The selective adsorption mechanism of V-type starches for key off-odors of sea cucumber intestinal peptides.

The off-odors of sea cucumber intestinal peptide (SCIP) severely limit its application. In this study, the V-type starches were derived from high amylose maize starch to adsorb odors of SCIP and the adsorption mechanism was explored. The inclusion complexes formed by V-type starches and volatile compounds of SCIP were characterized by X-ray diffraction and Fourier transform infrared spectroscopy. The electronic nose results revealed a decreasing trend in response values of SCIP, with significant differences before and after deodorization (p < 0.05). Furthermore, 82 volatiles were identified from SCIP, and six were determined as key volatiles using gas chromatography-mass spectrometry. The V6- and V7-type starches with smaller cavity sizes selectively adsorb butyric acid, isobutyric acid and nonaldehyde, and V8-type starches with a larger cavity size selectively adsorb trimethylamine. This study proved that using V-type starches for deodorization could effectively improve SCIP flavor.

A FTIR and DFT Combination Study to Reveal the Mechanism of Eliminating the Azeotropy in Ethyl Propionate-n-Propanol System with Ionic Liquid Entrainer.

Ionic liquids (ILs) have presented excellent behaviors in the separation of azeotropes in extractive distillation. However, the intrinsic molecular nature of ILs in the separation of azeotropic systems is not clear. In this paper, Fourier-transform infrared spectroscopy (FTIR) and theoretical calculations were applied to screen the microstructures of ethyl propionate-n-propanol-1-ethyl-3-methylimidzolium acetate ([EMIM][OAC]) systems before and after azeotropy breaking. A detailed vibrational analysis was carried out on the v(C=O) region of ethyl propionate and v(O-D) region of n-propanol-d1. Different species, including multiple sizes of propanol and ethyl propionate self-aggregators, ethyl propionate-n-propanol interaction complexes, and different IL-n-propanol interaction complexes, were identified using excess spectroscopy and confirmed with theoretical calculations. Their changes in relative amounts were also observed. The hydrogen bond between n-propanol and ethyl propionate/[EMIM][OAC] was detected, and the interaction properties were also revealed. Overall, the intrinsic molecular nature of the azeotropy breaking was clear. First, the interactions between [EMIM][OAC] and n-propanol were stronger than those between [EMIM][OAC] and ethyl propionate, which influenced the relative volatilities of the two components in the system. Second, the interactions between n-propanol and [EMIM][OAC] were stronger than those between n-propanol and ethyl propionate. Hence, adding [EMIM][OAC] could break apart the ethyl propionate-n-propanol complex (causing the azeotropy in the studied system). When x([EMIM][OAC]) was lower than 0.04, the azeotropy still existed mainly because the low IL could not destroy the whole ethyl propionate-n-propanol interaction complex. At x(IL) > 0.04, the whole ethyl propionate-n-propanol complex was destroyed, and the azeotropy disappeared.

Characterization of high amylose corn starch-cinnamaldehyde inclusion films for food packaging.

The antibacterial films prepared from high amylose corn starch-cinnamaldehyde (HACS-CIN) inclusion complex were reported in this work and the different structural, mechanical, physicochemical and antibacterial properties of the films were investigated. The FT-IR results supported that the CIN was encapsulated in the helical structure of HACS by self-assembly. The encapsulation efficiency was as high as 39.19%, and the releasing rate results showed HACS-CIN inclusion films could slow down the volatilization of CIN. The films showed excellent mechanical properties with tensile strength of 14.77 MPa and elongation at break of 44.95%; and good transparency with visible light transmittance of 70%. UV transmittance test showed good UV-blocking property with UV light transmittance of 30%. Antibacterial test indicated an inhibitory effect on S. aureus and E. coli. Strawberry preservation experiment showed the films delayed the shelf life of strawberries. This work provides the HACS-CIN inclusion films are potential candidates for biodegradable food packaging.

Antioxidant and antibacterial properties of essential oils-loaded ß-cyclodextrin-epichlorohydrin oligomer and chitosan composite films.

Chitosan (CS) is becoming increasingly popular in food packaging due to its natural degradability and great film-forming properties. Nevertheless, its poor antibacterial properties and inadequate antioxidant properties prevent it from being used effectively. In this study, ß-cyclodextrin-epichlorohydrin (ß-CD-EP) oligomers were prepared and encapsulated with natural essential oils cinnamaldehyde and thymol, and then the inclusion complexes (IC) were incorporated into chitosan in various contents to afford a series of CS-IC composite films. The impacts of IC on the morphological, mechanical, thermal, and water resistance properties, antioxidant and antibacterial activities of chitosan films, as well as the loading and sustained release behavior of IC, were thoroughly examined. The results turned out that the essential oils were well-loaded with high encapsulation efficiency and showed a significant slow-release effect. It was also found that the tensile strength and the elongation at break decreased with increasing IC contents, while the thermal stability was enhanced. The incorporation of IC dramatically promoted the antioxidant and antibacterial properties of the chitosan films towards Gram-positive bacteria. Based on our findings, chitosan films containing essential oils-loaded ß-CD-EP oligomers may serve as an effective food packaging material.