Recent insights into polysaccharide-based hydrogels and their potential applications in food sector: a review

partially neutralized poly (acrylic acid) incorporated into the hydrogels 
increase swelling capacity, hence, concluding the role of pectin in 
enhancing hydrogel swelling property 
[136]
. According to Chang et al. 
[137]
, the swelling capacity of hydrogels is affected by the method of 
preparation, such as heating and freezing. The study found that the 
hydrogels created by heating had larger equilibrium swelling ratios than 
the hydrogels prepared by freezing. The swelling ratio of polyvinyl 
alcohol/polyvinyl pyrrolidone (PVA/PVP) hydrogels is largely reduced 
by carrying out their swelling in the osmotic solution as compared to the 
non-osmotic one 
[138]
. However, natural polymers help to improve the 
hydrogel performance and make them with environment friendly. In this 
support, natural guar gum is added with partially neutralized acrylic 
acid and incorporated with a cross-linker (N, N
′
-methylene bis acryl-
amide). The synthesis initiation of superabsorbent hydrogels (e.g., guar 
gum-g-poly (sodium acrylate)) was credited to ammonium persulfate. 
The resulting hydrogel possessed improved swelling properties with 
excellent stability at a pH range of 4–11 in addition to giving enhanced 
water retention capabilities to sand soils 
[139]
. 
The thermostability of a smart hydrogel polymer is shown in 
Fig. 4
. It 
swells when get interacted with moisture (Gas water) and shrinks under 
the temperature of 50 
◦
C and releases liquid water 
[140]
. 
Hydrogel swelling behavior can also be controlled by the nature 
(physical or chemical) of the cross linker, in which NN
′
-methylene bis 
acrylamide was used to form the chemically cross-linked and precipi-
tation polymerization method with dioxane as solvent in physically 
cross-linked Poly (acrylamide-co-methyl methacrylate) (poly (AAm-co- 
MMA)) hydrogel of different ratios 
[141]
. The study witnessed an 
A. Manzoor et al.

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International Journal of Biological Macromolecules 213 (2022) 987–1006
996
increase in swelling ratio with an increase in acrylamide content. 
Moreover, the monomer units' molecular weights of the hydrogel alter 
their swelling nature as reported a few decades ago 
[142]
. This study 
showed that a monomer unit, poly (ethylene glycol) (PEG) with mo-
lecular weight (860, 3900, and 9300) was used for the formulation of 
oligo (poly (ethylene glycol) fumarate) (OPF) hydrogel. The result 
conveyed that each variant showed a percent swelling that was signifi-
cantly different from other hydrogels of different PEG molecular 
weights. 
3.2. Antimicrobial properties 
As a polysaccharide, hydrogels generally are gaining attention due to 
their potential antimicrobial properties. In this context, a recent study in 
which carrageenan-based functional hydrogels having incorporated 
copper oxide (CuO), zinc oxide (ZnO) nanoparticles, and combinations 
thereof were synthesized, showed increased antibacterial activity 
against L. monocytogenes and E. coli, (borne pathogens). ZnO incorpo-
ration in hydrogels resulted in better antimicrobial properties than the 
CuO-based hydrogels making them feasible for biomedical, cosmetic, 
and active food packaging applications 
[143]
. In another study, 
hydrogel films incorporated with silver nanoparticles and tocopherol as 
reducing and capping agents were synthesized, showing their potential 
in packaging various foods due to strong antimicrobial activities against 
various food pathogens 
[144]
. 
Nanocomposite hydrogel i.e., carboxylated cellulose nanofibers 
(CNF) formed by the incorporation of gelatin and aminated silver 
nanoparticles helps to inhibit the chances of bacterial infection during 
the wound treatment besides potential wound healing property 
[145]
. 
Moreover, self-healing hydrogels are prepared from chitosan and konjac