In recent years, a strong interest has emerged in hybrid composites and their potential uses, especially in chitosan-titanium dioxide (CS-TiO 2 ) composites, which have interesting technological properties and applications. This review describes the reported advantages and limitations of the functionalization of chitosan by adding TiO 2 nanoparticles. Their effects on structural, textural, thermal, optical, mechanical, and vapor barrier properties and their biodegradability are also discussed. Evidence shows that the incorporation of TiO 2 onto the CS matrix improves all the above properties in a dose-dependent manner. Nonetheless, the CS-TiO 2 composite exhibits great potential applications including antimicrobial activity against bacteria and fungi; UV-barrier properties when it is used for packaging and textile purposes; environmental applications for removal of heavy metal ions and degradation of diverse water pollutants; biomedical applications as a wound-healing material, drug delivery system, or by the development of biosensors. Furthermore, no cytotoxic effects of CS-TiO 2 have been reported on different cell lines, which supports their use for food and biomedical applications. Moreover, CS-TiO 2 has also been used as an anti-corrosive material. However, the development of suitable protocols for CS-TiO 2 composite preparation is mandatory for industrial-scale implementation.Materials 2020, 13, 811 2 of 27 they are synthesized by different methods (intercalation of the polymer, sol-gel, hydrothermal, electro-deposition, chemical and physical vapor deposition, suspension and liquid phase deposition). These methods are effective to enhance the technological and mechanical properties of each individual component and also reveal new functionalities [1,3]. Currently, there is a special interest in combining natural polymers such as chitosan (CS) with inorganic materials like titanium dioxide (TiO 2 ) to obtain hybrid composites (CS-TiO 2 ) with beneficial properties [3][4][5][6].Chitosan (CS) is a natural biopolymer (linear polysaccharide comprising 1-4 linked 2-amino-deoxy-β-D-glucan) generally obtained by deacetylation of chitin, the main structural component of crustacean exoskeletons. CS exhibits a poly-cationic character and is non-toxic and biodegradable [7]. CS is considered a biological functional compound with multiple interesting properties. It can form films for food and pharmaceutical applications, including edible coatings, packaging material, or as drug-eluting carrier [5,7]. Its adsorbent capacity can have environmental applications during photocatalytic processes of waste-water treatment [8], and it also has inherent antibacterial and antifungal properties [9]. It is biocompatible with several organic and inorganic compounds by the presence of free amino and hydroxyl functional groups in its structure, which can react with other functional groups by electrostatic forces, hydrogen bonds, or by compound-soak up into the polymeric matrix, thus improving its mechanical and biological properties [10]...

and balance, the response observed in adult scallops suggested that N. subnodosus presents a high capability to respond to acute temperature stress in the range of its thermal window tolerance. Our study examined the capability of scallops to respond to an acute challenge of 24 h, these results lead to additional unknowns regarding the metabolic and energetic capability of the response and homeostasis under repeated exposure to acute hyperthermia scenarios and regarding the increasing variability in seawater temperature as another possible large event in future global warming scenarios.

Supplementary fructooligosaccharides (FOS) were evaluated on growth, survival, gut morphology, digestive enzyme activity and expression of intestinal barrier genes in tropical gar (Atractosteus tropicus). Four treatments were designed to include FOS (5, 10, 15 and 20 g/Kg) and were compared with a control (0 g/Kg) and the current commercial trout diet. Ten fish were stocked (0.25 ± 0.01 g and 4.2 ± 0.4 cm total length) per experimental unit by triplicate in a 45-day experiment. Fish fed with 5 and 10 g/Kg of FOS had the highest average weight and total average length. Fish fed 5 g/Kg FOS showed the best growth indexes (absolute weight gain: 2.16; specific growth rate: 4.96; and feed conversion rate: 1.23) and survival (96.66%) and also had the highest acid protease, chymotrypsin and leucine aminopeptidase activities. Fish fed 5 g/Kg FOS had a high absorption area and accumulation of lipids in the liver. Finally, relative overexpression of occluding (occ), nucleotide-binding oligomerization domain-2 (nod2) and mucin 2 (muc2) was detected in fish fed 10 and 15 g/Kg FOS. The supplementation between 5 and 10 g/Kg FOS in diets for A. tropicus juveniles could be beneficial for growth, digestive enzyme activities, gut morphology and intestinal barrier function.

The aim of this study was to assess the regulatory process of digestive peptidases of crustaceans in the presence of soybean trypsin inhibitor (SBTI). This naturally occurring inhibitor in soybean meal was used to inhibit the activity of digestive serine peptidases of the whiteleg shrimp Litopenaeus vannamei. In vitro, SBTI inhibited the total proteolytic activity and chymotrypsin activity by 65%. Trypsin activity was reduced by SBTI from 40% to 15% from 2 to 4 hr of incubation, which is the average time of residence of feed in the shrimp digestive system. During the bioassays, experimental groups were fed with increasing concentration of supplemental SBTI (1 g kg −1 and 2 g kg −1 ) and digestive gland and faeces of individual specimens were collected daily.At the end of the bioassay, peptidase activity of digestive gland and faeces was shown, revealing differential inhibition after feeding for 5 days. Several serine peptidases were observed in zymograms, showing a compensation effect on the digestive gland through the activation of peptidases from different catalytic type. These results provide evidence that the shrimp digestive gland can overcome the effect of SBTI by two adaptive mechanisms: synthesis of additional peptidases of the serine class and other unidentified peptidases.

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Mannan-oligosaccharides (MOS) are non-digestible carbohydrates, and their use in aquaculture as prebiotics is well documented. The objective of this work was to test whether MOS supplemented in the diet of A. tropicus larvae (2, 4, and 6 g kg−1) influence growth parameters, the activity of digestive enzymes, and the expression of genes related to the intestinal barrier. The highest total length was observed in larvae fed 6 g kg−1 MOS compared to control larvae. Trypsin activity increased with the addition of MOS to the diets, but leucine aminopeptidase activity only increased with 6 g kg−1 MOS. Lipase and α-amylase activities increased in larvae fed with 2 and 4 g kg−1 MOS. The expression of zo-2 was higher with the 6 g kg−1 MOS treatment. The cl-3 transcripts were lower with 2 g kg−1 MOS but higher with 6 g kg−1 MOS. All tested concentrations of MOS increased the expression of muc-2. In this study, incorporating mannan-oligosaccharides into the diet of A. tropicus larvae had a positive effect, and the concentration of 6 g kg−1 produced the best results. Therefore, including this prebiotic in the diets for the culture of A. tropicus larvae is suitable.

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Functionalization of polysaccharide-based packaging incorporating inorganic nanoparticles for food preservation is an active research area. This review summarizes the use of polysaccharide-based materials functionalized with inorganic nanoparticles (TiO2, ZnO, Ag, SiO2, Al2O3, Fe2O3, Zr, MgO, halloysite, and montmorillonite) to develop hybrid packaging for fruit, vegetables, meat (lamb, minced, pork, and poultry), mushrooms, cheese, eggs, and Ginkgo biloba seeds preservation. Their effects on quality parameters and shelf life are also discussed. In general, treated fruit, vegetables, mushrooms, and G. biloba seeds markedly increased their shelf life without significant changes in their sensory attributes, associated with a slowdown effect in the ripening process (respiration rate) due to the excellent gas exchange and barrier properties that effectively prevented dehydration, weight loss, enzymatic browning, microbial infections by spoilage and foodborne pathogenic bacteria, and mildew apparition in comparison with uncoated or polysaccharide-coated samples. Similarly, hybrid packaging showed protective effects to preserve meat products, cheese, and eggs by preventing microbial infections and lipid peroxidation, extending the food product’s shelf life without changes in their sensory attributes. According to the evidence, polysaccharide-hybrid packaging can preserve the quality parameters of different food products. However, further studies are needed to guarantee the safe implementation of these organic–inorganic packaging materials in the food industry.