Exposure to Air Accelerates the Gelation of Gelatin: Steady and Dynamic Shear Rheological Characterization to See the Effect of Air on the Strength of Gelatin Gel

Recent Advances in Marine-Based Nutraceuticals and Their Health Benefits

The oceans have been the Earth's most valuable source of food. They have now also become a valuable and versatile source of bioactive compounds. The significance of marine organisms as a natural source of new substances that may contribute to the food sector and the overall health of humans are expanding. This review is an update on the recent studies of functional seafood compounds (chitin and chitosan, pigments from algae, fish lipids and omega-3 fatty acids, essential amino acids and bioactive proteins/peptides, polysaccharides, phenolic compounds, and minerals) focusing on their potential use as nutraceuticals and health benefits.

Assessment of Water Mobility in Surf Clam and Soy Protein System during Gelation Using LF-NMR Technique

Water mobility and distribution of a dual-protein system of surf clam myofibrillar protein (MP) and soy protein (SP) was investigated by the nondestructive low field nuclear magnetic resonance (LF-NMR) technique. Four proton populations were found in the contour plots of T₂ relaxation times for the SP-MP system. The first component, (T₂₁), was assigned to the highly integrated water located in protein macromolecules with a relaxation time of approximately 1.15 ms. The second signal, T₂₂, with a relaxation time of 2.20 to 38.00 ms was regarded as the inter-myofibrillar water trapped in organized protein structures. The third component, T₂₃, with a relaxation time of around 100 ms was ascribed to the extra-myofibrillar water. With an increase in temperature, T₂₄ appeared which was assigned to the free water within the extra-myofibrillar space. The gelation behavior occurred at 70, 62, and 52 °C as the proportion of SP/MP was 4:6, 2:8, and 0:10, respectively. The principal component analysis (PCA) and heatmap of LF-NMR data analysis showed potential for distinguishing the different dual-protein systems formed at various temperatures. The analysis of storage modulus G′, loss modulus G″, and tanδ confirmed the change trend of the LF-NMR results. The measurements of cooking loss, water holding capability, and gel strength further revealed that the SP and MP were likely to form a gel network with an increase of additional clam protein. The hydrophobicity analysis showed, for the systems with the SP/MP proportions of 4:6, 2:8, and 0:10, more hydrophobic groups were exposed when the temperature was over 50 °C. Scanning electron microscopy showed that the number of the micropores increased with an addition of MP in the dual-protein system of SP/MP. All the results demonstrated that LF-NMR has great potential for characterizing the gelation process of a dual-protein system.

Effects of xylitol and stevioside on the physical and rheological properties of gelatin from cod skin

Jelly and confectionery products are high in sugar and calories. Xylitol and stevioside are natural low-calorie sweeteners and they can be used as an alternative; however, their effects on fish gelatin are unknown. The gelatin was extracted from cod skins and added to xylitol or stevioside (0, 2, 6, 10, 14, and 20% (w/v)) to form gel products. This paper investigated how xylitol and stevioside affected the physical and rheological behaviors of fish gelatin, such as color, gel strength, texture profile analysis, storage modulus (G′), loss modulus (G″), and viscosity. Results showed that the change of color and viscosity in gel products were similar when various concentrations of xylitol or stevioside were added to the fish gelatin. But the effects of xylitol/stevioside on texture profile analysis and G′, G″ were different, which might due to the structure variation in xylitol and stevioside. The linear structure of xylitol resulted in ionic interaction, hydrogen bonding, van der Waals forces, and hydrophobic association between xylitol and fish gelatin. Therefore, xylitol is a promising sweetener substitute, which was probably related to its greater solubility and number of –OH groups.

Rheological properties of concentrated solutions of gelatin in an ionic liquid 1-ethyl-3-methylimidazolium dimethyl phosphate

Rheological properties of gelatin solutions were examined in concentrated regions. Gelatin species from porcine skin and from bovine bone were dissolved in an ionic liquid 1-ethyl-3-methylimidazolium dimethyl phosphate. The dynamic viscoelasticity data for the solutions exhibited rubbery plateaus, indicating the existence of entanglement coupling between gelatin chains in the solutions. From the analogy with rubber elasticity, assuming that the molecular weight between entanglements (Me) is the average mesh size of the entanglement network, Me for gelatin in the solutions were determined from the heights of the rubbery plateaus. Then the value of Me in the molten state (Me,melt), a material constant reflecting the chemical structure of polymer species, for gelatin was estimated to be 8.7×10(3). Compared to synthetic polyamides whose Me,melt were known, Me,melt for gelatin was significantly larger, which could be explained by the densely repeating amide bonds composing gelatin.