**2.6 Edible coatings**

Very fragile fruits, such as berries and tropical fruits, are good candidates for coating treatment since they are costly and have a short storability. A thin layer of edible material, often not exceeding 0.3 mm, placed to the surface of meals in addition to or as a substitute for natural coating materials is classified as an edible coating. The use of an active edible covering to enhance the longevity of fruits and vegetables is a unique and potential method [42]. Edible coverings with semipermeable film can improve post-harvest fruit life by minimising moisture, respiration, gas exchange, as well as oxidative reaction rates [43].

Li et al. [44], uses three edible coatings i.e., alginate, chitosan (CS), and pullulan (polysaccharide) during cold storage (4°C) to postharvest strawberry fruit. The experiment concluded that during 16 days of storage, polysaccharide coatings severely hampered fruit weakening and rot, as well as minimised modifications in TSS and titratable acidity content. These coatings also kept ascorbic acid and total phenolic content greater than controls from day 2 onwards, and dramatically reduced fruit deterioration and respiration after 12 days of storage. The enzymatic activities like peroxidase (POX), catalase (CAT), superoxide dismutase (SOD), and ascorbate peroxidase (APX) were increased by polysaccharide coatings, preventing lipid peroxidation and reducing membrane damage. Furthermore, among these coatings, CS-based coatings had the most beneficial impacts on the quality of fruit and had the highest relative antioxidant enzyme activity.

Aloe vera gel is more effective than CS. Nasrin et al. [45], performed an experiment by coating the strawberry with CS and aloe vera gel, keep in a polypropylene box and stored at 6°C ± 1°C with 50 ± 5% relative humidity. A. vera gel-coated strawberry retained their colour, wetness, firmness, fresh appearance, and general acceptability for longer than CS or uncoated ones. Furthermore, AV gel coating on strawberries slowed the emergence of microbe occurrence for approximately 15 days. While the moulds impacted control and CS (1.5% or 2%) coated strawberries on days 6 and 9 of storage, respectively.

In the sector of the food industry, the use of a CS-based antimicrobial coating to prolong the shelf life of strawberries throughout storage appears to be quite promising. Chitosan-monomethyl fumaric acid (CS-MFA) is an excellent antimicrobial coating derived from CS and its derivatives. Khan et al. [46] applied CS-MFA coating on strawberries and stored it at 10°C. The total weight loss and deterioration were considerably lower in the CS-MFA samples than in the CS and control samples. When compared to CS, CS-MFA coated fruit had a significantly lower yeast and mould load. Finally, the CS-MFA enhanced microbial properties and extended shelf life from 4 to 8 days.

The edible coating, which contains natural bioactive chemicals, could be used as a substitute for artificial additives and can help save money on cold storage. The orange peel essential peel (OPEP) and carnauba wax have been proven to decrease the damages in strawberries. Saeed et al. [47] designed an experiment to make an edible antifungal covering with different concentrations of OPEO and carnauba wax to protect strawberries against blue mould (fungus). Orange peel oil had a maximum growth constraint of 96% against fungus. Strawberry storage life was increased owing to an OPEP coating that preserved the fruit's quality.

When strawberry was treated with polysaccharide edible coating (alginate and pectin) containing citral and eugenol showed that the fruit have higher firmness, TSS, as well as enzymatic activity, while having lesser weight loss and microbiological deterioration [4].

Surface colour parameters were significantly affected by the cellulose coating. The impact of a methylcellulose edible covering on the qualitative, chemical, physical, and mechanical attributes of strawberries was studied. Nadim et al. [48] used methylcellulose on the surface of the berry and stored it for 11 days at 4°C. The edible coating inhibits weight loss and decay while also retaining a tiny quantity of fruit sugar, preserving the firmness of the strawberries and enhancing their quality and storage characteristics.

### **2.7 Treatment with chemicals**

Strawberry is counted in the list of fruits that are perishable and is especially prone to postharvest losses (up to 50%) owing to fungal disease outbreaks. For many years' different chemicals have been used to extend the durability of strawberries. However due to health issues now their uses are restricted. Liu et al. [49] treated the strawberry with different concentrations of melatonin for 5 min and stored it at 4°C with a relative humidity of 90% for 12 days. The results concluded that 1 mmol L−1 melatonin treatment delayed the ripening of berries, extend the shelf life, improve the fruit quality and minimised the concentration of hydrogen peroxide and malondialdehyde However, the total phenolics and flavonoid levels were enhanced, leading to increased antioxidant potential. These results suggest that melatonin administration could be a viable tactic for extending strawberry fruit postharvest life and improving quality.

### **2.8 Combined treatments**

When two or more post-harvest treatments are used together, they show a synergistic impact on the product's standard and usable viability. Feliziani et al. [50] compares the effect of CS, laminarin, extracts of *Abies* spp., *Polygonum* spp., and *Saccharomyces* spp., organic acids and calcium combination, and benzothiadiazole with fungicides. These chemicals were applied to the strawberry canopy every 5 days. In comparison to water-treated controls, alternative chemical treatments reduced strawberry postharvest loss by 30%, primarily against grey mould and Rhizopus rot instead of altering the colour or firmness of the fruit.
