哈密瓜常温贮运膜剂保鲜剂的研制

通过损伤接种试验筛选出抑菌剂A和氯硝胺能分别有效控制哈密瓜常温贮运的优势病原菌镰刀菌和根霉。虫胶中加入1500mg/L抑菌剂A和氯硝胺复配成的膜剂保鲜剂,不但能减少常温贮运的水分损失,保持硬度,而且能有效控制腐烂。     

蜜柚套袋种植中氯硝胺的迁移规律研究

采用气相色谱-串联质谱法检测套袋纸及蜜柚中氯硝胺的含量,并通过田间试验研究了氯硝胺从五种套袋纸向蜜柚不同部位的迁移规律。结果表明四种含有氯硝胺的套袋纸处理的蜜柚全果中氯硝胺的残留浓度随着套袋时间的延长逐渐升高,到第40 d达到最高值。以第70 d蜜柚正常成熟采收为计,全果中氯硝胺的最终残留浓度与套袋纸中氯硝胺的初始含量的相关关系符合预测方程y=-0.048×e（-x/26.156）+0.048,当全果中氯硝胺的最终残留浓度为0.01 mg/kg时,套袋纸中氯硝胺的初始临界含量为6.126 mg/kg。蜜柚套袋全过程中,五种套袋蜜柚果肉均未检出氯硝胺残留。通过提前10 d摘袋,全果中氯硝胺的残留量可降低23.8%。本研究为揭示蜜柚中氯硝胺残留污染的来源提供了科学依据,为今后蜜柚套袋种植以及套袋纸生产管理具有重要的指导意义。     

鱼鳞胶原蛋白基抗菌凝胶的抑菌效果

采用96孔板法探究了牛至精油、溶菌酶和茶多酚3种天然抑菌剂对大肠杆菌(Escherichia coli)、金黄色葡萄球菌(Staphylococcus aureus)的最小抑菌浓度(minimal inhibitory concentration,MIC)和最小杀菌浓度(minimum bactericidal concentration,MBC),同时采用吸光度法测定了抑菌率。结果发现,添加牛至精油、溶菌酶和茶多酚的鱼鳞胶原蛋白凝胶对E.coli的MIC分别为2.5μL/m L、6.25 mg/m L和0.156 mg/m L,MBC分别为2.5μL/m L、25 mg/m L和0.156 mg/m L,抑菌率分别为87.53%、49.26%和79.81%;对S.aureus的MIC分别为1.25μL/m L、12.5 mg/m L和0.156 mg/m L,MBC分别为2.5μL/m L、25 mg/m L和0.156 mg/m L,抑菌率分别为83.22%、51.16%和75.22%。可见添加3种天然抑菌剂的鱼鳞胶原蛋白凝胶对E.coli和S.aureus均有明显的抑制作用,且MIC均是:茶多酚牛至精油溶菌酶,抑菌率均是:牛至精油茶多酚溶菌酶,抑菌效果均是:茶多酚牛至精油溶菌酶。因此,添加牛至精油、溶菌酶和茶多酚的鱼鳞胶原蛋白凝胶具有较好的抑菌效果和应用前景。     

抑菌剂在异养小球藻发酵过程中的应用

通过抑菌圈试验、摇瓶发酵试验和50 L发酵试验,研究了安菌素、克菌灵、青霉素3种抑菌剂在小球藻培养过程中的应用,考察了抑菌剂添加对藻细胞干重和葡萄糖浓度的影响。结论:在小球藻发酵染菌4 d后,加入100 mg/L克菌灵可以有效抑制杂菌,并且不会对小球藻发酵造成影响。相同发酵周期内,小球藻染菌后抑菌发酵与正常发酵相比,藻细胞干重质量浓度达到75.2 g/L,平均干重增加速率为6.26 g/(L·d),与正常发酵相比,干重质量浓度与平均干重增加速率降低14.93%,能够成功地挽救染菌的发酵过程。而加入100 mg/L安菌素和青霉素均对小球藻的正常生长产生了抑制作用。     

新型抑菌剂K系对烟草青枯菌的抑制作用研究(Ⅰ)

为选择合适的抑菌剂和适宜的浓度来防治不同地区的烟草青枯病,采用平板菌落计数法测定了新型抑菌剂K系( K1、K2、K3)对我国46个不同地区烟草青枯菌的抑制率,同时比较了K系抑菌剂与农用链霉素的抑菌效果.结果表明:1)100 mg/L K1对印江等27个县市,100 mg/L K2对遵义县等30个县市,50 mg/L K3对莒县等25个县市,254.5 mg/L农用链霉素对保山等28个县市青枯菌的抑制率达100％.2)50 mg/L K1对金沙等15个县市,50 mg/L K2对仁怀等21个县市,50 mg/L K3对江口等23个县市的青枯菌抑制率显著高于同浓度农用链霉素;100 mg/L K1对洋溪乡等,100 mg/L K2对江口等青枯菌的抑制率显著高于同浓度农用链霉素.     

生料发酵中复合抑菌剂的应用

优化了生料发酵的复合抑菌剂配方。通过正交试验的方法对青霉素、莫能菌素、克菌灵及杆菌肽等添加方式进行优化。结果表明,复合抑菌剂在生料发酵中应用的最优条件为:青霉素1.5 mg/L、莫能菌素1 mg/L、克菌灵0.5 mg/L、杆菌肽0.5 mg/L。在此条件下,发酵后成熟醪酒精度可达16.87%vol。     

中药复合保鲜剂对灵武长枣常温贮藏效果的影响

采用正交试验确定对灵武长枣的发病腐烂有抑制作用的中药抑菌剂最佳浓度,并使用CaCl2、GA3与抑菌剂配制4种保鲜剂对长枣进行处理,在常温（18～22℃）条件下贮藏30d,对各处理样品和对照的失重率、腐烂率、软化率及品质指标进行分析。结果表明,保鲜剂中各成分的适宜浓度分别为40g／L的连翘乙醇提取液、20g／L的高良姜水提取液、12g／L的丁香乙醇提取液、10g／kg的CaCl2及75mg／kg的GA3,灵武长枣用此保鲜剂进行处理,常温条件下贮藏30d,腐烂率仅有12．64％,和对照相比有极显著差异（p〈0．01）,软化率也只有1．83％,失重率为1．82％,同时也保持了果实较好的内在品质,VC含量达259．36mg／100g,与对照差异为极显著,可溶性固形物为25．4％、酸度为0．4％、硬度为12．37kg／cm2,使长枣经常温贮藏后仍具有较好的脆度和风味。     

哈密瓜贮运保鲜剂筛选的研究

通过抑菌圈试验和采用培养皿最低抑制浓度法、确定了多菌灵和桔腐净对侵染哈密瓜优势菌的最低抑制浓度分别为25毫克/升和350毫克/升对不耐贮运的夏甜瓜,用多菌灵1000毫克/升和桔腐净500毫克/升混合．作采后浸渍处理,防治了甜瓜的病菌侵染,在20℃下贮藏15天、仍保留有市售一级商品瓜的品质。     

传统中草药对鲜食核桃防腐保鲜的研究

通过对能够使鲜食核桃发霉的菌种进行分离、纯化,研究发现导致核桃腐败的真菌主要有4种,即木霉1和木霉2、毛霉和丝孢酵母。并且研究了丁香、八角、肉桂、黄连、厚朴、甘草、虎杖7种天然药用植物对所分离的真菌的抑制作用,发现除虎杖外其余药用植物均对这4种真菌都具有不同程度的抑菌作用,而丁香、肉桂、八角的抑制作用最显著。通过比较这3种中药的最小抑菌浓度,选择出丁香和肉桂为复合天然抑菌剂成分。通过响应面法优化复合抑菌剂配方,得出最优的复配条件为:丁香浓度1.5mg/mL;肉桂浓度2.5mg/mL。通过进一步的试验初步验证复合抑菌剂的防腐效果显著,因此认为该复合抑菌剂能够起到抑菌作用,有利于延长鲜食核桃的贮藏期。     

气调结合生物保鲜剂对葡萄冷藏品质及电子鼻判别的影响

为了提高无核寒香蜜葡萄的贮运品质,在箱式气调的基础上,研究800、1000 mg/L浓度的纳他霉素和500、1000 mg/L浓度的ε-聚赖氨酸对无核寒香蜜葡萄微环境气体含量、感官、质地、营养、生理品质及电子鼻判别的影响。结果表明:生物保鲜剂的添加可以维持箱内较高的CO_2含量和较低的O_2含量,且不同浓度的相同生物保鲜剂间具有显著差别(P0.05);1000 mg/L纳他霉素和500 mg/L的ε-聚赖氨酸均可在不同程度保证无核寒香蜜葡萄的品质,且1000 mg/L纳他霉素处理无核寒香蜜葡萄的贮藏品质最佳,至60 d时,其落粒率和腐烂率为12.00%,果皮强度和脆性保持在4.04 N、196.00 g/s,TSS、TA及Vc含量分别为15.80%、0.68%、4.2 mg/100 g,呼吸强度和乙烯生成速率分别为40.60 mg CO_2/kg·h、1.20μL/kg·h。PCA和LDA方法均适用于气调结合生物保鲜剂处理无核寒香蜜葡萄冷藏期的风味分析判别,NATA800、ε-PL1000处理与其余处理风味有一定的差异。     

Investigation of the effectiveness of Ascopyrone P as a food preservative

Ascopyrone P (APP), a novel antibacterial from fungi, was evaluated as a food preservative. Efficacy was generally assessed by comparing the time taken for test strains to grow to 10(6) CFU/g in food +/- APP. In chilled chicken soup, 2000 mg kg-1 APP prevented Bacillus cereus, Listeria monocytogenes, Pseudomonas fluorescens, Salmonella and Escherichia coli reaching this threshold for >60 days. Good activity was also observed at 500-1000 mg kg-1 but not against L. monocytogenes. No activity was observed against Saccharomyces cerevisiae. Activity was reduced at 20 degrees C, although 2000 mg kg-1 was still effective against B. cereus and P. fluorescens. APP was less effective in chilled cooked meat systems and ineffective in raw meat. In a cooked meat system at 8 degrees C, bacteriostatic effect was generally observed at 2000 mg kg-1 against Salmonella typhimurium, E. coli and P. fluorescens but not against L. monocytogenes or Lactobacillus sake. Activity against Gram-negative enteric bacteria was enhanced by low temperature. In milk, 2000 mg l-1 was effective against P. fluorescens at chilled but not ambient temperature. APP was ineffective against yeasts and the mould Byssochlamys in apple juice. A minimum of 2000 mg kg-1 APP would appear to be necessary for antibacterial efficacy in food, although low-temperature storage may help. Observed variations in sensitivity may be related to APP stability, which decreases >pH 5.5. Toxicology testing is needed before consideration of APP for food use.     

1-甲基环丙烯处理对采后甜瓜活性氧代谢的影响

研究1- 甲基环丙烯(1-MCP)处理对甜瓜(Cucuis melo L.ssp.melo pang)果实在贮藏过程中对其活性氧(reactive oxygen species,ROS)相关代谢的影响,在室温 (22～25℃)条件下,用1μL/L 1-MCP 处理早熟甜瓜“早黄蜜” 24h,贮藏于22℃,对果实中活性氧代谢的相关酶：超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、过氧化物酶(POD)的活性及超氧阴离子(O2 － ·)和丙二醛(MDA)含量进行测定。结果表明：1-MCP 处理抑制了甜瓜果实CAT 活性的下降,贮藏前期提高了SOD 活性,促进POD 活性迅速升高,并使其在第4 天达到峰值,贮藏过程高于对照果实。1-MCP 处理可显著降低果实中O2 － ·的产生速率,抑制MDA 的产生,延缓甜瓜果实采后衰老。     

Alternative Sanitizers to Chlorine for Use on Fresh‐Cut “Galia” (Cucumis melo var. catalupensis) Melon

ABSTRACT: Chlorine is commonly used to reduce microbial load in fresh‐cut vegetables. However, the production of chlorinated organic compounds, such as trihalomethanes, which are potential carcinogens, has created the need to investigate the efficiency of nontraditional sanitizers and alternative techniques. The effects of 4 novel sanitizers were tested in fresh‐cut “Galia” melon: chlorine dioxide (ClO₂) at 3 mg/L, peracetic acid (PAA) at 80 mg/L, hydrogen peroxide (H₂O₂) at 50 mg/L, and nisin at 250 mg/L plus EDTA 100 mg/L (nisin + EDTA). A chlorine treatment (NaOCl at 150 mg/L) was used as a control. Pieces of melon were packed in polypropylene trays under passive modified atmosphere (3 to 4 kPa of O₂ and 10 to 11 kPa of CO₂) and stored up to 10 d at 5 °C. Microbial growth, firmness, respiration rate, gas composition, sensory evaluation, color, total soluble solids (TSS), and tritable acidity (TA) were evaluated at days 0, 7, and 10. The novel sanitizers PAA, H₂O₂, and nisin + EDTA, in the studied concentrations, reduced the microbial growth to a more efficient range than chlorine and ClO₂. In addition, those sanitizers delayed softness, did not affect the respiration rate, SST, or AT. The sensorial parameters were kept above the upper limit of marketability and they did not impart an “off flavor.” These sanitizers maintained quality and shelf life of fresh‐cut Galia melon for 10 d of storage at 5 °C. Nevertheless, other concentrations, in particular for ClO_2, could be tested to study an extended shelf life in melon pieces.     

1‐METHYLCYCLOPROPENE DELAYS POSTHARVEST RIPENING AND REDUCES DECAY IN HAMI MELON

ABSTRACT

The effects of 1‐methylcyclopropene (1‐MCP) on postharvest ripening and fruit decay in Hami melon were investigated. Melons were treated with 0, 0.1, 1, or 5 µL/L 1‐MCP at 25C for 24 h and then stored at 25C for 16 days. 1‐MCP treatment significantly inhibited respiration rate and ethylene production and delayed their climacteric rise. The treatment also significantly inhibited the decrease of firmness and the increase of electrolyte leakage. Moreover, treatment with 1 or 5 µL/L 1‐MCP maintained significantly higher total soluble solids, vitamin C and chlorophyll contents. In addition, 1‐MCP treatment significantly delayed the incidence of fruit decay and inhibited the increase of decay index. The efficacy of 1‐MCP on delaying postharvest ripening and controlling fruit decay increased with increasing concentration. These results indicate 1‐MCP treatment has great potential to extend shelf‐life and maintain quality in Hami melon during distribution at ambient temperature.

PRACTICAL APPLICATIONS

1‐Methylcyclopropene (1‐MCP) has been commercially used to delay postharvest ripening and extend the storage life on some climacteric fruits. Hami melon has a very short shelf‐life mainly due to fruit ripening and decay, which causes significant economic losses. In this study, a postharvest application of 1‐MCP significantly delayed ripening and reduced fruit decay while maintaining overall quality during storage at 25C. The results will allow long‐distance transportation and marketing of Hami melon and benefit growers, shippers and distributors of this melon fruit.     

自然发酵哈密瓜果汁中酵母分离与鉴定

从自然发酵的哈密瓜汁中分离得到25株形态较好的酵母菌株,经过初筛、复筛,得到1株产酒精能力好,产气较快,最适温度28℃,能耐受150mg／L的SO2,耐浓度为15％的酒精的酵母菌株HM02。经鉴定该酵母为酵母属的酿酒酵母（Saccharomyces cerevisive）。     

温控辅助离子液体分散液液微萃取-高效液相色谱检测果汁中杀菌剂残留

建立温控辅助离子液体分散液液微萃取结合高效液相色谱-二极管阵列检测器法检测果汁中7 种杀菌剂农药残留的新方法。对影响萃取效果的因素萃取剂和分散剂类型及体积、溶解温度、萃取时间和离心时间进行优化。在优化后的方法条件下,7 种杀菌剂富集倍数可达64～101;方法检出限在4.3～13.0 μg/L之间;在0.02、0.05 mg/L和0.10 mg/L三个水平下加标,果汁（苹果汁、梨汁、葡萄汁、桃汁和橙汁）的平均加标回收率在70.0%～116.2%范围内,相对标准偏差均小于9.8%,能满足多种果汁中杀菌剂农药多残留检测的要求。     

1-MCP suppresses ethylene biosynthesis and delays softening of 'Hami' melon during storage at ambient temperature

BACKGROUND: ‘Hami’ melon is susceptible to softening during postharvest storage at ambient temperature, which enhances postharvest deterioration and limits transportation and storage. To look for a method of softening control, the effect of 1‐methylcyclopropene (1‐MCP) on regulating postharvest softening of ‘Hami’ melon fruit was investigated. RESULTS: 1‐MCP treatment at 1 µL L^?1 significantly reduced ethylene production and maintained higher levels of fruit firmness. It also markedly inhibited the accumulation of 1‐aminocyclopropane‐1‐carboxylic acid (ACC) and maintained lower activities of ACC synthase and ACC oxidase. In addition, 1‐MCP treatment reduced the activities of fruit‐softening enzymes such as pectin methyl esterase, polygalacturonase, endo‐1,4‐β‐glucanase and β‐galactosidase. CONCLUSION: 1‐MCP was effective in suppressing ethylene production and delaying fruit softening in ‘Hami’ melon by decreasing the activities of ethylene biosynthesis enzymes and inhibiting fruit‐softening enzymes. Copyright © 2011 Society of Chemical Industry     

Control of grapevine powdery mildew with mineral oil: an assessment of oil concentration and spray volume

DC Tron, a highly refined mineral oil containing patented additives to prevent UV light induced breakdown, was evaluated in vineyards for control of powdery mildew. DC Tron suppressed development of powdery mildew but was not as effective as the conventional fungicide Topas. Of the oil treatments the 1% rate applied in spray volumes of 1000 L/ha was the most efficient. Poor control was achieved with oil rates less than 1% as well as spray volumes less than 1000 L/ha whereas phytotoxicity developed in many cases at concentrations greater than 1% or spray volumes higher than 1000 L/ha. In all oil treatments, powdery mildew developed less in leaves than on bunches. This difference was attributed to poor spray coverage on bunches compared to leaves.     

植物油中角鲨烯的提取与高效液相色谱法分析

建立了硅胶柱提取,高效液相色谱法分析植物油中角鲨烯的方法.样品用石油醚溶解,过硅胶柱净化,经C18柱分离,紫外检测(210 nm).结果表明,角鲨烯与其他杂质峰得到良好分离,在2～1 000 mg/L浓度范围内,峰面积与浓度呈良好线性,线性相关系数(R2)0.998.在大豆油中添加5.0、100、500和1 000mg/kg水平的角鲨烯,平均加标回收率为82.4％～ 89.3％,相对标准偏差小于7.1％(n=8),方法测定低限(LOQ)5 mg/kg.本方法准确、灵敏、可靠,已应用于实际样品分析.