高效液相法测定草鱼糜发酵过程中生物胺变化

本文采用纳豆芽孢杆菌和戊糖片球菌组成的混合发酵剂对草鱼鱼糜进行发酵,建立了发酵鱼制品中六种生物胺(色胺、腐胺、尸胺、组胺、酪胺、亚精胺)的高效液相色谱分析方法,研究了鱼糜发酵过程中生物胺含量的变化以及微生物数量的变化。结果发现,在30 min内各种生物胺得到很好的分离,且线性关系良好(R2>0.999),回收率在97.35%~103.00%,精密度、重现性RSD均小于10%。添加混合发酵剂可以明显抑制金黄色葡萄球菌、假单胞菌和大肠杆菌等杂菌的生长,降低发酵过程中腐胺、尸胺、组胺和酪胺含量的积累;利用纳豆芽孢杆菌,戊糖片球菌组成的混合发酵剂以及一系列负控脱羧酶活动能有效抑制鱼糜发酵过程中生物胺的形成,抑制腐败菌和致病菌的生长,提高鱼糜发酵食品的品质。      

Fermentation of bighead carp (Aristichthys nobilis) surimi and the characteristics of fermented bighead carp surimi products

BACKGROUND: To improve the properties and functionality of bighead carp (Aristichthys nobilis) muscle, bighead carp surimi was inoculated with combinations of Saccharomyces cerevisiae, Lactobacillus and Monascus and fermented, and then bighead carp sausages were prepared. The characteristics of fermented bighead carp surimi and sausages were investigated. RESULTS: During the 24 h fermentation at 30 °C, bighead carp surimi inoculated with mixed starter cultures resulted in a rapid decrease of pH, and suppression in the growth of Enterobacteria. The bighead carp sausages exhibited better colour, taste, flavour and appearance than the control (P < 0.05). The changes in non‐protein nitrogen (NPN), free amino acid in the fermented bighead carp surimi and SDS–PAGE patterns indicated that severe hydrolysis of muscle protein had occurred during fermentation. The sausages inoculated with the mixed starter cultures gained higher scores for flavour and overall acceptability than the control. CONCLUSIONS: The characteristic of fermented bighead carp surimi and sausages can be significantly improved by fermentation with the combinations of yeast, Lactobacillus and Monascus. Copyright © 2008 Society of Chemical Industry     

Effect of fermentation with mixed starter cultures on biogenic amines in bighead carp surimi

The effects of one group mixed starter cultures, combined with Lactobacillus casei, Streptococcus lactis, Saccharomyces cerevisiae Hansen, and Monascus anka, and a batch without starter as control on biogenic amines accumulation in the bighead carp surimi during fermentation were investigated. Determination of five different biogenic amines was carried out by reverse‐phase high‐performance liquid chromatography with UV detection. Results showed that mixed starter cultures decreased the pH quickly from initial pH value of 6.4 to 5.2, inhibited the growth of contaminant microorganisms, such as Enterobacteriaceae and Pseudomonas, present in the raw materials, and suppressed the accumulation of histamine, tyramines, spermine and spermidine. Fermentation inoculated with combination of Lactobacillus casei, Streptococcus lactis, Saccharomyces cerevisiae Hansen, and Monascus anka with negative‐decarboxylase activity may prevent biogenic amine formation in the fermented ssurimi and improve hygienic quality of fermented surimi.     

Improvement of sensory quality of lowfat kefalograviera-type cheese by using commercial special starter cultures

Two commercially available special starter culture systems, Alp DIP and a mixture of Alp DIP D and Joghurt V1, were compared with one commercial regular starter culture, CH-1, for their effects on the compositional, sensory and textural characteristics of lowfat (9.5%) high moisture (49.6%) Kefalograviera-type cheese during aging. A full-fat control Kefalograviera cheese (30.8% fat, 37.8% moisture) was also made with the regular starter culture. The results indicated that the type of starter did not affect the composition (moisture, fat, protein, salt and pH) of the lowfat cheese. Sensory analysis showed that the lowfat cheeses made with the special cultures received greater body and texture scores and significantly higher flavor scores than the lowfat control cheese after aging for 90 and 180 d. Moreover, the former cheeses received body and texture and flavor scores not significantly different from those of the full-fat cheese. Texture profile analysis by Instron showed that there were no significant differences in the textural characteristics (force and compression to fracture, cohesiveness, springiness, gumminess and chewiness) between lowfat cheeses made with the special cultures and that made with the regular starter, except for hardness which was significantly lower in the former cheeses.     

降胆固醇混合发酵剂制备工艺的研究

以具有高效降解胆固醇作用的植物乳杆菌和干酪乳杆菌为原料,利用真空冷冻干燥技术,制备出发酵性高、便于储藏、复水性好的混合肉品发酵剂。通过单因素实验和正交实验确定出最佳的菌株培养条件:2菌株的配比为1:1,培养pH为6.7,接种量为3%,培养时间为16h;最佳的冻干条件:预冻温度为-25℃,干燥温度为-35℃,冻干时间为12h,保护剂为5%蔗糖、3.5%甘油和2.5%碳酸钙。     

Changes of biogenic amines in Chinese low‐salt fermented fish pieces (Suan yu) inoculated with mixed starter cultures

In this study, two groups of mixed starter cultures (S1, S2), which were isolated from Suan yu, were inoculated for this experimental product, and a batch without starters was used as the control. The effect of the mixed starter cultures on the suppression of biogenic amine (BA) produced during the ripening of Suan yu was investigated. Changes in BA, pH, total volatile base nitrogen (TVB‐N), microbial counts and free amino acids (FAA) contents were detected during ripening. The results show that the mixed starter cultures rapidly decreased pH, inhibited the growth of contaminant microorganisms emerged in the sample and drastically reduced the accumulations of tyramine, putrescine and cadaverine. However, histamine and spermine were not produced in any batch. Besides, pH, FAA and BA production were not directly correlated. The study suggests that inoculation with S1 and S2 inhibited BA, thereby improving the product safety.     

油炸温度和时间对草鱼鱼片品质影响的研究

本实验以草鱼为研究对象,以油炸后鱼片的水分含量、含油量、色差、质构和感官评定为评价指标,研究了草鱼鱼片在温度为150、170、185℃的大豆油中分别油炸1、2、3、4、5、6min后品质的变化。结果表明:随着油炸时间的延长,油炸温度的升高,鱼片的水分含量降低,含油量升高,颜色加深,硬度和咀嚼性增加,弹性降低;在170℃温度下油炸5min时,鱼片水分含量为50.12%,含油量为13.01%,感官得分最高。      

发酵剂对牦牛乳硬质干酪成熟过程中生物胺的影响

乳酸菌产生物胺的能力具有菌株特异性,因此,为了探究不同种类发酵剂对牦牛乳硬质干酪中生物胺形成的影响,该试验利用高效液相色谱对3种不同发酵剂制作的硬质干酪成熟过程中生物胺进行了测定和分析。结果表明,嗜热和嗜温发酵剂牦牛乳硬质干酪中检测出2-苯乙胺、腐胺、尸胺、组胺和酪胺,混合发酵剂干酪中检测出腐胺、2-苯乙胺、尸胺和酪胺。各生物胺之间呈现正相关性。3种不同发酵剂干酪在1～6个月成熟过程中,其各生物胺整体呈现增加趋势,嗜热、嗜温和混合发酵剂干酪中总生物胺最高含量分别为(448.3±9.6)、(456.8±58.4)、(293±24.5)mg/kg。组胺和酪胺是2种毒性相对高的生物胺,嗜热发酵剂干酪中组胺和嗜温发酵剂干酪中酪胺最高,其最高含量分别为(20.8±7.9)、(92.9±6.7)mg/kg,混合发酵干酪中未检测出组胺,酪胺含量次之,3种不同发酵剂干酪中组胺、酪胺含量均低于推荐安全剂量50 mg/kg和100 mg/kg。这为合理选择发酵剂和控制干酪中生物胺形成提供了依据。     

草鱼皮明胶-可得然胶共混体系流变特性及作用机理的研究

为探讨可得然胶与草鱼皮明胶之间的相互作用,以草鱼皮明胶为原料,加入不同浓度的可得然胶,研究鱼皮明胶-可得然胶共混体系的粒径、流变学特性以及FTIR的影响。结果表明,共混体系的粒径随可得然胶浓度的增加而增大,当可得然胶浓度为0.5%时,粒径达到1203.8 nm,约为明胶分子的4倍;动态流变学表明,共混体系具有更高的储能模量G’和损耗模量G″,表现出较优越的黏弹特性,而且在低频率区域,可得然胶浓度对体系的粘性影响较大,在高频率区域对弹性影响较大;红外光谱扫描结果证实可得然胶与明胶发生相互作用。总之,添加可得然胶提高草鱼皮明胶的稳定性,对鱼皮明胶的广泛应用具有一定的价值。      

混合菌种联合发酵对鱼肉香肠品质的影响

本文研究乳酸菌、葡萄球菌和酵母菌混合菌种联合发酵对鱼肉香肠品质的影响。通过微生物测定、化学指标测定、色差分析和TPA质构分析,探讨发酵过程中鱼肉品质的变化规律。实验结果表明:在发酵的24h中,乳酸菌作为优势菌显著增殖,降低了鱼肉香肠的p H,抑制了假单胞菌和肠杆菌的生长;鱼肉香肠的挥发性盐基氮（TVB-N）含量和硫代巴比妥酸（TBA）值在发酵过程中显著降低,氨基态氮（AAN）含量、白度、硬度和弹性显著提高,说明混合菌种联合发酵可以延缓鱼肉香肠的腐败变质和油脂氧化,有助于风味的形成和营养价值的提高,并使得产品的色泽和质地得到改善。      

V_C、大蒜粉和柠檬酸对草鱼内脏调味基料风味的改善

以氨态氮、多肽的含量及感官评定值为指标,结合风味物质分析,分别研究了添加大蒜粉、VC和柠檬酸对草鱼内脏蛋白质调味基料风味的影响。结果表明,VC、大蒜粉和柠檬酸均能促进风味化合物的形成,大蒜粉最适添加量为0.1%,检测到22种香味活性化合物;VC最适添加量为0.2%,检测到25种香味活性化合物;柠檬酸最适添加量为1.5%,检测到23种香味活性化合物。      

核磁共振技术研究不同漂洗工艺对草鱼鱼糜的影响

利用核磁共振技术研究清水漂洗、盐水漂洗及碱水漂洗对草鱼鱼糜的影响。结果表明:清水和盐水漂洗可以提高草鱼鱼糜的凝胶强度,碱水漂洗会降低草鱼糜的凝胶强度;三种漂洗方法均能提高草鱼鱼糜的持水性,其中盐水漂洗的效果最佳,三种方法均在一次漂洗后达到最佳持水性;一定浓度的盐水漂洗会将一部分盐溶性蛋白溶出,但不会过度溶出;通过正交实验得出最佳漂洗方案为两次水洗一次盐洗,共三次漂洗的方法。      

高黏度低后酸酸奶发酵剂的筛选

对分离到的12株优良乳酸菌,进行了单发酵试验和复配发酵实验。在单发酵实验中分析嗜热链球菌的产粘特性和保加利亚乳杆菌的产酸特性,在复配发酵实验中测定在贮藏期内(21 d)酸度、pH值、黏度、脱水收缩性及对其进行感官鉴评。结果表明,组合PZST4-PZLB5在储存期间保持了良好的风味和流变学特性,并且后酸化程度较小、产黏高,因而适合作为优良的酸奶发酵剂。     

热加工对草鱼鱼肉品质及风味成分的影响

以草鱼为研究对象,以外形、质地、营养价值及风味为评价指标,研究草鱼鱼肉在60,70,80,90,100℃热处理后其品质、蛋白质组成及挥发性风味成分的变化。结果表明:随着热处理温度的增加,鱼肉的L*值升高,a*值降低,硬度、内聚性、氨基酸含量、E/N总体呈上升趋势。利用SPMEGC-MS检测出87种挥发性成分,烷烃类24种,醛类19种,酸类14种,酯类12种,醇类9种,酮类4种,其他化合物5种,其中醇类和醛类物质在所有样品中相对含量最高,是主体物质。     

煎炸草鱼鱼块的电导率与品质变化相关性研究

为探究煎炸草鱼鱼块的电导率与品质变化的相关性。利用LCR阻抗测试仪测定100 kHz下煎炸草鱼鱼片的电导率与电流方向的影响研究;测量煎炸过程中草鱼鱼块的水分含量、油含量、色泽与质构等品质变化,并与导电率进行拟合。结果表明,电流方向与鱼体平行时的电导率大于电流方向与鱼体交叉时的电导率(最大差异值为0.15 S/m);鱼片中膜的存在导致不同电流方向上鱼片电导率的不同;随着煎炸时间的增加((180±2)℃,0~4 min),草鱼鱼块的电导率、水分含量、亮度值下降,含油量、红度值和黄度值、硬度和咀嚼性升高;煎炸草鱼鱼块的电导率变化与鱼块的水分含量、油含量、色泽与质构变化均呈一定的相关性,相关系数均大于0.95。电导率测量方法对检测草鱼鱼片煎炸过程中的品质变化具有可行性,为煎炸草鱼鱼片的通电加热等新型加工方法的应用和淡水鱼制品的精深加工等方面提供基础数据和理论依据。      

草鱼肉蛋白酶解物功能特性及质量控制的研究

采用Neutrase对草鱼鱼肉蛋白进行了酶解,得到了水解度(DH)为4.72%、9.80%、13.32%的酶解产物(NH),并分析了pH与水解度对酶解产物功能特性的影响。结果表明,酶解产物的溶解性、乳化性、起泡性在pH为4时达到最低,而后随pH的增大而增加。在pH为3～8的范围内随水解度的增加,酶解产物的溶解性增加,起泡性降低。pH为4时,水解度为4.72%、9.80%、13.32%的酶解产物的热稳定性之间存在显著性差异(P<0.05),且随水解度升高而增大。在pH为3～5的范围内酶解产物的乳化性随水解度升高而降低。酶解产物的溶解性、乳化性、起泡性间存在相关性(P<0.05)。     

水温差阶段漂洗对草鱼鱼糜凝胶品质的影响

以草鱼鱼糜凝胶为研究对象,从凝胶白度、凝胶强度、TPA质地特性(硬度、压缩功、回复性、可恢复形变、内聚性、咀嚼性)以及凝胶析水率几方面研究了新型鱼糜漂洗方式——水温差阶段漂洗对草鱼鱼糜凝胶品质的影响,结果表明:水温差阶段漂洗可显著提高草鱼鱼糜凝胶的白度和凝胶强度,改善草鱼鱼糜凝胶的质构特性,提高鱼糜凝胶的保水能力。由此可知,水温差阶段漂洗是一种简便、有效的鱼糜漂洗方法。     

开菲尔功能菌组的复合及发酵特性研究

研究了开菲尔粒子中不同分离菌种的发酵情况,对不同比例的乳酸菌、酵母发酵产物的质量指标(如风味、酸度和发泡性)进行了评价,不同比例分离菌种(30～50g/L)在均质乳中(30℃,16h)连续发酵培养,分析检测其中的蛋白质、脂肪、粗多糖、酒精、黏度和VB含量。结果表明,L-1∶L-2∶L-3∶L-4∶L-5∶Y-1∶Y-2=1∶1∶1∶1∶1∶1发酵产物经评价其质量和感官特性最接近开菲尔。     

紫外减菌联合低温对草鱼肉品质及挥发性风味的影响

目的:研究紫外减菌前处理联合低温冷藏对草鱼鱼肉质构品质及挥发性风味物质的影响,并确定最佳的紫外照射时间。方法:以草鱼为试验对象,采用30 W紫外灯照射不同时间(0,30,60,90,150 min)预处理,测定鱼肉冷藏期间(0,3,6,9 d)各品质参数(鱼肉表面细菌总数、汁液流失率、质构参数、色泽、气味感官)及挥发性成分变化。结果:当紫外照射时间为0～150 min时,照射时间越长,草鱼鱼肉表面减菌效果越好,汁液流失率越低,出现腐败气味越晚,但对鱼肉的质构、色泽及冷藏后期(6～9 d)细菌总数影响较小。冷藏期间共检测到90种挥发性风味物质,主要为醛类、酮类、醇类、酯类和酸类,其中辛醛、壬醛、己醛、2,5-辛二酮、1-己醇、1-辛烯-3-醇为紫外处理草鱼肉的主要挥发性成分,且冷藏后期酯类和酸类物质含量逐渐增多。对比控制组,紫外处理可有效延缓冷藏草鱼肉腥味的产生和香味的下降。当紫外照射时间为90 min时,冷藏鱼肉表现出最佳的综合效果,随着照射时间的延长,鱼肉综合得分有所下降。结论:紫外减菌联合低温处理有利于延缓贮藏前期草鱼鱼肉质构品质劣化及风味下降,但对贮藏后期草鱼肉品质影响较小。