Banana, strawberry perishable how to do? Eggs dots / cellulose Nanocomposite Coating: fresh, antibacterial, and low cost!
Today, hunger and chronic malnutrition affects 800 million people worldwide, although countries are increasingly seeking to develop sustainable energy and agriculture to reduce poverty and hunger, the global annual production of fruit and food there are up to one third It is wasted, which is mainly due to the short shelf life of fresh fruits and vegetables and other agricultural products, highly perishable. Currently, there are a variety of preservation techniques are used to extend the shelf life of fruit, one is the fruit waxing, to extend fruit shelf life by applying a preservative, preservative but would adversely affect human health; as well as chilled or modified atmosphere packaging (MAP) method, but these methods are not only expensive and time-consuming, but also affect the appearance and taste of the fruit. Therefore, a need for an not affect the taste of the fruit, but also to extend the shelf life of green strategies.
Recently, Rice University Professor Pulickel M. Ajayan reported and an edible multifunctional biological washing nanocomposite coating . The coating is composed of eggs derived polymers and cellulose nano-material composition, the coating can be sprayed as a fresh surface of the fruit, by retarding the dehydration of fruits and reduce breathing and to microbial invasion extend the shelf life of fruit. Researchers strawberries, avocado, papaya and bananas proved that the coating can not only extend shelf life while maintaining the taste of the fruit, and edible and easy to clean. This is expected to become an economical and sustainable method of egg-based multifunctional coating to reduce global food waste by preventing the loss of perishable foods. Preparation of bio-nano composite coating is mainly composed of egg proteins, it can be dried to form a solid edible film. Researchers at as raw egg white , and add the glycerol as a plasticizer to increase the flexibility, the coating can be of any shape to cover fruit without cracking; added simultaneously yolk fraction of hydrophobic , reduce the sensitivity of water; then added with antimicrobial properties curcumin to inhibit the growth of microorganisms of the fruit surface, maintain the freshness of the fruit; Finally, [123 ] cellulose nanocrystals (CNC), and water to reduce the gas permeability of the coating and increase the mechanical strength.
The nanocomposite solution was applied to different fruit [123 ] researchers measured the relationship between the viscosity of the nanocomposite solution to shear rate, in order to study the workability of the solution as a conformal coating, the results shown in Figure, the shear viscosity of the solution reduced by nearly three orders of magnitude 2, the performance the shear thinning behavior. It indicates that the coating surface of the fruit may be coated by spraying manner, a thinner and more uniform coating on the surface of the fruit. Subsequently, the contact angle study compared the nanocomposite solution on bananas, papayas and avocado peel, to explore the solution affinity of the fruit. The results showed that the contact angle of the surface of the avocado is about 45 °, 25 ° and down to in 8 minutes, indicating that the coating solution has a high affinity for the surface of the avocado; Also, papaya and banana contact angle of the surface in 8 minutes also it reduced the more than 15%, indicating that the coating solution has broad applicability to a variety of the fruit surface.
Preservation of fruit nanocomposite coating
Subsequently, researchers evaluated preservation of the coating climacteric fruit banana, avocado and papaya and non-climacteric fruit strawberry. The results shown in FIG, 3 few days later, fruit appearance and internal uncoated browning and exhibited decay, while the After the coating solution via biological nanocomposite fruits are placed inside and outside the more than one week without any change .
confirmedprepared researchers to prolong the shelf life of perishable fruits.
nanocomposite film performance test
In order to prevent the processing and stored during premature failure or rupture, good mechanical properties, is one of the basic requirements of the coatings of fruit, independent nanocomposite film shown in FIG. 4 researchers prepared, the film having a high flexibility, and can be repeated bending folded without cracking,Having excellent mechanical properties. In addition, compared to other polymers for packaging, hydrophobic coatings prepared by researchers higher, this higher hydrophobicity low water permeability of the membrane, thereby reducing the diffusion of water in the fruit, can be better preserve freshness.
The nanocomposite gas barrier coating and antibacterial properties
Fruit rot one important reason is due to oxidation of the fruit respiration, the researchers tested the O2 barrier properties of the nanocomposite film. The results shown in Figure 5, compared with other packaging material, the oxygen permeability of the film (OP) is low, after the fruits show nanocomposite membrane coating will reduce cellular respiration, thereby extending the shelf life of fruit. In addition, the growth of microorganisms on the surface of the fruit can also cause fruit rot, researchers evaluated the use of the E. coli strain antimicrobial properties of the coating, the strain in the membrane overnight incubation, the bacteria concentration is reduced to zero. showed the film to the surface of the fruit can effectively eliminate bacterial growth within 24 hours, and strong antibacterial activity can also reduce rotten fruit can be reduced even foodborne disease outbreaks.
Toxicity and washed nanocomposite coating may be [123 ]
a biocompatible surface coating is essential for fruit, because consumers may knowingly or unknowingly ingested the coating in the consumption of fruit. The researchers used pancreatic cancer cells (PancO2) to evaluate the toxicity of the coating. 6, with a coating after 24 hours incubation, cell survival in each experimental group were more than 90%, and are all starting material is an edible coating. Thus the nanocomposite coating not only toxic but also edible. Finally, in order to prove the coating cleanability, researchers sol – gel coating tests to detect solubility in water, the nano-composite membrane was placed in a vial containing deionized water, at room temperature after shaking at about 2 minutes, the film was completely decomposed and dispersed in deionized water. This shows that compared to the current non-waxy cleaning paint used, the nanocomposite coating is washed with waterWashing and gently wiped surface can be easily removed from the peel.
FIG 6. toxicity nanocomposite film and washability testing