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

Effects of Different TiO2 Nanoparticles Concentrations on the Physical and Antibacterial Activities of Chitosan-Based Coating Film

In this investigation, the effect of different concentrations of titanium dioxide (TiO₂) nanoparticles (NPs) on the structure and antimicrobial activity of chitosan-based coating films was examined. Analysis using scanning electron microscopy (SEM) and atomic force microscopy (AFM) revealed that the modified TiO₂ NPs were successfully dispersed into the chitosan matrix, and that the roughness of the chitosan-TiO₂ nanocomposites were significantly reduced. Moreover, X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) analyses indicated that the chitosan interacted with TiO₂ NPs and possessed good compatibility, while a thermogravimetric analysis (TGA) of the thermal properties showed that the chitosan-TiO₂ nanocomposites with 0.05% TiO₂ NPs concentration had the best thermal stability. The chitosan-TiO₂ nanocomposite exhibited an inhibitory effect on the growth of Escherichia coli and Staphylococcus aureus. This antimicrobial activity of the chitosan-TiO₂ nanocomposites had an inhibition zone ranging from 9.86 ± 0.90 to 13.55 ± 0.35 (mm). These results, therefore, indicate that chitosan-based coating films incorporated with TiO₂ NPs might become a potential packaging system for prolonging the shelf-life of fruits and vegetables.

Citrus Essential Oils (CEOs) and Their Applications in Food: An Overview

Citrus is a genus belonging to the Rutaceae family and includes important crops like orange, lemons, pummelos, grapefruits, limes, etc. Citrus essential oils (CEOs) consist of some major biologically active compounds like α-/β-pinene, sabinene, β-myrcene, d-limonene, linalool, α-humulene, and α-terpineol belonging to the monoterpenes, monoterpene aldehyde/alcohol, and sesquiterpenes group, respectively. These compounds possess several health beneficial properties like antioxidant, anti-inflammatory, anticancer, etc., in addition to antimicrobial properties, which have immense potential for food applications. Therefore, this review focused on the extraction, purification, and detection methods of CEOs along with their applications for food safety, packaging, and preservation. Further, the concerns of optimum dose and safe limits, their interaction effects with various food matrices and packaging materials, and possible allergic reactions associated with the use of CEOs in food applications were briefly discussed, which needs to be addressed in future research along with efficient, affordable, and "green" extraction methods to ensure CEOs as an ecofriendly, cost-effective, and natural alternative to synthetic chemical preservatives.

Calcium maintained higher quality and enhanced resistance against chilling stress by regulating enzymes in reactive oxygen and biofilm metabolism of Chinese winter jujube fruit

The postharvest senescence of Chinese winter jujube fruit can be effectively delayed by refrigerated storage. However, chilling injury often occurs in jujube fruit during cold storage. In this study, Chinese winter jujubes were sprayed with CaCl₂ (4%) 3 times at intervals of 2 hr on the day of refrigeration. The results presented that maximum difference of 2.7 N firmness, 3.42% TAC, and 0.8 OD₂₈₀ /g polyphenol content were detected in calcium-treated fruit during cold storage, but the levels of O 2 - , MDA, hydrogen peroxide, browning rate, electrolyte leakage, and weight loss rate were significantly inhibited (p < .05). The maximum difference of enzymes activity of CAT, POD, SOD was 2.1, 10.8, and 40.6 mol h^-1 kg^-1 respectively, but 21.1 mol h^-1 kg^-1 PPO was restrained in the treated group. In conclusion, the results provided a reliable method for inhibiting cold injury and explained the internal molecular mechanism of the fruit regulated by calcium. PRACTICAL APPLICATIONS: Refrigerated storage is an important method for extending the storage time of Chinese winter jujube fruit. However, cold damage may occur when the jujubes are stored at low temperature for long-term. It is, therefore, of great significance to find a new method and reveal the molecular mechanism. We believe that our study makes a significant contribution to the literature because it provides an effective method of maintaining higher quality and mechanistic insights into the resistance against the chilling stress of jujubes.

The effect of clove essential oil loaded chitosan nanoparticles on the shelf life and quality of pomegranate arils

The effect of four different coating dispersions including chitosan, clove essential oil, chitosan nanoparticles and clove essential oil loaded chitosan nanoparticles (CEO-ChNPs or encapsulated oil) was investigated on shelf life and quality of minimally processed pomegranate arils during storage at 5 °C. Among tested dispersions, CEO-ChNPs extended aril shelf life for 54 days while uncoated arils became unusable at day 18 due to the incidence of fungal decay. At the end of storage, CEO-ChNPs could significantly maintain microbial quality, weight, total soluble solid, titratable acidity, pH, total phenol and total anthocyanin content, as well as antioxidant activity and sensory quality in pomegranate arils coated with CEO-ChNPs compared to uncoated arils, however only some of mentioned parameters maintained significantly in arils coated with other dispersions (P < 0.05). According to these results, CEO-ChNPs were the most effective coating for extending shelf life and controlling undesirable microbial, physicochemical and sensory alterations of pomegranate arils.

Effects of Controlled Atmosphere on the Storage Quality and Aroma Compounds of Lemon Fruits Using the Designed Automatic Control Apparatus

‘Eureka' lemon fruits were stored under four controlled atmosphere- (CA-) combinations at 8°C for 20 days to investigate the effects on weight loss (WL), total soluble solids (TSS), titratable acidity (TA), vitamin C (VC), total phenolic content (TPC), sodium carbonate-soluble pectin (SSP), malondialdehyde (MDA), and volatile compounds. Results showed that the contents of TSS, TA, VC, and SSP in the stored fruits reduced during the storage period, while the WL and MDA increased. Fruit stored under CA2-combination (6 % O₂+8 % CO₂) showed the lower contents of WL and MDA and the higher content of TSS, TA, TPC, and VC than that of other treated fruits. The main volatile compounds present in the lemons were terpenoids, aldehydes, alcohols, and esters. In addition, both the terpenoid and aldehyde content are substantially higher in lemons exposed to CA2 conditions. In contrast, the alcohols and esters displayed elevated levels in the regular air (RA) stored fruit. In conclusion, CA with the suitable conditions proves to be better than RA as a storage regimen to keep the quality of lemons. These results indicated that the application of 6% O₂+8% CO₂ CA conditions could maintain the quality of ‘Eureka' lemon fruit during the storage time of 20 days and should be the optimal storage environment for postharvest Eureka lemons.

Clove Essential Oil as an Alternative Approach to Control Postharvest Blue Mold Caused by Penicillium italicum in Citrus Fruit

Penicillium italicum causes blue mold disease and leads to huge economic losses in citrus production. As a natural antifungal agent, clove essential oil (CEO), which is a generally recognized as safe (GRAS) substance, shows strong in vitro activity against fungal pathogens. However, few studies on CEO for controlling postharvest blue mold disease caused by P. italicum in citrus fruit have been reported. Our aims were to investigate the control efficacy and possible mechanisms involved of CEO against P. italicum. In the present study, CEO treatment inhibited the disease development of blue mold when applied at 0.05% to 0.8% (v/v), and with the effective concentration being obtained as 0.4% (v/v). Besides its direct antifungal activity, CEO treatment also spurred a rapid accumulation of H2O2 compared with untreated fruits, which might contribute to enhancing an increase in the activities of defense-related enzymes, such as β-1,3-glucanase (β-Glu), chitinase (CHI), phenylalanine ammonia-lyase (PAL), peroxidase (POD), polyphenol oxidase (PPO), and lipoxygenase (LOX) in citrus fruit. Results of real time-quantitative polymerase chain reaction (RT-qPCR) showed that the gene expressions of β-Glu, CHI, PAL, POD and PPO were up-regulated in CEO-treated fruits. At the same time, CEO treatment led to down-regulated expression of the LOX gene in citrus fruit. Clove essential oil effectively control the disease incidence of blue mold decay in citrus fruit by motivating the host-defense responses, suppressing the malondialdehyde (MDA) accumulation while enhancing the activities and gene expressions of defense-related enzymes. Our study provides an alternative preservative applying CEO to reduce postharvest fungal decay in citrus fruit.

Antimicrobial Nanoparticles Incorporated in Edible Coatings and Films for the Preservation of Fruits and Vegetables

Edible coatings and films (ECF) are employed as matrixes for incorporating antimicrobial nanoparticles (NPs), and then they are applied on the fruits and vegetables to prolong shelf life and enhance storage quality. This paper provides a comprehensive review on the preparation, antimicrobial properties and mechanisms, surface and physical qualities of ECF containing antimicrobial NPs, and its efficient application to vegetables and fruits as well. Following an introduction on the properties of the main edible coating materials, the preparation technologies of ECF with NPs are summarized. The antimicrobial activity of ECF with NPs against the tested microorganism was observed by many researchers. This might be mainly due to the electrostatic interaction between the cationic polymer or free metal ions and the charged cell membrane, the photocatalytic reaction of NPs, the detachment of free metal ion, and partly due to the antimicrobial activity of edible materials. Moreover, their physical, mechanical and releasing properties are discussed in detail, which might be influenced by the concentration of NPs. The preservation potential on the quality of fruits and vegetables indicates that various ECF with NPs might be used as the ideal materials for food application. Following the introduction on these characteristics, an attempt is made to predict future trends in this field.

Application and Evaluation of a Pectin-Based Edible Coating Process for Quality Change Kinetics and Shelf-Life Extension of Lime Fruit (Citrus aurantifolium)

Uncertain storage conditions lead to considerable quality loss in lime fruits, which affect their consumer acceptability. Studies aimed at quantifying the kinetics of quality changes under different storage conditions are valuable for minimizing the product quality loss and improving their marketability. The objective of this study was to quantify the effect of pectin-based coating on the kinetics of quality change in stored limes fruits using a pre-established coating process. Lime fruits were immersed in the coating emulsion and then surface dried, cooled, and evaluated after storage for different times at selected temperatures (10–25 °C). Quality characteristics evaluated include physical (texture and color), chemical (ascorbic acid, pH, titrable acidity, total soluble solids), and physiological (respiration rate) properties. Results revealed that with the passage of time, the fruits showed progressive increase in shriveling or wilting and loss in green color, and higher temperatures accelerated these changes. The respiration rate in control samples reached 79, 35, and 7 mL CO2/(kg·h) after 7 days at 25 °C and 22 days at 15 and 10 °C, respectively, while those of coated samples were limited to 40, 32, and 1.06 mL CO2/(kg·h) after 11, 25, and 32 days at the same storage temperatures. Control fruits suffered 6%, 10%, and 24% weight loss following 8 days of storage at 10, 15, and 20 °C, respectively, while the losses in coated fruits were lower (2%, 4%, and 17%, respectively). A zero-order model was found appropriate for weight loss, along with a color a value and ΔE, while a first-order model was found to be better for firmness, brix to acidity ratio, ascorbic acid, and b and L values (R2 > 0.9). The Arrhenius model was suitable for temperature sensitivity of the rate constants.

Extension of postharvest shelf-life in green bell pepper (Capsicum annuum L.) using exogenous application of polyamines (spermidine and putrescine)

To extend the postharvest shelf-life of green bell pepper (Capsicum annuum L.), an exogenous application of two polyamines, Spermidine and Putrescine (SPD-PUT), was tested in multiple combinations (10 μM plus 10 μM, 20 μM plus 20 μM, and 30 μM plus 30 μM) at 4 ± 1 °C for 40 days. The titratable acidity, protein content, activities of catalase and peroxidase, chlorophyll and capsaicin content gradually decreased for all the treated and untreated fruits throughout the storage period. On the other hand, proline content and antioxidant 1,1-diphenyl-2-picryl-hydrazyl (DPPH) radical scavenging activity continuously increased with the extension of time-span under storage. Among the three treatment combinations, the combination of 20 µM SPD and 20 µM PUT was found to be the optimum, based on the response of all the morphological and physicochemical traits assessed. The same combination was effective in sustaining the quality of green bell pepper following its harvest, for a period of at least 40 days.

Effect of chitosan-based coatings enriched with savory and/or tarragon essential oils on postharvest maintenance of kumquat (Fortunella sp.) fruit

The present study assessed the ability of chitosan-based coatings incorporating savory and/or tarragon essential oils (EOs) to preserve the postharvest quality of kumquats. Changes in weight loss, titratable acidity, total soluble solids, and vitamin C content were determined over 30 days of storage at 7°C. Savory (Satureja hortensias L.) essential oil was characterized by thymol (29.1%), carvacrol (26.6%), and γ-terpinene (24.72%) as major constituents. While, in the tarragon (Artemisia dracunculus L.) essential oil, estragol (81.89%), β-cis-Ocimene (4.62%), and β-trans-Ocimene (3.44%) were the main ones. The CH-EOs coatings were effective in reducing weight loss of kumquats fruits during storage. Moreover, the tested composite coatings showed positive effects in maintaining vitamin C and fruits treated with CH-oil coatings retained good sensory acceptability. The obtained results demonstrate the potential of the combined application of chitosan and savory and/or tarragon EOs as a promising postharvest treatment for maintaining the postharvest quality of kumquats fruits.

The Effect of Edible Chitosan Coatings Incorporated with Thymus capitatus Essential Oil on the Shelf-Life of Strawberry (Fragaria x ananassa) during Cold Storage

The strawberry is a fruit appreciated in the food industry for its high content of bioactive compounds. However, it is considered a highly perishable fruit, generally attacked by pests of phytopathogenic origin, which decreases its shelf-life. Normally, to diminish the losses caused by pathogenic microbes, coatings of polysaccharides in combination with natural products like essential oils are applied. In this work, we describe the effect of edible coatings from chitosan (CT) incorporating Thymus capitatus essential oil (TCEO), applied to strawberries stored under refrigeration conditions (5 ± 0.5 °C). Different concentrations of TCEO were applied to chitosan coatings, with different effects on the physical and microbiological properties of the strawberries. All the products had greater acceptance and quality than the controls, being more effective those with essential oil incorporation. It is noteworthy that all the essential oil treatments lead to an increase in the shelf-life of strawberries of up to 15 days. Scanning electron microscopy (SEM) analysis of the microstructure showed a decrease in compactness with TCEO introduction, but without compromising food preservation after 15 days. In addition, treated strawberries delayed the loss of physicochemical and antioxidant properties, due to protection against the microbial development of aerobic mesophylls, molds, and yeasts.

Challenges and opportunities related to the use of chitosan as a food preservative

Chitosan has attracted a growing attention as a food preservative due to its versatility, nontoxicity, biodegradability and biocompatibility. This review aims to provide a critical appraisal of the limitations and opportunities of the use of chitosan as a food preservative. The application of chitosan as a food preservative necessitates insights into mechanisms of chitosan-mediated cell death and injury, factors affecting chitosan activity and effects of chitosan on food safety and quality. Chitosan exerts antimicrobial activity by perturbing the negatively charged cell envelope of micro-organisms with its polycationic structure. Intrinsic characteristics, including molecular weight and degree of deacetylation (DD), and other ambient conditions, including pH, temperature and neighbouring components, affect chitosan activity. Because the antimicrobial activity of chitosan is mainly based on ionic interactions with negatively charged components of the bacterial cell envelope, the food matrix can strongly interfere with the antimicrobial activity of chitosan. Despite its limited antimicrobial efficacy, chitosan demonstrates both bactericidal and bacteriostatic effects in specific food products. Moreover, chitosan can also enhance the efficacy of commercial intervention technologies, such as heat and pressure treatment, and aid the preservation of food quality, including retardation of lipid oxidation, weight loss and deterioration in sensory attributes.

Polyphenols and carotenoids in pickled bell pepper from organic and conventional production

Sweet bell pepper is a perfect source of flavonoids and carotenoids. Some experiments indicated that fresh organic vegetables contained more of these bioactive compounds in comparison to the conventional ones. It could be expected that pickled organic vegetables also contain more antioxidant compounds. The aim of this study was therefore to analyse and to compare the concentration of bioactive compounds in organic vs. conventional pickled bell pepper. Two cultivars of sweet red pepper (Roberta and Berceo) from organic and conventional cultivation were used in the experiment. The content of dry matter, polyphenols and carotenoids in fruit has been determined. The conventional pickled bell pepper fruits appeared to be richer in phenolic acids, while organic samples contained significantly more flavonoids, including myricetin, quercetin, kaempferol, apigenin, and carotenoids such as beta-carotene, alpha-carotene, capsorubin, cryptoxanthin and cryptoflavin in comparison to the conventional ones.

Effects of Chitosan-Based Coatings Enriched with Cinnamaldehyde on Mandarin Fruit cv. Ponkan during Room-Temperature Storage

The current work aimed to evaluate the efficacy of four coating formulations—chitosan coating (CH), 0.5% cinnamaldehyde + chitosan (0.5% CI–CH), 1.0% cinnamaldehyde + chitosan (1.0% CI–CH), and 1.5% cinnamaldehyde + chitosan (1.5% CI–CH)—on fresh mandarin fruit cv. Ponkan quality maintenance (weight loss, decay rate, total soluble solids, titratable acidity, vitamin C, color index, malondialdehyde, and antioxidant activity) over 100 days of storage at 20 °C. Compared to the control, chitosan treatment effectively reduced the decay and weight loss rates of mandarin fruit cv. Ponkan during storage at room temperature, delayed the decline of nutritional quality in fruits, increased the antioxidant capacity, and inhibited the accumulation of malondialdehyde (MDA). In comparison to chitosan coating, 1.5% CI–CH did not improve the fruit storage effect, but inhibited the normal color change of fruits and increased the accumulation of MDA. Both 0.5% CI–CH and 1.0% CI–CH effectively reduced the rate of fruit decay, improved the quality of fruits after harvest, and delayed fruit aging. Our study suggests that 0.5% CI–CH and 1.0% CI–CH might be good formulations for maintaining the quality of mandarin fruit cv. Ponkan during room-temperature storage.

Encapsulation of cinnamon essential oil in whey protein enhances the protective effect against single or combined sub-chronic toxicity of fumonisin B1 and/or aflatoxin B1 in rats

Fumonisin B1 (FB1) and aflatoxin B1 (AFB1) are fungal metabolites that frequently co-occur in foodstuffs and are responsible for mycotoxicosis and several primary cancers. Cinnamon essential oil (CEO) has a spacious range of benefit effects but also has some limitations owing to its strong taste or its interaction with some drugs. This study aimed to use the cinnamon oil emulsion droplets (COED) for the protection against oxidative stress, cytotoxicity, and reproductive toxicity in male Sprague-Dawley rats sub-chronically exposed to FB1 and/or AFB1. The composition of CEO was identified using GC-MS then was encapsulated using whey protein as wall material. Male rats were divided into eight groups and treated orally for 8 weeks as follows: control group, AFB1-trreated group (80 μg/kg b.w), FB1-treated group (100 mg/kg b.w), FB1 plus AFB1-treated group, and the groups treated with COED plus FB1 and/or AFB1. Blood and samples of the kidney, liver, and testis were collected for different analysis and histopathological examination. The GC-MS analysis revealed that cinnamaldehyde, α-copaene, trans-cinnamaldehyde, caryophyllene, and delta-cadinene were the main compounds in COE. The average size of COED was 235 ± 1.4 nm and the zeta potential was - 6.24 ± 0.56. Treatment with FB1 and/or AFB1 induced significant disturbances in the serum biochemical analysis, oxidative stress parameters, DNA fragmentation, gene expression, and testosterone and severe pathological changes in the tested organs. Moreover, treatment with both mycotoxins induced synergistic toxic effects. COED did not induce toxic effects and could normalize the majority of the tested parameters and improve the histological picture in rats treated with FB1 and/or AFB1. It could be concluded that COED induce potential protective effects against the single or combined exposure to FB1 and AFB1.

The preparation, characterization and in vitro application evaluation of soluble soybean polysaccharide films incorporated with cinnamon essential oil nanoemulsions

In this study, we developed the new bioactive film from soluble soybean polysaccharide (SSPS) incorporated with different concentrations of cinnamon essential oil nanoemulsions (CNO) and the functional properties of them were evaluated. Then CNO-SSPS film was applied on the meat during refrigerate for 8 days. The use of CNO in film production has reduced thickness, water vapor permeability, water solubility, lightness (L*), redness (a*) and whiteness (WI) and increased antioxidant activity of SSPS-films. Also, the SSPS- film containing 0.6% CNO activity only on gram-positive bacteria (Staphylococcus aureus and Streptococcus pyogenes) and SSPS- film containing 0.8% CNO had antimicrobial activity on gram-positive and gram-negative bacteria. In vitro application, the pH of the meat treated with CON remained in the natural pH of meat during storage (8 days). Based on the results, the highest and lowest hardness values were for the samples of CNO- 0.8 and control, respectively. Incorporating CON at 0.6 and 0.8% concentration of cinnamon reduced 4.14 and 5.71 log cycle in the total aerobic viable count compared to uncoated and decreased of yeast and molds on 8th day by 1 log cycle compared uncoated. These resulted showed CNO-SSPS film can be used as a good preservative in meat products.

Citrus essential oils: Extraction, authentication and application in food preservation

Citrus EOs is an economic, eco-friendly and natural alternatives to chemical preservatives and other synthetic antioxidants, such as sodium nitrites, nitrates or benzoates, commonly utilized in food preservation. Citrus based EOs is obtained mainly from the peels of citrus fruits which are largely discarded as wastes and cause environmental problems. The extraction of citrus oils from the waste peels not only saves environment but can be used in various applications including food preservation. The present article presents elaborated viewpoints on the nature and chemical composition of different EOs present in main citrus varieties widely grown across the globe; extraction, characterization and authentication techniques/methods of the citrus EOs; and reviews the recent advances in the application of citrus EOs for the preservation of fruits, vegetables, meat, fish and processed food stuffs. The probable reaction mechanism of the EOs based thin films formation with biodegradable polymers is presented. Other formulation, viz., EOs microencapsulation incorporating biodegradable polymers, nanoemulsion coatings, spray applications and antibacterial action mechanism of the active compounds present in the EOs have been elaborated. Extensive research is required on overcoming the challenges regarding allergies and obtaining safer dosage limits. Shift towards greener technologies indicate optimistic future towards safer utilization of citrus based EOs in food preservation.

Improvement of post-harvest quality of pear fruit with optimized composite edible coating formulations

Application of edible coatings is a suitable method to maintain the quality and reduce post-harvest losses in fresh vegetables and fruits. Pear fruits being climacteric have a short shelf life, and coating is considered as one of the most popular techniques to prolong its shelf life.The present study evaluates the effect of optimized edible coatings containing soy protein isolate (SPI) in combination with additives like hydroxypropyl methylcellulose (HPMC) and olive oil on 'Babughosha' Pears (Pyrus communis L.) stored at ambient temperature (28 ± 5 °C and 60 ± 10% RH). Four different coatings optimized by response surface methodology study were used in the present experiment. The results of the present study shows that the optimized edible coatings help retain the firmness of fruits and lowered the moisture loss. The tested combination of coating could also withhold the levels of ascorbic acid, chlorophyll and sugar contents in the treated fruits. Activities of enzymes associated with fruit softening (β-galactosidase, polygalacturonase, pectin methyl esterase) showed delayed peaks. Amongst all treatments, T1 (SPI 5.0%, HPMC 0.40%, Olive oil 1%, Potassium sorbate 0.22%) and T2 (SPI 5.0%, HPMC 0.40%, Olive oil 0.98% Potassium sorbate 0.20%) were found to have pronounced effect on retention of nutritional quality in pears. Observations of shelf-life extension established that T2 (SPI 5.0%, HPMC 0.40%, Olive oil 0.98% Potassium sorbate 0.20%) was successful in extending shelf-life of pear fruits up to 15 days, as compared to 8 days for untreated pear fruits.

Shelf life extension of fresh fruit and vegetables by chitosan treatment

Among alternatives that are currently under investigation to replace the use of synthetic fungicides to control postharvest diseases in fresh produce and to extend their shelf life, chitosan application has shown promising disease control, at both preharvest and postharvest stages. Chitosan shows a dual mode of action, on the pathogen and on the plant, as it reduces the growth of decay-causing fungi and foodborne pathogens and induces resistance responses in the host tissues. Chitosan coating forms a semipermeable film on the surface of fruit and vegetables, thereby delaying the rate of respiration, decreasing weight loss, maintaining the overall quality, and prolonging the shelf life. Moreover, the coating can provide a substrate for incorporation of other functional food additives, such as minerals, vitamins, or other drugs or nutraceutical compounds that can be used to enhance the beneficial properties of fresh commodities, or in some cases the antimicrobial activity of chitosan. Chitosan coating has been approved as GRAS substance by USFDA, and its application is safe for the consumer and the environment. This review summarizes the most relevant and recent knowledge in the application of chitosan in postharvest disease control and maintenance of overall fruit and vegetable quality during postharvest storage.

Influence of Edible Coatings on Biochemical Fruit Quality and Storage Life of Bell Pepper cv. “Yolo Wonder”

The present study was carried out to investigate the influence of food grade coatings on fruit quality and storage life of bell pepper cv. “Yolo Wonder” at8±1°C with 90–95% RH for 24 days. Coating treatments were given to bell pepper fruits by dipping in aqueous solutions of gum arabic (6, 9, and 12%),Aloe veragel (4, 5, and 6%), and cinnamon oil (0.5, 0.75, and 1%). Physicochemical characteristics as well as quality of bell pepper fruits improved in all coating treatments. Results revealed that 12% gum arabic coating exhibited significantly reduced weight loss, membrane leakage, chilling injury, and decay incidence with less increase in pH, total soluble solids, and sugar percentage, whereas appealing fruit color (L⁎,a⁎, andb⁎) along with higher values of ascorbic acid (1.84 mg/100 g), titratable acidity (0.19%), and firmness (4 N) was observed in cold storage environment. Our results clearly suggested that coating of bell pepper fruits with 12% gum arabic can maintain postharvest storage quality of bell pepper fruits.

Chitosan films and coatings containing essential oils: The antioxidant and antimicrobial activity, and application in food systems

Chitosan edible films and coatings have shown great promise for their application in food preservation and also are promising systems to be used as essential oil (EO) carriers. This review reports the most recent and relevant studies concerning chitosan films and coatings containing EOs. The effect of EO incorporation on the antioxidant, antibacterial and antifungal activities of chitosan films and coatings in vitro and in vivo, as well as their applications in food systems have been discussed. In general, incorporation of EOs significantly increased the antioxidant, antibacterial and antifungal efficacy of chitosan films and coatings in vitro. EO-incorporated films and coatings also showed greater effectiveness against postharvest fungi and foodborne bacteria in food systems than pure films and coatings. The application of chitosan films and coatings containing EOs usually led to an extension of the shelf-life and reduction of lipid peroxidation of fish and meat products over pure chitosan films and coatings. In addition, chitosan coatings incorporated with EOs were more effective in maintaining fruit and vegetable quality, and controlling their postharvest decay during storage and shelf life than pure chitosan coatings.

Shelf life extension of green chillies (Capsicum annuum L.) using shellac-based surface coating in combination with modified atmosphere packaging

Shellac-based surface coating was used in combination with passive modified atmosphere (MA) packaging for shelf life extension of fresh green chillies. The green chillies were coated with shellac coating, packed in anti-fog film and kept at 8 ± 1 °C for storage along with uncoated control. The coated and MA packed chillies showed significantly lower respiration rates as compared to control. The physico-chemical characteristics showed significantly lesser variations in terms of physiological loss in weight, firmness, colour, pigments, ascorbic acid and antioxidant activity during storage. A shelf life extension of 48 days was observed for coated and MA packed chillies against uncoated and MA packed (28 days) and control (15 days) ones. Shellac coated chillies showed a shelf life of 30 days at 8 ± 1 °C. Shellac coating along with the passive MA packaging resulted in restriction of metabolic activities (respiration) and delayed senescence and was found most effective in maintaining the postharvest quality of green chillies during low temperature storage.

Hydrogen Sulfide Alleviates Postharvest Senescence of Grape by Modulating the Antioxidant Defenses

Hydrogen sulfide (H₂S) has been identified as an important gaseous signal in plants. Here, we investigated the mechanism of H₂S in alleviating postharvest senescence and rotting of Kyoho grape. Exogenous application of H₂S released from 1.0 mM NaHS remarkably decreased the rotting and threshing rate of grape berries. H₂S application also prevented the weight loss in grape clusters and inhibited the decreases in firmness, soluble solids, and titratable acidity in grape pulp during postharvest storage. The data of chlorophyll and carotenoid content suggested the role of H₂S in preventing chlorophyll breakdown and carotenoid accumulation in both grape rachis and pulp. In comparison to water control, exogenous H₂S application maintained significantly higher levels of ascorbic acid and flavonoid and total phenolics and reducing sugar and soluble protein in grape pulp. Meanwhile, H₂S significantly reduced the accumulation of malondialdehyde (MDA), hydrogen peroxide (H₂O₂), and superoxide anion (O₂^∙−) in grape pulp. Further investigations showed that H₂S enhanced the activities of antioxidant enzymes ascorbate peroxidase (APX) and catalase (CAT) and decreased those of lipoxygenase (LOX) in both grape peels and pulp. In all, we provided strong evidence that H₂S effectively alleviated postharvest senescence and rotting of Kyoho grape by modulating antioxidant enzymes and attenuating lipid peroxidation.

Effect of different drying technologies on drying characteristics and quality of red pepper (Capsicum frutescens L.): a comparative study

BACKGROUND

Hot air drying and sun drying are traditional drying technologies widely used in the drying of agricultural products for a long time, but usually recognized as time-consuming or producing lower-quality products. Infrared drying is a rather effective drying technology that has advantages over traditional drying technologies. Thus, in order to investigate the application of infrared drying in the dehydration of red pepper, the drying characteristics and quality of infrared-dried red pepper were compared with those of sun-dried and hot air-dried red pepper.

RESULTS

The infrared drying technology significantly enhanced the drying rate when compared with hot air drying and sun drying. Temperature was the most important factor affecting the moisture transfer during the process of infrared drying as well as hot air drying. Effective moisture diffusivity (Deff ) values of infrared drying ranged from 1.58 × 10(-9) to 3.78 × 10(-9) m(2) s(-1) . The Ea values of infrared drying and hot air drying were 42.67 and 44.48 kJ mol(-1) respectively. Infrared drying and hot air drying produced color loss to a similar extent. Relatively higher crispness values were observed for infrared-dried samples.

CONCLUSION

Sun drying produced dried red pepper with the best color when compared with hot air drying and infrared drying. Meanwhile, infrared drying markedly improved the drying rate at the same drying temperature level of hot air drying, and the products obtained had relatively better quality with higher crispness values. © 2015 Society of Chemical Industry.

Preservation Mechanism of Chitosan-Based Coating with Cinnamon Oil for Fruits Storage Based on Sensor Data

The chitosan-based coating with antimicrobial agent has been developed recently to control the decay of fruits. However, its fresh keeping and antimicrobial mechanism is still not very clear. The preservation mechanism of chitosan coating with cinnamon oil for fruits storage is investigated in this paper. Results in the atomic force microscopy sensor images show that many micropores exist in the chitosan coating film. The roughness of coating film is affected by the concentration of chitosan. The antifungal activity of cinnamon oil should be mainly due to its main consistent trans-cinnamaldehyde, which is proportional to the trans-cinnamaldehyde concentration and improves with increasing the attachment time of oil. The exosmosis ratios of Penicillium citrinum and Aspergillus flavus could be enhanced by increasing the concentration of cinnamon oil. Morphological observation indicates that, compared to the normal cell, the wizened mycelium of A. flavus is observed around the inhibition zone, and the growth of spores is also inhibited. Moreover, the analysis of gas sensors indicate that the chitosan-oil coating could decrease the level of O₂ and increase the level of CO₂ in the package of cherry fruits, which also control the fruit decay. These results indicate that its preservation mechanism might be partly due to the micropores structure of coating film as a barrier for gas and a carrier for oil, and partly due to the activity of cinnamon oil on the cell disruption.