In this study, different amounts of cinnamomum essential oil (CEO) were encapsulated in chitosan nanoparticles (NPs) (CS-NPs) through oil-in-water emulsification and ionic gelation. An ultraviolet-visible spectrophotometer, Fourier-transform infrared spectroscopy, synchronous thermal analysis, and X-ray diffraction were employed to analyze the CEO encapsulation. As observed by field-emission scanning electron microscopy, NP size analysis and zeta potential, the prepared CS-NPs, containing CEO (CS-CEO), were spherical with uniformly distributed sizes (diameters: 190–340 nm). The ranges of encapsulation efficiency (EE) and loading capacity (LC) were 4.6–32.9% and 0.9–10.4%, with variations in the starting weight ratio of CEO to CS from 0.11 to 0.53 (w/w). It was also found that the antioxidant activity of the CS-NPs loaded with CEO increased as the EE increased. The active ingredients of the CEO were prevented from being volatilized, significantly improving the chemical stability. The antioxidant activity of CS-CEO was higher than that of the free CEO. These results indicate the promising potential of CS-CEO as an antioxidant for food processing, and packaging applications.

Deep eutectic solvents (DESs) is a newly developed green solvent with low cost, easy preparation and regeneration. Because of its excellent solubility and swelling effect in lignocellulose, it has received widespread attention and recognition. In this study, choline-based deep eutectic solvents (DESs)—choline chloride-urea (CC-U), choline chloride-ethylene glycol (CC-EG), choline chloride-glycerol (CC-G), choline chloride-lactic acid (CC-LA), and choline chloride-oxalic acid (CC-OA)—were used to extract and separate bagasse. The effects of hydrogen bond donors on lignin separation and the fiber and lignin structure were investigated. All five DESs could dissolve lignin from bagasse; acidic DESs exhibited higher solubility than basic DESs. CC-OA effectively separated lignin and hemicellulose. CC-LA showed weaker lignin separation ability than CC-OA. CC-G, CC-EG, and CC-U were more inclined to selectively separate lignin than hemicellulose. The crystalline cellulose II structure was retained after DES pretreatment. Acidic DESs effectively improved the crystallinity of bagasse fiber; the crystallinities for CC-OA and CC-LA pretreatment were 62.26% and 61.65%, respectively. The lignin dissolved in DES was mainly syringyl lignin. The lignin dissolved in CC-U, CC-LA, and CC-OA contained a small amount of guaiacyl lignin.

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As novel materials for food contact packaging, inorganic silicon oxide (SiO) films are high barrier property materials that have been developed rapidly and have attracted the attention of many manufacturers. For the safe use of SiO films for food packaging it is vital to study the interaction between SiO layers and food contaminants, as well as the function of a SiO barrier layer in antioxidant migration resistance. In this study, we deposited a SiO layer on polylactic acid (PLA)-based films to prepare SiO/PLA coated films by plasma-enhanced chemical vapour deposition. Additionally, we compared PLA-based films and SiO/PLA coated films in terms of the migration of different antioxidants (e.g. t-butylhydroquinone [TBHQ], butylated hydroxyanisole [BHA], and butylated hydroxytoluene [BHT]) via specific migration experiments and then investigated the effects of a SiO layer on antioxidant migration under different conditions. The results indicate that antioxidant migration from SiO/PLA coated films is similar to that for PLA-based films: with increase of temperature, decrease of food simulant polarity, and increase of single-sided contact time, the antioxidant migration rate and amount in SiO/PLA coated films increase. The SiO barrier layer significantly reduced the amount of migration of antioxidants with small and similar molecular weights and similar physical and chemical properties, while the degree of migration blocking was not significantly different among the studied antioxidants. However, the migration was affected by temperature and food simulant. Depending on the food simulants considered, the migration amount in SiO/PLA coated films was reduced compared with that in PLA-based films by 42-46%, 44-47%, and 44-46% for TBHQ, BHA, and BHT, respectively.

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Background Enzymatic browning and microbial decay are the primary concerns that limit the postharvest life of longan fruit. These factors can be effectively prevented by sulfur dioxide (SO2) fumigation; however, due to the safety and regulatory issues of SO2, other alternatives must be tested. In this study, antioxidant and antimicrobial activities of thymol were determined against the pericarp browning and decay of longan fruit. A simple, cost-effective method was designed for its controlled release. Thymol vapors were obtained from the slurry prepared from 5 g of thymol in 5 mL of distilled water in a 180-mL glass jar, hermetically sealed and allowed for 24 h to accumulate the vapors in the headspace. Fruits were packed in polyethylene packages and fumigated with thymol through a septum. Non-fumigated fruits served as control and all the packages were stored at 25 ± 2 °C for 8 days. Results Thymol significantly (P ≤ 0.05) retarded pericarp browning (BI), delayed the decay incidence (DI) and maintained high color values of longan pericarp. Thymol also retained high total phenolic (TPC) and total flavonoid (TFC) contents, inhibited polyphenol oxidase (PPO) and peroxidase (POD) activities than those in control. A high coefficient of correlation of PPO with BI (r = 0.86), L* (r =  − 0.94), weight loss (r = 0.93), TPC (r =  − 0.77), TFC (r =  − 0.80), DI (r = 0.92) and many other quality and color parameters indicated the antioxidant efficacy of thymol. Longer shelf life of 8 days with good quality attributes was obtained in thymol-treated fruits than 6 days in control. Conclusion Thymol could be effectively used as a natural antioxidant for a wide range of fruits. Graphic abstract

IntroductionChlorine dioxide (ClO2) is a safe and efficient bactericide with unique advantages in reducing foodborne illnesses, inhibiting microbial growth, and maintaining the nutritional quality of food. However, gaseous ClO2 is sensitive to heat, vibration, and light, which limits its application.MethodsIn this study, a ClO2 precursor-stabilized ClO2 aqueous solution was encapsulated by the double emulsion method, and a high-performance ClO2 self-releasing polyvinyl alcohol (PVA) film was prepared to investigate its performance and effect on blueberry quality during storage.ResultsThe self-releasing films had the best overall performance when the microcapsule content was 10% as the film's mechanical properties, thermal stability, and film barrier properties were significantly improved. The inhibition rates of Listeria monocytogenes and Escherichia coli were 93.69% and 95.55%, respectively, and the mycelial growth of Staphylococcus griseus was successfully inhibited. The resulting ClO2 self-releasing films were used for blueberry preservation, and an experimental study found that the ClO2 self-releasing antimicrobial film group delayed the quality decline of blueberries. During the 14-day storage period, no mold contamination was observed in the ClO2 self-releasing film group, and blueberries in the antibacterial film group had higher anthocyanin accumulation during the storage period.DiscussionResearch analysis showed that films containing ClO2 microcapsules are promising materials for future fruit and vegetable packaging.