Development of a colorimetric pH indicator based on bacterial cellulose nanofibers and red cabbage (Brassica oleraceae) extract.

This work aimed to develop and characterize a smart label for pH monitoring based on bacterial cellulose (BC) nanofibers doped with anthocyanins extracted from red cabbage (Brassica oleracea). The relationship between the concentration of anthocyanins (32 and 193mgL-1) and the morphological properties and color response efficiency of pH indicator labels was investigated. The FT-IR results reflected that some new interactions have occurred between BC membrane and anthocyanins. The XRD analyses showed a decrease in diffraction intensities of BC by addition of concentrated form of anthocyanins. SEM results indicated that concentrated anthocyanins caused to partial disintegration and deformation of the cellulose microfibrils with more cracks on the labels. But the intrinsic morphology and structure of the BC nanofibers were preserved by addition of diluted anthocyanins. A concentration dependent decrease was observed in the tensile strength of anthocyanin loaded labels but elongation percentage and moisture absorption of BC was increased by addition of anthocyanins. The color variation in different pH range (2-10) was measured with the CIELab methodology. The label containing diluted anthocyanins showed a more clear response to pH variation. Therefore, it has potential to be used as a visual indicator of the pH variations during storage of packaged food.

The effects of feeding with synbiotic (Pediococcus acidilactici and fructooligosaccharide) enriched adult Artemia on skin mucus immune responses, stress resistance, intestinal microbiota and performance of angelfish (Pterophyllum scalare).

The aim of this study was to evaluate the effects of feeding on synbiotic (Pediococcus acidilactici and fructooligosaccharide) enriched adult Artemia franciscana on skin mucus immune responses, stress resistance, intestinal microbiota and growth performance of angelfish (Pterophyllum scalare). Three hundred and sixty fish with initial weight 3.2 ± 0.13 g were randomly divided into twelve aquaria (50 L) assigned to four groups in triplicates. Fish were fed for 7 weeks with dietary treatments, including treatment 1: feeding adult Artemia without enrichment (control group), treatment 2: feeding adult Artemia enriched with lyophilised probiotic P. acidilactici (700 mg L(-1)), 3: feeding adult Artemia enriched with prebiotic fructooligosaccharide (FOS) (100 mg L(-1)), group 4: feeding adult Artemia enriched with synbiotic (P. acidilactici (700 mg L(-1)) + FOS (100 mg L(-1))). Skin mucus immune responses (lysozyme activity, total Immunoglobulin and protease), stress resistance against environmental stress (acute decrease of temperature and increase salinity), intestinal microbiota as well as growth indices were measured at the end of feeding trial. Artemia enriched with synbiotic significantly improved growth performance compared to other treatments (P < 0.05). The highest weight gain and specific growth rate (SGR) was observed in synbiotic fed fish (P < 0.05). Compared to the other treatments, the population of lactic acid bacteria was significantly higher in the intestinal microbiota of fish fed synbiotic supplemented diet (P < 0.05). In the environmental stress challenge test, the maximum resistance to abrupt decrease of temperature (17 °C) or elevation of salinity (12 g per liter) was observed in the synbiotic treatment. Also, the total immunoglobulin and lysozyme activity level of skin mucus was significantly elevated in fish fed Artemia enriched with synbiotic (P < 0.05). These results revealed that feeding angelfish with synbiotic enriched Artemia was more effective than singular enrichment with probiotics or prebiotics.

Effects of chitosan on hematological parameters and stress resistance in rainbow trout (Oncorhynchus mykiss).

The aim of our study was to evaluate the effects of chitosan as immune stimulator on some hematological parameters and stress resistance in rainbow trout. Nine hundred rainbow trout (with initial body weight of 25 ± 0.1 g) were obtained from a local farm and acclimated to the laboratory conditions for one week. After that fish were randomly divided into four groups in three replicates. Each group received chitosan in diet at four concentrations as 0 (Control), 0.25, 0.5 and 1 percent chitosan, respectively. The trial was conducted for 8 weeks then feeding with chitosan stopped for 3 weeks later and during this time all fish were feed by control diet. The sampling was conducted to assay the hematological parameters of all groups every two weeks. In this study we assayed the resistance of fish against some environmental stresses immediately after changing the diet to the control. The results showed that using 0.25 percent chitosan in trout diets had a significant effect (P < 0.05) on hematological indices and stress resistance of rainbow trout in comparison the control group. Serum glucose level was higher in all treatment than control without any significance difference (P < 0.05). Based on the obtained results it concluded that the adding chitosan at 0.25 percent into the diet could enhance the hematological parameters and resistance against some environmental stresses in rainbow trout.