Benjamín Paredes

The use of sub-critical water hydrolysis for the recovery of peptides and free amino acids from food processing wastes. Review of sources and main parameters.

Food industry processing wastes are produced in enormous amounts every year, such wastes are usually disposed with the corresponding economical cost it implies, in the best scenario they can be used for pet food or composting. However new promising technologies and tools have been developed in the last years aimed at recovering valuable compounds from this type of materials. In particular, sub-critical water hydrolysis (SWH) has been revealed as an interesting way for recovering high added-value molecules, and its applications have been broadly referred in the bibliography. Special interest has been focused on recovering protein hydrolysates in form of peptides or amino acids, from both animal and vegetable wastes, by means of SWH. These recovered biomolecules have a capital importance in fields such as biotechnology research, nutraceuticals, and above all in food industry, where such products can be applied with very different objectives. Present work reviews the current state of art of using sub-critical water hydrolysis for protein recovering from food industry wastes. Key parameters as reaction time, temperature, amino acid degradation and kinetic constants have been discussed. Besides, the characteristics of the raw material and the type of products that can be obtained depending on the substrate have been reviewed. Finally, the application of these hydrolysates based on their functional properties and antioxidant activity is described.

Influence of the amination conditions on the textural properties and chromatographic behaviour of amino-functionalized glycidyl methacrylate-based particulate supports

Abstract Amino-functionalization of particulate macroporous poly(glycidyl methacrylate-co-ethylene dimethacrylate), obtained by “bulk” polymerization of a novel mixture of monomers, was carried out by reaction with concentrated ammonia, diethylamine (DEA) and the mixture DEA/THF (1:1). The influence of the amination conditions on the polymer mechanical and thermal stability, porous structure and degree of amination was analyzed; it was also found a narrow correlation between these properties and the chromatographic behaviour of the supports. The polymers functionalized with ammonia and DEA/THF were used for hen egg white proteins separation in column packed experiments; both resins carried out the separation of a mixture of lysozyme, ovalbumin and trypsin inhibitor. The DEA/THF functionalized resin showed better performance for egg white protein separation and very good retention capacity (38 mg ovalbumin/ml resin).

Functionalized glycidyl methacrylate based polymers as stationary phases for protein retention

The search for new materials for chromatographic separation of proteins is a major endeavor nowadays. In order to obtain better chromatographic separation media, poli(glycidyl methacrylate co-ethylen dimethacrylate) matrices were synthesized, milled, classified, functionalized with different reagents and then comparatively tested in batch experiments for protein retention. The Methacrylate/Dimethacrylate resin was treated in different sequences of experiments with Urea, Iminodiacetic acid, N-N dimethyl formamide and ammonia, in order to determine whether functionalization provides sufficient amino groups to capacitate them for protein retention. Fixed bed experiments with particulate resin were also carried out. Previous characterization confirms that the polymeric matrix is macroporous and exhibits a unimodal pore size distribution. The resin also presents a good thermal stability.

Inert and Oxidative Subcritical Water Hydrolysis of Insoluble Egg Yolk Granular Protein, Functional Properties, and Comparison to Enzymatic Hydrolysis

The use of enzymes to recover soluble peptides with functional properties from insoluble proteins could prove to be very expensive, implying high reaction times and low yields. In this study, the insoluble granular protein, previously delipidated, was hydrolyzed using enzymes (trypsin) as a comparison to the proposed alternative method: subcritical water hydrolysis (SWH) using both nitrogen and oxygen streams. The result of the hydrolysis was characterized in terms of the yield and peptide size distribution as well as different functional properties. The SWH of the delipidated granules resulted in a higher recovery yield than that obtained by enzymatic hydrolysis in half of the time. The foaming capacity of the peptides obtained by SWH was higher than that obtained by trypsin hydrolysis, although the foam stability was lower. Slight differences were detected between these peptides in terms of their emulsifying properties.

Gels prepared from egg yolk and its fractions for tissue engineering

New biomaterials prepared from egg yolk and its main fractions (plasma and granules) have been developed for use in tissue engineering. Protein gels obtained via transglutaminase cross‐linking were characterized by rheometry, texturometry and scanning electron microscopy. All the gels exhibited suitable physical and mechanical characteristics for use as potential biomaterials in skin regeneration. Specifically, results showed that these materials presented a compact, uniform structure, with granular gel being found to be the most resistant as well as the most elastic material. Accordingly, these gels were subsequently evaluated as scaffolds for murine fibroblast growth. The best results were obtained with granule gels. Not only adhesion and cell growth were detected when using these gels, but also continuous coatings of cells growing on their surface. These findings can be attributed to the higher protein content of this fraction and to the particular structure of its proteins. Thus, granules have proved to be an interesting potential raw material for scaffold development.