The
design of gelatin-based hydrogels with high mechanical strength,
high gelation temperature, and a rapid self-healing property still
presents a challenge to researchers. In the present study, single
cross-linked gelatin–oxidized tannic acid (SC-GT/OTA) hydrogels
were fabricated through covalent cross-linking between gelatin and
tannic acid (TA) oxidized by using sodium periodate (NaIO4). Double cross-linked gelatin–OTA–FeCl3·6H2O (DC-GT/OTA/FeIII) hydrogels were
also created using metal coordination bonds formed between the catechol
groups present in OTA and FeIII in ferric chloride. As
a result, the maximum gelling temperature of the SC-GT/OTA hydrogel
(37 °C) was considerably higher than that of the pure gelatin
hydrogel (15.4 °C). Moreover, the maximum values of compressive
stress of SC-GT/OTA hydrogels increased significantly by almost seven
times the original value as the molar ratio of NaIO4 to
TA increased from 3:1 to 5:1. When the molar ratio of NaIO4 to TA was maintained at the constant of 4:1, the storage modulus
values of DC-GT/OTA/FeIII hydrogels with the FeIII-to-TA molar ratio of 1.5:1 were three to 4 orders of magnitude higher
than those of SC-GT/OTA hydrogels in the whole angular frequency range.
The double cross-linked gelatin hydrogels developed in this research
can be used widely in agriculture and material science fields.
As a renewable resource, the market trend of plant protein has increased significantly in recent years. Compared with animal protein, plant protein production has strong sustainability factors and a lower environmental impact. Many bioactive substances have poor stability, and poor absorption effects limit their application in food. Plant protein-based carriers could improve the water solubility, stability, and bioavailability of bioactive substances by different types of delivery systems. In this review, we present a detailed and concise summary of the effects and advantages of various plant protein-based carriers in the encapsulation, protection, and delivery of bioactive substances. Furthermore, the research progress of food-grade bioactive ingredient delivery systems based on plant protein preparation in recent years is summarized, and some current challenges and future research priorities are highlighted. There are some key findings and conclusions: (i) plant proteins have numerous functions: as carriers for transportation systems, a shell or core of a system, or food ingredients; (ii) plant protein-based carriers could improve the water solubility, stability, and bioavailability of bioactive substances by different types of delivery systems; and (iii) plant protein-based carriers stabilize bioactive substances with potential applications in the food and nutrition fields.
At present, the physical properties of hydrocolloids limit their wide application in food industry. To improve the viscoelasticity of sodium carboxymethyl cellulose (CMC) and sodium alginate (SA), cellulose nanocrystals (CNCs) were added into CMC and SA solutions to regulate the non‐Newtonian flow behaviors of composite systems under different conditions. The rheological properties of CMC/CNCs or SA/CNCs composite systems were studied using steady rheological measurements, dynamic rheological measurements, and creep compliance experiments. It was found that the viscosities and elastic modulus of CMC were positively related to CNCs concentrations in acid, neutral or alkaline environments. When the CNCs content was higher than 5% at pH 9.45, the gelation of CMC was accelerated, and the gelation strength was increased. The damping factor of SA decreased with increasing calcium ions contents. When calcium ions content was higher than 0.07%, the damping factor of SA was less than 1, indicating that SA system achieved gel transformation. The effect of CNCs on the apparent viscosity, shear stress, and storage modulus of CMC was more obvious in comparison to that of SA. Overall, as a rheology modifier, CNCs can minimize the contents of food colloids in any functional fluid while maintaining the thickening rheology.
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