电子束辐照对鲐鱼肉品质的影响

以真空包装和普通包装的鲐鱼肉为原料,分别用3、5和7kGy的电子束进行辐照,测定冷藏期间鲐鱼肉挥发性盐基氮(VBN)、过氧化值(POV)、组胺及其不饱和脂肪酸(UFA)的含量,结合感官评价研究电子束辐照处理对鲐鱼肉品质的影响。结果表明,电子束辐照处理使鲐鱼肉VBN、组胺含量得到了控制,减缓了样品在冷藏期间不饱和脂肪酸氧化的速度。因此电子束处理能延长鲐鱼肉保质期,冷藏前,对其采取普通包装、5kGy电子束辐照处理较为合适。     

电子束辐照对美国红鱼杀菌保鲜效果的研究

以美国红鱼为对象,利用不同剂量电子束处理,对冷藏期内鱼肉菌落总数、总挥发性盐基氮（TVB-N）、过氧化值（POV）及鲜度指标K值进行测定,分析不同剂量电子束辐照对美国红鱼肉的杀菌效果及品质影响。结果表明：电子束辐照能有效降低美国红鱼肉的菌落总数,其中D10=161kGy,D=540kGy,冷藏期间辐照组样品菌落生长缓慢,且辐照剂量越大,杀菌效果越强;电子束处理后美国红鱼肉TVB-N值、POV均有不同程度增加,但在冷藏期内对照组TVB-N值、POV、K值的上升速度大于辐照组样品;辐照对美国红鱼肉感官影响不明显,但6kGy辐照组鱼肉色泽略微变红。综合考虑,美国红鱼肉经4kGy 电子束辐照,能有效杀灭其中的微生物,冷藏条件下保质期可达到14d,比对照延长5d左右。     

电子束辐照对素鸡杀菌效果及品质特性影响的研究

以素鸡为试验对象,研究电子束辐照对素鸡杀菌效果及其营养品质和感官品质的影响。结果表明,电子束辐照对素鸡的杀菌效果显著,D10=0．48kGy;8．8kGy以下电子束辐照对素鸡蛋白质、脂肪、脂肪酸、氨基酸的影响在5％水平上差异不显著,在水分含量方面差异显著;经8．8kGy电子束辐照处理的素鸡与对照素鸡相比,其感官品质未呈现显著差异。综合考虑,2．4kGy电子束辐照处理可以有效控制素鸡中的细菌而不影响其营养和感官品质,其货架期可达8d;电子束辐照素鸡的最高耐受剂量至少为8．8kGy。     

适宜电子束辐照延长醉泥螺货架期及蛋白质保持

为探明电子束辐照对醉泥螺的杀菌效果及辐照后醉泥螺感官品质与蛋白质营养价值的变化,为生食醉泥螺的辐照保鲜应用提供理论依据。以生食醉泥螺为研究材料,研究不同剂量电子束辐照对醉泥螺菌落总数、感官评分、蛋白质含量及其氨基酸组成的影响,并分析辐照后醉泥螺在冷藏和常温贮藏条件下的货架期变化。结果表明：1）经1～9 kGy剂量电子束辐照,醉泥螺的色泽和形态几乎没有变化,但7、9 kGy剂量组醉泥螺产生异味;2）辐照剂量越高,杀菌效果越好,当醉泥螺的初始菌落总数为1200 cfu/g时,菌落总数降至初始值10%所需的辐照剂量D10为3.46 kGy;3和5 kGy剂量的辐照对醉泥螺的抑菌效果明显,无论是冷藏还是常温贮藏,360 d内菌落总数均未超过5000 cfu/g;3）辐照对醉泥螺蛋白质含量无明显影响(P?0.05),不改变醉泥螺的限制性氨基酸种类,但经1、3、5 kGy辐照后,氨基酸总量、必需氨基酸总量及各必需氨基酸的氨基酸评分增加;4）结合电子束辐照对醉泥螺菌落总数及感官评分的影响,辐照剂量以3 kGy为宜,醉泥螺保质期冷藏条件下由对照组的5个月延长至12个月,常温条件下由对照组的不到1个月延长到3个月。该结果能为电子束辐照保鲜醉泥螺提供依据。     

电子束辐照对冷鲜猪肉品质的影响

以冷鲜猪肉为试验对象,研究电子束辐照对冷鲜肉品质的影响.采用不同剂量电子束(0、2.0、3.8、6.2、8.3、10.5 kGy)辐照肥瘦比为1∶6的冷鲜肉,测定冷鲜肉的蛋白质与粗脂肪含量的变化;研究了冷鲜肉的TBARS值、过氧化值、双烯值的变化,分析冷藏过程中猪肉氧化程度的变化,并进行色度及感官的测定.结果表明:经电子束处理后,冷鲜肉的蛋白、粗脂肪含量没有明显变化;冷鲜肉的TBARS值、过氧化值有增加,总双烯值有一定程度的增加;3.8、6.2 kGy剂量组在贮藏期内色泽好;不同剂量电子束处理,对冷鲜猪肉感官品质无显著影响.综合考虑:经过4 ～6 kGy电子束处理能有效延长冷鲜肉保质期,并对其品质无明显影响.     

以生物胺变化评价冷藏罗非鱼片腐败进程

为了探讨生物胺指标评价鱼肉腐败进程的可能性及其安全范围,应用反相高效液相色谱法测定冷藏罗非鱼片贮藏过程的生物胺变化,用以判断鱼片的腐败进程。结果表明:新鲜鱼片初始单胺和多胺总量较高,二胺总量很低。贮藏过程中单胺和多胺波动变化并呈下降趋势,尸胺、腐胺含量快速增加成为主要生物胺。含有尸胺+腐胺的二胺、生物胺指数、总生物胺等指标与其两者增长趋势相似。相关分析表明尸胺、腐胺、二胺、生物胺指数、总生物胺与贮藏时间、微生物数量和氨基态氮具有高度相关性。经回归分析表明假单胞菌、肠杆菌的增长与尸胺、腐胺具有重要的对应关系。尸胺、腐胺和二胺可简便有效评价鱼片腐败进程;但综合考虑组胺和酪胺的毒性,则生物胺指数(BAI)更适用,冷藏罗非鱼片生物胺指数的初步判别范围为:<20mg/kg,新鲜;20～40mg/kg,可接受;>40mg/kg,腐败。该研究为冷藏罗非鱼片生物胺的限量标准提供数据参考。     

辐照对泡椒凤爪感官品质的影响

辐照可以有效的控制泡椒凤爪中的乳酸菌含量,从而延长其货架期。本文根据相关的标准和调研,以色泽及形态（权重30%）、香气（权重30%）、质地及滋味（权重40%）为评价指标,制定了泡椒凤爪的感官分析标准,并用此标准对辐照处理后的泡椒凤爪进行了感官品质分析。结果表明贮藏3d后的3、5、8、12kGy辐照的样品,其感官评价结果与对照相比无显著差异,辐照剂量为10 kGy的样品感官评价结果还显著优于对照组。贮藏11d后,样品的感官品质也未降低。由此得出结论：辐照不会影响泡椒凤爪的感官品质,适当剂量的辐照还有助于提高泡椒凤爪的被接受程度。     

辐照灭菌对红薯干品质和贮藏特性的影响

为了获得标准化的红薯干辐照灭菌工艺,本试验以γ射线与电子束为不同辐射源,就不同辐照剂量和剂量率对红薯干主要成分、外观品质和贮藏特性的影响开展研究。结果表明,经γ射线≥4 kGy剂量辐照,36℃恒温培养10 d或常温贮存90 d两种方式处理的红薯干;经γ射线≥6 kGy剂量辐照,36℃恒温培养30 d或常温贮存360 d两种方式处理的红薯干,均未检测出微生物。γ射线辐照处理后,红薯干的可溶性固形物、类胡萝卜素含量和感官指标均未发生显著变化。相同剂量下,剂量率越高对红薯干的外观影响越大。电子束剂量率高,辐照处理后的红薯干外观呈黄白色,发生了显著变化。红薯干货架期90 d的辐照灭菌最低有效剂量为4 kGy。本研究结果为红薯干辐照加工工艺的制定提供了依据。     

高能电子束辐照对鲜切哈密瓜生理生化品质的影响

通过0．5、1．0、1．5和2．0kGy剂量的电子柬辐照处理鲜切哈密瓜,采用聚丙烯（PP）材质托盘和聚乙烯（PE）保鲜膜包装,置于5℃,相对湿度85％-95％的冷库中贮藏,研究高能电子束辐照对鲜切哈密瓜生理生化品质的影响。结果表明,电子束辐照能显著降低呼吸速率,显著抑制Vc、可溶性固形物的含量的下降,减少丙二醛积累,降低多酚氧化酶和过氧化物酶活性,并提高苯丙氨酸解氨酶活性。1．5kGv辐照处理的鲜切哈密瓜在贮藏至第13天时,感官品质保持良好。综合电子束辐照对鲜切哈密瓜的保鲜效果,确定最佳处理剂量为1．5kGy。     

电子束辐照对蓝莓品质及生理代谢的影响

探讨电子束辐照对"艾利奥特"蓝莓采后冷藏期间品质及生理代谢的影响,为探索实用、有效的蓝莓贮藏技术提供一定的理论依据和技术支撑。辐照剂量分别为0.5、1、1.5、2和3kGy,以未辐照的处理为对照,蓝莓辐照后置于温度为(1±0.5)℃、相对湿度为80%~85%的冷库中,定期检测各项指标,研究不同剂量辐射对蓝莓生理代谢及品质的影响。结果表明:适宜剂量的电子束处理可显著降低蓝莓的腐烂率、失重率,并可有效抑制蓝莓的呼吸强度,较好的保持了细胞膜结构的完整性;延缓可溶性固形物、维生素C、及可滴定酸含量的下降;对蓝莓果皮无显著褪色的副作用,延长了其有效贮藏期。其中以辐照剂量为1kGy的电子束辐照处理对"艾利奥特"蓝莓的贮藏效果最为显著,可将其有效贮藏期由原来的30d延长至60d,好果率可达90%以上,失水率控制在10%以内,显著优于其他处理组。     

Determination of biogenic amines in squid and white prawn by high-performance liquid chromatography with postcolumn derivatization

A simple method was developed for the determination of biogenic amines in aquatic food products using a reverse-phase high-performance liquid chromatography with postcolumn automatic o-phthalaldehyde derivatization and fluorescence detection. The linearity, repeatability, and recovery of the method for seven amines (tyramine, putrescine, cadaverine, histamine, agmatine, spermidine, and spermine) were evaluated. This optimized method was applied to detect biogenic amines in squid and white prawn during refrigerated storage. Sensory analysis, pH value, and total volatile base nitrogen value were combined to evaluate the freshness quality of these two raw materials. Agmatine and cadaverine in squid, cadaverine, and putrescine in white prawn were the most obviously changed amines during the storage at two different temperatures, and these biogenic amines could be the effective quality indicators for the freshness of the raw aquatic materials.     

Relation of biogenic amines' formation with microbiological and sensory attributes in Lactobacillus-inoculated vacuum-packed rainbow trout (Oncorhynchus mykiss) fillets

The biogenic amine (BA) content of vacuum-packed filleted rainbow trout (Oncorhynchus mykiss) inoculated or not with two different Lactobacillus strains, individually or in combination, was monitored during refrigerated storage for 20 days and related to respective bacteriological and sensory changes occurring during the same period. Eight amines, namely putrescine, cadaverine, tyramine, tryptamine, beta-phenylethylamine, histamine, spermine, and spermidine, were determined, whereas agmatine was not detected in any of the samples. In all cases, BA concentration was higher (P < or = 0.05) in the controls compared to all inoculated treatments, whereas the trend with regard to the bacterial populations (Enterobacteriaceae, pseudomonads, and H2S-producing bacteria) and the off-odor scores was similar. Inoculation with Lactobacillus sakei CECT 4808 showed the best preservative effect among inoculated treatments. Concentrations of putrescine and cadaverine, the main BAs formed, correlated well with both spoilage bacterial counts and off-odor scores and can be useful indicators of shelf life. Spermine and spermidine contents decreased during storage, while levels of the other determined BAs remained below 10 mg/kg even after sensory rejection.     

Influence of cultivar and germination on bioactive amines in soybeans (Glycine max L. Merril)

The levels of amines in soybeans as affected by cultivar in two consecutive years and by germination were investigated. Spermidine, spermine, putrescine, agmatine, and cadaverine were detected, whereas tyramine, histamine, tryptamine, serotonine, and phenylethylamine were not. Spermidine was the predominant amine followed by spermine. High concentrations of these amines confirmed soybean as a rich source. Cadaverine was confirmed to be inherent to soybean. The percent contribution of spermidine and spermine to total levels was not affected by cultivar in either years. However, amine levels were affected by cultivars in different ways in the consecutive years. Cadaverine was affected more by the cultivar, whereas spermidine, spermine, and agmatine were affected by harvest year. During germination the levels of amines from soybean increased significantly, except for agmatine. Spermidine and spermine accumulated in the cotyledon, whereas cadaverine and putrescine accumulated in the radicle and hypocotyl.     

High-performance liquid chromatographic determination of biogenic amines in poultry carcasses

Biogenic amines, produced by bacterial decarboxylation of amino acids, have been associated with toxicological symptoms in broilers fed various poultry byproducts. A reversed-phase high-performance liquid chromatographic method is described for the quantitation of eight biogenic amines (tryptamine, phenylethylamine, putrescine, cadaverine, histamine, tyramine, spermidine, and spermine) in chicken carcasses. Amines were extracted with perchloric acid, derivatized with dansyl chloride, separated using gradient elution (methanol and water), and detected by fluorescence. Benzylamine was used as the internal standard. Linearity, repeatability, and recovery of the method were evaluated. The method was linear for all of the amines studied at concentrations ranging from 0.05 to 25 microg/mL. Average recoveries ranged from 92.6% to 96.8% for all amines except for histamine, which was 74.6%.     

Biogenic amine profile in unripe Arabica coffee beans processed according to dry and wet methods

Immature coffee fruit processing contributes to a high amount of defective beans, which determines a significant amount of low-quality coffee sold in the Brazilian internal market. Unripe bean processing was tested, taking the levels of bioactive amines as criteria for evaluating the extent of fermentation and establishing the differences between processing methods. The beans were processed by the dry method after being mechanically depulped immediately after harvest or after a 12 h resting period in a dry pile or immersed in water. Seven bioactive amines were quantified: putrescine, spermine, spermidine, serotonin, cadaverine, histamine, and tyramine, with global amounts ranging from 71.8 to 80.3 mg/kg. The levels of spermine and spermidine were lower in the unripe depulped coffee than in the natural coffee. The specific conditions of dry and wet processing also influenced cadaverine levels, and histamine was reduced in unripe depulped coffee. A resting period of 12 h does not induce significant alteration on the beans and can be improved if performed in water. These results confirm that peeling immature coffee can decrease fermentation processes while providing more uniform drying, thus reducing the number of defects and potentially increasing beverage quality.     

High-performance liquid chromatographic method for determination of biogenic amines in feedstuffs, complete feeds, and animal tissues

Numerous methods to analyze biogenic amines in biological materials have been described. A versatile and rapid methodology to analyze these compounds in feedstuffs, complete feeds, and animal tissues, however, has not been reported. The current method was developed to address this need. Biogenic amines in feedstuffs, complete animal feeds, and animal tissues were extracted with 10% trichloroacetic acid, reacted with O-phthaladehyde using high-performance liquid chromatographic employing a cation exchange column. Detection limits were 50 pmol/mL for tyramine, histamine, putrescine, and spermine; 40 pmol/mL for cadaverine; and 25 pmol/mL for spermidine. Extraction efficiency of biogenic amines in feedstuffs, duodenum, liver, ileum + jejunum, and whole shrimp and shrimp hepatopancreas ranged between 99-105, 93-135, 80-85, 65-102, 88-98, and 88-97%, respectively. It can be concluded that the current method can be applied to individual feedstuffs, complete feeds, and animal tissues for the rapid and accurate determination of concentration of biogenic amines.     

Development of stable isotope dilution assays for the simultaneous quantitation of biogenic amines and polyamines in foods by LC-MS/MS

Microbial amino acid metabolism may lead to substantial amounts of biogenic amines in either spontaneously fermented or spoiled foods. For products manufactured with starter cultures, it has been suggested that certain strains may produce higher amounts of such amines than others; however, to support efforts of food manufacturers in mitigating amine formation, reliable methods for amine quantitation are needed. Using 10 isotopically labeled biogenic amines as the internal standards, stable isotope dilution assays were developed for the quantitation of 12 biogenic amines and of the 2 polyamines, spermine and spermidine, in one LC-MS/MS run. Application of the method to several foods revealed high concentrations of, for example, tyramine and putrescine in salami and fermented cabbage, whereas histamine was highest in Parmesan cheese and fermented cabbage. On the other hand, ethanolamine was highest in red wine and Parmesan cheese. The results suggest that different amino acid decarboxylases are active in the respective foods depending on the microorganisms present. The polyamine spermine was highest in salami and tuna.