Impact of pretreatment with dielectric barrier discharge plasma on the drying characteristics and bioactive compounds of jackfruit slices.

BACKGROUND: Hot-air drying is a popular method for preserving the production of jackfruit, but heat treatment damages its nutritional qualities. Cold plasma is one of the pretreatment methods used to preserve quality attributes of fruits before drying. In the present work, we studied the effect of dielectric barrier discharge (DBD) plasma on the drying characteristics, microstructure, and bioactive compounds of jackfruit slices with different pretreatment times (15, 30, 45, and 60 s), followed by hot-air drying at 50, 60, and 70 °C. A homemade DBD device was operated via three neon transformers. RESULTS: Optical emission spectrophotometry revealed the emitted spectra of the reactive species in DBD plasma, including the N2 second positive system, N2 first negative system, nitrogen ion, and hydroxyl radical. The results showed that the DBD plasma promoted moisture transfer and enhanced the drying rate, related to the changes in the surface microstructure of samples damaged by DBD plasma. The modified Overhults model was recommended for describing the drying characteristics of jackfruit slices. The contents of ascorbic acid, total phenolics, total flavonoids, total polysaccharides, and antioxidant activity in pretreated jackfruit slices were improved by 9.64%, 42.59%, 25.77%, 27.00%, and 23.13%, respectively. However, the levels of color and carotenoids were reduced. CONCLUSION: Thus, the bioactive compounds in dried jackfruit slices can be improved using the DBD plasma technique as a potential pretreatment method for the drying process. © 2023 Society of Chemical Industry.

Efficiency of liquid tin(ii) n-alkoxide initiators in the ring-opening polymerization of l-lactide: kinetic studies by non-isothermal differential scanning calorimetry.

Novel soluble liquid tin(ii) n-butoxide (Sn(OnC4H9)2), tin(ii) n-hexoxide (Sn(OnC6H13)2), and tin(ii) n-octoxide (Sn(OnC8H17)2) initiators were synthesized for use as coordination-insertion initiators in the bulk ring-opening polymerization (ROP) of l-lactide (LLA). In order to compare their efficiencies with the more commonly used tin(ii) 2-ethylhexanoate (stannous octoate, Sn(Oct)2) and conventional tin(ii) octoate/n-alcohol (SnOct2/nROH) initiating systems, kinetic parameters derived from monomer conversion data were obtained from non-isothermal differential scanning calorimetry (DSC). In this work, the three non-isothermal DSC kinetic approaches including dynamic (Kissinger, Flynn-Wall, and Ozawa); isoconversional (Friedman, Kissinger-Akahira-Sunose (KAS) and Ozawa-Flynn-Wall (OFW)); and Borchardt and Daniels (B/D) methods of data analysis were compared. The kinetic results showed that, under the same conditions, the rate of polymerization for the 7 initiators/initiating systems was in the order of liquid Sn(OnC4H9)2 > Sn(Oct)2/nC4H9OH > Sn(Oct)2 ≅ liquid Sn(OnC6H13)2 > Sn(Oct)2/nC6H13OH ≅ liquid Sn(OnC8H17)2 > Sn(Oct)2/nC8H17OH. The lowest activation energies (E a = 52, 59, and 56 kJ mol-1 for the Kissinger, Flynn-Wall, and Ozawa dynamic methods; E a = 53-60, 55-58, and 60-62 kJ mol-1 for the Friedman, KAS, and OFW isoconversional methods; and E a = 76-84 kJ mol-1 for the B/D) were found in the polymerizations using the novel liquid Sn(OnC4H9)2 as the initiator, thereby showing it to be the most efficient initiator in the ROP of l-lactide.