.     

ε-聚赖氨酸抑菌性能研究

分别采用分光光度法、菌体量法以及孔扩散法研究了ε-聚赖氨酸对细菌和真菌的抑菌活性及ε-聚赖氨酸浓度、pH值和温度对其抑菌活性的影响。结果表明,ε-聚赖氨酸对金黄色葡萄球菌、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6种供试微生物均有一定的抑制作用,对大肠杆菌、金黄色葡萄球菌、保加利亚乳杆菌抑制效果较好,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12.5 mg/L;枯草芽孢杆菌25 mg/L;酿酒酵母800 mg/L;黄曲霉1 600 mg/L。ε-聚赖氨酸的抑菌活性随其浓度的增加而增强,热稳定性非常好,能耐100℃的高温,在pH5～8抑菌活性最强,与甘氨酸、Nisin都有协同增效的作用。     

雪地茶甲醇提取物体外抑菌活性及其稳定性研究

为初步探究雪地茶体外抑菌活性及其稳定性,采用平板打孔法测定雪地茶甲醇提取物对常见致病菌的体外抑菌活性,以金黄色葡萄球菌作为指示菌,测定不同温度、pH、紫外照射时间等因素对抑菌稳定性的影响,使用石油醚、乙酸乙酯、正丁醇分级萃取甲醇提取物,确定其抑菌活性物质的极性,并测定其松萝酸含量。结果表明雪地茶甲醇提取物对革兰氏阳性菌如金黄色葡萄球菌、枯草芽孢杆菌、斯氏李斯特菌、表面葡萄球菌、伊氏李斯特氏菌,革兰氏阴性菌如甲型副伤寒杆菌、乙型副伤寒杆菌以及致病真菌白色念珠菌等具有良好的抑菌效果。其中,对金黄色葡萄球菌的最小抑菌浓度和最小杀菌浓度分别为0.625、10 mg/mL;抑菌稳定性实验结果表明,温度对雪地茶甲醇提取物的抑菌活性无显著影响（P>0.05）,100 ℃处理30 min后仍具有较高的抑菌活性;紫外光照射40 min及50 min的处理组抑菌活性显著下降（P<0.05）,但抑菌率仍保持在90%以上;pH对雪地茶甲醇提取物的抑菌稳定性影响最大,当pH接近生理中性时（pH=6.0）,其抑菌活性与对照组（pH=4.83）无显著差异（P>0.05）,表现出较高抑菌活性,当pH较高（8.0、10.0）或较低（2.0、4.0）时,处理组的抑菌活性极显著下降（P<0.05）,且随着pH的升高或降低而降低;雪地茶甲醇提取物中松萝酸含量为0.8613%,乙酸乙酯萃取物中松萝酸含量为0.9379%。本实验结果证实雪地茶甲醇提取物具有一定的广谱抑菌效果且作用浓度较低,稳定性较好,可用于天然食品防腐剂和植源性抑菌药物的开发利用。     

抗菌肽研究进展

寻找新型更安全、环保的食品防腐剂和无残留、无耐药性的饲料添加剂是目前食品行业和畜牧行业的一个研究热点。与传统的食品防腐添加剂相比,抗菌肽具有抗菌谱广、对环境无污染、可生物降解、协同作用、不易产生耐药性、稳定性好、作用范围广等优点,本文主要对抗菌肽的特点、作用机制与应用进行了介绍。随着人们生活水平的提高和对健康、长寿的重视,逐渐对一些可以直接或间接在体内蓄积的食品及饲料添加剂提出了更安全、更环保的要求,而抗菌肽的特点符合这一时代的需求特征,必将在防腐添加剂方面得到广泛应用。     

响应面法优化南极磷虾亚铁螯合肽制备工艺及其理化性质

以南极磷虾为原料,酶解制备亚铁螯合肽。以亚铁螯合率为主要指标,水解度为辅助指标,在单因素实验基础上,利用响应面优化制备南极磷虾亚铁螯合肽(Antarctic krill iron-chelating peptides,AKIP),并对其理化性质进行分析。结果表明:Alcalase 2.4 L是南极磷虾酶解的最适用酶,最佳酶解条件为:酶解温度57.6 ℃,加酶量5.5%,pH8.8,酶解时间5 h,在此条件下酶解液的亚铁螯合率为77.77%±0.72%,水解度为23.22%±0.16%,实测结果与预测值符合良好。氨基酸组成分析表明,南极磷虾亚铁螯合肽具有良好的亚铁螯合活性位点。AKIP的相对分子质量主要分布在180~1000 Da之间,约占89.28%。体外抗氧化实验表明,AKIP对DPPH自由基和羟自由基均有良好的清除能力(IC₅₀分别为1.92、2.09 mg/mL),且呈现较好的量效关系,在食源性螯合肽和天然抗氧化剂领域具有一定的开发利用价值。