Putrescine-polysaccharide conjugates as transglutaminase substrates and their possible use in producing crosslinked films

A novel polysaccharide/zein conjugate as an alternative green plastic

The flax seed cake is a waste product from flax oil extraction. Adding value to this wasted material aligns with the concept of circularity. In this study, we explored zein protein conjugation with flax mucilage for packaging material development. Although both flax mucilage and zein have excellent film-forming properties, they lack the required mechanical properties for industrial processing and are sensitive to high humidity. We present a simple and non-toxic one-pot method for developing the novel flax mucilage/zein conjugate. Where the flax mucilage undergoes oxidation to form aldehyde groups, which then react with zein's amino groups in a glycation process. The conjugates were analyzed using different techniques. The flax mucilage conjugate had a water-holding capacity of 87-62%. Increasing the zein content improved the surface smoothness of the films. On the other hand, higher levels of zein led to a significant decrease in film solubility (p < 0.05). The flax mucilage conjugate exhibited thermoplastic and elastic properties; revealing Young's modulus of 1-3 GPa, glass transition temperature between 49 °C and 103 °C and excellent processability with various industrial techniques. Showing its potential as a sustainable alternative to traditional plastics.

Microbial Transglutaminase as a Tool to Improve the Features of Hydrocolloid-Based Bioplastics

Several proteins from animal and plant origin act as microbial transglutaminase substrate, a crosslinking enzyme capable of introducing isopeptide bonds into proteins between the aminoacids glutamines and lysines. This feature has been widely exploited to modify the biological properties of many proteins, such as emulsifying, gelling, viscosity, and foaming. Besides, microbial transglutaminase has been used to prepare bioplastics that, because made of renewable molecules, are able to replace the high polluting plastics of petrochemical origin. In fact, most of the time, it has been shown that the microbial enzyme strengthens the matrix of protein-based bioplastics, thus, influencing the technological characteristics of the derived materials. In this review, an overview of the ability of many proteins to behave as good substrates of the enzyme and their ability to give rise to bioplastics with improved properties is presented. Different applications of this enzyme confirm its important role as an additive to recover high value-added protein containing by-products with a double aim (i) to produce environmentally friendly materials and (ii) to find alternative uses of wastes as renewable, cheap, and non-polluting sources. Both principles are in line with the bio-economy paradigm.

Effect of the Fish Oil Fortified Chitosan Edible Film on Microbiological, Chemical Composition and Sensory Properties of Göbek Kashar Cheese during Ripening Time

Objective of the present study is to investigate the effect of coated edible films with chitosan solutions enriched with essential oil (EO) on the chemical, microbial and sensory properties of Kashar cheese during ripening time. Generally, no differences were found in total aerobic mesophilic bacteria, streptococci and lactoccocci counts among cheeses but these microorganism counts increased during 60 and 90 d storage especially in C1 (uncoated sample) as compared with coated samples. Antimicrobial effectiveness of the films against moulds was measured on 30, 60, and 90 d of storage. In addition of fish EO into chitosan edible films samples were showed to affect significantly decreased the moulds (p<0.05) as 1.15 Log CFU/g in C4 (with fish oil (1% w/v) fortified chitosan film) on the 90(th) d, while in C1 as 3.89 Log CFU/g on the 90(th) d of ripening. Compared to other cheese samples, C2 (coated with chitosan film) and C4 coated cheese samples revealed higher levels of water-soluble nitrogen and ripening index at the end of storage. C2 coated cheese samples were preferred more by the panellists while C4 coated cheese samples received the lowest scores.

Chitosan/whey Protein (CWP) Edible Films Efficiency for Controlling Mould Growth and on Microbiological, Chemical and Sensory Properties During Storage of Göbek Kashar Cheese

The objective of present study was to evaluate the effects of the application of chitosan and chitosan/whey protein on the chemical, microbial and organoleptic properties of Göbek Kashar cheese during ripening time (on 3(rd), 30(th), 60(th) and 90(th) d). Difference in microbiological and chemical changes between samples was found to be significant (p<0.05) during ripening period. Cheese samples with edible coating had statistically lower mould counts compared to the uncoated samples. Furthermore the highest and lowest mould counts were determined in control (4.20 Log CFU/g) and other samples (<1 Log CFU/g) at 60(th) and 90(th) d of storage. All samples exhibited higher levels of water soluble nitrogen and ripening index at the end of storage process. At the end of 90 day storage period, no signicant dierences in salt and fat values were observed among the cheeses studied. The edible coatings had a beneficial effect on the sensory quality of cheese samples. In the result of sensory analysis, while cheese C and the chitosan coated cheese samples were more preferred by the panellists, the chitosan/whey protein film-coated cheese samples received the lowest scores. This study shows coating suggests could be used to improve the quality of cheese during ripening time.

Transglutaminase 2 is secreted from smooth muscle cells by transamidation-dependent microparticle formation

Transglutaminase 2 (TG2) is a pleiotropic enzyme involved in both intra- and extracellular processes. In the extracellular matrix, TG2 stabilizes the matrix by both covalent cross-linking and disulfide isomerase activity. These functions become especially apparent during matrix remodeling as seen in wound healing, tumor development and vascular remodeling. However, TG2 lacks the signal sequence for a classical secretory mechanism, and the cellular mechanism of TG2 secretion is currently unknown. We developed a green fluorescent TG2 fusion protein to study the hypothesis that TG2 is secreted via microparticles. Characterization of TG2/eGFP, using HEK/293T cells with a low endogenous TG2 expression, showed that cross-linking activity and fibronectin binding were unaffected. Transfection of TG2/eGFP into smooth muscle cells resulted in the formation of microparticles (MPs) enriched in TG2, as detected both by immunofluorescent microscopy and flow cytometry. The fraction of TG2-positive MPs was significantly lower for cross-linking-deficient mutants of TG2, implicating a functional role for TG2 in the formation of MPs. In conclusion, the current data suggest that TG2 is secreted from the cell via microparticles through a process regulated by TG2 cross-linking.