海参超高压保鲜的工艺研究

以新鲜海参为研究对象,通过单因素试验和正交试验对影响海参中微生物存活率的工艺参数(压力、pH值、保压时间)进行考察和评价;对比两种加压方式对保鲜效果的影响,确定超高压处理海参的最佳工艺条件。实验结果表明：处理压力300～500MPa、保压时间10～30min、pH6.1～6.9 对海参中各种微生物杀灭作用显著。最终确定采用循环加压、压力500MPa、保压时间30min、pH6.5 作为海参超高压保鲜的最佳工艺。     

保鲜剂与臭氧处理对冰温MA贮藏板栗生理及品质的影响

以短丰板栗为实验材料,测定了保鲜剂和臭氧处理后贮藏期间板栗的呼吸强度、淀粉含量、水分含量、过氧化物酶活性、失重率以及好果率的变化,研究保鲜剂与臭氧处理对冰温MA贮藏板栗生理及品质的影响。结果表明:保鲜剂和臭氧处理抑制了冰温MA贮藏板栗的呼吸强度和水分的蒸发,降低了板栗淀粉消耗和过氧化物酶活性,抑制了板栗表面微生物的生长繁殖,延长了贮藏寿命,并保持了良好品质,且臭氧处理效果更好,到贮藏末期(180d)仍有99.16%的好果率。     

植物精油与壳聚糖复配涂膜保鲜剂对鸡蛋的保鲜效果研究

探讨了一种新型、安全的涂膜保鲜剂的配制,并对鸡蛋保鲜效果进行了研究。选取植物精油和壳聚糖为涂膜保鲜剂中的抑菌物质,以沙门氏菌抑菌率为指标,确定了最佳的复合抑菌物质浓度组合为:桉叶精油0.8mg/m L、连翘精油1.1mg/m L、壳聚糖15mg/m L;同时确定以0.20%的明胶作为成膜剂,配制出鸡蛋的涂膜保鲜剂。通过测定涂膜处理组和未涂膜对照组的鸡蛋在高温(37℃)条件下的贮藏过程中失重率、哈夫单位、蛋白系数、蛋黄指数、pH、游离脂肪酸和菌落总数等指标的变化。结果表明经过涂膜保鲜剂处理后的鸡蛋在贮藏过程中的品质远优于未涂膜的鸡蛋;且在37℃下贮藏,经涂膜保鲜剂处理的鸡蛋保鲜期至少延长了1周。     

植物精油与壳聚糖复配涂膜保鲜剂对鸡蛋的保鲜效果研究

探讨了一种新型、安全的涂膜保鲜剂的配制,并对鸡蛋保鲜效果进行了研究。选取植物精油和壳聚糖为涂膜保鲜剂中的抑菌物质,以沙门氏菌抑菌率为指标,确定了最佳的复合抑菌物质浓度组合为:桉叶精油0.8mg/m L、连翘精油1.1mg/m L、壳聚糖15mg/m L;同时确定以0.20%的明胶作为成膜剂,配制出鸡蛋的涂膜保鲜剂。通过测定涂膜处理组和未涂膜对照组的鸡蛋在高温(37℃)条件下的贮藏过程中失重率、哈夫单位、蛋白系数、蛋黄指数、pH、游离脂肪酸和菌落总数等指标的变化。结果表明经过涂膜保鲜剂处理后的鸡蛋在贮藏过程中的品质远优于未涂膜的鸡蛋;且在37℃下贮藏,经涂膜保鲜剂处理的鸡蛋保鲜期至少延长了1周。      

蒸煮贻贝冰温贮藏保鲜剂的筛选、优化及评价

目的 筛选用于改善冰温贮藏蒸煮贻贝品质、延长蒸煮贻贝保质期的生物保鲜剂,对复合保鲜剂的配方及保鲜工艺进行优化,并评价其保鲜效果。方法 通过测定保鲜剂作用于贻贝优势腐败菌的抑菌圈大小,筛选出抑菌效果较强的保鲜剂,运用响应面法优化复合保鲜剂配方,采用肉汤稀释法测定最小抑菌浓度(minimuminhibitoryconcentration,MIC);利用正交实验确定复合保鲜剂用于蒸煮贻贝保鲜的最佳工艺;通过测定蒸煮贻贝冰温贮藏8 d后的感官评分、pH、挥发性盐基氮(total volatile basic nitrogen, TVB-N)含量、菌落总数、汁液流失率来评价复合保鲜剂的效果。结果 筛选出的3种保鲜剂分别为溶酶菌、乳酸链球菌素和丁香酚,复合保鲜剂对枯草芽孢杆菌和假单胞菌的MIC分别为16、8μg/mL,复合保鲜剂的优化配方(质量分数)为溶菌酶4%、乳酸链球菌素2%和丁香酚0.75%,最佳保鲜工艺为保鲜剂溶液p H 5.5、料液比1:2.5 (m:V)、浸泡时间60 min,采用优化的配方和工艺用于蒸煮贻贝的冰温贮藏,贻贝品质的综合评分为空白样品的2倍。结论 复合保鲜剂可以有效改善蒸...     

现代果蔬贮藏保鲜技术研究进展

综述了国内外有关果蔬贮藏保鲜的新技术及研究进展情况,包括天然果蔬保鲜剂的应用、利用调压技术贮藏、臭氧及负氧离子保鲜、利用生物技术保鲜、静电场处理贮藏、低剂量辐射处理和紫外线处理保鲜以及细胞水结构化气调保鲜等国内外近几年发展起来的现代果蔬贮藏保鲜技术.     

天然复合保鲜剂对麻竹笋贮藏品质的影响

为探究天然复合保鲜剂对麻竹笋贮藏保鲜的影响,以麻竹笋为原料,对8种天然保鲜剂进行筛选和复配得到一种天然复合保鲜剂,然后用天然复合保鲜剂处理新鲜麻竹笋,考察麻竹笋在贮藏期间的品质变化。结果表明,质量分数为1. 5%壳聚糖+0. 05%纳他霉素+1. 5%茶多酚可作为一种有效的天然复合保鲜剂,与空白对照组相比,天然复合保鲜剂可将麻竹笋的贮藏期限延长至36 d左右。天然复合保鲜剂处理组的麻竹笋在贮藏期间呼吸强度一直呈下降趋势,且始终低于实验对照组(1. 5%壳聚糖处理组)。与空白对照组相比,贮藏期间实验对照组和天然复合保鲜剂组的麻竹笋苯丙氨酸解氨酶和过氧化物酶活性较低,并呈现出先上升后下降的趋势,酶活性峰值出现的时间延后至27 d。天然复合保鲜剂处理的麻竹笋在贮藏期间木质素含量最少,增加程度最小,在贮藏后期硬度下降、质地变软,仍具有良好的感官品质。同时,天然复合保鲜剂能延缓麻竹笋中Vc的降解,贮藏期间最大程度地保留了麻竹笋的营养成分。     

臭氧水对鲜切藕片保鲜效果的影响

为了探讨臭氧水复合保鲜剂处理对鲜切藕片的保鲜效果,采用臭氧水(1.2 mg/L)、复合保鲜剂(0.2%植酸+0.5%氯化钠+0.2%氯化钙)、臭氧水(1.2 mg/L)加复合保鲜剂(0.2%植酸+0.5%氯化钠+0.2%氯化钙)处理鲜切藕片,以蒸馏水浸泡作为对照,并贮藏在4℃环境下,研究不同处理对鲜切藕片品质和生理的影响。研究结果表明,臭氧水加复合保鲜剂(0.2%植酸+0.5%氯化钠+0.2%氯化钙)处理能够降低鲜切莲藕的失重率和菌落总数,有效延缓丙二醛含量的上升和藕片L*值的下降,抑制PPO的活性,防止褐变;同时使可溶性固形物和硬度维持在较高水平。总之,臭氧水加复合保鲜剂(0.2%植酸+0.5%氯化钠+0.2%氯化钙)处理有利于提高鲜切藕片贮藏期间的品质,有效延长鲜切藕片的贮藏保鲜期。     

金银花、三七和蛹虫草提取物对即食海参品质变化影响的研究

目的 比较金银花、三七和蛹虫草3种不同来源提取物对即食海参贮藏稳定性的影响。方法 以新鲜海参为原料,以金银花、三七和蛹虫草提取物对海参体壁进行预处理后制成即食海参并在37℃条件下贮藏28 d,监测海参体壁的质构特性、挥发性盐基氮、挥发性成分、胶原蛋白热变性温度及游离氨基酸等指标的变化。结果 三七提取物处理后的即食海参硬度最大,为(487.75±52.05) g,样品中无机硫化物和有机硫化物的含量随贮藏时间延长而逐渐下降。各组即食海参在贮藏期内,游离氨基酸总量虽略有增加,但总体稳定在较低水平。除了三七组在贮藏28 d时挥发性盐基氮含量达到34.74 mg/100 g外,其他样品均在15～25 mg/100 g范围内。3个处理组即食海参的热变性温度随贮藏时间的延长普遍呈下降的趋势,但均高于对照组。结论 三七提取物处理能够显著提高即食海参样品的硬度;蛹虫草提取物能够使海参在贮藏期间保持较好的弹性;金银花提取物对即食海参蛋白质的降解有一定的抑制作用。     

几种生物保鲜剂对植物基人造肉保鲜效果的影响

利用壳聚糖、茶多酚、Nisin、纳他霉素、ε-聚赖氨酸5种生物保鲜剂对植物基人造肉进行处理,并在4℃条件下进行贮藏,在不同贮藏时间条件下对植物基人造肉的pH、硫代巴比妥酸值、菌落总数、大肠杆菌进行测定,比较分析不同生物保鲜剂的保鲜效果.生物保鲜剂处理后的植物基人造肉的储存期和品质均较未处理的试样有明显提升,其中Nisi...     

响应面法优化海参性腺酶解工艺

为有效提高海参性腺利用价值,本实验以水解度为主要指标,进行海参性腺水解蛋白酶的筛选,并考察底物浓度、酶用量、水解时间、pH值及温度等单因素对水解度的影响。在此基础上,利用响应面中心组合设计优化海参性腺水解工艺,建立水解度与底物浓度、酶用量和水解时间的二次回归模型,通过方差分析和验证实验,得出该模型能够较好地反映海参性腺水解度的变化规律。结果表明：最佳的水解工艺条件为底物浓度10.4%(m/m)、酶用量1154U/g、水解时间89min,在此条件下海参性腺水解度可达63.12%。     

Survival of Escherichia coli O157:H7 in cucumber fermentation brines

Abstract: Bacterial pathogens have been reported on fresh cucumbers and other vegetables used for commercial fermentation. The Food and Drug Administration currently has a 5‐log reduction standard for E. coli O157:H7 and other vegetative pathogens in acidified pickle products. For fermented vegetables, which are acid foods, there is little data documenting the conditions needed to kill acid resistant pathogens. To address this knowledge gap, we obtained 10 different cucumber fermentation brines at different stages of fermentation from 5 domestic commercial plants. Cucumber brines were used to represent vegetable fermentations because cabbage and other vegetables may have inhibitory compounds that may affect survival. The 5‐log reduction times for E. coli O157:H7 strains in the commercial brines were found to be positively correlated with brine pH, and ranged from 3 to 24 d for pH values of 3.2 to 4.6, respectively. In a laboratory cucumber juice medium that had been previously fermented with Lactobacillus plantarum or Leuconostoc mesenteroides (pH 3.9), a 5‐log reduction was achieved within 1 to 16 d depending on pH, acid concentration, and temperature. During competitive growth at 30 °C in the presence of L. plantarum or L. mesenteroides in cucumber juice, E. coli O157:H7 cell numbers were reduced to below the level of detection within 2 to 3 d. These data may be used to aid manufacturers of fermented vegetable products determine safe production practices based on fermentation pH and temperature. Practical Application: Disease causing strains of the bacterium E. coli may be present on fresh vegetables. Our investigation determined the time needed to kill E. coli in cucumber fermentation brines and how E. coli strains are killed in competition with naturally present lactic acid bacteria. Our results showed how brine pH and other brine conditions affected the killing of E. coli strains. These data can be used by producers of fermented vegetable products to help assure consumer safety.     

酶解刺参内脏蛋白制备抗氧化肽的研究

对刺参内脏所含的内源蛋白酶的性质进行了初步研究,在此基础上分析和比较了利用内源蛋白酶和外源蛋白酶酶解内脏蛋白制备抗氧化肽的工艺。刺参内脏主要含有四种内源蛋白酶,最适pH分别为2.0、5.0、8.0和12.0。以羟自由基和超氧阴离子自由基清除率为指标,比较了内源蛋白酶和八种外源蛋白酶酶解内脏蛋白制备抗氧化肽的效果,结果表明菠萝蛋白酶为最佳用酶;用正交实验L9(34)对其水解条件进行优化,确定最佳酶解条件为:pH7.8、温度35℃、加酶量5.0g/100g、酶解时间1h,在此条件下所得酶解液对羟自由基和超氧阴离子自由基的清除率分别为79.15%和28.57%。      

南方刺参性腺多肽酶解工艺优化及抗氧化活性分析

研究南方养殖刺参性腺多肽的酶解提取条件,并分析南北刺参性腺多肽抗氧化活性。选用复合蛋白酶对刺参性腺进行水解,以酶解多肽得率为指标,选取酶解温度、底物浓度、pH、酶解时间、酶用量等为主要影响因素,在单因素实验基础上应用响应面分析法对以上5个因子进行优化,确定刺参性腺多肽酶解工艺。试验结果表明,刺参性腺多肽酶解最佳条件:温度为56 ℃,底物浓度11.5%,酶添加量0.5 mKat/g,pH7.1,酶解时间4.5 h,此时刺参性腺多肽得率可达到67.97%±0.96%,与预测值相差0.26%。抗氧化试验结果表明,刺参性腺多肽浓度在40 mg/mL时,羟自由基抑制率与超氧自由基抑制率均大于0.1 mg/mL的维生素C溶液,60 mg/mL刺参性腺多肽的FRAP值大于0.1 mg/mL的维生素C溶液,南、北方养殖刺参性腺酶解多肽的抗氧化能力无显著差异。     

天津市2015~2019年生鲜果蔬病原微生物污染排查分析

为排查天津市即食生鲜果蔬病原微生物污染情况,2015~2019年在生产环节和流通环节抽取生菜、番茄、黄瓜、苦菊、桃和梨等6种即食果蔬品种共计654批次样品,采用国家标准方法分析样品中菌落总数、大肠菌群、沙门氏菌、金黄色葡萄球菌、单增李斯特氏菌、蜡样芽孢杆菌和大肠杆菌O157:H7污染状况进行风险分析。结果显示,654批次样品中检出食源性致病菌135批次,检出率为20.6%,其中包括沙门氏菌1份,金黄色葡萄球菌6份,蜡样芽孢杆菌128份,其他致病菌均未检出。食源性致病菌检出率较高的样品多出现在超市和农贸市场,表明即食果蔬致病菌的污染易发生在流通环节。即食生鲜果蔬中食源性致病菌污染对消费者健康存在潜在的安全隐患,需加强采后流通环节污染防控,保障即食果蔬食品安全,防止食源性疾病暴发。     

NUTRITIONAL CONSEQUENCES OF MINIMAL PROCESSING OF FRUITS AND VEGETABLES

Consumption of fresh or minimally processed fruits and vegetables is increasing due to consumer concern about the effects of processing on nutrients in foods. Relatively little information is available in the literature regarding specific storage and handling techniques that have an impact on nutritional value for fruits and vegetables. Commonly used technologies such as low temperature and controlled atmosphere storage affect vitamin content. The information about other operations such as preparation for the table and irradiation on vitamin losses is fragmentary and may not reflect current practices. It appears that conditions that preserve sensory quality of fruits and vegetables also maintain nutritional value.     

供应链中生鲜果蔬品质劣变机制、共性管控及智能检测技术研究进展

供应链中生鲜果蔬由于呼吸作用、蒸腾作用和乙烯释放等因素,持续消耗有机物质(如糖和淀粉),导致生鲜果蔬品质降低。在整个供应链中,生鲜果蔬的生理、生化变化受内在因素(种类与品种、产地与采收期、成熟度或生长期)和环境因素(如温度、湿度、O₂和CO₂体积分数、乙烯体积分数、挤压、撞击、振动等)的影响。目前,供应链中应用了许多采后技术来提高品质和保留率,以减少生鲜果蔬的品质劣变,提高其市场竞争力。作者简要介绍了供应链中生鲜果蔬品质劣变(如霉变、萎蔫、褐变、软化、黄化等)机制、生鲜果蔬品质劣变影响因素,以及通过采用共性管控技术减缓生鲜果蔬的品质劣变,并综述了智能标签在生鲜果蔬新鲜度检测中的研究进展。     

东海乌参重金属脱除工艺的研究

东海乌参是众多海参品种中的重要一类,资源丰富,营养价值高,但其体壁重金属含量高,不能被充分开发利用。为探索东海乌参体表重金属的脱除方法,研究了各种重金属在东海乌参体壁上的分布状况,并分别采用化学法和酶-化学法脱除东海乌参体表重金属,对浸泡试剂和温度、酶类型和用量、处理时间等工艺条件进行优化,结果发现,采用酶-化学法脱除重金属,从外观品质和脱除效果上,都优于化学法。最优的脱除条件是采用0.10%（w/w）的木瓜蛋白酶,在37℃酶解1h,再用2.0%（w/v）食品级柠檬酸浸泡48h。经过酶-化学法处理后的东海乌参重金属脱除率可达90%以上。      

Survival and growth of Enterobacter sakazakii on fresh-cut fruits and vegetables and in unpasteurized juices as affected by storage temperature

Enterobacter sakazakii is an emerging foodborne pathogen that has caused illnesses and deaths in infants and elderly immunocompromised adults. Outbreaks of E. sakazakii infection have been associated with infant formulas, but the documented presence of this pathogen in a wide variety of ready-to-eat foods, including lettuce and other raw vegetables, makes it important to learn more about its behavior in these environments. We investigated the survival and growth characteristics of E. sakazakii on fresh-cut apple, cantaloupe, strawberry, watermelon, cabbage, carrot, cucumber, lettuce, and tomato and in juices prepared from these fruits and vegetables. Produce and juices were inoculated with E. sakazakii at 2 to 3 log CFU/g and 1 to 2 log CFU/ml, respectively, and stored at 4, 12, or 25 degrees C. Populations either did not change or gradually decreased in fresh-cut produce and juices stored at 4 degrees C but grew at 12 degrees C on fresh-cut apple, cantaloupe, watermelon, cucumber, and tomato and in all juices except apple, strawberry, cabbage, and tomato juices. All fresh-cut fruits and vegetables except strawberry supported growth of E. sakazakii at 25 degrees C. Growth occurred in all juices except apple, strawberry, and cabbage juices, followed by decreases in population to < 1 CFU/ml after 48 to 72 h, which coincided with decreases in pH and an increase in the population of lactic acid bacteria. Increases in total counts occurred in all juices except strawberry juice stored at 25 degrees C and apple and strawberry juices stored at 12 degrees C. Total counts increased in cantaloupe, carrot, cucumber, and lettuce juices stored at 4 degrees C. Populations of molds and yeasts increased in apple and tomato juices stored at 25 degrees C but decreased to <1 CFU/ml in cabbage, lettuce, and cucumber juices. Further characterization of the behavior of E. sakazakii on fresh produce and in unpasteurized juice as affected by commercial packaging and handling practices is needed.