辐照对真空包装鲫鱼的保藏作用及对鲫鱼中沙门氏菌属和志贺氏菌属的杀灭作用

为研究辐照对真空包装鲫鱼的保藏作用进行本试验.发现30℃条件下不适于辐照鲫鱼的保藏.在4℃条件下,2.5 kGy的辐照可明显延长鲫鱼的保存期,随着辐照剂量的增加,保存期不断延长.对辐照后鲫鱼进行微生物分析发现,辐照可明显地降低鲫鱼试样中菌落总数和大肠菌群数,1.0 kGy的辐照剂量可使鲫鱼中大肠菌群的MPN值小于30/100 g.1.0 kGy的辐照剂量可有效地杀灭鲫鱼中人工污染的志贺氏菌,1.5 kGy的辐照剂量可有效地杀灭鲫鱼中人工污染的沙门氏菌.     

辐照保鲜技术对碱面条品质特性的影响

采用不同剂量γ射线辐照小麦粉并添加碳酸钠制作碱面条，研究辐照处理对碱面条保质期及品质特性的影响。结果表明：γ射线辐照处理小麦粉可有效降低小麦粉中的菌落总数，当辐照剂量为4 kGy时，小麦粉中菌落总数灭活率高达99%;在1～5 kGy剂量范围内，辐照处理协同碳酸钠作用可以改善碱面条的品质特性和感官评价，并能够有效延长其保质期。相比于未处理的生鲜湿面，当辐照剂量为4 kGy时，可将碱面条的保质期延长至6倍。     

电子束辐照对松花粉脂质氧化及其品质的影响

以原松花粉为试材,研究电子束辐照对其杀菌效果、脂肪酶活力、脂质氧化性能和营养品质的影响,并分析了破壁松花粉在加速氧化过程中色泽、过氧化值和挥发性成分的变化。结果表明,电子束辐照可显著降低松花粉中微生物含量,且辐照剂量越大,杀菌效果越显著;菌落总数、霉菌酵母数和大肠菌群的D10值分别为2.20、1.95和1.84 kGy;随着辐照剂量的增加,松花粉中脂肪酶活力、类胡萝卜素含量和游离脂肪酸含量显著降低,过氧化值略有升高但总体仍处于较低水平,当辐照剂量为8 kGy时,脂肪酶灭活率为53.52%,类胡萝卜素保留率为60.81%,游离脂肪酸含量为1.38 mg/kg,过氧化值为0.46 meq/kg;此外,8 kGy剂量辐照对松花粉的基本营养成分及氨基酸含量无明显影响,在加速氧化过程中,破壁松花粉的色泽无明显变化,过氧化值、己醛和己酸含量增幅不大。表明8 kGy电子束辐照对松花粉营养品质影响不大,并能有效杀灭微生物,抑制脂质氧化,提高产品储藏稳定性。     

电子束辐照处理对生鲜猪肉的保鲜作用

为研究电子束辐照处理对生鲜猪肉品质的影响,该实验使用1 kGy、3 kGy、5 kGy、7 kGy、9 kGy辐照剂量对生鲜猪肉进行处理,于4 ℃环境下贮藏。在贮藏期间进行理化指标的测定,结果表明：小于3 kGy的辐照剂量,对生鲜猪肉色泽有一定促进作用。高剂量（大于7 kGy）的辐照处理,会影响生鲜肉色泽感官。辐照对生鲜肉脂肪氧化促进作用以及杀菌效果十分明显,在第12 d时空白组TBARS值最低,仅为0.446 mg/kg,9 kGy组数值最高,达到了0.650 mg/kg。空白组货架期仅为7~8 d,而7 kGy、9 kGy组第12 d时菌落值仍在合格肉标准内,延长了5 d货架期。挥发性风味物质种类方面,0 kGy、1 kGy组均检测出13种化合物,3 kGy组检测出了10种,5 kGy组检测出了16种,7 kGy组检测出了15种,9 kGy组检测出了14种化合物。高剂量（大于7 kGy）的辐照能够增加生鲜猪肉风味化合物的种类和含量,低剂量的辐照处理对生鲜猪肉风味促进作用不大。通过对各项理化指标的综合考虑,采用3 kGy的辐照处理生鲜猪肉效果最佳。     

X射线辐照对冷鲜猪肉品质和货架期的影响

为研究X射线辐照对冷鲜猪肉品质的影响。该实验用0.1~1.0 kGy梯度的辐照剂量对纯培养细菌、冷鲜猪肉进行处理,评估不同辐照剂量和贮藏时间下微生物、理化指标和感官特性的变化。结果表明：微生物菌落数随辐照剂量的增加而减少。纯培养大肠杆菌和单核细胞增生李斯特氏菌的D10值分别为0.177 kGy和0.180 kGy。0.6 kGy X射线辐照处理时,纯培养细菌菌落数显著（p<0.05）减少3.0 log值以上;人工接种细菌菌落数显著（p<0.05）减少2.0 log值以上。1.0 kGy辐照处理冷鲜猪肉,固有微生物菌落数显著（p<0.05）减少2.0 log值以上;货架期从原来的4 d延长到9 d;贮藏前期感官评分无显著（p>0.05）差异,后期感官评分下降缓慢;与对照相比TVB-N和pH值的上升速率在贮藏期内显著降低（p<0.05）;辐照后冷鲜猪肉TBA值有所增加,但在贮藏中对照组TBA值上升速率大于辐照组。综合考虑,1.0 kGy X射线辐照处理冷鲜猪肉,在保证冷鲜猪肉符合国家食品安全标准规定的同时将货架期延长了 4~5 d,为冷鲜猪肉的辐照保鲜技术提供科学依据。     

不同剂量60Co γ辐照对蓝莓果实贮藏品质的影响

目的探索~(60)Coγ辐照处理对蓝莓果实保鲜效果的影响。方法采用不同的辐照剂量处理"蓝丰"蓝莓,以辐照的蓝莓为研究对象,研究其果实表面微生物的种类和数量、果实腐烂率和硬度、以及相关感官品质在冷藏期间的变化规律。结果辐照处理对蓝莓果实表面微生物有很好的杀灭和抑制作用,辐照剂量越高,效果越好,且微生物对辐照剂量的敏感程度依次为:细菌霉菌酵母菌。0.5 kGy的辐照处理对冷藏期间蓝莓果实保鲜效果不明显(P0.05),3.0 kGy的辐照处理能够加速冷藏后期蓝莓的腐烂变质,适当的辐照剂量(1.0~2.5 kGy)能够很好地降低腐烂率,保持果实硬度和保护果实感官品质,其中2.5 kGy辐照剂量对蓝莓果实的保鲜效果最佳,贮藏35 d后,果实腐烂率最低(3.35%),果实硬度最高(1.08 kg/cm~2)。结论辐照保鲜蓝莓的最低有效剂量为1.0 kGy,最高耐受剂量为2.5 kGy,本研究为蓝莓的辐照保鲜提供了应用基础和科学依据。     

辐照处理对柄曲霉素的降解效果研究

采用不同剂量(0、3、6、9、12、15 kGy)60Co-γ射线对柄曲霉素(sterigmatocystin,STC)溶液进行辐照处理,研究辐照剂量、不同溶剂以及不同初始浓度对柄曲霉素辐照降解效果的影响。结果表明:60Co-γ射线可有效降解溶液中的柄曲霉素,且降解率随着辐照剂量的增大而增加。当辐照剂量为3 kGy时,STC的降解速率依次为水>氯仿>乙腈>甲醇。当辐射剂量大于6 kGy时,水、乙腈和氯仿中STC的降解率相近,且甲醇中STC降解率也相对增加。在同一辐照剂量下,柄曲霉素的初始浓度越低,其降解率越高。     

淇河鲫鱼辐照保藏效果研究

利用0 kGy～10 kGy的辐照剂量时真空包装淇河鲫鱼的保存期、保藏条件进行了系统研究.对样品感官、微生物(细菌总数、大肠菌群数和致病菌)和理化指标(挥发性盐基氮)进行检验.结果表明:25℃不适于保存上述剂量辐照的样品;冷藏(4℃)条件下保存的辐照样品辐照剂量与样品保存期呈正相关;辐照使样品菌落总数的增长明显减慢;一定剂量的辐照可将样品大肠菌群数值降至300个/kg以下,并可杀灭其中人工污染的志贺氏菌、沙门氏菌;2.5kGy的辐照剂量可延缓淇河鲫鱼样品中挥发性盐基氮的增高.     

串珠镰刀菌辐照效应的研究

为研究γ射线在常温下对生理盐水和玉米中不同浓度串珠镰刀菌（Fusarium momiliforme）孢子的辐照杀灭效果，用不同剂量的^60Co γ射线对生理盐水和玉米中高、低2种浓度串珠镰刀菌孢子进行辐照，采用PDA培养基平板稀释法计数孢子数。γ射线辐照剂量与存活串珠镰刀菌数有明显的剂量-反应关系，生理盐水中高、低浓度串珠镰刀菌孢子试样中D10值为0．57、0．60kGy，最小杀灭剂量为4．0、3．0kGy；玉米中高、低浓度串珠镰刀菌孢子试样中D10值为0．66、0．81kGy，最小杀灭剂量为4．0、3．0kGy。γ射线对串珠镰刀菌孢子有明显的杀灭作用，4．0kGy可全部杀灭实验浓度的串珠镰刀菌孢子。     

冷却肉低剂量辐照后的理化和感官特性变化

研究真空包装冷却猪肉经保鲜液处理和未经过保鲜液处理,再分别经1kGy、2kGy和3kGy低剂量辐照后的理化和感官特性变化,进而确定最佳的辐照处理方式以延长冷却猪肉的货架期。结果表明:经过2kGy辐照的处理组,在贮藏的过程中,鲜红色泽保持相对的稳定。冷却猪肉经过保鲜液处理 2kGy剂量辐照 冷藏(4±1℃),可以有效的延长冷却猪肉的货架期。     

Taenia solium metacestode viability in infected pork after preparation with salt pickling or cooking methods common in Yucatán, Mexico

The cestode parasite Taenia solium is an important cause of foodborne infection throughout tropical and subtropical regions. Ingestion of pork meat infected with T. solium larvae can lead to taeniasis infection in humans. With tourism and the consumption of native food increasing, it is important to investigate potential risks of transmission associated with food preparation methods. In this study, traditional Mexican salt pickling and two methods of pork preparation (as roast pork [cochinita pibil] and in pork and beans [frijol con puerco]) were evaluated in order to determine their effects on T. solium cyst viability in infected tissue. In the control groups, all metacestodes isolated were 100% viable, and only small changes in pH (from 6.0 to 5.9) and temperature (29 to 30 degrees C) were recorded. No viable cysts were detected after 12 and 24 h of salt pickling. The pH of the meat during salting dropped from 6.0 to 5.3. Osmotic changes and dehydration from the salting, rather than a change in pH, could be considered the main cause of cyst death. Temperatures of >65 degrees C damaged T. solium metacestodes in roast pork and in pork and beans. The results of this study indicate that if traditional pork dishes are prepared properly, T. solium cysts are destroyed. The criteria used in this study to evaluate the viability of tissue cysts are discussed.     

Radiation preservation of meat and meat products: A review

The World Health Organisation (WHO) in 1980 clarified the position regarding the medical acceptability of irradiated foods when it said‘…no health hazard results from consuming any food irradiated up to a dose of one megarad (1 Mrad)’. This resulted in renewed interest in irradiation as a cost-effective alternative to traditional preservation methods such as canning and freezing. Thus, radurisation (the application of ionising radiation at a dose level which substantially reduces the microbial population) increases the shelf life of poultry, comminuted meat and meat dishes significantly. Low dose irradiation, or radicidation, eliminates parasites such as Trichinae and cysticerci in pork and, very importantly, salmonella organisms in poultry and red meat. Therefore, irradiation has an important rôle to play in public health protection. High dose irradiation, or radappertisation (‘cold sterilisation’), uses doses in excess of 1 Mrad and is analogous to retorting as understood in the canning industry. However, it can adversely affect quality in producing ‘free radicals’ in high protein foods such as meat. To prevent this, special precautions are necessary, e.g. irradiation is conducted at very low temperatures and the product is usually vacuum packed.A further potential use of irradiation is its ability to reduce the quantity of nitrite necessary in cured meats. This may become of practical significance if legislation further reduces the amount of nitrite permitted in these products.     

辐照对猪肉火腿肠风味与品质的影响

分别以1、3、5、7、9 kGy剂量辐照处理火腿肠,然后对其辐照异味强度、脂质氧化、挥发性风味化合物、色差等指标进行检测,分析辐照对火腿肠风味及颜色品质的影响。结果发现,辐照处理可以显著促进火腿肠中脂质的氧化(P0.05),使得红度值(a~*)相比对照组显著降低(P0.05),但是对亮度值(L~*)和黄度值(b~*)影响不显著(P0.05)。随着辐照剂量加大,火腿肠的辐照异味明显增强,1~5 kGy范围内辐照异味不明显,当辐照剂量增加到7 k Gy时,火腿肠产生明显的令消费者不能接受的辐照异味。挥发性含硫化合物、2-丁烯、戊烷、1-戊烯、辛烷、己烷以及醛类化合物含量与对照组相比显著增多(P0.05),且与辐照剂量呈正相关。二硫化碳、二甲基二硫醚、2-甲基丙醛、3-甲基丁醛、己醛、丁烯和二甲苯是火腿肠辐照后产生的最主要挥发性化合物。结果表明,火腿肠经辐照处理后风味和色泽会发生劣变,特别是5 kGy以上的辐照剂量,并且这些品质变化与火腿肠中脂质的氧化密切相关。     

Color Characteristics of Irradiated Aerobically Packaged Pork, Beef, and Turkey

Color changes in irradiated meat were species-dependent. Irradiated pork and beef became less red as a result of irradiation and display time. The redness values of turkey increased after irradiation but decreased during display time. The yellowness of the irradiated samples, for all species, increased as a result of irradiation and display. Visual evaluation of irradiated pork and beef indicated an increase in brownness, whereas turkey increased in redness as dose increased. The surface color of irradiated pork became less uniform than unirradiated pork. Reflectance spectra indicated that irradiation induced a metmyoglobin-like pigment in pork and beef, whereas the pigment in turkey was unchanged.     

Color Characteristics of Irradiated Vacuum-Packaged Pork, Beef, and Turkey

Changes in color of irradiated meat were observed to be species-dependent. Irradiated pork and turkey became redder due to irradiation but irradiated beef a* values decreased and yellowness increased with dose and storage time. The extent of color change was irradiation dose-dependent and was not related to myoglobin concentration. Visual evaluation indicated pork and turkey increased in red ness whereas beef decreased in redness as dose levels increased. Reflectance spectra showed that irradiation induced an oxymyoglobin-like pigment in pork and that both oxymyoglobin and metmyoglobin developed in beef as a result of irradiation.     

Lipid oxidation of irradiated pork products

The effect of irradiation (2, 5 and 8 kGy) and vacuum storage for 60 days on fatty acid and cholesterol oxidation was determined in three Italian cured pork products (salame Milano, coppa and pancetta).A significant increase in the degree of fatty acid oxidation was observed starting from 8 kGy irradiation dose. Unlike the unirradiated samples, the vacuum storage was not sufficient to curb fatty acid oxidation in the irradiated pork products.The cholesterol oxidation of all of the pork products investigated was affected by the highest dose of irradiation and sometimes by storage. The effect induced by the ionising radiation was different depending on the type of pork product. The cholesterol oxide molecules were qualitatively similar in both irradiated and unirradiated pork products and the levels detected were about 100 times lower than the toxic level for in vitro and in vivo experiments.     

Effects of fat levels on changes in flavor pattern of irradiated pork patties

The effects of fat levels on changes in flavor pattern of irradiated pork patties were evaluated by using electronic nose. Total peak amount decreased with increasing fat level and irradiation dose, and the increased fat level and irradiation dose influenced the formation of new peaks at latter retention time. For the principal component analysis, the irradiated pork patties with containing higher fat level were clearly separated from the other treatments. The irradiation dose also affected the position of spot in identical fat level. It is possible to distinguish the changes in flavor patterns due to fat content and irradiation dose by using electronic nose.     

电子束辐照对冷藏猪脊肉品质特性的影响

本文对冷却猪里脊肉经电子束辐照处理后感官特性变化进行了分析研究。结果表明:在剂量不超过3 kGy时,在(3±1)℃下经21 d贮存后,TVB-N值、过氧化物值和汁液流失率分别15.02×10-2mg/g、24.7 meq/kg、0.30 mg/kg和9.91%,肉品色泽鲜红,没有或仅有轻微的辐照味,并在贮藏14 d后逐渐消失;当剂量在3 kGy以上时,TVB-N值、过氧化物值和汁液流失率最高分别为20.08×10-2mg/g、27.2 meq/kg、0.52 mg/kg和12%,超过了规定的限量值,虽色泽呈良好的鲜红色,但产生了不良的辐照味,影响风味;上述结果表明:在不影响脊肉品质的前提下,低剂量的电子束辐照(本实验不超过3 kGy),能够起到一定程度的保鲜效果。     

Effect of gamma or beta radiation on Salmonella DT 104 in ground pork

Mixtures of six Salmonella Typhimurium DT 104 strains were inoculated into three ground pork products to determine the effect of fat content on the radiation resistance of Salmonella DT 104. The ground pork products were 90% lean, 50:50 fat:lean, and 100% fat. Inoculated products were irradiated using a gamma radiation source in a self-contained 137Cesium irradiator or a 10 MeV accelerator producing electrons (e-beam). The radiation D10-values (dose required for a 90% inactivation of viable CFU) for Salmonella DT 104 inoculated into 90% lean ground pork, 50:50 fat/lean ground pork, and 100% pork fat and subjected to beta radiation were 0.42 kGy, 0.43 kGy, and 0.43 kGy, respectively. The corresponding radiation D10-values for Salmonella DT 104 subject to gamma radiation were 0.56, 0.62, and 0.62 kGy, respectively. There was no statistical significant difference (P = 0.3) in radiation D10-values for Salmonella in the three products subject to either radiation treatment. Therefore, fat content had no effect. There was a significant difference (P = 0.001) between the radiation D10-values obtained with the two radiation sources. The radiation D10-values were within the reported range for irradiation destruction of Salmonella contaminated raw meat products.     

Effect of Radiation and Conventional Processing on the Thiamin Content of Pork

A study was undertaken to compare the effect of ionizing radiation and thermal processing on the thiamin content of pork. Ground pork was either thermally processed in cans or, after enzyme-inactivation, irradiated in pouches with electrons or gamma rays. Thiamin in treated and untreated samples was measured by the thiochrome method. The results show that thiamin retention in pork decreases as the irradiation dose increases, but that retention increases as the temperature of irradiation decreases. Moreover, irradiation with gamma rays (low dose-rate) leads to lower retention than irradiation with electrons (high dose-rate). Results also show that conventional thermal processing causes loss of thiamin comparable to or greater than irradiation at effective processing conditions for sterilization.