Effects of Pressure Level and Time Treatment of High Hydrostatic Pressure (HHP) on Inulin Gelation and Properties of Obtained Hydrogels

Abstract

The aim of this study was the evaluation of the influence of different HHP levels (150 and 300 MPa) and time treatment (5, 10, 20 min) on the gelation and properties of hydrogels with different inulin concentration (15, 20, 25 g/100 g). High-pressure treatment, in tested ranges, induces inulin gels and allows obtaining gel structures even at a lowest tested inulin content (i.e., 15 g/100 g). Selecting the pressure parameters, it is possible to modify the characteristics of the created hydrogels. The use of higher pressure (i.e., 300 MPa) allows to increase the stability of the hydrogels and change their structure to more compressed, which results in higher yield stress, lower spreadability, harder and more adhesive structure. For example, increasing the inulin gelling induction pressure (concentration 20 g/100 g) from 150 to 300 MPa with a time treatment of 10 min resulted in an increase in yield stress from 38.1 to 711.7 Pa, spreadability force from 0.59 to 4.59 N, firmness from 0.11 to 1.46 N, and adhesiveness from −0.06 to −0.65 N. Extending the time treatment of HHP increases this effect, but mainly when higher pressure and a higher concentration of inulin are being used. For example, extension of time treatment at 300 MPa pressure from 5 to 20 min resulted in an increase in yield stress from 774.8 to 1273.8 Pa, spreadability force from 6.28 to 8.43 N, firmness from 1.87 to 2.98 N, and adhesiveness from −0.94 to −1.27 N. The obtained results indicate the possibility of using HHP to create inulin hydrogels tailored to the characteristics in a specific food product.

A Comparative Evaluation of the Structural and Biomechanical Properties of Food-Grade Biopolymers as Potential Hydrogel Building Blocks

“…When using physical (mechanical and thermal) induction techniques, inulin can form a hydrogel with a sponge-like structure. The formation of inulin hydrogel is based on particles attraction caused by Van der Waals forces [ 57 ]. Furthermore, Beccard et al, (2019) [ 58 ] in their studies stated that inulin gelation is based on a crystallization process, which explains why (in terms of PCA and HCA, Figure 5 ) inulin hydrogels differed significantly from the other biopolymers.…”

Progress in the Preparation and Application of Inulin-Based Hydrogels

“…Avoids thermal degradation, higher elasticity, higher viscosity, and lower fluidity Requires specialized equipment; the operation may be more complex [18,[35][36][37][38] Chemical Methods…”

Binary Hydrogels: Induction Methods and Recent Application Progress as Food Matrices for Bioactive Compounds Delivery—A Bibliometric Review

“…Moreover, when using HHP, it is possible to obtain hydrogels at lower induction temperatures, which has excellent potential in incorporating thermolabile food compounds and nutraceuticals into the quinoa protein gel matrix. In a study conducted by Florowska et al [28] regarding the effects of pressure level and time treatment of HHP on inulin gelation and properties of obtained hydrogels, the use of HHP pressure (higher than 300 MPa) was reported. The obtained hydrogels had higher stability and a more compressed and changed structure, which resulted in higher yield stress, lower spreadability, and more rigid and adhesive hydrogels.…”

“…Polysaccharide hydrogel formation can be induced through various methods, among others heat and cooling, pH and salt modulation, the addition of sucrose, and freezethaw cycles [20]. Among the widely used in the food industry polysaccharides that have gelling abilities are carrageenan [21,22], chitosan [23,24], alginate [25,26], inulin [27,28], starch [29,30], cellulose [31,32], gum arabic [33,34], gellan gum [35,36], etc.…”