35.3 Film/Coating Made from Agri-Food Waste

547

improved mechanical and barrier properties than the carbohydrate- and lipid-based

edible films [5].

Lignocellulosic material of corn stover was used to produce polyols, which

form biopolymer. The polyols by cross-linking with cyclic acid, anhydrides, and

polyurethane foams lead to the formation of biodegradable polyester [17]. Soy

protein, zein, and gluten extracted from the food residues or wastes are commonly

used for the development of edible films. Defatted soybean meal-based edible film

has limited application due to its low moisture barrier and mechanical properties.

Guo et al. [21] developed a composite film using wheat gluten and corn zein

and studied the effect of different factors. The results showed reduced water vapor

permeability due to the zein hydrophobicity, and with the increase in glycerol

content the barrier property values increased and provided a good mechanical

property. Starch and its derivatives are utilized as biopolymers in the edible film

development due to their low cost and availability. The structure, size, chemical

composition, and shape of film vary depending on the sources. Starch consists of two

polysaccharides, namely amylose and amylopectin. Amylose is mainly responsible

for film formation [5]. Starch from corn, having high amylose content, shows an

excellent film character due to its strong gelation and good gas barrier properties.

The by-product after oil extraction from the oil seeds like olive, flaxseed, rapeseed,

coconut, cotton, sunflower, peanut, and sesame is called as meal or cake, which is

rich in protein and carbohydrates. Extracted compounds from these by-products or

a whole by-product material can be utilized for the edible biopolymer packaging

material. An edible film based on the defatted mustard meal, a by-product from

the defatted biofuel industry, was developed [22]. This film showed antimicrobial

activity against the Listeria monocytogenes without adding any external antimicro-

bial additives and a good physical property. The study demonstrated that the film has

the potential to be used as the film and coating material for food. The edible films

made from the agri-waste residues are shown in Table 35.1.

35.3.3

Bioactive Compounds from Plant Residues

The plant-originated waste residues are used for the extraction of the bioactive

compounds such as phenolics, terpenoids, and flavonoids having antioxidant and

antimicrobial characters. Dietary fibers are also extracted from plant residues [9].

The sources of these compounds are citrus peel, pomegranate peel, seed extracts,

grape skin, and tomato pulp. A study was conducted [16] on the development of

active biodegradable packaging film by utilizing the industrial wastes, dietary fibers

from blueberry juice processing, and gelatin capsule waste containing glycerol as

a plasticizer. This film showed prolonged shelf life of food. In another study [19],

incorporation of clove oil resulted in an antimicrobial character after wrapping

on the bread. In another study [27], a gelatin-based nanocomposite film was

developed by incorporating black rice anthocyanins, and it showed a slight decrease

in mechanical properties but an excellent UV light barrier and antioxidant nature.

So, the plant extracts containing high antioxidant and antimicrobial compounds

will be useful for the development of active food packaging.