Recent advances in the structure, synthesis, and applications of natural polymeric hydrogels.

Hydrogels, polymeric network materials, are capable of swelling and holding the bulk of water in their three-dimensional structures upon swelling. In recent years, hydrogels have witnessed increased attention in food and biomedical applications. In this paper, the available literature related to the design concepts, types, functionalities, and applications of hydrogels with special emphasis on food applications was reviewed. Hydrogels from natural polymers are preferred over synthetic hydrogels. They are predominantly used in diverse food applications for example in encapsulation, drug delivery, packaging, and more recently for the fabrication of structured foods. Natural polymeric hydrogels offer immense benefits due to their extraordinary biocompatible nature. Hydrogels based on natural/edible polymers, for example, those from polysaccharides and proteins, can serve as prospective alternatives to synthetic polymer-based hydrogels. The utilization of hydrogels has so far been limited, despite their prospects to address various issues in the food industries. More research is needed to develop biomimetic hydrogels, which can imitate the biological characteristics in addition to the physicochemical properties of natural materials for different food applications.

Properties of Ternary Biopolymer Nanocomplexes of Zein, Sodium Caseinate, and Propylene Glycol Alginate and Their Functions of Stabilizing High Internal Phase Pickering Emulsions.

A pH-cycle method based on preparing an alkaline solution of zein followed by neutralization with an acid can be used to prepare zein nanoparticles. In the present work, partial alkaline hydrolysis of propylene glycol alginate (PGA) to a lower pH was studied to prepare binary zein-PGA nanocomplexes and ternary complexes with additional sodium caseinate (NaCas). 0.5% or more PGA was sufficient to reduce the pH to 7.5 or lower, eliminating the need for titration, and resulted in simultaneous nanocomplex formation. The addition of NaCas into alkaline zein-PGA solution resulted in smaller complexes with all biopolymers, whereas adsorption on binary zein-PGA complexes was observed when NaCas was added into the neutral zein-PGA dispersions. The formation of nanocomplexes involved with hydrophobic and electrostatic attractions and hydrogen bonds and was further affected by the amount of NaCas. The ternary nanocomplexes with equal masses of zein and NaCas had an excellent capacity to prepare gel-like Pickering emulsions with as much as 80% v/v oil with characteristics suitable for texture modification and delivery systems of bioactive compounds in food and consumer products. Therefore, PGA can be used to possibly scale-up the pH-cycle method to produce zein-based nanoparticles with unique functional properties.

Comparison of cellulose derivatives for Ca2+ and Zn2+ adsorption: Binding behavior and in vivo bioavailability.

Cellulose with distinct colloidal states exhibited different adsorption capability for ions and whether the intake of cellulose would bring positive or negative influence on the mineral bioavailability is inconclusive. This work investigated the binding behavior of carboxymethyl cellulose (CMC), TEMPO-oxidized nanofibrillated/nanocrystalline cellulose (TOCNF/TOCNC), and microcrystalline cellulose (MCC) with Ca2+and Zn2+ and compared their effects on mineral bioavailability in vitro and in vivo. The results suggested that CMC displayed a higher adsorption capability (36.6 mg g-1 for Ca2+ and 66.2 mg g-1 for Zn2+) than the other types of cellulose because of the strong interaction between carboxyl groups of cellulose and the ions. Although the cellulose derivatives had adverse effects on ion adsorption in vitro, the fermentability endowed by TOCNF/TOCNC counterbalanced the negative impacts in vivo. The findings suggested that the colloidal states of cellulose affected the bioavailability of minerals and could provide useful guidance for applications of specific cellulose.

In Vitro Colonic Fermentation Profiles and Microbial Responses of Cellulose Derivatives with Different Colloidal States.

Although cellulose derivatives are widely applied in the food industry, the effects of their structural properties on colonic health is unknown. Here, four types of cellulose derivatives, including microcrystalline cellulose (MCC), TEMPO-oxidized nanofibrillated cellulose (TOCNF), TEMPO-oxidized nanocrystalline cellulose (TOCNC), and carboxymethyl cellulose (CMC) were selected to investigate their in vitro fermentation profiles. TOCNF exhibited the highest production of total short-chain fatty acids (SCFAs), followed by TOCNC. The results suggested that reduced particle size and increased aspect ratio improved the fermentability of insoluble cellulose derivatives. MCC and CMC were barely fermented with similar total SCFAs production as the blank. 16S rRNA sequencing revealed that the fermentation of cellulose derivatives resulted in divergent microbial community structures. Moreover, Bacteroides cellulosilyticus showed high specificity to utilize TOCNF and TOCNC. The findings demonstrated that the colloidal states of cellulose derivatives, such as size and solubility, were important factors governing microbial community composition and metabolites.

Cellulose and cellulose derivatives: Different colloidal states and food-related applications.

Development of new sources and isolation processes has recently enhanced the production of cellulose in many different colloidal states. Even though cellulose is widely used as a functional ingredient in the food industry, the relationship between the colloidal states of cellulose and its applications is mostly unknown. This review covers the recent progress on illustrating various colloidal states of cellulose and the influencing factors with special emphasis on the correlation between the colloidal states of cellulose and its applications in food industry. The associated unique colloidal states of cellulose like high aspect ratio, crystalline structure, surface charge, and wettability not only promote the stability of colloidal systems, but also help improve the nutritional aspects of cellulose by facilitating its interactions with digestive system. Further studies are required for the rational control and improvement of the colloidal states of cellulose and producing food systems with enhanced functional and nutritional properties.