Analysis of water adsorption capacity and thermal behavior of porous carbonaceous materials by glycerol ester

Abstract

The addition of glycerol, a traditional humectant, during the storage of reconstituted tobacco accelerated the deterioration of product quality due to the excessive absorption of moisture from the air by the tobacco and glycerol, which have strong hygroscopic properties. Therefore, it is crucial to develop a new humectant with moderate moisture resistance properties. In this study, a series of compounds glycerol esters were synthesized by transesterification reaction with vinyl benzoate and vinyl cinnamate via Novozym 435 using glycerol as a starting material. Nuclear magnetic resonance (1H NMR, 13C NMR), infrared spectroscopy (IR), and high resolution mass spectrometry (HRMS) were used to confirm the structure of synthesized glycerol esters. The target compounds were added to the reconstituted tobacco shreds for 100 h hygroscopic desorption assay, model validation, moisture proof index and moisture retention index. The hygroscopicity and moisturizing ability was assessed using water activity and low-field nuclear magnetic resonance (LF-NMR). It showed that 3a (2,3-dihydroxypropyl benzoate) and 3b (2,3-dihydroxypropyl cinnamate) possessed better moisture absorption and moisturizing effect. In addition, thermogravimetric analysis (TG) and pyrolysis–gas chromatography/mass spectrometry (Py-GC/MS) techniques were applied to study the thermal behavior of 3a and 3b. These results indicated that the target compounds (3a and 3b) had good moisture absorption and moisture retention effects, high temperature stability and thermal properties for flavour release. They could effectively improve the water absorption, enhance the flavour of reconstituted tobacco, and were suitable for use in the storage and smoking process of reconstituted tobacco.

Keywords

• Glycerol esters
• Moisture property
• LF-NMR
• Py-GC/MS
• Thermal behaviors