大蒜挥发油对米象成虫的控制作用

采用索氏提取法,分别以乙醚、正已烷作为有机溶剂提取大蒜挥发油,详细研究了其对米象成虫的控制作用。结果表明:两种有机溶剂提取的大蒜挥发油对米象成虫均具有较强的驱避、触杀、抑制和熏蒸作用,尤其是乙醚提取的大蒜挥发油的驱避作用和熏蒸作用效果最为明显。     

乙醇和山梨酸钾对鲜食葡萄采后灰霉菌的抑制作用

灰葡萄孢接触10％和20％的乙醇30s后接种在PDA培养基上的萌发率分别是87％和56％，而对照是99％。用山梨酸钾进行同样处理，灰葡萄孢萌发率分别是84％和68％。用10％和20％乙醇加0．5％和1．0％山梨酸钾协同处理能显著提高对灰葡萄孢的抑制效果。20％乙醇和0．5％山梨酸钾处理后孢子萌发率是9．7％。接种灰葡萄孢的散粒“火焰无核”葡萄用水、10％和20％乙醇、0．5％和1．0％山梨酸钾单独处理后灰霉发生率分别为55．2％、42．1％、31．0％、37．7％和24、4％，而10％和20％乙醇加0．5％和1、0％山梨酸钾协同处理腐烂率都降到10％以下。接种灰葡萄孢的“汤姆森无核”葡萄串用10％和20％乙醇、0．5％和1．0％山梨酸钾单独及协同处理30s，在1℃下贮藏30d后发现20％乙醇加0．5％和1．0％山梨酸钾协同处理对灰葡萄孢的抑制效果与使用S0：药垫的效果相当，并且对葡萄无任何伤害。     

ANTIFUNGAL ACTIVITIES OF THYME, CLOVE AND OREGANO ESSENTIAL OILS

The antifungal potential of essential oils of oregano (Origanum vulgare), thyme (Thymus vulgaris) and clove (Syzygium aromaticum) was determined. To establish this antifungal potential, two molds related to food spoilage, Aspergillus niger and Aspergillus flavus, were selected. The agar dilution method was employed for the determination of antifungal activities. The three essential oils analyzed presented inhibitory effects on both molds tested. Oregano essential oil showed the highest inhibition of mold growth, followed by clove and thyme. Aspergillus flavus was more sensitive to thyme essential oil than A. niger. Clove essential oil was a stronger inhibitor against A. niger than against A. flavus.     

PILOT PLANT FOR OSMOTIC DEHYDRATION OF FRUITS: DESIGN AND EVALUATION

This work proposes a pilot scale equipment for osmotic dehydration (OD) of apple cubes that consists of a novel agitation‐immersion device, a bag filter and a vacuum evaporator to conduct simultaneously the OD process, filtration and reconcentration of the osmotic solution (OS). The functional method analysis was used to design the pilot plant. Apple cubes (～1 cm³) were dehydrated using a 60 ° Brix sucrose syrup OS at 50C and a syrup/fruit ratio of 5. OD was conducted either with or without reconcentration of the OS. During the OD process particles of fruit were eliminated from the OS by filtration and the OS concentration was kept at 60 ° Brix by reconcentration in the evaporator. A comparison of the dehydration parameters of apple cubes obtained at pilot scale to those obtained at laboratory scale was done to evaluate the performance of the pilot equipment. The results show that the proposed set‐up can be suitable for commercial production of osmodehydrated fruits.     

EFFECT OF SOME HERB ESSENTIAL OILS ON LIPOLYSIS IN WHITE CHEESE

The influence of some herb essential oils on the lipolysis of white cheese was examined. The essential oils of Sirmo (wild Allium sp.), thyme (wild Thymus sp.) and mint (wild Mentha sp.) were added individually or in combinations to cheeses. The cheese samples were ripened for 90 days at 5C. Lipolysis rate increased from the beginning to the sixtieth day of ripening, then decreased up to 90 days in cheese samples. The highest lipolysis rate was observed in the control sample while the lowest was in thyme and sirmo-thyme added samples. Differences between cheese samples and ripening periods were found to be statistically significant (P<0.01) in terms of fatty acids production rates. Sirmo and mint essential oils did not affect the lipolysis of white cheese. The sensory acceptability ofsirmo and mint essential oils added cheeses was superior to that of other samples.     

EVALUATION OF PRODUCTIVITY AND POSTHARVEST QUALITY DURING STORAGE OF FIVE AGARICUS BISPORUS STRAINS

Five Agaricus bisporus commercial strains (S100, A15, F56, F40 and F62) were evaluated as regards their colonization rates, yields, quality characters and storability. Concerning their colonization performance, the mycelial growth rates examined in “race tubes” on sterile compost, as well as earliness in fructification did not differ significantly. Significantly lower was the yield of strain S100 compared to the yield of strains F62 and F56, which presented the greatest cumulative biological efficiency values. However, mushroom number and average weight presented negative relation. For the storage and quality study, mushrooms at the “closed‐cap” stage packaged in 500‐g plastic containers were stored for 5 days at 2C and 5 days at 18C (shelf life). The respiration behavior of the five strains was similar with the mass loss not exceeding 15% during storage at 2C and 40–50% at the end of the shelf life. Also, no differences in the whiteness and texture change were detected and a correlation between the period of pileus diameter increase and the respiration rate was found. According to their color and texture quality assessment, mushrooms deriving from the first four strains may be considered well acceptable at the end of the shelf life, whereas these from strain F62 just saleable.     

PRELIMINARY EVALUATION OF THE APPLICATION OF THE FTIR SPECTROSCOPY TO CONTROL THE GEOGRAPHIC ORIGIN AND QUALITY OF VIRGIN OLIVE OILS

ABSTRACT

A rapid Fourier transform infrared (FTIR) attenuated total reflectance spectroscopic method was applied to determine qualitative parameters such as free fatty acid (FFA) content and the peroxide value (POV) in virgin olive oils. Calibration models were constructed using partial least squares regression on a large number of virgin olive oil samples. The best results (R² = 0.955, root mean square error in cross validation [RMSECV] = 0.15) to evaluate FFA content expressed in oleic acid % (w/w) were obtained considering a calibration range from 0.2 to 9.2% of FFA relative to 190 samples. For POV determination, the result obtained, built on 80 olive oil samples with a calibration range from 11.1 to 49.7 meq O₂/kg of oil, was not satisfactory (R² = 0.855, RMSECV = 3.96). We also investigated the capability of FTIR spectroscopy, in combination with multivariate analysis, to distinguish virgin olive oils based on geographic origin. The spectra of 84 monovarietal virgin olive oil samples from eight Italian regions were collected and elaborated by principal component analysis (PCA), considering the fingerprint region. The results were satisfactory and could successfully discriminate the majority of samples coming from the Emilia Romagna, Sardinian and Sicilian regions. Moreover, the explained variance from this PCA was higher than 96%.

PRACTICAL APPLICATIONS

The verification of the declared origin or the determination of the origin of an unidentified virgin olive oil is a challenging problem. In this work, we have studied the applicability of Fourier transform infrared coupled with multivariate statistical analysis to discriminate the geographic origin of virgin olive oil samples from different Italian regions.

     

CO2熏蒸对杏果呼吸速率及内源乙烯的影响

主要探讨赛买提杏果经不同浓度、不同时间的CO2熏蒸处理后在不同贮藏条件下对其呼吸速率及内源乙烯产生的影响,为新疆赛买提杏的贮藏保鲜新技术的开发应用提供理论依据.试验采用0%、5%、10%、15%浓度的CO2分别熏蒸处理赛买提杏12h及24h,将处理后的杏果放置在常温(18℃～25℃)和低温(1℃)条件下贮藏,定期对杏果贮藏过程中呼吸速率及内源乙烯产生量进行测定分析,研究结果表明:CO2熏蒸处理对杏果呼吸速率的影响,在低温条件下贮藏比常温贮藏更有效抑制杏果的呼吸作用和内源乙烯的生成,其中当CO2的熏蒸浓度为10%,熏蒸时间为12 h对杏果抑制作用较强.     

粘红酵母对水果采后病害生物防治的研究进展

粘红酵母作为一种用于生物防治的拮抗菌,具有拮抗效果好,不产生毒素,.可以和化学杀菌剂共同使用等优点.对粘红酵母(Rhodotorula glutinis)对水果采后病害生物防治的研究现状进行了综述,其中包括防治效果、防治机理、防治的优势、存在的问题以及未来的研究方向等.还提出了使用生物技术改造粘红酵母从而提高其生物防治效果,是现在应用粘红酵母对水果采后病害生物防治研究的最新领域.     

A MONOLITHIC DEVICE FOR EV-PACKAGE SO2 GENERATION FOR THE CONTROL OF POSTHARVEST BOTRYTIS DECAY OF TABLE GRAPES

The occurrence of Botrytis cinerea and sulphur dioxide (SO₂) bleaching on table grapes are the main causes for the deterioration of fruit quality during postharvest storage. Efficacy tests were conducted with novel monolithic type devices which release SO₂ at a constant rate over an extended period. The devices comprise a polymer matrix, with sodium metabisulphite (Na₂S₂O₅) particles dispersed evenly throughout the matrix. Treatment combinations consisting of various Na₂S₂O₅ concentrations (10% to 50%) and number of devices (2 and 4) placed amongst the grapes, were tested along with the inclusion or exclusion of paper liners, acting as barrier between the grapes and the SO₂ device. The efficacy of the new SO₂ device was compared with the dual release SO₂ system. The new device reduced SO₂ bleaching as result of lower initial SO₂ levels and the emission of lower levels of SO₂ over an extended period. Storage decay was also reduced with the use of the new devices. The number of discs used within the carton, the concentration Na₂S₂O₅ incorporated in the discs, and the use of corrugated paper liners, affected the proficiency of the devices. Decay control was more effective in absence of a liner than in its presence, while SO₂ damage increased when the liners were omitted. Reduced control was associated with the packaging treatments where only two discs were included, or when devices of low Na₂S₂O₅ concentrations were used. Decay control was dramatically improved by increasing the Na₂S₂O₅ concentration incorporated in the new polymer SO₂ devices.