非对称富马酸二酯类的合成及对细菌的抗菌特性研究

以马来酸酐为原料先进行CnH2n+1OH（n=2～9）醇解合成马来酸单酯，然后催化转型生成富马酸单酯，再与甲醇酯化合成了一系列非对称富马酸酯类，产率85％以上．抗菌效果试验结果表明，非对称富马酸酯类可使微生物的生长适应期（t0）延长2～8倍，半对数生长期（t0.5）缩短1／3－2／3，相对生长量降低75％以上，生长势（t0．5／t0）仅为对照的1／28～1／6，并可显著地诱导和促进微生物菌群的自溶作用．     

富马酸二酯类的合成及抗菌效果研究

以马来酸酐为原料先进行ＣｎＨ２ｎ＋１ＯＨ（ｎ＝２～９）醇解合成马来酸单酯，然后催化转型生成富马酸单酯，再与甲醇化合成一系列非对称富马酸酯类，产率８５％以上。抗菌效果试验结果表明，非对称富马酸酯类可使微生物的生长适应期（ｔ０）延长２～８倍，半对数生长期（ｔ０．５）缩短１／３～２／３，相对生长量降低７５％以上，生长势（ｔ０．５／ｔ０）仅为对照为１／２８～１／６并可显著了诱导和促进微生物菌群的自溶作用。     

非对称富马酸二酯类的合成及对细菌的抗菌特性研究

以马来酸酐为原料先进行ＣｎＨ２ｎ＋１ＯＨ（ｎ＝２～９）醇解合成马来酸单酯，然后催化转型生成富马酸单酯，再与甲醇酯化合成了一系列非对称富马酸酯类，产率８５％以上，抗菌效果试验结果表明，非对称富马酸酯类可使微生物的生长适应期（ｔ０）延长２～８倍，半对数生长期（ｔ０．５）缩短１／３～２／３相对生长量降低７５％以上，生长势（ｔ０．５／ｔ０）仅为对照的１／２８～１／６，并可显著地诱导和促进微生物菌群的自溶作     

高效防霉剂富马酸单甲酯的合成与抑菌活性研究

以TiSiW12O40/TiO2为催化剂，用富马酸与甲醇直接酯化合成了防霉剂富马酸单甲酯（MMF），通过正交试验确定了醇酸物质的量比、催化剂用量、反应温度和反应时间对反应产率的影响。得到最佳工艺条件为：n（富马酸）：n（甲醇）=1、0：1、0，催化剂用量为w（TiSiW12O40/TiO2）=2％（占富马酸的质量分数），反应温度为60℃，反应时间为3h，MMF的产率可达91．6％。抑菌活性试验和防腐保鲜试验结果表明，MMF对多种霉菌具有良好的抑制作用，尤其对黄曲霉菌、黑根霉菌和棒柬青霉菌的抑制作用更好，MMF的防霉和防腐保鲜效果优于DMF、丙酸钙。     

富马酸单甲酯-3-没食子酸异戊酯的合成与性能研究

防腐剂富马酸单甲酯（MMF）与氯化亚砜作用,得到富马酸单甲酯单酰氯,优化条件为：n（MMF）：n（SOCl2）=1.0：4.0,反应时间为60min,富马酸单甲酯单酰氯产率96.5%;富马酸单甲酯单酰氯与抗氧化剂没食子酸异戊酯（i-AG）缩合,合成了兼具抗氧化性和防腐性能的化合物富马酸单甲酯-3-没食子酸异戊酯（MMF-3-i-AG）,优化条件为：n（富马酸单甲酯单酰氯）：n（i-AG）=1.0：1.0,吡啶作催化剂,m（吡啶）：m（i-AG）=1：1,110℃反应60 min,MMF-3-i-AG产率86.3%.用IR、1H NMR和元素分析对MMF-3-i-AG的结构进行了确认.研究了MMF-3-i-AG的抑菌活性和抗氧化性能,结果表明MMF-3-i-AG的抑菌能力与MMF相当,其抗氧化性能亦与PG相当.     

新型防腐剂富马酸淀粉甲酯的合成及抑菌活性研究

富马酸淀粉甲酯（SMF）的合成分为2步：先由富马酸单甲酯（MMF）与亚硫酰氯反应生成富马酸单甲酯单酰氯（MMFC）,MMFC再与可溶性淀粉反应可得SMF。用单因素试验法确定酯化度为12．03的SMF合成工艺为：摩尔比为3：1的亚硫酰氯和MMF在100℃下回流45rain,得无色MMFC液体,收率可达92％以上。摩尔比为40：1的MMFC与可溶性淀粉在25℃反应16h,再分别经40％乙醇溶液和10％KHCO,溶液洗涤至pH=7,所得白色固体即为富马酸淀粉甲酯,其抗菌活性与富马酸单甲酯相当。     

提高低度青稞酒质量的途径

酒度为40％（v/v)的低度青稞酒，加入2‰－4‰的酒头（贮存3个月以上）和1％－3％酒尾（贮存3个月以上，事先用2‰－4‰活性炭处理），可获得理想效果，在调味过程中，要特别注意酸、醇，酯的酯比，酸高酯低，缺乏青稞酒典型风格，酒体粗糙，出现邪杂味，酯高酸低，则酒味寡淡，香味短，勾兑调味后，低度青面贮存3个月以上。     

富马酸烷·3-PG酯的合成工艺条件研究

以顺丁烯二酸酐为起始原料,与甲、乙、丙、丁、戊醇发生酯化反应制得五种马来酸单酯,马来酸单酯异构化为相应的富马酸单酯,后者与亚硫酰氯作用得到五种富马酸单酯单酰氯,用制得的富马酸单酯单酰氯酰化没食子酸丙酯(PG)分子中的3-羟基制得五种具有良好的抗氧化和抗菌活性的新型化合物—富马酸甲(乙、丙、丁、戊)·3-PG酯犤1犦。本文对每步反应的合成工艺条件进行了较详细的摸索和研究,揭示其规律,这对于没食子酯丙酯-富马酸酯衍生物的制备具有一定的参考价值。     

活性炭负载磷钨酸催化合成香料苹果酯-B

制备了环境友好催化剂活性炭负载磷钨酸H3PW12O40/C，并以H3PW12O40/C为催化剂催化合成了香料苹果酯-B。得到了苹果酯-B合成的适宜工艺条件：n（1，2-丙二醇）：n（乙酰乙酸乙酯）=1．5：1，H3PW12O40/C负载量为23．1％，H3PW12O40/C用量为反应物总质量的1．0％，反应时间为120min，苹果酯-B的收率为84．8％，目的产物经红外光谱、质谱和元素分析确证。     

毛细管气相色谱/质谱法分析熏茶植物白兰花中挥发性化学成分

利用同时蒸馏萃取法（SDE）提取白兰花中的挥发性组分。HP－5柱和Supelco-10－10柱上用气相气谱－质谱法分别检出103个和96个峰。其中有61个峰质谱检索结果相同，它们占总峰面积的77．2％。含量较高的组分有：芳樟醇（70．21％和72．33％），2－甲基丁酸甲酯（4．11％和3．96％），2－甲基丁酸乙酯（2．28％和2．73％），（Z）－3，7－二甲基－1，3，6－辛三烯（2．30％和2．45％），（E）－3，7－二甲基－3，6－辛三烯（1．98％和2．23％），甲基丁香油酚（2．03％和1．86％），1－乙烯基－1甲基－2，4－二（1－甲基乙烯基）－环己烷（1．13％和1．16％），桉叶油素（1．02％和1．078％）。从化合物的种类来看，主要为烯类（15种），酯类（13种），醇类（9种），醛类（5种），烷类（4种），酚类（2种），酮类（1种）等。     

1-Methylcyclopropene Counteracts Ethylene-Induced Microbial Growth on Fresh-Cut Watermelon

ABSTRACT:  The effects of exogenous ethylene, 1-methylcyclopropene (1-MCP), or both on microbial growth on watermelon fruit and watermelon slices were investigated. Freshly harvested seedless watermelons ( Citrullus lanatus , cv. Sugar Heart) were treated with 0.5 or 1.0 ppm 1-MCP, 10 ppm ethylene, 1-MCP + ethylene, or left untreated as controls. Fruits were processed into wedge-shaped slices, packaged into rigid trays sealed with a polyethylene film with a 29.2 pmol s⁻¹ m⁻² Pa⁻¹ oxygen transmission rate. The slices were evaluated after 0-, 6-, and 12-d storage at 5 °C. Ethylene treatment alone increased the populations of aerobic bacteria, lactic acid bacteria, and yeasts and molds on the packaged slices during storage compared to those on corresponding control slices and resulted in extensive juice leakage from the slices. The ethylene treatment also resulted in high aerobic bacterial counts throughout the flesh of whole melons compared to the controls. Treating watermelons with 0.5 or 1.0 ppm 1-MCP prior to ethylene exposure counteracted the deleterious effects of ethylene. Extending the time from harvest to 1-MCP treatment increased the population of aerobic bacteria, but had no detectable effect on the growth of lactic acid bacteria or yeasts and molds. The results indicate that low concentrations (0.5 or 1.0 ppm) of 1-MCP can be used on whole watermelon to avoid deleterious effects of exogenous ethylene to which the melons could be exposed during shipping or storage.     

三聚氰胺对嗜热链球菌生长影响的研究

通过在MRS液体培养基里分别添加0‰、0.25‰、0.5‰、1‰、2‰、3‰及饱和的三聚氰胺,接种嗜热链球菌,在42℃下培养48h,通过测定培养液的pH变化和计数细菌总数来考察三聚氰胺对嗜热链球菌生长的影响。结果表明:嗜热链球菌不能以三聚氰胺为氮源物质而加以降解利用,三聚氰胺在水溶解度范围内对嗜热链球菌的生长没有促进作用,只有微弱的抑制效果。     

EFFECTS OF NISIN AND MODIFIED ATMOSPHERE PACKAGING (MAP) ON THE QUALITY OF EMULSION‐TYPE SAUSAGE

ABSTRACT

The aim of this work was to study the effects of nisin (30 ppm) and modified atmosphere packaging (MAP) on the chemical, microbial and sensory properties of emulsion‐type sausage stored under two different atmospheres (%CO₂/%N₂/%CO/%O₂): 39.5/60/0.5/0 and 39.5/20/0.5/40. The samples were stored at 3 ± 1C for 42 days. Microbial count, values of pH, CIE L*, a* and b* color parameters, lipid oxidation, production of nitrosomyoglobin and sensory properties were assessed throughout the storage period. The data showed that nisin was able to reduce the growth of mesophilic, psychrotrophic and lactic acid bacteria. In addition, the MAP did not show any significant effects on microbial growth. However, free O₂ MAP, in combination with nisin, reduced the growth of yeast and mold. MAP could produce a stabilized red color and minimize the oxidative reactions in the samples. Packaging conditions had no significant effect on pH and sensory properties.

PRACTICAL APPLICATIONS

The results of this study confirmed that nisin can reduce the growth rate of lactic acid bacteria, psychrotrophic and mesophilic bacteria in emulsion‐type sausage, and free O₂ MAP, in combination with nisin, inhibits the growth of yeast and mold. The use of 30 ppm nisin, in combination with MAP containing 39.5% CO₂ and 0.5% CO gases, can lead to better quality preservation of the emulsion‐type sausages stored at low temperature and can extend their shelf life.     

Combined effect of gamma irradiation,ascorbic acid,and edible coating on the improvement of microbial and biochemical characteristics of ground beef

This study was conducted to evaluate the combined effect of gamma irradiation and the incorporation of natural antimicrobial compounds in cross-linked films on the microbiological and biochemical characteristics of ground beef. Medium-fat (23% fat) ground beef patties were divided into three separate treatment groups: (i) control samples without additives, (ii) ground beef samples containing 0.5% (wt/wt) ascorbic acid, and (iii) ground beef samples containing 0.5% ascorbic acid and coated with a protein-based cross-linked film containing immobilized spice powders. Meat samples were irradiated at doses of 0, 1, 2, and 3 kGy and stored at 4 +/- 2 degrees C. Microbial growth (based on total aerobic plate counts [APCs] and total coliforms) was evaluated, as were the content of thiobarbituric acid-reactive substances (TBARS) and that of free sulfydryl groups. At the end of the storage period, Enterobacteriaceae, presumptive Staphylococcus aureus, presumptive Pseudomonas spp., Brochothrix thermosphacta, and lactic acid bacteria were enumerated. Regardless of the treatment group, irradiation significantly (P < or = 0.05) reduced the APCs. Irradiation doses of 1, 2, and 3 kGy produced immediate APC reductions of 2, 3, and 4 log units, respectively. An APC level of 6 log CFU/g was reached after 4, 7, and 10 days for samples irradiated at 1, 2, and 3 kGy, respectively. Lactic acid bacteria and B. thermosphacta were more resistant to irradiation than were Enterobacteriaceae and Pseudomonas. The TBARS and free sulfydryl contents were stabilized during postirradiation storage for samples containing ascorbic acid and coated with the protein-based cross-linked film containing immobilized spice powders.     

生物炭对土壤碳组分及烟草生长发育的影响

为探索生物炭对植烟土壤改良和烟草生长发育的影响效果,采用大田试验设置5个处理[T0(对照)：0 t/hm²生物炭+0.64 t/hm²氮肥;T1:0.5 t/hm²生物炭+0.64 t/hm²氮肥;T2:1 t/hm²生物炭+0.64 t/hm²氮肥;T3:1.5 t/hm²生物炭+0.64 t/hm²氮肥;T4:2 t/hm²生物炭+0.64 t/hm²氮肥],分析了生物炭对植烟土壤碳排放、有机碳组分以及烟草生理指标的影响。结果表明：(1)与T0相比,中低用量(0.5～1.5 t/hm²)的生物炭处理可降低土壤CO2排放总量;其中T1、T2和T3处理较T0分别降低28.14%、25.25%和8.41%;而高用量(2 t/hm²)生物炭处理则促进了土壤碳排放,T4处理较T0提高8.79%。(2)生物炭处理可提高土壤总有机碳、微...     

Effect of packaging atmosphere on the microbial attributes of pearlspot (Etroplus suratensis Bloch) stored at 0-2 degrees C

Effect of packaging atmosphere (air and under different modified atmospheres (MAs), 40% CO2/60% O2, 50%/50% O2, 60% CO2/40% O2, 70% CO2/30% O2 and 40% CO2/30% O2/30% N2) on the microbial and biochemical attributes of fresh pearlspot (Etroplus suratensis Bloch) stored at 0-2 degrees C was investigated. Trimethylamine nitrogen (TMA-N) and thiobarbituric acid (TBA) values remained lower than the proposed acceptability limits throughout the storage period. Results demonstrated that storage of pearlspot under air and MA 40% CO2/30% O(2)/30% N(2) resulted in growth of Enterobacteriaceae, Aeromonas and H(2)S-producing bacteria including Shewanella putrefaciens, while all other packaging atmospheres did not allow multiplication of Enterobacteriaceae and Aeromonas within 3 weeks. Aeromonas spp. identified were Aeromonas hydrophila, Aeromonas veronii biovar sobria and A. veronii biovar veronii. Significant reduction (p<0.01) was noticed in Aeromonas population of pearlspot stored under MA 60% CO2/40% O2 and 70% CO2/30% O2. A delay of growth of Pseudomonas below 5.0log(10)cfug(-1) was observed during the 15th day of storage at 0-2 degrees C under modified atmosphere packaging (MAP) conditions. Growth of faecal streptococci was significantly inhibited in all the packaging atmospheres at 0-2 degrees C during the entire storage period. Survival of coagulase positive Staphylococci (<50cfug(-1)) in low numbers was noticed during storage in all the packaging atmospheres. Clostridium botulinum toxin was not detected. All the packaging atmospheres did not allow multiplication of sulphite-reducing clostridia at 0-2 degrees C during the entire storage period. Packaging in MA 60% CO2/40% O2 resulted in the inhibition of growth of Aeromonas and Enterobacteriaceae, and the slowest growth of psychrotrophic bacteria, H(2)S-producing bacteria, including Shewanella putrefaciens and Pseudomonas and extended microbiological shelf life to 9-10 days. This study confirms the survival of potentially pathogenic A. hydrophila, A. veronii biovar sobria and A. veronii biovar veronii capable of growth at low temperature in pearlspot stored under MA.     

红果龙葵水提液与乙醇提取液的抑菌作用

使用无菌蒸馏水和70% 乙醇从红果龙葵果实中提取活性成分并探讨其抑菌作用。结果表明,提取物对微生物有明显的抑制作用。水提液的最低抑菌质量浓度分别为大肠杆菌2mg/mL、金黄色葡萄球菌1mg/mL、枯草杆菌0.5mg/mL、短小芽孢杆菌3mg/mL、产气芽孢杆菌0.5mg/mL;乙醇提取液的最低抑菌质量浓度分别为大肠杆菌2mg/mL、金黄色葡萄球菌2mg/mL、枯草杆菌1mg/mL、短小芽孢杆菌5mg/mL、产气芽孢杆菌1mg/mL。     

Effect of adding essential oils of coriander (Coriandrum sativum L.) and hyssop (Hyssopus officinalis L.) on the shelf life of ground beef

This study examined the effect of adding essential oils of hyssop and coriander at the highest concentration (0.02% v/w) sensorially acceptable to a panel of assessors on the microbiological and biochemical characteristics of stored ground beef. Vacuum-packed meat was stored at 0.5 ± 0.5 °C and 6 ± 1 °C for 15 days. The greatest beneficial effect of both additives was in inhibiting the development of undesirable sensory changes (extending acceptability by up to 3 days) and the growth of Enterobacteriaceae (by up to approximately 1-2 log cycles compared with the controls). The effect on lactic acid bacteria, total viable bacterial count and other groups of microorganisms investigated was minor (up to 1 log cycle) and similar for both oils. Neither did these additives significantly affect amino nitrogen levels, protease activity, the proportions of meat pigments, protein electropherograms and pH levels. This indicates the limited effect of these essential oils in the concentrations applied on preserving vacuum-packed minced beef.