Effect of Internal Ethylene and 1-Methylcyclopropene on Ethylene Metabolism and Membrane Lipid Peroxidation in Papaya Fruit

[Objective] This study was conducted to evaluate the effect of 1-methylcy- clopropene （1-MCP） on fruit firmness, and the activity of the enzymes involved in ethylene metabolism and membrane lipid peroxidation. [Method] The nearly ripe fruits of the papaya cultivar Risheng were randomly assigned to one of four groups. Two groups were treated under hypobaric and hypoxic （HH） atmosphere condition for six hours, and immediately soaked in deionized water （HH alone）, or fumigated with 2.0 mg/L 1-MCP （HH＋I-MCP） for 24 h. The other two groups untreated under HH condition were also soaked in deionized water （negative control）, or fumigated with 2.0 mg/L 1-MCP （1-MCP alone） for 24 h. After that, the fruits of all the four treatments were stored at room temperature （23＋1） ℃. Cell membrane permeability, fruit firmness, respiration rate, ethylene release rate, SOD activity, POD activity, CAT activity, MAD content and LOX activity were measured once every three days during storage. [Result] Treatment with 1-MCP delayed the occurrence of the peaks of respiration rate and ethylene release rate, significantly reduced the accumulation of malondialdehyde （MDA）, and inhibited the decrease in papaya fruit firmness. Compared with the control, 1-MCP treatment significantly increased the SOD （su- peroxide dismutase）, POD （peroxidase） and CAT （catalase） activity, reduced the ac- tivity of lipoxygenase （LOX）, a product of lipid peroxidatlon in membranes, and in- hibited ethylene biosynthesis, thus delaying the aging process and prolonging the storage life of papaya fruits. [Conclusion] The results will provide a theoretical basis for analvzina the key factors controllinq postharvest maturity and aging of papaya fruits.

Design of reactive distillation processes for the production of butyl acrylate:Impact of bio-based raw materials

The chemical industry is nowadays predominantly using fossil raw materials,but the alternative use of bio-based resources is investigated to account for the foreseeable scarcity of fossil feedstocks.A main challenge of using biobased feedstocks is the complexity of the impurity profile.For an economic production of bio-based chemicals,the use of intensified processes is inevitable and approaches are needed for the various process intensification techniques to identify their applicability to be used for the production of bio-based components.In the presented study,an approach is shown for the reactive distillation(RD) technology to identify the most critical bio-based impurities and their impact on the reactive distillation process.The investigated case-study is the production of n-butyl acrylate from acrylic acid and n-butanol.Among all initially identified impurities,the key impurities,having the biggest impact on the product purity in the reactive distillation process,are found.These impurities are then studied in more detail and an operating window depending on the impurity concentration is identified for the reactive distillation column.Furthermore,an integrated design of upstream and downstream processes is facilitated,as the presented results can be used in the development of the fermentation processes for the production of the bio-based reactants by decreasing the concentration of the critical impurities.