In vitro release kinetics of nisin as affected by Tween 20 and glycerol co-encapsulated in spray-dried zein capsules

Delivery systems with sustained release of antimicrobials have been proposed to improve long-term effectiveness of antimicrobials in foods. In this work, we studied the effect of Tween 20 and glycerol in spray-drying formulations on resultant microstructures of zein capsules and release profiles of encapsulated nisin. Tween 20 and glycerol changed capsules from a continuous matrix to shell-type structures. All samples showed complete release of nisin in 30 min at pH 2.0. Capsules with a higher amount of Tween 20 showed more complete release of nisin at pH 8.0, in contrast to no apparent impact by glycerol. Addition of 0.05% Tween 20 or glycerol in the feed both reduced the burst release of nisin at pH 6.0, but no conclusive trends were observed for the impact of their usage levels. Our work showed that an appropriate formulation is needed to obtain desirable delivery systems of antimicrobials such as nisin.     

Combined effect of natural antimicrobials and thermal treatments on Alicyclobacillus acidoterrestris spores

Commercial fruit juices are currently pasteurized at temperatures between 80 °C and 100 °C and Alicyclobacillus acidoterrestris spores can survive these thermal treatments. A. acidoterrestris produces several chemical off-odour compounds which cause the fruit juice spoilage. The purpose of this research was to evaluate the effect of the combination of a thermal treatment with natural antimicrobials (nisin, citral and limonene) on the survival and recovery of A. acidoterrestris spores. Heat resistance determinations at 95 °C in pH 3.5 McIlvaine buffer with or without the addition of these antimicrobials (alone or combined) in the heating or recovery media were performed. None of the antimicrobials reduced the heat resistance of A. acidoterrestris spores when added to the heating medium. However, nisin (1.5 mg L⁻¹) alone was able to reduce the viable counts of this microorganism by more than two log cycles when added to the plating medium, even when no thermal treatment was previously applied. The different combinations of nisin with citral on the recovery medium, showed a strong synergistic effect on A. acidoterrestris. Limonene showed no inhibitory effect in either media (heating and recovery). The addition of natural antimicrobials such as nisin or citral, which would not affect the flavor or taste of citrus juices, alone or even combined, can help to the control of A. acidoterrestris.     

Nisin及其在果蔬制品中的应用

Nisin是一种新型天然食品防腐、保鲜剂，它是目前世界上唯一允许使用在食品防腐方面的抗菌素。本文综述了Nisin的结构、性质、作用机理等，并论述其在蔬菜制品上的应用。     

生物保鲜剂结合微冻保藏对杂色蛤肉的保鲜作用

目的评价生物保鲜剂在微冻条件下的保鲜作用。方法以杂色蛤肉为研究对象,经溶菌酶、乳酸链球菌素及真空包装处理,测定其在(-3±0.5)℃贮藏过程中的细菌总数、理化等指标的变化。结果在-3℃条件下贮藏25 d后,经溶菌酶、乳酸链球菌素处理的杂色蛤肉挥发性盐基氮分别达到了14.73 mg/100 g和14.92mg/100 g,均接近国家规定的卫生标准;溶菌酶、乳酸链球菌素复合处理的杂色蛤肉贮藏30 d其挥发性盐基氮为14.38 mg/100 g,比未经处理的对照组延长了15 d以上。各处理组的pH值、细菌总数、挥发性盐基氮、硫代巴比妥酸和Ca2+-ATPase活性变化也均与贮藏时间相关(P0.05)。结论相对于其他实验组,溶菌酶、乳酸链球菌素复合处理组保鲜效果最好。     

微波诱变对乳酸乳球菌Nisin产量的影响

用微波诱变Nisin产生茼，获得一突变菌株WY-4，用琼脂扩散法测得WY-4菌株的生物效价为511．56IU/mL．比原始菌株提高42．13％。遗传稳定实验证明其遗传性状稳定。     

生物防腐剂用于酱油保鲜的研究

通过对酿造酱油中G+、G-菌组成情况的分析,研究了天然生物防腐剂Nisin对酿造酱油中腐败细菌的抑制效力。对腐败细菌在不同Nisin含量的营养肉汤培养基及酱油原液中培养试验的结果显示:在腐败菌最适生长温度36℃下培养,当Nisin的含量达到100μg/mL时,营养肉汤(pH4.60)中腐败细菌的总数急剧减少;当Nisin的含量达到50～100μg/mL时,即能有效地抑杀酱油中的腐败细菌。这表明Nisin可替代化学防腐剂用于酱油的防腐保鲜,以减轻酱油的巴氏灭菌强度,保持酱油原有营养成分、风味、色泽,延长制品货架期。     

溶菌酶与Nisin生物保鲜剂对缢蛏保鲜效果的研究

实验研究了冷藏条件下用Nisin与溶菌酶复合生物保鲜剂对缢蛏的保鲜效果,研究结果表明:Nisin和溶菌酶单独使用或混合添加与单纯冷藏(对照组)相比均具有明显的保鲜效果,混合添加保鲜效果更佳,该研究对于延长缢蛏的冷藏期具有一定的实际意义。     

冷却肉生产中保鲜技术的研究——溶菌酶、Nisin、GNa液复合性保鲜试验

本试验详细研究了GNa液、乳酸菌肽(Nisin)、溶菌酶在冷却肉保鲜中的效果。试验得出GNa液对维持肉的感官指标具有良好的效果，Nisin对于抑制脂肪的酸败和G^ 细菌及大肠杆菌的增殖方面具有明显的效果，而溶菌酶对于控制细菌总数的增殖、减缓TVB—N值的上升方面具有极其重要的作用。在试验中由于采用了GNa液、Nisin、溶菌酶三者配合使用，取得了非常理想的效果，以第五组的保鲜效果最为理想。     

红曲色素、乳酸链球菌素、山梨酸钾对肉毒梭状芽孢杆菌的抑制研究

试验对红曲色素、乳酸链球菌素和山梨酸钾三种物质抑制肉毒梭状芽孢杆菌的情况与ＮａＮＯ＿２抑制肉毒梭状芽孢杆菌进行了比较，证明三种物质都具有不同程度的抑制肉毒梭菌生长的能力。Ｎｉｓｉｎ和山梨酸钾的抑制作用较红曲色素更强。     

产生菌株的筛选及其鉴定

以从传统乳制品中分离得到的7株乳酸菌为出发菌株,应用琼脂扩散法,以黄色微球菌为指示菌,筛选到了一株具有较大抑菌作用的乳酸菌.对S7产生的抑菌物质的物理化学性质研究表明,该抑菌物质的性质与Nisin一致;同时16SrDNA序列分析结果显示,S7是一株乳酸乳球菌,综合以上结果,可以认为这是一株Nisin产生菌.