Peroxidation of membrane lipids in minimally processed cucumbers packaged under modified atmospheres

Karakaş, Barçın
Peroxidation of membrane lipids is an inherent feature of ripening and senescence of plant tissues. Increased lipid peroxidation has also been observed in the development of chilling injury in susceptible tissues. In this study, the effect of storage conditions and physical tissue damage on membrane peroxidation of minimally processed cucumber (Cucumis sativus, L.) was investigated. Model modified atmospheres were achieved passively by storage of the minimally processed cucumbers at 4°C and 20°C in hermetically sealed jars. Treatments such as oxygen flushing of the packages and bruising of the fruit previous to sealing resulted in different atmospheric compositions and respiration rates. Lipid peroxidation in samples packaged under these conditions of modified atmosphere packaging (MAP) and also in covered petri plates (non- MAP) were determined by the FOX2 method. The TBARS assay was also carried out as an alternative assessment of lipid peroxidation. The initial level of lipid hydroperoxides and TBARS were found as 48-59 umoles H2O2 equivalents and 0.11-0.20 nmoles MDA equivalents per gram. The results of the two assays correlated significantly for nonbruised samples. The levels of lipid hydroperoxides increased by 2-5 fold in chilled non-MAP tissues and MAP was effective in reducing the generation of lipid hydroperoxides and TBARS. The effect of dipping solutions containing CaCİ2 and/or ascorbic acid on the development of lipid hydroperoxides investigated in non-MAP tissues had varying results. Tissue hardness of MAP samples increased for the first 3 days for all tissues but chilled tissues started to soften on the 6th day.


AKIN, H; Hasırcı, Vasıf Nejat; Hasırcı, Nesrin (1990-02-01)
Poly(2-vinylpyridine) is known to be hydrophobic, and a membrane prepared from it would not permeate water-soluble substances in aqueous media. By introducing hydrophilic poly(2-vinyl-N-methylpyridinium iodide) particles into the membrane, it would be possible to control permeation. This type of membrane was prepared and an increase in permeability was observed on increasing the amount of hydrophilic component in the membrane and decreasing the crosslink density of the hydrogel part. The size of the hydroge...
Immune modulatory effects of pediococcus pentosaceus derived membrane vesicles: mechanism of action and therapeutic applications
Alpdündar Bulut, Esin; Gürsel, Mayda; Department of Biology (2018)
In our previous studies, we characterized 5 different human gram positive commensal bacteria derived membrane vesicles (MVs) and compared their activity with non-pathogenic E.coli derived membrane vesicles. Results showed that commensal bacteria derived MVs had immunomodulatory properties whereas non-pathogenic E.coli derived membrane vesicles had immune stimulatory properties. In this thesis, we aimed to focus our attention to Pediococcus pentosaceus-derived MVs that displayed the highest immunomodulatory ...
EROGLU, I; ZUBAT, BM; Yücel, Ayşe Meral (1991-09-01)
Purple membrane fragments isolated from the cell membrane of the photosynthetic bacteria Halobacterium halobium S.9 strain are incorporated into egg yolk phosphatidylcholine liposomes. Purple membrane contains crystalline patches of a retinal protein called bacteriorhodopsin. Upon illumination, bacteriorhodopsin undergoes a reversible photoreaction in which a proton is released on one side of the membrane and a proton is bound on the other side, thus resulting in an electro-chemical gradient across the me...
Immunomodulatory effects of commensal bacteria-derived membrane vesicles
Alpdündar, Esin; Gürsel, Mayda; Department of Biology (2013)
Constitutive secretion of extracellular membrane vesicles is a common feature of cells from all domains of life including Archaea, Bacteria, and Eukarya. Although the contribution of gram negative bacterial outer membrane vesicles in disease pathogenesis has been extensively studied, whether commensal bacteria constitutively secrete such vesicles is still unknown. Given the importance of microbiota as regulators of immune homeostasis, we aimed to assess the immunomodulatory properties of extracellular vesic...
Kinetic analysis of aspergillus oryzae cultivations on starch
Bayındırlı, Alev; UNGAN, S (Informa UK Limited, 1991-01-01)
Cultivation of Aspergillus oryzae on starch is described as a combination of two rate processes: Starch hydrolysis and the cellular activities of the fungi including growth, enzyme production and maintenance. Kinetic models are presented to describe growth, enzyme production, starch hydrolysis and uptake of the hydrolysis products. Numerical values of the model parameters indicated that the rate controlling step of A. oryzae growth on starch was not starch hydrolysis, but the substrate uptake process. Gluco...
Citation Formats
B. Karakaş, “Peroxidation of membrane lipids in minimally processed cucumbers packaged under modified atmospheres ,” M.S. - Master of Science, Middle East Technical University, 2002.