热水喷淋处理对草莓果实采后腐烂和品质的影响

本实验验采用55、60和65℃,20s热水喷淋(hot water rinsing and brushing,HWRB)处理"丰香"草莓,研究此热处理对常温贮藏(20℃ 3d)和冷藏(0℃12d)后的果实腐烂和品质的影响.研究发现,热水喷淋处理能显著降低处理后果实表面的微生物数量,有效抑制果实失重率和呼吸强度的上升,保持了较高的VC含量;经65℃热水处理的果实发病率最低,但部分果实在处理后其表面出现漂白干缩的现象,影响了它们的商品价值.60℃热水喷淋处理使果实的发病率显著低于对照组,在冷藏下对病害的防治效果更好,同时对果实的颜色、硬度、可溶性固形物和可滴定酸含量未产生不良影响,所以比较适合草莓的采后防腐保鲜处理.     

中草药提取液对桃果实采后致腐真菌抑制效应

为探讨甘草、高良姜、黄柏、北豆根、艾叶、连翘等6种中草药提取液对桃果实采后致腐真菌毛霉和青霉的抑制效果,采用生长速率法与活体果实接种孢子悬液法,对不同中草药提取液的抑菌效果进行对比,筛选出抑菌效果良好的中草药种类,并进一步通过体积浓度梯度稀释法,对其最小抑菌浓度(MIC)和最小杀菌浓度(MBC)进行了探讨。结果表明:不同中草药提取液对桃果实采后致腐真菌毛霉和青霉均有不同程度的抑制作用,其中甘草和连翘提取液的抑菌效果较强,黄柏和高良姜提取液的抑菌效果一般,艾叶和北豆根提取液的抑菌效果较弱。甘草和连翘提取液对毛霉的MIC均为培养液体积分数的25%、MBC均为培养液体积分数的50%;甘草和连翘提取液对青霉的MIC均为培养液体积分数的12.5%、MBC均为占培养液体积分数的25%。     

热水处理促进胡萝卜的愈伤

目的：研究热水处理对胡萝卜伤口处聚酚软木脂及木质素积累的影响及相关机制。方法：用45 ℃热水浸泡人工损伤的胡萝卜直根5 min,测定损伤胡萝卜愈伤期间的质量损失率和损伤接种Botrytis cinerea后的病情指数,观察伤口处聚酚软木脂和木质素的积累,测定伤口处苯丙烷代谢相关酶和过氧化物酶活力,以及苯丙烷代谢产物和H2O2含量。结果：热水处理显著降低了胡萝卜愈伤期间的质量损失率和病情指数（P＜0.05）,第5天时,处理组的质量损失率低于对照组21%,第3天时,处理组的病情指数低于对照组22%。热水处理加速了胡萝卜伤口处聚酚软木脂及木质素的沉积,第3天时,伤口处聚酚软木脂厚度高出对照组18%,第5天时,木质素细胞层厚度高出对照组16%。热水处理提高了胡萝卜伤口处苯丙氨酸解氨酶、肉桂酸-4-羟化酶、4-香豆酰辅酶A连接酶及肉桂醇脱氢酶的活性,促进了伤口处肉桂酸、咖啡酸、阿魏酸、芥子酸、总酚和类黄酮的合成,提高了肉桂醇、松柏醇、芥子醇及木质素的含量。此外,热水处理还提高了胡萝卜伤口处H2O2含量和过氧化物酶活性。结论：热水处理可通过激活苯丙烷代谢、提高H2O2含量和过氧化物酶活性、加速伤口处聚酚软木脂和木质素的积累来促进胡萝卜愈伤。     

Reduction of Pathogens Using Hot Water and Lactic Acid on Beef Trimmings

Beef trimmings from young or mature beef cattle were obtained commercially. Trimmings within age type then were inoculated with about 6.0 log₁₀ CFU/mL of rifampicin-resistant. Escherichia coli O157:H7 and Salmonella typhimurium (ATCC 13311) were randomly assigned to 1 of 3 treatments (control; 95 °C hot water alone, or with 2% L-lactic acid). After treatment, trimmings were ground, held for 0, 14, 28, or 42 d in chub packages at 4 °C, and total aerobic plat counts, E. coli O157:H7, and S. typhimurium counts were determined. Non-inoculated trimmings were also treated and samples were evaluated for pH, fat, moisture, TBA, meat color by colorimeter, and meat color, and odor by trained sensory panels. Trimmings treated with water or hot water plus lactic acid reduced levels of E. coli O157:H7 and S. typhimurium and tended to be darker after treatment. Meat odor in the final product was not affected by treatment.     

5株桃、李果实采后褐腐病菌鉴定、rDNA ITS序列与碳源代谢指纹图谱分析

从采后贮藏过程中发病的桃、李果实中分离到5株丝状病原真菌。对其进行形态学特征观察以及核糖体rDNA ITS序列分析和95种碳源代谢指纹图谱分析。结果表明:5株病原真菌均为果生链核盘菌(Monilinia fructicola),其中091#和089#菌与Monilinia fructicola(FJ515894)的亲缘关系较近。5株褐腐病菌对D-果糖、麦芽糖、蔗糖等共56种碳源的代谢能力相同,包括51种最适碳源和5种不可利用碳源,其中Monilinia fructicola 091#与089#的代谢指纹图谱最接近,而Monilinia fructicola 086#、071#、072#的代谢指纹图谱最接近。因此利用rDNA ITS序列和碳源代谢指纹图谱均可区分桃、李果实5株褐腐病菌不同菌株之间的差异,且两种方法具有可比性。     

Effect of Non-Thermal Plasma-Activated Water on Fruit Decay and Quality in Postharvest Chinese Bayberries

Recently, non-thermal plasma-activated water (PAW) became a relatively new concept developed in the food industry. The effects of PAW on fruit decay, microbial loads, and quality of postharvest Chinese bayberry were investigated. Chinese bayberries were treated by PAW for 0.5, 2, or 5 min and then stored at 3 °C for 8 days. Experimental results show that all PAW treatments could reduce fruit decay by around 50 % compared to control at the end of storage. There was no dose-effect relationship between PAW treatment time and fruit decay. Meanwhile, a 0.5-min PAW treatment could remarkably decrease microbial population on Chinese bayberries during storage, and the maximum reductions reached around 1.1 log CFU/g both for bacteria and fungi at the end day of storage. Scanning electron microscopy results reveal that PAW could significantly change the morphology of microbial cells on Chinese bayberries. Moreover, physicochemical properties analysis of PAW demonstrates that the microbial inactivation of PAW is mainly attributed to the combined action of high oxidation reduction potential and low pH. Additionally, PAW-treated fruits exhibited markedly higher firmness, color index of red grapes, and total soluble solids than the control did at the eighth day. These results indicate that PAW might be a promising strategy to control fruit decay and maintain quality of Chinese bayberry during postharvest storage.     

油桃采后衰老与病害发生中挥发性物质变化的主成分分析

采用固相微萃取与气相色谱-质谱联用技术,对油桃果实采后衰老与褐腐病害发生中近表皮和近果核的挥发性物质进行测定;用主成分分析(PCA)法研究不同样品挥发物谱的差异并对香气品质进行综合评价.结果表明,共检测到油桃果实挥发性物质14种,主要为C6化合物、酯类和内酯类物质.贮藏期间油桃果实挥发性物质逐渐由近果核处转向近表皮,褐腐病害发生后加速了这种转变.PCA结果表明,5-羟基-2,4-癸二烯酸-γ-内酯、γ-癸内酯、δ-辛内酯和乙醇可作为区分油桃果实贮藏4d时衰老与病害发生的标志性挥发物;C6醛类、乙醇和乙酸乙酯则可作为区分油桃果实贮藏0、2d与贮藏4、6d时的标志性挥发物.病害组贮藏2d后近表皮处香气品质最佳,贮藏4d后病害组香气品质远低于衰老组.     

Quality of Fresh-Market Melting- and Nonmelting-Flesh Peach Genotypes as Affected by Postharvest Chilling

After storage for 3 wk at 4°C and ripening 3 days at 20°C, nonmelting-flesh peaches(‘Oro A’, FL 90–35C, FL 90–47C) did not develop visual symptoms of mealiness, while melting-flesh (MF) fruit (FL 90-20, FL 90-21, FL 91-16) did. Sensory evaluation showed that only MF fruit were more “mealy” and less “sweet” and “peachy” as a result of chilling. Volatile analysis revealed that chilling caused increases in(E)-2-hexenal and decreases in γ and δ decalactones in both MF and NMF types. However, the decline was considerably less in NMF than in MF fruit. Results indicate that chilling affects the quality of MF more than NMF genotypes.     

果蔬采后病原真菌分泌胞外酶的研究进展

果蔬采后腐烂大部分由真菌引起,真菌侵染寄主后能否导致发病,取决于病原菌的致病能力、寄主自身的防卫反应和环境条件。在适宜的环境条件下,病原菌大量繁殖,并通过分泌胞外酶、产生毒素和病原物激素从而引起寄主发病。在发病过程中,胞外酶是最重要的致病因子。本文综述了病原真菌产生胞外酶的种类、致病机理及影响因素,为果蔬采后病害的控制提供理论依据。     

贮前热处理对番茄采后生理的影响

绿熟番茄采后用38℃热水处理60min,晾干,1±1℃,RH80%～95%冷藏37d后,转入20℃后熟,以20℃室温水处理为对照。结果显示,热处理果实的后熟率比对照提高了1.8倍。贮前热水处理对冷藏中果实的硬度和多聚半乳糖醛酸酶(PG)活性无显著影响,但促进该酶在后熟期间的增加,却减缓果实的软化;热处理刺激果实的呼吸、1-氨基环丙烷-1-羧酸(ACC)含量的增加,和ACC合酶(ACS)活性、乙烯含量的减少,但长期冷藏后作用消失,且显著增加后熟期间ACS的活性、ACC含量、乙烯生成以及呼吸强度。热处理可能通过调节乙烯的代谢来促进果实的后熟,降低果实的冷害。     

不同采后处理对云南油桃和水蜜桃的贮藏保鲜效果对比

为探索延长云南油桃和水蜜桃保鲜期的方法,以云南文山黄金油桃和红蜜桃为试材,研究了1-MCP、ClO2、2种涂膜处理对黄金油桃和红蜜桃两种桃贮藏保鲜效果,结果表明:虽然1-MCP处理对两种桃L*、a*值和b*值的维持均有效果,但云南黄金油桃和红蜜桃适宜的采后处理方法不同;1-MCP处理的黄金油桃色差值最高,贮藏25d,L*、a*值和b*均维持较高,相对电导率值最低(54.43%),质量损失率较低(1.05%),TSS含量为16.27%最高,表明1-MCP处理是较适宜黄金油桃贮藏保鲜的处理。ClO2处理有利于红蜜桃外观的维持,贮藏25 da*值和b*值均高于其他处理,且具有最低的质量损失率和最高的TSS含量,相对电导率值为55.81%,低于1-MCP处理;表明ClO2处理是较适宜红蜜桃的采后处理。     

Postharvest Control of Green Mold Decay of Citrus Fruit Using Combined Treatment with Sodium Bicarbonate and Rhodosporidium paludigenum

The objective of this study was to analyze the impact of the marine yeast Rhodosporidium paludigenum and sodium bicarbonate (SBC) treatments applied separately or in combination to control green mold of two cultivars of citrus fruit (Citrus reticulata Blanco cv. Subcompressa and C. reticulata Blanco cv. Ponkan) caused by Penicillium digitatum. In the assay of C. reticulata Blanco cv. Subcompressa, R. paludigenum at 10⁷ cells/mL significantly (P?<?0.05) reduced green mold incidence compared to the control, and the combination of 10⁷ cells/mL R. paludigenum and 5 % SBC was as effective as fungicide (500 ppm Fungaflor). In the assay of C. reticulata Blanco cv. Ponkan, the treatment with R. paludigenum at 10⁸ cells/mL and 2 % SBC were equally effective and significantly (P?<?0.05) reduced the decay incidence. Moreover, the combination of the two treatments completely eliminated the decay incidence, matching the effectiveness of fungicide. This work demonstrated that proper combination of R. paludigenum and SBC can be an alternative to synthetic fungicides for the control of postharvest green mold decay of citrus.     

Quality Changes in Fresh-cut Peach and Nectarine Slices as Affected by Cultivar, Storage Atmosphere and Chemical Treatments

The shelf-life of slices from 13 cultivars of peaches and 8 cultivars of nectarines, varied (between 2 and 12 days at 0°C). Controlled atmospheres of 0.25 kPa O₂ and/or 10 kPa or 20 kPa CO₂ extended the shelf-life at 10°C of ‘O'Henry’ or ‘Elegant Lady’ peach slices by 1–2 days beyond the air control. Low (0.25 kPa) O₂ acted synergistically with CO₂ levels of 10 and 20 kPa to induce fermentative metabolism as indicated by ethanol and acetaldehyde production. A 2% (w/v) ascorbic acid + 1% (w/v) calcium lactate postcutting dip resulted in limited reduction of cut surface browning and tissue softening in ‘Carnival’ peach slices.     

脱水香菇不同贮藏水分活度下细菌菌落演替规律及关键菌控制

脱水香菇是目前香菇加工产品的主要形式,贮藏环境的湿度和微生物污染是导致脱水香菇品质变化的主要因素。本实验通过高通量测序方法研究了不同水分活度（water activity,aw）（0.43、0.67、0.76、0.84）环境下脱水香菇贮藏50 d,各处理样品细菌群落的变化,并对发现的关键危害菌进行了控制技术研究。结果表明：脱水香菇携带的细菌主要为肠杆菌科,丰度达50%,贮藏50 d后,高aw环境促进了葡萄球菌科和微球菌科微生物生长。对能够导致食品安全问题的金黄色葡萄球菌控制技术研究显示,5 kGy剂量的电子束辐照杀菌几乎可以杀灭脱水香菇中全部的金黄色葡萄球菌。本研究可为脱水香菇的品质控制、延长货架期提供理论基础。     

Biological control of Monilinia laxa and Rhizopus stolonifer in postharvest of stone fruit by Pantoea agglomerans EPS125 and putative mechanisms of antagonism

Treatment of stone fruits (apricot, peach and nectarine) with Pantoea agglomerans strain EPS125 decreased the incidence and diameter of lesions of brown rot caused by Monilinia laxa and soft rot caused by Rhizopus stolonifer. Root control was achieved on fruits either wounded and subsequently inoculated with the pathogens or non-wounded and naturally infected from orchards. The efficacy of biocontrol was dependent on the concentration of the biocontrol agent and pathogen. At medium to low pathogen dose, optimal EPS125 concentrations were above 10(7) CFU ml(-1). The median effective dose (ED(50)) of EPS125 was 4.5x10(4) in M. laxa and 2.2x10(5) CFU ml(-1) in R. stolonifer. However, EPS125 was more effective in M. laxa than in R. stolonifer as indicated by the ratio between ED(50) of the biocontrol agent and pathogen (K(z)/K(x)) which was 166 and 1263, respectively. Interactions between the strain EPS125 and the fruit surface, and M. laxa and R. stolonifer, were studied to determine the mechanisms of protection from postharvest rots. The strain EPS125 colonizes, grows and survives on stone fruit wounds. Significant inhibition of conidial germination and hyphal growth of R. stolonifer and M. laxa was achieved when the fungal and EPS125 cells were cocultivated on peel leachate or nectarine juice. However, no effect was observed when the antagonist and the pathogen cells were physically separated by a membrane filter which permits nutrient and metabolite interchange. Therefore, a direct interaction between the strain and the pathogen cells is necessary for antagonism, without a significant contribution of the production of antibiotic substances or nutrient competition. Preemptive exclusion by wound colonization and direct interaction with the pathogen is proposed as the mechanism of biocontrol.     

热镀锌助镀剂的使用与环保

论述钢丝热镀锌助镀剂处理的作用 ,助镀剂处理的方式 ,应用的热镀锌助镀剂种类 ,重点介绍无烟雾或少烟雾助镀剂 ;给出了 9个专利配方 ,以便尽可能优化车间的工作条件并减轻周边的环境污染。     

植物精油对草莓果实腐烂和品质的影响

以“丰香”草莓为试材,研究不同添加量(0.5、1、5、10μL/L)的香芹酚、肉桂醛、紫苏醛、沉香萜醇和异硫氰酸稀丙酯(AITC)处理对草莓果实常温和低温保鲜的效果。结果表明,五种植物精油都能显著抑制草莓果实在20℃和5℃贮藏期间腐烂的发生,其中以AITC处理的效果最好。但处理水平过高,即AITC和紫苏醛处理水平达到5μL/L、其他3种精油处理水平为10μL/L时,会对果实产生药害。采用适宜处理水平的各种植物精油处理还可显著抑制果实在5℃贮藏时质量损失率的上升和硬度的下降、保持较高的可滴定酸、可溶性固形物、VC、总糖和还原糖含量,从而保持果实品质。因此,植物精油处理在草莓果实防腐保鲜中具较好的应用前景。