Effects of chitosan coating enriched with cinnamon oil on qualitative properties of sweet pepper (Capsicum annuum L.)

Chitosan-Based Coating with Antimicrobial Agents: Preparation, Property, Mechanism, and Application Effectiveness on Fruits and Vegetables

Chitosan coating is beneficial to maintaining the storage quality and prolonging the shelf life of postharvest fruits and vegetables, which is always used as the carrier film for the antimicrobial agents. This review focuses on the preparation, property, mechanism, and application effectiveness on the fruits and vegetables of chitosan-based coating with antimicrobial agents. Chitosan, derived by deacetylation of chitin, is a modified and natural biopolymer as the coating material. In this article, the safety and biocompatible and antimicrobial properties of chitosan were introduced because these attributes are very important for its application. The methods to prepare the chitosan-based coating with antimicrobial agents, such as essential oils, acid, and nanoparticles, were developed by other researchers. Meanwhile, the application of chitosan-based coating is mainly due to its antimicrobial activity and other functional properties, which were investigated, introduced, and analyzed in this review. Furthermore, the surface and mechanical properties were also investigated by researchers and concluded in this article. Finally, the effects of chitosan-based coating on the storage quality, microbial safety, and shelf life of fruits and vegetables were introduced. Their results indicated that chitosan-based coating with different antimicrobial agents would probably have wide prospect in the preservation of fruits and vegetables in the future.

Non-Conventional Tools to Preserve and Prolong the Quality of Minimally-Processed Fruits and Vegetables

The main topic of this paper is a focus on some non-conventional tools to preserve the microbiological and physico-chemical quality of fresh-cut fruits and vegetables. The quality of fresh-cut foods is the result of a complex equilibrium involving surface microbiota, storage temperature, gas in the headspace and the use of antimicrobials. This paper proposes a short overview of some non-conventional approaches able to preserve the quality of this kind of product, with a special focus on some new ways, as follows: (1) use of edible or antimicrobial-containing coatings (e.g., chitosan-based coatings) on fruits or vegetables; (2) alternative modified atmospheres (e.g., high O2-modified atmosphere packaging (MAP)) or the use of essential oils in the headspace; (3) conditioning solutions with antimicrobials or natural compounds for fruit salad; and (4) biopreservation and use of a probiotic coating.

Effect of chitosan coating with cinnamon oil on the quality and physiological attributes of China jujube fruits

Effects of chitosan coating with cinnamon oil on the physiological attributes and preservation quality of China jujube fruits during storage at 4°C for 60 days were investigated. Results indicated that weight loss and decay of jujube fruits were significantly reduced by chitosan-oil coating during the period of 60-day storage, which also exhibited a quite beneficial effect on maintaining the sensory quality for jujube fruits. Meanwhile, the contents of vitamin C and titratable acid decreased to 3.08 mg·g(-1) and 0.342% for the fruits treated by chitosan-oil coating (1.0% + 0.10%), respectively. Polyphenol oxidase, superoxide dismutase, and peroxidase activities were 13.40 U·g(-1), 14.53 U·g(-1), and 63.6 U·g(-1) at the end of storage, respectively. The contents of total soluble phenolics and MDA were 34.51 mg·g(-1) and 19.43 μmol·g(-1) for the combined coating treated samples and control fruits, respectively. These results suggested that the chitosan-oil coating might be recognized as one efficiency technology on the preservation quality of jujube fruits during the storage time.

Application of Volatile Antifungal Plant Essential Oils for Controlling Pepper Fruit Anthracnose by Colletotrichum gloeosporioides

Anthracnose caused by Colletotrichum gloeosporioides has been destructive during pepper fruit production in outdoor fields in Korea. In vitro antifungal activities of 15 different plant essential oils or its components were evaluated during conidial germination and mycelial growth of C. gloeosporioides. In vitro conidial germination was most drastically inhibited by vapour treatments with carvacrol, cinnamon oil, trans-cinnamaldehyde, citral, p-cymene and linalool. Inhibition of the mycelial growth by indirect vapour treatment with essential oils was also demonstrated compared with untreated control. Carvacrol, cinnamon oil, trans-cinnamaldehyde, citral and eugenol were among the most inhibitory plant essential oils by the indirect antifungal efficacies. Plant protection efficacies of the plant essential oils were demonstrated by reduced lesion diameter on the C. gloeosporioides-inoculated immature green pepper fruits compared to the inoculated control fruits without any plant essential oil treatment. In planta test showed that all plant essential oils tested in this study demonstrated plant protection efficacies against pepper fruit anthracnose with similar levels. Thus, application of different plant essential oils can be used for eco-friendly disease management of anthracnose during pepper fruit production.

Effect of meadowsweet flower extract-pullulan coatings on rhizopus rot development and postharvest quality of cold-stored red peppers

The study involved an examination of the antifungal activity on red peppers of pullulan coating (P) and pullulan coating containing either water-ethanol (P + eEMF) or ethanol extract of meadowsweet flowers (P + eEMF). Pullulan was obtained from a culture of Aureobasidium pullulans B-1 mutant. Both non-inoculated peppers and those artificially inoculated with Rhizopus arrhizus were coated and incubated at 24 °C for 5 days. The intensity of the decay caused by Rhizopus arrhizus in the peppers with P and P + eEMF coatings was nearly 3-fold lower, and in the case of P + weEMF 5-fold lower, than that observed in the control peppers. Additionally, the P + weEMF coating decreased, almost two-fold the severity of pepper decay compared to other samples. The influence of coating of pepper postharvest quality was examined after 30 days of storage at 6 °C and 70%-75% RH. All coatings formed a thin and well-attached additional layer of an intensified gloss. During storage, color, total soluble solid content and weight loss of coated peppers were subject to lower changes in comparison with uncoated ones. The results indicate the possibility of the application of pullulan coatings containing MFEs as an alternative to the chemical fungicides used to combat pepper postharvest diseases.

Films and edible coatings containing antioxidants - a review

The incorporation of natural antioxidants into films and edible coatings can modify their structure, improving their functionality and applicability in foods, such as in fresh-cut fruits. This paper reviews the more recent literature on the incorporation of antioxidants from several sources into films and edible coatings, for application in fruits and vegetables. The use of synthetic antioxidants in foods has been avoided due to their possible toxic effects. Instead, a wide range of natural antioxidants (such as essential oils and plant extracts, as well as pure compounds, like ascorbic acid and α-tocopherol) have been incorporated into edible films and coatings to improve their bioactive properties. Films and coatings containing added antioxidants help to preserve or enhance the sensory properties of foods and add value to the food products by increasing their shelf life.

Evaluation of cinnamon essential oil microemulsion and its vapor phase for controlling postharvest gray mold of pears (Pyrus pyrifolia)

BACKGROUND

Essential oil of cinnamon (CM) is a potential alternative to chemical fungicides. Thus this work aimed to investigate the possible effects of CM microemulsions on decay developments and qualitative properties of pears.

RESULTS

The decay incidence of samples treated with 500 µg L⁻¹ microemulsion was significantly reduced by 18.7% in comparison to that of 500 µg L⁻¹ non-microemulsion after 4 days' storage at 20 °C. In the vapor phase, the CM microemulsion with the lowest concentration had the best control for decay incidence and lesion diameter. The interval between inoculations also influenced decay development. Pears treated with Botrytis cinerea and immediately followed by CM microemulsion showed the lowest decay incidence. Moreover, in the natural decay experiment, the percentage of rotted pears was 3.8% in the CM microemulsion treatment and 5.8% in the control. CM microemulsion delayed the loss of ascorbic acid, yet it had no significant influence on pear qualities such as firmness and color.

CONCLUSION

CM microemulsion may be an alternative way to control the gray mold of pears without a negative influence on its qualities.

Investigations on the antifungal effect of nerol against Aspergillus flavus causing food spoilage

The antifungal efficacy of nerol (NEL) has been proved against Aspergillus flavus by using in vitro and in vivo tests. The mycelial growth of A. flavus was completely inhibited at concentrations of 0.8 μL/mL and 0.1 μL/mL NEL in the air at contact and vapor conditions, respectively. The NEL also had an evident inhibitory effect on spore germination in A. flavus along with NEL concentration as well as time-dependent kinetic inhibition. The NEL presented noticeable inhibition on dry mycelium weight and synthesis of aflatoxin B₁ (AFB₁) by A. flavus, totally restraining AFB₁ production at 0.6 μL/mL. In real food system, the efficacy of the NEL on resistance to decay development in cherry tomatoes was investigated in vivo by exposing inoculated and control fruit groups to NEL vapor at different concentration. NEL vapors at 0.1 μL/mL air concentration significantly reduced artificially contaminated A. flavus and a broad spectrum of fungal microbiota. Results obtained from presented study showed that the NEL had a great antifungal activity and could be considered as a benefit and safe tool to control food spoilage.

Efficacy of the application of a coating composed of chitosan and Origanum vulgare L. essential oil to control Rhizopus stolonifer and Aspergillus niger in grapes (Vitis labrusca L.)

This study evaluated the efficacy of the combined application of chitosan (CHI) and Origanum vulgare L. essential oil (OV) in the inhibition of Rhizopus stolonifer URM 3728 and Aspergillus niger URM 5842 on laboratory media and on grapes (Vitis labrusca L.) and its influence on the physical, physicochemical and sensory characteristics of the fruits during storage (25 °C, 12 days and 12 °C, 24 days). The application of mixtures of different CHI and OV concentrations (Minimum Inhibitory Concentration - MIC, 1/2 MIC and 1/4 MIC) inhibited the mycelial growth of the test fungi. The application of CHI and OV at sub-inhibitory concentrations (CHI 1/2 MIC + OV 1/4 MIC; CHI 1/2 MIC + OV 1/2 MIC) inhibited spore germination and caused morphological changes in fungal spores and mycelia, in addition to inhibiting the growth of the assayed fungi strains in artificially infected grapes as well as the autochthonous mycoflora of grapes stored at both room and cold temperature. In general, the application of a coating composed of CHI and OV at sub-inhibitory concentrations preserved the quality of grapes as measured by their physical and physicochemical attributes, while some of their sensory attributes improved throughout the assessed storage time. These results demonstrate the potential of the combination of CHI and OV at sub-inhibitory concentrations to control post-harvest pathogenic fungi in fruits, in particular, R. stolonifer and A. niger in grapes.

Effect of chitosan coating enriched with thyme oil on postharvest quality and shelf life of shiitake mushroom (Lentinus edodes)

The effect of chitosan-oil coating on the postharvest quality and shelf life of shiitake (Lentinus edodes) mushrooms stored at 4 ± 1 °C for 16 days was investigated. Mushroom weight loss, firmness, total phenolics, ascorbic acid, malondialdehyde (MDA), electrolyte leakage rate, and microbial and sensory quality were measured. The results indicate that treatment with chitosan-oil coating maintained tissue firmness, inhibited increase of respiration rate, and reduced microorganism counts, such as yeasts and molds and pseudomonad, compared to control treatment. The efficiency was better than that of thyme oil treatment or chitosan coating. Furthermore, shiitake mushrooms treated with chitosan-oil coating also exhibited significantly higher levels of total phenolics, flavonoids, as well as individual phenolic compounds than control. Sensory evaluation proved the efficacy of chitosan-oil coating by maintaining the overall quality of shiitake mushroom during the storage period. Our study suggests that chitosan-oil coating might be a promising candidate for maintaining shiitake mushroom quality and extending their postharvest life.

Antimicrobial Activity of Microencapsulated Cinnamon Oil and Its Application on Cherry Tomato

In this investigation, antibacterial property of microencapsulated cinnamon oil was investigated. Microencapsulated cinnamon oil was prepared by simple coacervation. Microencapsulated cinnamon oil exhibited good antimicrobial activities.Moreover, the effect of microencapsulated cinnamon oil on the quality of cherry tomato was investigated. Result showed microencapsulated cinnamon oil could reduced fruit decay and keep the quality of cherry tomato.