Food waste is already a local issue as fruit and vegetable peels are discarded by households due to mass consumption. Potato and red onion peels are one of the most discarded food waste as potatoes are the fourth most consumed carbohydrate and onions are used globally and a staple in every cuisine despite possessing high and efficient antioxidant properties and health benefits.

To address the issue of food waste, creating edible film or coating is a good candidate as food waste such as vegetables can be repurposed, and it can protect fresh fruit products from surrounding environments by acting as a barrier to limit gaseous exchange and retain moisture to increase shelf life. 

This study’s edible coating is composed of lipids, proteins, polysaccharides from the potato peels and anti-microbial properties from the onion peels. The polysaccharides and protein will act as a gas barrier to prevent gas exchange, the lipids will act as a hydrophobic layer to prevent moisture loss and the added anti-microbial properties will protect the fresh fruit product from external bacteria.

Extraction of Potato and Onion Peels

• Wash and clean the food waste

• Dehydrate at 50C for 24 hours

• Powderise the dried food waste and combine it with distilled water

• Sonicate at 25C for 5 minutes then filter with cheesecloth

• Centrifuge the potato and onion solution for 15 minutes

• Evaporate the excess liquid until the solution becomes thick

Preparation of Edible Film

• Solubilize designated amount of PPE and ROPE in 50ml of water until in room temperature  until dissolved 

• Add 10% v/w PPE glycerol to improve the flexibility of the coating 

• Using a pipet, add 0.1 ml of tween-80 to emulsify the coating

• Combine the solution with 0.1ml of coconut oil to create the lipid barrier 

• In another beaker, add 5g of whey concentrate with 50ml of distilled water 

• Heat both solutions at 80 degrees Celsius for 30 minutes and use a magnetic stirrer to  ensure that both solutions are stirred consistently 

• Combine the first and second mixture and stir until completely dissolved. Leave the solution  until it reaches 50-degree Celsius room temperature and ready to apply test. 

• Repeat steps 1-10 with accordingly with the variables of potato and onion peel extract. (0,2.5,  5) g.

Result

Based on the data from the extraction, the yield of both PPE and ROPE is very small. However, there was  more PPE as there was a greater mass and volume of potato peels while red onion peels are very light and  are not as dense. Hence, more PPE was produced. Although water was used as the solvent as it was the  simplest, most available and “greenest” solvent, more extract could be harvested by evaporating the  remains of the potato peel pulp and red onion skin pulp with ethanol. In terms of film effectiveness, the films were most effective when stored in the fridge. Based on the visual  observations and the decreasing mass.

Conclusion

To conclude the research, the film was effective when stored in the fridge. With a higher  polysaccharide content from the PPE, the strawberry was able to retain its firmness as  the film allowed for respiration to slow down. However, the anti-oxidant properties of the  ROPE was not very effective with smaller amounts as mold was still growing.