Table 3.

Zein-EOs NPs characteristics and potential applications.

Characteristics of zein used	EOs loaded into zein NPs	NPs size (nm)	NPs polydispersity index	NPs zeta potential (mV)	Methods used	Type of study	Functionality	Medical or veterinary applications	References
Zein from maize, Strongly hydrophobic because of a high proportion of cationic amino acids.	Clove (Eugenia caryophyllata) Garlic (Allium sativum)	150	<0.2	+30	Antisolvent precipitation, which consists of a hydro-ethanolic zein solution injection into an aqueous solution	In vitro	Encapsulation efficiency of more than 90%, stability in storage for 90 days	Applications in aquaculture, thanks to its bactericidal activity against Streptococcus iniae (Gram+), Aeromonas hydrophila, Edwardsiella tarda (Gram-).	(Luis et al., 2020)
Zein from maize	Oregano (Origanum vulgare) Thyme (Thymus vulgaris)	138–162	0.165–0.191	+20.9–+23.2	Nanoprecipitation with a nonionic Pluronic surfactant	In situ	Physical and chemical stability in storage for 90 days at 4 °C and 20 °C, release profile controlled by the Korsmeyer-Peppas kinetic model	Greater antimicrobial activity against Gram + bacteria, such as Listeria monocytogenes ATCC 7644 and Staphylococcus aureus ATCC 2593 than Gram – bacteria, such as Escherichia coli ATCC 25922 and Salmonella enterica serovar Typhimurium ATCC 14028 (because of their external lipopolysaccharide layer in their membrane which avoids the diffusion of hydrophobic compounds)	(Gonçalves da Rosa et al., 2020)
Zein from maize	Phenolic monoterpenes: Thymol and Carvacrol. There are components of several EOs extracted from Thyme (Thymus vulgaris) or Oregano (Origanum vulgare)	108–122	0.223 − 0.277	+9–+30	Nanoprecipitation	In vitro	Stability in storage for 90 days at 6 °C and 20 °C, release profile controlled by the Korsmeyer-Peppas kinetic model (50% in 72 h without burst effects)	Greater antimicrobial activity against Gram + bacteria, such as Listeria monocytogenes ATCC 7644 and Staphylococcus aureus ATCC 2593 than Gram– bacteria, such as Escherichia coli ATCC 25922 and Salmonella enterica serovar Typhimurium ATCC 14028	(da Rosa et al., 2015)
Zein from maize	Ocimum gratissimum Pimenta racemosa	150	<0.3	+16–+32	Nanoprecipitation	In vitro	High encapsulation efficiency, physical and chemical stability in storage for 180 days at 6 °C and 20 °C	Promising potential to application in a food system. Can act as natural preservative due to good physicochemical stability during 180 days of storage at 6 and 20 °C	(Paula Zapelini de Melo et al., 2019)
Zein from maize	Thyme (Thymus capitatus)	<180	0.250	Not reported	Self-assembly	In vitro	Not reported	Bacteriostatic activity improved against Gram + bacteria: Listeria monocytogenes, andGram – bacteria: Escherichia coli O157:H7	(Merino et al., 2019)
Zein with a minimum protein content of 97 g/100g	Thymol and Carvacrol, essentially found in Thyme (Thymus vulgaris) or Oregano (Origanum vulgare)	<800	<0.3	Not reported	Liquid-liquid dispersion	In vitro	Not reported	Antimicrobial activity against nonpathogenic Escherichia coli ATCC 53323 (Gram-). The nonpathogenic bacteria have been chosen because of their similarity to well-known pathogenic bacteria responsible for several foodborne illness outbreaks	(Wu et al., 2012)