Characteristics of some nutritional composition of melon (Cucumis melo hybrid 'ChunLi') seeds

Seeds from a melon hybrid ‘ChunLi’ were analysed for their proximate composition. The seeds contained high percentages of lipids (35.36%) and proteins (29.90%). Hexane‐extracted oil had acid, peroxide, iodine and saponification values of 1.51, 3.95, 89.5 and 226.73, respectively. Gas chromatographic analysis of the oil revealed the presence of twenty‐five fatty acids varying from C₄ to C₂₄ with the exception of C₅, C₇, C₁₁ and C₁₉. The concentrations of individual fatty acids varied from trace quantities to about 54.8%. Linoleic, oleic, palmitic and stearic acids were the principal fatty acids contributing to 53.9%, 12.1%, 23.9% and 5.7%, respectively, of the total fatty acids which had a relatively high percentage (67.5%) of unsaturated fatty acids. Seed proteins were rich in arginine, aspartic and glutamic acids while limiting amino acids were methionine and lysine.     

Characterisation of wines and distilled spirits from melon (Cucumis melo L.)

Melon fermentation and distillation was studied with a view to produce melon spirits. Three different substrates were obtained from melon (Cucumis melo L.). Sugar concentration was around 60–70 g L^?1 and the pH between 4.6 and 5.2. The substrates were clarified and then fermented at one of two pH levels at 20 °C. A commercial Saccharomyces cerevisiae starter culture was used to obtain melon wines with an alcohol concentration of 3.8–5.8% (v/v). The melon wines were distilled in a distillation column to yield distillates with an alcohol content of 33–60% (v/v). The major volatiles in the melon wines and in the distillates were analysed by gas chromatography (GC). The results demonstrated that melon could be a good substrate of fermentation and distillation but also yielded significant differences in the volatiles analysed in the different melon wines and distillates obtained from the different substrates in the different conditions of the experiment. Fermentation pH greatly affected the methanol, acetaldehyde, and butanol contents and thus the final quality of the spirits produced.     

Interaction of Salmonella enterica subspecies enterica serovar Typhimurium and mung bean (Phaseolus aureus) plants

The effect of Salmonella enterica subspecies enterica serovar Typhimurium, a zoonotic serovar, on mung bean (Phaseolus aureus) cultivar Pant Mung-3 plants was studied. Inoculation of mung bean seeds with Salmonella Typhimurium (7.2 x 10(5) CFU/ml) reduced sprouting rate (P < 0.07). This effect was more pronounced at higher levels of contamination. In the soil inoculated with Salmonella Typhimurium (7.2 x 10(6) CFU/g), germination was retarded and the number of defective sprouts was also significantly higher (P < 0.002). Salmonella Typhimurium grew inside germinating seeds and plant tissues and persisted in seedlings, adult plants, and harvested seedlings dried and stored at room temperature (30 degrees C) up to 45 days. Phaseolus aureus plants grown in sterile soil was resistant to Salmonella Typhimurium infection at 15 days of age and cleared Salmonella from all the aerial parts within 3 h of infection. However, Salmonella Typhimurium could be reisolated from the basal area of the stem and from soil even after 45 days of exposure to the pathogen.     

Virulence-resistance plasmids (pUO-StVR2-like) in meat isolates of Salmonella enterica serovar Typhimurium

During a screening of Salmonella enterica in foods of animal origin four isolates of serovar Typhimurium carrying hybrid virulence-resistance plasmids were detected. Three of them, one from pork and two from chicken meat, contained pUO-StVR2, a derivative of the pSLT virulence plasmid with the bla_OXA-1, catA1, aadA1, sulI and tet(B) genes, which confer resistance to ampicillin, chloramphenicol, streptomycin-spectinomycin, sulfonamides and tetracycline, respectively. The fourth isolate, from pork, harbored a pUO-StVR2 variant (termed ν8) with an additional dfrA10 gene responsible for resistance to trimethoprim. This gene is part of the orf513-dfrA10-qacEΔ1-sul1 element characteristically found in complex class 1 integrons. Pulsed-field gel electrophoresis identified two XbaI-BlnI combined profiles: X2-B2 generated from the three pUO-StVR2 isolates, and X12-B17 shown by the pUO-StVR2-ν8 isolate. The same profiles have also been found in clinical and ill pig isolates, supporting chicken and pork meat as vehicles for transmission of Typhimurium carrying pUO-StVR2-like plasmids.     

Evaluation of Potent Odorants in Cucumbers (Cucumis sativus) and Muskmelons (Cucumis melo) by Aroma Extract Dilution Analysis

The volatile components of cucumbers and muskmelons were analyzed by a technique which reveals the odorants having the highest odor units (ratio of the concentration to the odor threshold). (E/Z)-2,6-Nonadienal, followed by (Z)-2-nonenal and (E)-2-nonenal were the most significant odorants of cucumbers. The flavor of muskmelons was more complex. Methyl 2-methylbutanoate, (Z)-3-hexenal, (E)-2-hexenal, and ethyl 2-methylpropanoate were identified as the primary odorants.     

Rapid Detection of Salmonella enterica Subspecies enterica serovar Typhimurium by Loop Mediated Isothermal Amplification (LAMP) Test From Field Chicken Meat Samples

Considering the importance of Salmonella enterica subsp. enterica serovar Typhimurium in the foodborne diseases, a Typhimurium specific loop mediated isothermal amplification (LAMP) test was standardized for its rapid detection in chicken meat. The Optimum results were obtained at 64^oC and 70 min temperature-time combination. The sensitivity of LAMP and PCR were compared with serial 10-fold dilution of the 100 ng of DNA. The LAMP test detected 2 pg DNA per reaction tube, whereas PCR detected 200 pg DNA per reaction. Therefore, the LAMP test was considered 100 times more sensitive than the PCR. The specificity of LAMP and PCR analyzed with six different isolates of non-Salmonella and 22 serovars of non-Typhimurium. None of these isolates were found positive by both LAMP and PCR. Twenty-eight pure isolates of Salmonella Typhimurium from diverse sources were also examined by Typhimurium specific LAMP and were all found positive. Two-hundred twenty-five field chicken meat samples were screened by cultural, PCR, and LAMP methods. The LAMP and PCR tests were performed by using DNA isolated from 8 h and 18 h enrichment samples, respectively. Typhimurium specific LAMP was shown to be in 100% correlated with cultural and PCR methods. However, LAMP test delivered the results within 26 h without sophisticated equipment while PCR and cultural methods took 48 h and 6 d, respectively. The LAMP test developed in this study has potential to detect and as well as differentiate S. Typhimurium from other Salmonella serovars.     

热辅助超声波处理中VBNC态鼠伤寒沙门氏菌产生及其机制

为了研究热辅助超声波(TS)处理中鼠伤寒沙门氏菌进入活的非可培养态(VBNC)的情况及可能机制,本文采用RT-qPCR与平板计数法检测其VBNC态发生情况,采用ESR方法定性、定量检测TS处理中产生自由基并用数学模型分析其与VBNC态发生率指数之间的关系。结果表明:TS处理强度与VBNC态鼠伤寒沙门氏菌产生及自由基强度有重要影响。经TS处理,在BPY培养基中主要产生3种自由基,包括以碳为中心自由基、羟基自由基与氢质子自由基。自由基强度与VBNC态发生率指数之间高度相关,可用Boltzmann模型进行拟合和验证。以丙酮酸钠作为自由基清除剂,验证了自由基对鼠伤寒沙门氏菌进入VBNC态具有重要作用。本研究结果对于TS处理技术的应用具有指导意义。     

Antimicrobial efficacy of gaseous chlorine dioxide against Salmonella enterica Typhimurium on grape tomato (Lycopersicon esculentum)

The aim of this study was to investigate the effects of gas level and treatment condition on antimicrobial efficacy of ClO₂ gas against Salmonella enterica Typhimurium on grape tomato (Lycopersicon esculentum). Grape tomatoes were dip‐inoculated with inoculum of S. enterica Typhimurium TISTR 292 (ATCC 13311) (9.79 ± 0.39 log CFU mL^?1) and allowed to dry before treatments. The pre‐inoculated samples were exposed to 0.15–0.85 mg of ClO₂ gas, for up to 58 min. The treatments at 4 and 25 °C resulted in population reductions of S. enterica Typhimurium of up to 3.95 ± 0.22 and 7.37 ± 0.39 log CFU per fruit, respectively. The population reduction results were used to construct statistical models to predict efficacy of ClO₂ gas. The second‐order equations for treatments at 4 and 25 °C had R² of 0.87 and 0.95, respectively, and indicated that efficacy of ClO₂ gas was significantly influenced by ClO₂ gas level, exposure time and treatment temperature.     

Evaluation of the effects of different thawing methods on texture,colour and ascorbic acid retention of frozen hami melon (Cucumis melo var. saccharinus)

The effects of different thawing methods (room temperature thawing, running water thawing, microwave thawing at 300 W, 500 W, 700 W and high‐pressure thawing at 100 MPa, 150 MPa, 200 MPa) on quality (drip loss, texture, colour, ascorbic acid contents and sensory quality) of frozen hami melon were investigated. The results showed that different thawing treatments affected the quality of hami melon significantly (P < 0.05). Samples thawed by microwave at 500 W best preserved ascorbic acid for nearly half of fresh hami melon. Less drip loss, texture damage and discolouring were observed for the samples thawed by microwave at 700 W than other thawed samples; however, serious ascorbic acid loss was detected. High‐pressure‐thawed samples exhibited shorter thawing time but severe quality losses. The results suggested that microwave thawing at 500 W was an appropriate method to thaw frozen hami melon with the highest sensory score (6.7).     

In vitro inhibitory effect of oriental melon (Cucumis melo L. var. makuwa Makino) seed on key enzyme linked to type 2 diabetes: Assessment of anti-diabetic potential of functional food

As the world’s population continues to increase, the agricultural discards of plant origin have attracted considerable attention for various purposes in the pharmaceutical and food industry. The objective of present study was to evaluate the potential of oriental melon (Cucumis melo L. var. makuwa Makino) seed for management of hyperglycaemia-linked to type 2 diabetes. Ethanol and hexane extracts from oriental melon seed were used to evaluate their inhibitory activities against α-glucosidase and α-amylase. Low phenolic-containing hexane extract exhibited much higher inhibitory activities against α-glucosidase and α-amylase than ethanol extract. The GC–MS result revealed that hexane extract constituted linoleic acid (29.6%), oleic acid (17.3%), and palmitic acid (6.5%). At high concentration, hexane extract exhibited strong inhibitory activities against α-glucosidase (35.3%) and α-amylase (61.8%). These in vitro studies indicated that hexane extract of oriental melon seed could be used as a potent alternative for controlling type 2 diabetes.     

Comparison of sublethal injury induced in Salmonella enterica serovar Typhimurium by heat and by different nonthermal treatments

We have studied sublethal injury in Salmonella enterica serovar Typhimurium caused by mild heat and by different emerging nonthermal food preservation treatments, i.e., high-pressure homogenization, high hydrostatic pressure, pulsed white light, and pulsed electric field. Sublethal injury was determined by plating on different selective media, i.e., tryptic soy agar (TSA) plus 3% NaCl, TSA adjusted to pH 5.5, and violet red bile glucose agar. For each inactivation technique, at least five treatments using different doses were applied in order to cover an inactivation range of 0 to 5 log units. For all of the treatments performed with a technique, the logarithm of the viability reductions measured on each of the selective plating media was plotted against the logarithm of the viability reduction on TSA as a nonselective medium, and these points were fined by a straight line. Sublethal injury between different techniques was then compared by the slope and the y intercept of these regression lines. The highest levels of sublethal injury were observed for the heat and high hydrostatic pressure treatments. Sublethal injury after those treatments was observed on all selective plating media. For the heat treatment, but not for the high-pressure treatment, sublethal injury occurred at low doses, which were not yet lethal. The other nonthermal techniques resulted in sublethal injury on only some of the selective plating media, and the levels of injury were much lower. The different manifestations of sublethal injury were attributed to different inactivation mechanisms by each of the techniques, and a mechanistic model is proposed to explain these differences.     

过氧化氢处理中鼠伤寒沙门氏菌VBNC态形成及其机制解析

为确定过氧化氢的有效杀菌浓度,以鼠伤寒沙门氏菌为目标微生物,借助分子生物学手段,探究过氧化氢对自来水中鼠伤寒沙门氏菌活性和可培养性的影响及其活的非可培养状态(viable but non-culturable,VBNC)的形成原因。结果表明:较低过氧化氢浓度(0～15 mmol/lL)处理可达到部分杀菌的效果,1 mol/L以上过氧化氢可完全灭菌。而15 mmol/L过氧化氢处理导致4.08 lg(CFU/mL)鼠伤寒沙门氏菌全部进入VBNC状态。该状态的沙门氏菌形态和结构改变,过氧化氢酶、超氧化物歧化酶和谷胱甘肽过氧化物酶几乎完全被钝化,处理中产生的自由基强度在0～30 min内与VBNC发生系数呈正相关。     

不同贮藏温度对采后86-1哈密瓜果实冷害及品质的影响

为了研究不同贮藏温度对采后哈密瓜果实冷害及品质的影响,分别对1、3、5℃贮藏条件下86-1哈密瓜果实的冷害症状、冷害指数、冷害率、细胞膜相对透性、硬度、可溶性固形物含量、可滴定酸及维生素C含量进行了系统观察、统计与测定。结果表明:86-1哈密瓜冷害的发生与贮藏温度及持续时间有关,1℃贮藏条件下,86-1哈密瓜果实冷害出现的时间较早,果实的冷害指数、冷害率及细胞膜相对透性较高;硬度、可溶性固形物及维生素C含量下降较快,可滴定酸出现先上升后下降的趋势。3℃贮藏有利于维持86-1哈密瓜果实的品质,5℃贮藏果实虽未发生冷害,但后期品质劣变较快,腐烂较重。      

不同贮藏温度对采后86-1哈密瓜果实冷害及品质的影响

为了研究不同贮藏温度对采后哈密瓜果实冷害及品质的影响,分别对1、3、5℃贮藏条件下86-1哈密瓜果实的冷害症状、冷害指数、冷害率、细胞膜相对透性、硬度、可溶性固形物含量、可滴定酸及维生素C含量进行了系统观察、统计与测定。结果表明:86-1哈密瓜冷害的发生与贮藏温度及持续时间有关,1℃贮藏条件下,86-1哈密瓜果实冷害出现的时间较早,果实的冷害指数、冷害率及细胞膜相对透性较高;硬度、可溶性固形物及维生素C含量下降较快,可滴定酸出现先上升后下降的趋势。3℃贮藏有利于维持86-1哈密瓜果实的品质,5℃贮藏果实虽未发生冷害,但后期品质劣变较快,腐烂较重。     

Decontamination of Salmonella enterica Typhimurium on green onions using a new formula of sanitizer washing and pulsed UV light (PL)

Pathogenic bacteria such as Salmonella and Shigella flexneri have been linked to green onion contamination. This study was conducted to evaluate decontamination of Salmonella Typhimurium using a new formula of sanitizer washing (0.4 mg/mL thymol and five new formula sanitizers including 300 ppm H₂O₂ + 4% SDS, 2 mg/mL citric acid + 4% SDS, 0.2 mg/mL thymol + 4% SDS, 0.2 mg/mL thymol + 2 mg/mL citric acid and 0.2 mg/mL thymol + 2 mg/mL acetic acid), pulsed UV light (PL) as well as synergy between the sanitizer wash and PL. New formula sanitizers based on decontamination efficacy of single washing solutions (organic acids, hydrogen peroxide (H₂O₂), essential oil or surfactant) were applied to decontaminate spot inoculated green onions. PL, the novel technique, alone has been applied to inactivate Salmonella on both dip and spot inoculated green onions. Salmonella inactivation of PL–new formula sanitizer combinations on dip inoculated green onions was investigated for their potential synergy. As a result, for spot inoculated green onions, 0.4 mg/mL thymol individually and the five new formula sanitizers all achieved higher log reduction of Salmonella (4.5–5.3 log 10 CFU/g reduction) than the 200 ppm chlorine washing. These new formulas of sanitizer would be potential alternatives to chlorine. The 5 s dry PL (4.6 log 10 CFU/g) or 60 s wet PL treatment (3.6 log 10 CFU/g) was better or comparable as chlorine washing. The sanitizer combinations did not provide significantly higher log reduction than PL, and PL has the potential of being used in the green onion industry for decontamination purpose. For dip inoculated green onions, none of our treatment provided > 0.8 log 10 CFU/g (0.6–0.8 log 10 CFU/g) reduction of Salmonella. As a result, the PL–new formula sanitizer combinations had no or minimal synergy to inactivate Salmonella dip inoculated on green onions.     

Temperature alters the structure of membrane lipids and pulsed electric field (PEF) resistance of Salmonella Typhimurium

The effect of culture temperature on the conformation of membrane lipid of Salmonella Typhimurium as well as their pulsed electric field (PEF) resistance was investigated. Results revealed that S. Typhimurium cells cultured at relatively lower temperature (10 and 25 °C) were more easily inactivated by PEF treatment than those cultured at relatively higher temperature (37 and 45 °C). Using a Weibull model, it was determined that the PEF treatment time to inactivate 90% S. Typhimurium cells cultured at 45 °C was almost fourfold compared to those cultured at 10 °C. Results of micro‐Raman spectroscopy indicated that as the culture temperature increased, the order degree of C–C and lateral packing order of membrane lipid chain also increased, resulting in a drop in the membrane fluidity. These results are important in considering the use of heat and PEF to inactivate microbe contaminants in food.     

EFF对薄皮甜瓜采后相关生理因素的影响

研究不同体积分数EFF(促进保鲜配方)(enhanced freshness formulation,EFF)对薄皮甜瓜贮藏过程中部分采后生理因素的影响,为薄皮甜瓜的贮藏保鲜提供参考依据。以“金亨二号”薄皮甜瓜为试材,分别用1%和2%的EFF溶液浸泡后,以浸泡清水为对照(CK),测定了甜瓜在10℃贮藏期间果实品质和相关生理指标的变化。经EFF浸泡之后,减慢了果实贮藏期间质量、硬度、水分的降低速率,延缓了可溶性固形物的消耗;EFF处理延迟了乙烯高峰的出现,极显著地降低了乙烯的峰值(P＜0.01);显著提高了过氧化氢酶(catalase,CAT)和超氧化物歧化酶(superoxide dismutase,SOD)的活性(P＜0.05),极显著降低了过氧化物酶(peroxidase,POD)和多酚氧化酶(polyphenol oxidase,PPO)的活性(P＜0.01),延缓了果实的成熟和衰老,延长贮藏期。经EFF处理的果实,贮藏前期2%EFF醛类总量显著高于CK和1% EFF(P＜0.05);贮藏后期果肉中总芳香物质、总酯类、乙酸酯类和草酸酯类含量均显著升高,而且使芳香物质高峰延迟3d出现;减少了香气成分的缺失,较好地保持了甜瓜果实的品质。综合分析得出,体积分数2% EFF更有利于保持果实品质,延缓果实衰老。