Edible coating as postharvest management strategy for shelf-life extension of fresh tomato (Solanum lycopersicum L.): An overview

Optimization of guar gum-based anti-browning coating for prolonging the shelf life of cut potatoes

The impact of guar gum (GG), crude algae ethanolic extract (CAEE), and turmeric essential oil (TEO) incorporated edible coating formulations on the quality of cut potatoes was investigated at room temperature (27 ± 3 °C, 70-85 % RH) storage using a rotatable central composite design. Besides, 30 % glycerol, 5 % calcium chloride, and 3 % ascorbic acid (w/w) were added to the coating solution as additives. The surface color, respiration rate, water vapor transmission rate, visible mold growth, and sensory analysis were assessed after seven days of storage. The inclusion of ascorbic acid and TEO in edible coating demonstrated a more effective delay in browning. The coated potatoes had lower OTR, CTR, and WVTR values for GG concentrations of 0.5 to 1 g/100 mL than the control. Compared to additives, higher concentrations of GG improved response parameters. The WVTR value of coated potatoes was significantly impacted by the interaction between CAEE and TEO with GG. Incorporating CAEE and TEO into the formulations of guar gum led to a reduction in the permeability of the coating to oxygen and water vapor. The seven days of extended shelf life compared to two days of control were observed with the optimized coating formulation. Furthermore, the application of the coating treatment proved effective in preventing enzymatic browning and creating a barrier against moisture and gases, contributing to prolonged freshness during extended storage periods.

Antifungal Activities of Biogenic Silver Nanoparticles Mediated by Marine Algae: In Vitro and In Vivo Insights of Coating Tomato Fruit to Protect against Penicillium italicum Blue Mold

In an attempt to reduce such decay induced by pathogenic causes, several studies investigated the effectiveness of nanoparticles (NPs) that play a vital role in saving food products, especially fruits. Current research delves into biogenic silver nanoparticles (using marine alga Turbinaria turbinata (Tt/Ag-NPs) and their characterization using FT-IR, TEM, EDS, and zeta potential. Some pathogenic fungi, which cause fruit spoilage, were isolated. We studied the impact of using Tt/Ag-NPs to protect against isolated fungi in vitro, and the influence of Tt/Ag-NPs as a coating of tomato fruit to protect against blue mold caused by Penicillium italicum (OR770486) over 17 days of storage time. Five treatments were examined: T1, healthy fruits were used as the positive control; T2, healthy fruits sprayed with Tt/Ag-NPs; T3, fruits infected with P. italicum followed by coating with Tt/Ag-NPs (pre-coating); T4, fruits coated with Tt/Ag-NPs followed by infection by P. italicum (post-coating); and T5, the negative control, fruits infected by P. italicum. The results displayed that Tt/Ag-NPs are crystalline, spherical in shape, with size ranges between 14.5 and 39.85 nm, and negative charges. Different concentrations of Tt/Ag-NPs possessed antifungal activities against Botrytis cinerea, Rhodotorula mucilaginosa, Penicillium expansum, Alternaria alternate, and Stemphylium vesicarium. After two days of tomatoes being infected with P. italicum, 55% of the fruits were spoilage. The tomato fruit coated with Tt/Ag-NPs delayed weight loss, increased titratable acidity (TA%), antioxidant%, and polyphenol contents, and decreased pH and total soluble solids (TSSs). There were no significant results between pre-coating and post-coating except in phenol contents increased in pre-coating. A particular focus is placed on the novel and promising approach of utilizing nanoparticles to combat foodborne pathogens and preserve commodities, with a spotlight on the application of nanoparticles in safeguarding tomatoes from decay.

Edible packaging as sustainable alternative to synthetic plastic: a comprehensive review

The choice of an appropriate packaging materials enhances the shelf life and improves quality of food during transportation, storage, and distribution. Development and innovations in food packaging systems have become essential in the food industry. Most widely used packaging materials are non-biodegradable plastics and are harmful to environment and human health. Thus, food industry is replacing non-biodegradable plastics with biodegradable plastics to reduce environmental pollution, health hazards, and food waste. Edible packaging may reduce food waste and keep perishables fresh. This review article compares edible packaging materials to synthetic ones and discusses their pollution-reducing effects. The several types of food packaging discussed in the review include those produced from polysaccharides, proteins, lipids, and composite films. The various characteristics of edible packaging are reviewed, including its barrier qualities, carrier properties, mechanical capabilities, and edibility. The carrier properties describe the capacity to transport and manage the release of active substances, and the edibility indicates acceptance of these items by the customers. Plasticizers, antimicrobials, antioxidants, and emulsifiers were included in the edible packaging to enhance the characteristics of the film. The development and implementation of edible packaging on food products from the laboratory to large-scale industrial levels, as well as their potential industrial applications in the dairy, meat, confectionary, poultry, fish, fruit, and vegetable processing sectors are addressed.

Effect of guar gum-chitosan composites edible coating functionalized with essential oils on the postharvest shelf life of Khasi mandarin at ambient condition

In the present study, the effects of guar gum (0.7 %):chitosan (0.3 %) based composite edible coating functionalized with coconut oil and essential oils like clove bud oil and cinnamon bark oil were investigated on the postharvest shelf life of Khasi mandarins at ambient conditions (25 ± 5 °C, RH 75 ± 5 %) up to 20 days of storage period. The postharvest characteristics such as weight loss, firmness, acidity, total soluble solids (TSS) and reducing sugar of control and treated fruits were evaluated at 5 days intervals throughout the storage period. The obtained results indicated that the application of guar gum/chitosan-based composite edible coating with coconut oil, clove bud and cinnamon bark essential oil was effective in prolonging the postharvest shelf life of Khasi mandarins as compared to control fruits by minimizing the decay and loss of postharvest quality attributes. The treatment of composite such as guar gum/chitosan/coconut oil/clove oil/cinnamon oil (GGCsC-Cl-Cn) was most effective in maintaining postharvest characteristics of fruits compared to other treatments and control. The significant (p < 0.05) lowest weight loss (38 %) with retention of higher firmness (5.9 N), titratable acidity (0.29 %), and total soluble solid (10.8 %) was noticed in the Khasi mandarins treated with GGCsC-Cl-Cn composite coating on 20 days of storage. Furthermore, the present study confirmed the significance of the developed composite formulation in improving the shelf life of Khasi mandarin.

Valorizing pomegranate wastes by producing functional silver nanoparticles with antioxidant, anticancer, antiviral, and antimicrobial activities and its potential in food preservation

The food sector generates massive amounts of waste, which are rich in active compounds, especially polyphenols; therefore, valorizing these wastes is a global trend. In this study, we produce silver nanoparticles from pomegranate wastes, characterized by enhanced antioxidant, anticancer, antiviral, and antimicrobial properties and investigated their potential to maintain the fruit quality for sixty days in market. The pomegranate waste-mediated silver nanoparticles (PPAgNPs) were spherical shape (measured by TEM), 20 nm (Zeta sizer), negatively charged -25.98 mV (Zeta potential), and surrounded by active groups (FTIR). The PPAgNPs scavenged 94 % of DPPH radicals and inhibited the growth of pathogens, i.e., Staphylococcus aureus, Listeria monocytogenes, Campylobacter jejuni, Salmonella typhi and Candida with inhibition zones diameters (16-45 mm). They impeded the development of breast and colon cancer cell lines by 80 and 78 %, increased the activity of apoptosis marker caspase 3, and inhibited 82 % of COVID-19. The PPAgNPs were added to the rat diet at 80, 160, and 320 µg/kg levels. PPAgNPs administered at a concentration of 160 µg/kg in the rat diet resulted in the best growth performance, normal liver and kidney parameters (p = 0.029-0.038), lowered lipid profile, malondialdhyde (MDA), and raised glutathion reduced (GSH), total protein (TP). Also, the reduced gene expression of Interleukin 6 (IL-6) and Tumor necrosis factor alpha (TNF-α) in albino rats' serum indicates the anti-inflammatory effect of PPAgNPs. PPAgNPs developed a functional coating to preserve mandarin fruit for 60 days by dipping technique. The active coat containing PPAgNPs can effectively preserve the fruit for 60 days.

Valorization of waste biomass for synthesis of carboxy-methyl-cellulose as a sustainable edible coating on fruits: A review

The coating on fruits and vegetables increases the shelf-life by providing protection against their spoilage. The existing petroleum-based coating materials have considerable health threats. Edible coating materials prepared with the cellulose derivative extracted from the waste biomass could be a sustainable alternative and environment friendly process to increase the shelf-life periods of the post-harvest crops. Selection of suitable waste biomass and extraction of cellulose are the critical steps for the synthesis of cellulose-based edible film. Conversion of extracted cellulose into cellulosic macromolecular derivatives such as carboxy-methyl-cellulose (CMC) is vital for synthesizing edible coating formulation. Applications of sophisticated tools and methods for the characterization of the coated fruits would be helpful to determine the efficiency of the coating material. In this review, we focused on: i) criteria for the selection of suitable waste biomass for extraction of cellulose, ii) pretreatment and extraction process of cellulose from the different waste biomasses, iii) synthesis processes of CMC by using extracted cellulose, iv) characterizations of CMC as food coating materials, v) various formulation techniques for the synthesis of the CMC based food coating materials and vi) the parameters which are used to evaluate the shelf-life performance of different coated fruits.

Bay Leaves Extracts as Active Additive for Food Protective Coatings

Ethanolic extracts of bay leaves were obtained using the Soxhlet method (extraction yield of 22.3 ± 1.2%) and further analyzed through different methods, thus determining the chemical composition with gas chromatography, phenolic content with the Folin-Ciocalteu technique (11.8 ± 0.4% wt.) and antioxidant power with the radical 2,2'-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) method (75.06%). Furthermore, its effect on the growth of two bacteria, Escherichia coli and Bacillus cereus, and on two yeasts, Candida glabrata and Saccharomyces cerevisiae, was determined, showing a minimum inhibitory concentration of 0.65 mg/mL on the growth of B. cereus. Finally, edible films were prepared using different polymers (carboxymethyl cellulose, gum Arabic, polyvinyl pyrrolidone, and polyvinyl alcohol) containing 0, 5, 10, or 15% wt. of bay leaf extract as troubleshooting for perishable fruits, specifically for cultivated strawberry. The prepared composites presented reduced water vapor permeabilities (up to 4.3 × 10-7 g·Pa-1·m-1·h-1), high specific transparencies (≈30%/mm), as well as the effective blocking of ultraviolet radiation (>99.9%). In vivo tests showed that the most suitable treatment for strawberry protection was the impregnation with a composite comprising polyvinyl alcohol and a 15% wt. bay leaf extract, resulting in a noteworthy reduction in mass loss (22% after 6 days). It can be asserted that food packaging with the designed composites would be an effective alternative for the reduction in postharvest losses.

Characterization of Microbial Diversity of Two Tomato Cultivars through Targeted Next-Generation Sequencing 16S rRNA and ITS Techniques

Even though the nutritional and economic values of Solanum lycopersicum (tomato) are substantially impacted by microbial spoilage, the available data on its microbial community, particularly during spoilage, are limited and have primarily been characterized using conventional culture-dependent methods. This study employed a targeted high-throughput next-generation sequencing method to longitudinally characterize the microbial diversity of two South African tomato cultivars (jam and round) at varied storage intervals (1, 6, and 12 days). Throughout the storage period, the bacterial communities of the two cultivars were more diverse than the fungal communities. The microbial diversity of both bacteria and fungi was greater and comparable between the cultivars on day 1, but becomes distinct as the storage period increases, with round tomatoes being more diverse than jam tomato, though, on day 12, jam tomato develops greater diversity than round tomato. Overall, the most abundant phyla (though Proteobacteria was most dominant) were Proteobacteria, Firmicutes, and Bacteriodota in the bacterial communities, while Ascomycota and Basidiomycota formed most fungal communities with Ascomycota being dominant. At the genus level, Pantoea and Klebsiella (bacteria), Hanseniaspora, Stemphylium, and Alternaria (fungi) were prevalent. Taken together, this study casts light on a broad microbial diversity profile thus, confirms the cultivars' diversity and abundance differences.

Ultrasound and autoclave-deacetylated Achatina fulica shell chitosan: Characterisation and effect on tomato and cucumber fruit qualities during storage

Chitosan from African giant snail (Achatina fulica) shells derived through autoclave- (SSC_A) or ultrasound-assisted (SSC_U) deacetylation was characterised and evaluated for quality and shelf life of tomatoes and cucumbers over 10 days of ambient (26 ± 2 °C) and refrigerated (4 ± 2 °C) storage. A 64.03 and 54.41% deacetylation degrees were achieved for SSC_A and SSC_U, respectively with the SEM showing uniform surface morphologies. Moisture loss in tomatoes was effectively moderated by SSC_A and SSC_U treatments as depicted by higher weight retention (93.65% and 81.80%) compared to untreated samples (58.52%) after 10 days of refrigerated storage. Autoclave-derived chitosan significantly retained colour of tomato and cucumber. Ascorbic acid retentions were 88.76% and 87.34%, and 86.40% and 77.01% for SSC_A and SSC_U-treated tomatoes at ambient and refrigerated storage, respectively. Yeast and mould growths were completely inhibited for 10 days of refrigerated storage. Chitosan treatment enhanced quality and shelf life of tomatoes and cucumbers in the order SSC_A > SSC_U > control.

Effect of plasma-activated water and buffer solution combined with ultrasound on fungicide degradation and quality of cherry tomato during storage

The purpose of this study was to examine plasma-activated buffer solution (PABS) and plasma-activated water (PAW) combined with ultrasonication (U) treatment on the reduction of chlorothalonil fungicide and the quality of tomato fruits during storage. To obtain PAW and PABS, an atmospheric air plasma jet was used to treat buffer solution and deionized water at different treatment times (5 and 10 min). For combined treatments, fruits were submerged in PAW and PABS, then sonicated for 15 min, and individual treatment without sonication. As per the results, the maximum chlorothalonil reduction of 89.29% was detected in PAW-U₁₀, followed by 85.43% in PABS. At the end of the storage period, the maximum reduction of 97.25% was recorded in PAW-U₁₀, followed by 93.14% in PABS-U₁₀. PAW, PABS, and both combined with ultrasound did not significantly affect the overall tomato fruit quality in the storage period. Our results revealed that PAW combined with sonication had a significant impact on post-harvest agrochemical degradation and retention of tomato quality than PABS. Conclusively, the integrated hurdle technologies effectively reduce agrochemical residues, which helps to lower health hazards and foodborne illnesses.

Characterizations of konjac glucomannan/curdlan edible coatings and the preservation effect on cherry tomatoes

In this study, konjac glucomannan (KGM) and curdlan were used to fabricate composite coating (KC). The coating solutions were investigated using a rheological method, and the coatings were characterized by water solubility tests, water vapor permeability (WVP), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). The preservation effect of KC coating on cherry tomatoes stored at room temperature was determined. Results indicated that the curdlan addition can adjust the hydrophilicity/hydrophobicity of KGM coatings. Curdlan addition enhanced intermolecular entanglement and film-forming property. Increasing curdlan content in KC coatings significantly decreased the moisture content, dissolution and swelling ratio, and WVP. The KGM-curdlan composites behaved as high-performance coatings with good compatibility and uniformity. The K₃C₂ coating showed the best uniformity, water barrier, and thermal stability. The application of K₃C₂ coating significantly reduced the weight loss, decay loss, and delayed the decreases of firmness, soluble solids, total acid, and VC contents of cherry tomatoes. The KGM/curdlan edible coatings have promising potential for prolonging the shelf life of cherry tomatoes and applications in fruits preservation in the future.

Development and Characterization of Biocomposite Films Based on Polysaccharides Derived from Okra Plant Waste for Food Packaging Application

Polysaccharide-based composite films were developed using mucilage polysaccharides (OLP) and carboxymethyl cellulose (CMC) extracted from okra leafstalk wastes. The rheological properties of biocomposite OLP/CMC film-forming solutions were characterized using the Power-law model, and fabricated films were characterized for their potential food packaging applications. OLP/CMC solutions exhibited pseudo-plastic fluid characteristics and differences in rheological behavior (n, 0.478-0.743), and flow consistency (K, 1.731-9.154) with increasing content of OLP (5 to 30 % w/w of CMC) were associated with variations in the physical, mechanical, and barrier properties of films. Surface hydrophobicity (24%) increased and oxygen (39%) and water vapor (32%) permeability reduced in OLP/CMC films containing up to 10% OLP. Moreover, a higher content of OLP enhanced the antioxidant activity and thermal stability of OLP/CMC films. Subsequently, OLP/CMC was applied as a coating to preserve cherry tomatoes for 14 days at 30 °C. Quality deterioration characterized by high weight loss (22%), firmness loss (74.62%), and discoloration (∆E, 21.26) occurred in uncoated tomatoes and were within unusable/unmarketable limits based on their visual quality score. In contrast, OLP/CMC effectively minimized quality losses, and coated tomatoes exceeded the limit of marketability after 14 days of storage. This study successfully applied value-added polysaccharides derived from okra plant residues for edible food packaging.

Biopreservation of Refrigerated Mackerel (Auxis thazard) Slices by Rice Starch-Based Coating Containing Polyphenol Extract from Glochidion wallichianum Leaf

Both microbial decomposition and oxidative deterioration contribute to the qualitative degradation of fresh or minimally preserved fish, which negatively impacts the shelf-life of fish, especially those with dark flesh like mackerel. It is becoming more typical to use edible coatings to preserve the freshness of fish products. Herein, the effects of a rice starch (RS) based coating incorporated with dried crude, aqueous Mon-pu (Glochidion wallichianum) leaf extract (MPE) at varying concentrations (0, 0.02, 0.1, 0.5, and 1.0% w/w) on the quality characteristics of mackerel (Auxis thazard) slices during storage at 4 °C were investigated. Uncoated slices had a shelf-life of 6 days, whereas samples coated with RS and 0.5% MPE extended the shelf-life to 9 days by keeping the overall microbiological quality below the permitted level of 6 log CFU/g. The changes in thiobarbituric acid reactive substances (TBARS; <2 mg malondialdehyde equivalent/kg), propanal content, heme iron degradation, myoglobin redox instability, and surface discoloration (a* value and total color difference; ΔE) can all be delayed by this coating condition. Additionally, the RS-MPE coating can maintain the sensory quality of refrigerated mackerel slices and preserve the textural property (water holding capacity and hardness), as well as postpone the development of an off-odor as indicated by lowered contents of total volatile base-nitrogen (TVB-N; not exceeding the acceptable limit of 25 mg/100 g) and trimethylamine (TMA; not exceeding the acceptable limit of 10 mg/100 g). Therefore, a biopreservative coating made of RS and MPE, especially at 0.5%, can be employed to extend the shelf-life of refrigerated mackerel slices up to 9 days.