ReviewZein and zein -based nano-materials for food and nutrition applications: A review
Introduction
Biopolymers are alternatives to synthetic polymers, however they have faced two major problems, including low degradation temperatures, and high water vapor permeabilities (Hernandez-Sanchez & Gutierrez-Lopez, 2015; Sanchez-Garcia & Lagaron, 2010). There are some possibilities to overcome these problems by taking into consideration of the combined following effects: use of additives and applying nanotechnology to improve their properties. Properties (chemical, biological, electrical, thermal, mechanical, optical, and magnetic) of nano materials are different from bulk materials (Nalwa, 2004). Changes in the properties of nano-sized materials are the basis of the unique nature of nano-materials in novel technologies. The high quality of foods can be produced using nanotechnology. Bio-composite materials have been fabricated using nanotechnology in order to improve oxidative stability of conventional food polymeric matrices (Silvestre, Duraccio, & Cimmino, 2011).
Materials with the following characteristics: one dimension in nanometer-length scale (1–100 nm); a large surface area; a large surface area per volume; and at least one property that deviates from the value of the equivalent bulk material having the same composition, create novel properties and phenomena (Nalwa, 2004; Silvestre et al., 2011). They become ideal for applications that involve in food composite materials, chemical reactions, and controlled release of substances in several branches of food technologies (Lafdi, 2010; Sanchez-Garcia & Lagaron, 2010). Nano-science and nanotechnology are growing in various sectors of science, technology and engineering and result in significant changes in the world in the near future. Different research subjects including preparations, properties, characterizations and applications in vitro and in vivo of nano-materials are now under investigating composition (Nalwa, 2004; Silvestre et al., 2011).
The revolution in food nanotechnology has been started in 1864 by Pasteur to kill the spoilage of bacteria (size of bacteria ≤3000 nm) (Robinson, 2002). The genetic information of living organisms, encoded on the DNA (with a size 2–3 nm), opened the gateway to progress in nano-biotechnology (Watson & Crick, 1953). The information obtained on the sizes of proteins (3–150 nm) (Hay, 1991), expands their possible applications in different branches of food and nutrition nanotechnology. Applications of nano-sized materials result in products with a better (properties, characteristics or functionalities) quality in comparison with the bulk counterparts (Moraru, Huang, Takhistov, Dogan, & Kokini, 2009).
Zein with positive charges is suitable for delivery of negatively-charged drugs, foods, and nutrients. The wide range of isoelectric point for zein is appropriate conditions for delivering different nutrients into the body. Because of the several advantages of zein in comparison with other proteins, efforts have been made to explore the possibilities of utilizing zein nanoparticles (NPs) for food and nutrition applications (Reddy & Yang, 2011).
Zein, an environmentally friendly material, recognized as safe for food applications (Weissmueller, Lu, Hurley, & Prud'homme, 2016). It is generated as a co-product, when corn grains are processed for food, feed, agriculture products, and fuel (Reddy & Yang, 2011). Incorporating of nano-particles with zein-based compounds expands their number of possible applications.
To date, no review report on zein-based nano-materials for food and nutrition applications has been published at least within the past 8 years. This manuscript focuses on food and nutrition applications of zein-based nano-materials. A review article on different aspects of zein nano-materials serves as a collection, up-date information, and a ready reference for researchers who are involved in both research laboratories and industries. Even though this review focused on food and nutrition applications, the topic is of interest to other readers in different fields (agriculture, pharmacy, medicine, and environment). Zein as a byproduct for ethanol production is one of the most important industrial biopolymers for the 21St century. This paper provides an up-to-date evaluation of the existing development on zein/zein based nano-materials, and implication of nanotechnology in food and nutrition sectors. This study presents various properties and characteristics of zein nano-materials affecting their applications. Various procedures for preparations and size measurements of zein nano-materials have been also described. Nano-encapsulation of food and nutrient bioactive compounds is the major section, and food packaging is out of this study.
Section snippets
Characteristics, properties and functions of zein
Zein is the major storage protein in corn (Guo, Liu, An, Li, & Hu, 2005; Hudson, 1997). It consists of four components (alpha, beta, gamma and delta) having different peptide chains, molecular sizes, and solubilities. The most abundant protein in commercial zeins is the alpha one having complex groups of prolamines with molecular weights of 19 and 22 kDa (Parris, Dickey, Tomasula, Coffin, & Vergano, 2001), and comprise 70–85% of the whole zein (Shukla & Cheryan, 2001). Hudson (1997) reported
Preparation of zein/zein-based nano-particles, and their size measurements
Zein NPs were prepared by the liquid-liquid dispersion process with the following steps: (i) zein was dispersed in an ethanol–water mixture; (ii) the dispersed solute was sheared into smaller droplets (iii) the inter-diffusion of ethanol and water resulted in a reduction in the solubility of zein; and (iv) the precipitated zein was formed NPs. Zein micro- and NPs were prepared by dissolving zein in aqueous ethanol solution and then being sheared into water (Zhong & Jin, 2009). Zein NPs were
Nano-materials with a particular attention on zein-nano-materials: heath-care applications
Based on information given by Chau, Wu, and Yen (2007), approximately 9% of nano-products of manufacturer markets, were employed for food and beverages industries. Most of the nano-products were used for food packaging and only a few nano-products were employed for other branches of food industries. Advantages of nano-materials over the bulk and conventional materials with the same compositions for food and nutrition applications are presented as bulleted points in the following:
- >
Improvement in
Conclusions
(1) The average diameter of zein nanoparticles was reported to be 50–200 nm. The size of zein depends on the composition of the subclasses (alpha, beta, gamma, delta), the concentration of zein in solutions, and the degree of aggregation; (2) each subclass of the zein nanoparticles are somewhat mono-disperse with a globular/spherical morphology; (3) zein with an amphiphilic (hydrophobic/hydrophilic) character is a desirable component to be a part of a designed (assembly, delivery, or
Perspectives and challenge for future work
Use of nanotechnology and nano-sized zein materials with a particular attention on the unique characteristics and properties of zein open large area of investigations for zein-based formulations and their further applications in food and nutrition industries. Nano-sized zein/zein-based nano-materials have potential towards the development of biosensor tools to detect food and nutrient allergens and food/nutrient deficiencies. The potential risks of zein nano-materials to human health and to the
Description on funding
This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.
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