电子鼻检测黄山毛峰茶贮藏时间方法研究

利用电子鼻对6个不同贮藏时间下5个等级黄山毛峰茶进行检测。首先获取反映茶叶香气的原始特征向量,再通过主成分分析法(PCA)提取出前5个主成分作为主特征向量,然后以主特征向量作为BP神经网络(BPNN)的输入,建立黄山毛峰茶贮藏时间预测模型(称为PCA-BPNN)。通过对75个测试样本(每等级15个)实验测试表明:PCA-BPNN对于贮藏0 d的茶叶,最大预测误差为7 d,5个(6.67%)样本预测误差超过10 d;对于贮藏60 d的茶叶,最大预测误差为10 d,4个(5.33%)样本预测误差超过10 d;对于贮藏120 d的茶叶,最大预测误差为16 d,7个(9.33%)样本预测误差超过10 d;对于贮藏180 d的茶叶,最大预测误差为19 d,8个(10.67%)样本预测误差超过10 d;对于贮藏240 d的茶叶,最大预测误差为21 d,8个(10.67%)样本预测误差超过10 d;对于贮藏300 d的茶叶,最大预测误差为14 d,6个(8.00%)样本预测误差超过10 d。验证了PCA-BPNN预测模型用于检测黄山毛峰茶贮藏时间的可行性,同时与以原始特征变量作为输入的BPNN预测模型相比,性能更好。     

不同施肥方式及水肥调控对烟叶产质量的影响

研究了不同施肥方式和水肥调控对烟叶产、质量的影响.结果表明,在总施氮相同情况下,增加在移栽后10-15 d及打顶前后各淋施1次追肥,能合理调控营养供给,平衡上、中、下各部位烟叶的生长发育,使氮碳代谢主阶段适时过度,保证烟叶正常成熟,明显提高烟叶的产、质量.本试验以20%在移栽时施入,移栽后10d施10%,20 d施10%,30 d施40%,50 d施20%,效果最好.     

不同品牌酸乳中德氏乳杆菌的分离鉴定及RAPD分析

从不同品牌的10 种酸乳中分离得到10 株德氏乳杆菌(Lactobacillus delbrueckii),经生理生化实验及特异性PCR 鉴定,L.d3、L.d4、L.d5、L.d6、L.d8、L.d10 为德氏乳杆菌保加利亚亚种(Lactobacillus delbrueckii subsp.bulgaricus),L.d1、L.d2、L.d7、L.d9 为德氏乳杆菌乳酸亚种(Lactobacillus delbrueckii subsp. lactis)。利用24 个随机引物对上述10 株德氏乳杆菌进行随机扩增DNA 多态性分析,并使用NTSYSpc-2.10e 软件对扩增图谱数据进行处理,得出10 个菌株之间的遗传相似系数矩阵及聚类分析图。结果表明,10 个菌株相互间的遗传相似系数在0.4167～0.8833 之间,不同菌株间存在一定的亲缘关系及遗传异质性。     

超高压处理对冷藏牡蛎保鲜效果及品质变化的影响

本文以牡蛎为原料,研究了不同超高压处理对牡蛎体内微生物、p H、挥发性盐基氮、K值、基本成分的变化情况。实验结果显示,牡蛎经350 MPa超高压处理10 min,贮藏7 d其菌落总数符合生食标准,冷藏货架期延长至14 d;经450 MPa处理10 min的牡蛎贮藏14 d的菌落总数符合生食标准,其冷藏货架期延长至21 d。牡蛎经350 MPa超高压处理10 min贮藏14 d,或经450 MPa超高压处理10 min贮藏21 d后,TVB-N和K值仍然符合新鲜度标准。同时,超高压处理后牡蛎的营养成分基本保持不变,仍能保持其较高的营养价值。     

熏硫处理荔枝贮藏过程中二氧化硫残留研究

研究了经熏硫处理荔枝在贮藏过程中二氧化硫残留的变化。采用相同的处理方法,对不同的品种而言,果皮和果肉中的二氧化硫残留会相差较大。对于适量熏硫的荔枝,在2℃下贮藏,2d后果皮中的二氧化硫含量不超过200×10-6,而且在2℃下贮藏,10d以后果肉中的二氧化硫含量才能降至10×10-6以下。对于过量熏硫荔枝,在2℃下贮藏,26d内果皮中的二氧化硫含量仍然超出150×10-6,果肉中的二氧化硫含量在16d后才能降到10×10-6以下。     

气候条件对福建烤烟生长和烟叶质量风格特征的影响

通过设置烤烟不同播栽期,研究了烤烟大田期不同气候条件对烤烟生长与烟叶质量风格特征的影响。结果表明,大田期不同气候条件显著影响烤烟大田生育期。与正常移栽期相比,早20 d、10 d移栽,生育期分别延长了23 d、14 d,迟10 d、20 d移栽的生育期分别缩短了2 d和12 d。不同处理之间除淀粉外,其余化学成分未呈现规律性的变化。随着移栽期推迟,烟叶淀粉含量呈现上升的变化趋势。不同处理之间上中部烟叶感官评吸风格和质量特征差异明显,且烟叶风格与质量特征变化趋势一致,随播栽期推迟,上中部烟叶香型从"清香型"向"浓透清"、"浓香"转变。在本试验条件下,早10 d移栽的大田气候条件最有利于彰显烟叶清香风格特色,烟叶感官质量较好。     

鱼腥草干燥过程中化学成分含量及抑菌效果变化的研究

以鱼腥草地上部分和地下部分为材料,研究了鱼腥草在室温干燥条件下化学成分含量和抑菌效果的变化,结果显示,鱼腥草在干燥过程中Vc、脂肪、黄酮含量呈下降趋势,总糖含量上升,蛋白质含量相对稳定。鱼腥草干燥0d和0.5d后,样品挥发油对金黄色葡萄球菌和八叠球菌的最小抑菌浓度(MIC)均为5×10-4mL/mL;干燥1d、2d、4d和8d后,挥发油对两种细菌的MIC均变为10-3mL/mL,抑菌效果降低;样品干燥16d后,挥发油对两种细菌的MIC上升到2×10-3mL/mL。     

酱香型蓝莓利口酒贮存过程中品质稳定性研究

采用食品加速货架期测试法（ALST）对酱香型蓝莓利口酒的货架期进行预测,首先通过对其理化指标、微生物指标和感官品质的检测,得到了产品在55 ℃条件下的货架期为6 d,在45 ℃条件下的货架期为20 d。再利用Q10模型计算出Q10值为10/3,预测酱香型蓝莓利口酒在商业贮存温度（20 ℃）条件下的货架期约为406 d。     

不同真空处理对水蜜桃贮藏效果的研究

对水蜜桃在10～20 kPa和20～30 kPa不同时间的真空处理后进行常压冷藏试验,研究了水蜜桃贮藏过程中的生理生化变化.结果表明,采用10～20 kPa的高真空处理水蜜桃7 d以上,可明显提高水蜜桃的贮藏效果,而真空处理时间少于4 d时,其贮藏效果与普通常压冷藏差异不明显,其中以10～20 kPa高真空压力处理7 d,调节真空压力至20～30 kPa再处理7 d后移入常压库冷藏的贮藏效果最佳.     

去鳞处理对鲤鱼鱼体冷藏期间品质变化的影响

为研究去鳞处理对冷藏条件下鱼类品质的影响,将鲤鱼经去鳞和不去鳞两种处理后贮藏于4℃的冰箱中,以感官评分、挥发性盐基氮(TVB-N)、硫代巴比妥酸(TBA)、K值和菌落总数为指标每2d进行测定。结果表明,感官可接受极限去鳞组为贮藏8d,不去鳞组为10d。在整个冷藏过程中,去鳞和不去鳞组TVB-N值均较稳定。TBA值去鳞组第8d为2.14mg/100g,不去鳞组第10d为2.11mg/100g。在整个冷藏过程中,菌落总数呈增长趋势,在贮藏的最后去鳞组菌落总数为6.55logcfu/g,不去鳞组为5.85logcfu/g,均未达到7.0logcfu/g。K值保持增长趋势,去鳞组第10d的K值为38.1%,但是不去鳞组第8d的K值已达43.5%。综合各指标,不去鳞处理组鱼体保藏期为10d,延长了2d。     

Inhibition of Listeria monocytogenes and Salmonella by Combinations of Oriental Mustard,Malic Acid,and EDTA

The antimicrobial activities of oriental mustard extract alone or combined with malic acid and EDTA were investigated against Salmonella spp. or Listeria monocytogenes at different temperatures. Five strain Salmonella or L. monocytogenes cocktails were separately inoculated in Brain Heart Infusion broth containing 0.5% (w/v) aqueous oriental mustard extract and incubated at 4 °C to 21 °C for 21 d. For inhibitor combination tests, Salmonella Typhimurium 02:8423 and L. monocytogenes 2–243 were individually inoculated in Mueller Hinton broth containing the mustard extract with either or both 0.2% (w/v) malic acid and 0.2% (w/v) EDTA and incubated at 10 °C or 21 °C for 10 to 14 d. Mustard extract inhibited growth of the L. monocytogenes cocktail at 4 °C up to 21 d (2.3 log₁₀ CFU/mL inhibition) or at 10 °C for 7 d (2.4 log₁₀ CFU/mL inhibition). Salmonella spp. viability was slightly, but significantly reduced by mustard extract at 4 °C by 21 d. Although hydrolysis of sinigrin in mustard extract by both pathogens was 2 to 6 times higher at 21 °C than at 4 °C to 10 °C, mustard was not inhibitory at 21 °C, perhaps because of the instability of its hydrolysis product (allyl isothiocyanate). At 21 °C, additive inhibitory effects of mustard extract with EDTA or malic acid led to undetectable levels of S. Typhimurium and L. monocytogenes by 7 d and 10 d, respectively. At 10 °C, S. Typhimurium was similarly susceptible, but combinations of antimicrobials were not more inhibitory to L. monocytogenes than the individual agents.     

柚皮提取物抗氧化作用和对正常小鼠免疫功能的影响

研究了柚皮提取物的抗氧化作用和对正常小鼠免疫功能的影响,结果表明柚皮提取物在一定浓度下可以有效的抑制菜油的氧化,但是不具有剂量-效应关系。500×10-6的柚皮提取物抗氧化效果最好,并强于1000×10-6的VC和BHT,但柚皮提取物在高浓度时 (1000×10-6、2000×10-6)反而有轻微的助氧化作用。抗坏血酸对柚皮提取物抗氧化效果具有明显的协同增效作用;柚皮提取物可明显增强正常小鼠细胞免疫和非特异性免疫功能,能显著地提高正常小鼠血清SOD的活性、降低血清MDA的含量,且呈明显的剂量-效应关系。     

茶薪菇酚类提取物的抗氧化功效评价

目的:研究茶薪菇提取物的酚类物质对体外和体内抗氧化活性的影响。方法:在分析茶薪菇水提物、丙酮提取物、乙醇提取物的总酚、总糖含量以及体外抗氧化的基础上,以阿魏酸、维生素E为阳性对照组,以生理盐水为空白对照组,检测连续灌胃10 d茶薪菇水提物[以总酚含量计,12 mg/(kg bw·d)]对正常小鼠的抗氧化功效,采用D-半乳糖衰老小鼠模型评价茶薪菇水提物[以总酚含量计,12,20,40 mg/(kg bw·d)]对衰老小鼠的抗氧化功效。结果:茶薪菇水提物的总酚含量为1.25‰,介于丙酮提取物和乙醇提取物之间,当茶薪菇水提物质量浓度为60.00 mg/mL时,对羟自由基的清除率高达87.00%,对卵黄脂蛋白不饱和脂肪酸过氧化的抑制率高达65.31%。茶薪菇水提物对正常小鼠的抗氧化结果显示:茶薪菇水提物不影响正常小鼠体重增长,有调高肝脏指数和脾脏指数的趋势,茶薪菇水提物组的超氧化物歧化酶(SOD)活力最高达130.43 U/mL;丙二醛(MDA)含量明显低于生理盐水对照组(P<0.05),抗氧化能力与维生素E和阿魏酸相当。茶薪菇水提物对衰老小鼠的抗氧化结果显示:与D-半乳糖诱导的衰老小鼠比较,10,20,40 mg/(kg bw·d)的茶薪菇水提物极显著降低了衰老小鼠的MDA含量(P<0.01),20 mg/(kg bw·d)剂量组下降率高达94.53%;10 mg/(kg bw·d)剂量组谷胱甘肽过氧化物酶(GSH-Px)活力极显著提高22.98%(P<0.01)。结论:茶薪菇水提物中酚类物质是体外和体内抗氧化的主要功效成分,通过提高SOD、GSH-Px等抗氧化酶活力,降低MDA含量,发挥维持机体抗氧化稳态和拮抗D-半乳糖诱导的衰老损伤的作用。     

Loss of viability by Listeria monocytogenes in commercial bovine pepsin-rennet extract

Loss of viability by Listeria monocytogenes strains California, V7, and Scott A in commercial bovine pepsin-rennet extract was determined during storage for 56 d at 7 degrees C. Four levels (10(3) to 10(6)/ml) of L. monocytogenes were added to the coagulant, and McBride listeria agar was used to determine numbers of survivors. Selected colonies thought to be L. monocytogenes were confirmed biochemically. Samples also were tested during and after completion of cold enrichment (up to 8 wk at 4 degrees C). Coagulant inoculated with 10(3) to 10(4) L. monocytogenes/ml usually was free of viable cells of the pathogen after 28 d and sometimes after 14 d, as determined by direct plating and cold enrichment. When the inoculum was 10(5) to 10(6) cells/ml, samples of coagulant usually were free of viable L. monocytogenes after 42 d and sometimes after 28 d. The three strains of L. monocytogenes behaved similarly, although strain California was somewhat less hardy in the environment of the coagulant than were the other two strains. Bovine pepsin-rennet extract, before inoculation, was free of L. monocytogenes (direct plating and cold enrichment).     

桑叶水提物改善肠肌运动及缓解便秘的作用

目的:研究桑叶水提物对豚鼠离体回肠收缩活动及对便秘大鼠的影响,探讨其改善便秘的作用及相关机制。方法:通过离体肠肌张力测定手段,观察桑叶水提物对豚鼠离体回肠运动的影响。采用洛哌丁胺（10 mg/kg/d）构建3 d及7 d便秘大鼠模型,并以桑叶水提物（5 g/kg/d）同期灌胃给药进行干预,观察大鼠第一白便时间、24 h粪便粒数和小肠推进率等,以及卡巴胆碱（carbachol,CCh）诱发各组大鼠回肠收缩反应的情况;通过石蜡切片HE染色观察大鼠结肠组织形态学变化,免疫组化检测结肠组织水通道蛋白3（aquaporin 3,AQP3）的表达。结果:桑叶水提物能促进豚鼠回肠的自主运动,表现为收缩幅度增强,平均张力升高。桑叶水提物对造模3 d和造膜7 d大鼠的第一白便时间、24 h粪便粒数（造模7 d,P<0.05）及小肠推进率（造模7 d, P<0.05）等指标均有不同程度改善;桑叶水提物明显改善卡巴胆碱诱发的便秘大鼠离体回肠平均张力的降低（P<0.05）;桑叶水提物对洛哌丁胺引起的大鼠结肠组织肌层变薄有改善作用,并显著降低洛哌丁胺引起的结肠AQP3表达的增加（P<0.05）。结论:桑叶水提物明显促进豚鼠回肠运动,并可能通过降低AQP3的表达,抑制结肠水分过度吸收,使粪便含水量增加,促进肠肌运动而改善便秘。     

Lactoferrin reduces mortality in preweaned calves with diarrhea

Calf diarrhea is the most common reason for mortality and antimicrobial therapy in preweaned calves on dairy farms in the United States. Conventional and organic livestock producers require alternative therapies for calf diarrhea to reduce the necessity of conventional antimicrobials. Alternatives administered for mild cases or early in the disease course may be useful to mitigate disease progression and reduce the likelihood of septicemia and negative sequelae. Lactoferrin is a bioactive protein naturally found in colostrum that has been shown to prevent septicemia in high-risk infants. Among organic producers, garlic extract is widely used for the treatment of disease and perceived to be efficacious. The objectives of the study were to determine the effectiveness of lactoferrin and garlic extract to reduce mortality and culling, improve weight gain, and reduce the duration of disease in preweaned calves with the first diagnosis of diarrhea. In total, 628 calves with diarrhea from a single commercial dairy were enrolled in a blinded, randomized field trial. Calves diagnosed with diarrhea (fecal score ≥3), were randomized to 3 consecutive days of oral garlic extract, lactoferrin, or water (control). Calves were clinically evaluated for up to 10 d. Body weight was measured at enrollment and 10 d later. For calves receiving garlic extract, the risk of death or culling was not significantly different than calves in the control group; however, calves that received lactoferrin had approximately half the risk of death or culling in the 120 d following diagnosis. Additionally, the relative risk of death or culling in the 60 d following diagnosis was significantly lower for the subset of calves with severe diarrhea at enrollment. Neither garlic nor lactoferrin had a significant effect on disease duration or average weight gain during the 10-d period. Lactoferrin significantly reduced mortality and culling when administered to preweaned calves with the first diagnosis of diarrhea; however, additional studies conducted across multiple farms are necessary to corroborate the observed reduction in mortality and culling. If the results are confirmed, lactoferrin may become an important tool to improve treatment outcomes and reduce the necessity of antimicrobials.     

不同处理条件下红牛肝菌保鲜品质的对比分析

本文研究了不同处理条件(采集后原态、整理态及保鲜剂)对红牛肝菌贮藏期间保鲜效果的影响,以红牛肝菌为研究对象,对其贮藏过程(1 d、4 d、7 d、10 d、13 d、16 d和19 d)中理化指标(失重率、呼吸强度、硬度和相对电导率等)进行对比分析,实验分为五组,第1组为对照组,第2组去泥脚、不清洗,第3组去泥脚、清洗,第4组用保鲜剂保鲜,第5组用保鲜剂保鲜并用吸水纸。结果表明,红牛肝菌贮藏过程中整理态保鲜效果优于原态;配方为1%黑虎掌菌提取液+0.75%竹荪提取液+0.5%壳聚糖的保鲜剂有利于红牛肝菌的保鲜,贮藏19 d后仍可食用,但贮藏过程中是否用吸水纸对红牛肝菌保鲜效果的影响不明显。因此,红牛肝菌保鲜可采用去泥脚、清洗后用可食性保鲜剂保鲜,保鲜期可延长7 d以上。     

迷迭香提取物对冷藏调理猪肉饼品质的影响

研究不同剂量迷迭香提取物对4 ℃冷藏调理猪肉饼抗脂肪氧化、抑菌能力及品质特性的影响。将0.03%、0.06%和0.09%的迷迭香提取物分别添加到调理猪肉饼中,测定其在10 d冷藏过程中硫代巴比妥酸值、菌落总数、pH值、颜色（L*、a*、b*值）、出品率和感官指标的变化。结果表明：与对照组相比,添加迷迭香提取物的各处理组具有显著的抗脂肪氧化效果和更高的出品率（P＜0.05）,效果与添加0.02%二丁基羟基甲苯相当。迷迭香提取物添加量为0.06%和0.09%的处理组在冷藏7 d后表现出显著的抑菌能力（P＜0.05）,这两组的pH值在冷藏期间显著低于对照组（P＜0.05）。迷迭香提取物添加量为0.06%的猪肉饼在冷藏4 d后红度值（a*）与对照组相比显著升高（P＜0.05）,迷迭香提取物添加量为0.09%的猪肉饼在10 d冷藏过程中亮度值（L*）显著低于对照组（P＜0.05）,而这两组猪肉饼的黄度值（b*）在冷藏期间均显著高于对照组（P＜0.05）。此外,猪肉饼的香气、质地和总体可接受程度均没有随迷迭香提取物添加量的增加而发生显著变化（P＞0.05）。可见,迷迭香提取物在调理猪肉饼中具有较好的抗氧化和抑菌效果,并且在一定程度上能改善肉饼颜色,而对肉饼的感官品质不会造成不良影响。     

汉麻籽壳多酚的提取及抗氧化活性评价

汉麻籽壳是汉麻籽加工的副产物,其中含有丰富的抗氧化物质。本文以汉麻籽抗氧化多酚得率为指标,筛选出汉麻籽壳抗氧化多酚提取的适宜条件,并对提取物的抗氧化性能进行评价。结果表明,汉麻籽壳中抗氧化成分最适宜提取的条件为液料比（10：1）、提取时间（30min）、提取次数（3次）、提取液浓度（60％乙醇溶液）;市售大孔树脂中HPD．600对汉麻籽壳抗氧化成分的吸附能力最强;汉麻籽壳中抗氧化成分最适宜的洗脱条件为洗脱流速（1mL／min）的梯度洗脱,40％乙醇洗脱溶液为目标产物;经过大孔树脂分离提取的汉抗氧化多酚对于质粒DNA、人血低密度脂蛋白（LDL）和牛血清蛋白（BSA）的氧化损伤都有显著的保护作用。