https://www.foodinfotech.com/wp-content/uploads/2021/11/Edible-bouquet-fruits-366x245.jpg

INTRODUCTION

The popularity of high-quality food with good nutritional properties and long shelf life is increasing consumer and market demand for natural preservatives, which has piqued the interest of researchers in developing sustainable and safe cultivation, environmentally friendly preservation techniques and increasing the value of the product supply chain. As a consequence of a better knowledge of the respiration process of fresh fruits, several approaches for prolonging the shelf life of fresh fruits have been devized. Edible coatings on fresh and fresh-cut fruit have also been investigated as an alternative to modified environment storage. By altering and regulating the interior environment of a single fruit, these coatings assist to postpone quality deterioration and quantity losses. Eating coatings can also be used to impart or supply taste compounds, growth regulators, antioxidants and antimicrobials, all of which increase food quality and safety. These biopolymers protect fruits from physical, chemical and biological degradation caused by moisture migration, microbial development on the surface, light-induced chemical changes and nutrient oxidation. By dipping or spraying the coating solution on the surface of fresh/fresh-cut fruits, the edible coating is applied (Figure 1) (Reddy & Singh, 2020).

Generalized flow process of fruits & vegetables coating treatment
Fig 1: Generalized flow process of fruits & vegetables coating treatment (Source: Tahir et al., 2019)

Properties of Edible coating

• The edible coating should be non-toxic, contain non-allergic substances and be easily manufactured.
• The edible coating should handle mechanical damage during handling, transportation and storage.
• Have good adhesion and water barrier property.
• Provides semi permeability to maintain the internal equilibrium of gases which is involved during anaerobic and aerobic respiration.
• Should not affect the nutritional and organoleptic properties of fruit and vegetable.

Types of edible coatings

Proteins, polysaccharides and lipids are commonly used to make edible coatings, either alone or in combination. In mechanical and barrier properties, whey protein-based films outperform competitive protein-based (e.g., corn zein, wheat gluten, and soy protein isolate) or polysaccharide-based (e.g., starch, cellulose, carrageenan, and pectin) films and they are somewhat comparable to the best synthetic polymer films in the market. Highly polar polymers with hydroxyl groups, such as proteins and polysaccharides, provide an excellent barrier to oxygen at low relative humidity (RH). However, because they are hydrophilic, they create a weak moisture barrier. Several bio-based polymers have been studied to create a continuous structure of films or coatings. The most frequent type of biopolymer utilized in the manufacture of edible materials is hydrocolloids, which includes both polysaccharides and proteins. They can be derived from plants, animals or microbes. The most common polysaccharides utilized in the manufacture of edible films and coatings are cellulose derivatives, starches, alginates, pectins and chitosans, whereas the most common proteins are soybean proteins, wheat gluten, maize zein and sunflower proteins (Figure 2) (Raghav et al., 2016; Reddy & Singh, 2020; Sharma et al., 2019).

Regulatory aspects of edible coatings

The primary components of edible coating include proteins, polysaccharides, lipids and a combination of minor components to improve functionality such as plasticizers, emulsifiers and active chemicals such as antimicrobials and antioxidants. To achieve the proposed impact, a certain quantity of edible coating components must be maintained. As a result, the composition of edible coatings must comply with the standards of the specific food product. Notably, the components must be in the Generally Recognized As Safe (GRAS) category and be registered in the United States Code of Federal Regulations. According to European Directive (1998), arabic and karaya gum, pectins, shellac, beeswax, candelilla wax and carnauba wax can be included in the formulation for edible coatings by suggesting various elements such as lecithin, polysorbates, fatty acids and fatty acid salts (Maringgal et al., 2020). Polydextrose, sorbitan monostearate, sucrose fatty acid esters, cocoa butter and castor oil have been identified as new additives that can be utilized as elements of protective coatings used on fresh fruits and vegetables by the United States Food and Drug Administration (FDA, 2006).

Types of coating used on fruits & vegetables
Fig 2: Types of coating used on fruits and vegetables (Galus et al., 2020; Raghav et al., 2016; Reddy & Singh, 2020; Sharma et al., 2019)

Effect of edible coatings on fruit and vegetable crops

External appearance

The external appearance of the horticultural commodity is essential. Retaining the colour of commodities is one of the main advantages of edible coatings. Rough physical handling of fruits during the postharvest phase is one of the primary causes of natural wax layer destruction and bruising injury during packing and shipping activities. The edible coating creates a physical barrier between the fruit surface and the external environment of the product, resulting in the preservation of postharvest quality (Reddy & Singh, 2020).

Texture

The edible coating maintains firmness by avoiding excessive transpiration and respiration, which are directly engaged in decreasing shelflife. The edible coating has a direct influence on fruit firmness by reducing the activity of the cell wall destroying enzymes and delaying ripening. Because calcium has been shown to have a direct influence on fruit firmness, the inclusion of calcium in the edible coating was also found to be highly efficient in enhancing fruit firmness (Zhang et al., 2018).

Physiological weight loss

Farmers’ returns are determined by the weight of their horticultural output. The major cause of physiological weight loss in a specific product is transpiration, which is governed by the change in water vapour pressure between the fruit and the environment. Edible coatings provide an additional barrier between the fruit surface and the environment, causing a decrease in transpiration rate (Hazrati et al., 2017).

Ethylene production and respiration

The edible coating prevents oxygen from entering the fruit, therefore controlling ethylene production and lowering respiration rate. As a result, the fruits stay fresher, firmer and more nutritious for longer and their shelf life nearly doubles. The natural coating on fruits as well as the kind and amount of additional coating, will all contribute to the creation of an interior modified environment (O2 and CO2) (Anjum et al., 2020).

Bioactive compounds (Total phenolic content and antioxidants)

The presence of phenolic and antioxidant compounds affects the shelf life of fruits and vegetables. The presence of these chemicals enhances resilience to a variety of postharvest quality maintenance factors. Antioxidants from both internal and external sources enhance the shelf life of fruits and vegetables. Edible coatings have the capacity to change/increase the antioxidant content of harvested horticulture commodities and total phenolic content has the same impact as antioxidants (Dávila-Aviña et al., 2014).

Lipid peroxidation and enzymatic activities

The activity of cell wall-related enzymes is influenced by edible coating. The impact has been observed with enzymes such as polyphenol oxidase, phenylalanine ammonia-lyase and malondialdehyde, all of which play key roles in cell wall breakdown and peel browning. Edible coatings also govern the process of lipid peroxidation, which is responsible for cell wall disintegration and the production of free radicals, both of which have an impact on postharvest quality (Li et al., 2021).

Advantages and disadvantages of Edible Coating
Fig 3: Advantages and disadvantages of Edible Coating

Conclusion

Edible coatings have been used for many years in the food industry to store fruits and vegetables. It is both safe and environmentally friendly and can be consumed alongside fruits and vegetables. Edible coatings increase shelf life by reducing water and moisture loss, delaying the ripening process and preventing microbial growth, particularly in fresh fruits and vegetables. Herbal edible coatings and coatings incorporated with anti-microbial substances like turmeric and essential oils is a new trend in the edible coating that has recently been introduced. Combining such coatings can open new avenues for research in nutrition and medicinal substance edible coatings.

References

1. Anjum, M. A., Akram, H., Zaidi, M., & Ali, S. (2020). Effect of gum arabic and Aloe vera gel based edible coatings in combination with plant extracts on postharvest quality and storability of ‘Gola’ guava fruits. Scientia Horticulturae, 271(February), 109506. https://doi.org/10.1016/j.scienta.2020.109506

2. Dávila-Aviña, J. E., Villa-Rodríguez, J. A., Villegas-Ochoa, M. A., Tortoledo-Ortiz, O., Olivas, G. I., Ayala-Zavala, J. F., & González-Aguilar, G. A. (2014). Effect of edible coatings on bioactive compounds and antioxidant capacity of tomatoes at different maturity stages. Journal of Food Science and Technology, 51(10), 2706–2712. https://doi.org/10.1007/s13197-012-0771-3

3. Galus, S., Kibar, E. A. A., Gniewosz, M., & Kraśniewska, K. (2020). Novel materials in the preparation of edible films and coatings-A review. Coatings, 10(7), 1–14. https://doi.org/10.3390/coatings10070674

4. Hazrati, S., Beyraghdar Kashkooli, A., Habibzadeh, F., Tahmasebi-Sarvestani, Z., & Sadeghi, A. R. (2017). Evaluation of Aloe vera Gel as an Alternative Edible Coating for Peach Fruits During Cold Storage Period. Gesunde Pflanzen, 69, 131–137. https://doi.org/10.1007/s10343-017-0397-5

5. Li, L., Yi, P., Li, C., Xin, M., Sun, J., He, X., Sheng, J., Zhou, Z., Zheng, F., Li, J., Liu, G., Ling, D., Tang, J., Li, Z., Yang, Y., & Tang, Y. (2021). Influence of polysaccharide-based edible coatings on enzymatic browning and oxidative senescence of fresh-cut lettuce. Food Science and Nutrition, 9(2), 888–899. https://doi.org/10.1002/fsn3.2052

6. Maringgal, B., Hashim, N., Mohamed Amin Tawakkal, I. S., & Muda Mohamed, M. T. (2020). Recent advance in edible coating and its effect on fresh/fresh-cut fruits quality. Trends in Food Science and Technology, 96(July 2019), 253–267. https://doi.org/10.1016/j.tifs.2019.12.024

7. Raghav, P. K., Agarwal, N., & Saini, M. (2016). Edible Coating of Fruits and Vegetables : A Review. International Journal of Scientific Research and Modern Education, 1, 188–204.

8. Reddy, K. S., & Singh, J. (2020). Edible Coatings in Fruits -A Review. International Journal of Current Microbiology and Applied Sciences, 9(11), 2953–2969. https://doi.org/10.20546/ijcmas.2020.911.359

9. Sharma, H. P., Chaudhary, V., & Kumar, M. (2019). Importance of edible coating on fruits and vegetables: A review. Journal of Pharmacognosy and Phytochemistry, 8(3), 4104–4110.

10. Zhang, L., Chen, F., Lai, S., Wang, H., & Yang, H. (2018). Impact of soybean protein isolate-chitosan edible coating on the softening of apricot fruit during storage. Lwt, 96(June), 604–611. https://doi.org/10.1016/j.lwt.2018.06.011

About the Authors:
Potdar Pratik Pandit1. Potdar Pratik Pandit
PhD Scholar, Department of Processing and Food Engineering,
Punjab Agricultural University, Ludhiana, Punjab.

 

 

Ruchika Zalpouri2. Ruchika Zalpouri
PhD Scholar, Department of Processing and Food Engineering,
Punjab Agricultural University, Ludhiana, Punjab.
*Corresponding Author
Email Id: zalpouri28@gmail.com

Disclaimer:

The views/opinions expressed by authors on this website solely reflect the author(s) and do not necessarily reflect the views/opinions of the Editors/Publisher. Neither the Editors nor the Publisher can be held responsible and liable for consequences that may arise on account of errors/omissions appearing in the Articles/Opinions.

Author

An up-&-coming bloody creative professional passionately involved with both print and digital media; constantly trying to be an irritating perfectionist and surviving solely on inspiration (sometimes from the most inert objects)… Currently, staying busily engaged with producing mouth-watering content for the much anticipated and less explored Indian Food Processing Sector; interested to cover anything about the food and beverages business, whose works are unconventional, yet sustainable for the planet onto my list of forthcoming works...

Write A Comment

14 − one =