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The effect of storage temperature and ozone treatment on the post-harvest quality of cucumber and tomato was investigated. Cucumber and tomato were stored together with or without gaseous ozone treatment at 20 °C and 14 °C for 16 days. Firmness, color, weight loss, DA index and decay percentage of samples were evaluated during storage period. The results showed that the combination of ozone treatment and cold storage could maintain the quality of these horticultural products and decreased the decay incidence. Additionally, this combination also reduced the weight loss of samples during storage. Furthermore, ozone treatment maintained the green skin color of cucumber. No sign of chilling injury occurred during storage at 14 °C. Commodities stored with approximately 0.1 ppm gaseous ozone at 14 °C retained the firmness compared to other treatments until the end of the experiment. This study suggests a promising use of gaseous ozone treatment in storage chamber where ethylene-producing and ethylene-sensitive vegetables are stored together.

The aim of this study was to evaluate the effect of edible coating on hydroponic strawberry during storage. Strawberries were coated with either 1% or 1.5% chitosan (CS) or with solution containing 1.5% chitosan and 0.5% calcium gluconate (CaGlu). After treatment, samples were stored at 10 °C, RH 90% for 10 days. The weight loss, soluble solid content, firmness, surface color, pH, and percentage of decay were evaluated each day during the experiment. It was observed that coating extended the postharvest life of hydroponic strawberry compared to control. Fungal growth occurred on control group at the 5th day and fruit treated with 1% CS at the 8th day of the storage period, whereas no visible sign was detected for other treatments. Soluble solid content and pH showed only minor change for all samples. Weight loss of coated fruit was below 6% after 10 days of storage, whereas the weight loss of control samples was around 10% at the end of measurement. Moreover, coating could maintain the firmness of strawberry compared to the control. The combination of chitosan and calcium gluconate showed the potential for prolonging the storage period of hydroponic strawberry till 10 days without decay, whereas the control sample had more than 60% of rotted fruit.

Four strains of Lactobacillus and Bifidobacterium including L. plantarum 01, L. fermentum D13, L. rhamnosus B01725, and B. bifidum B7.5 exhibiting naringinase production were applied in grapefruit juice fermentation. All investigated strains grew well in grapefruit juice without nutrition supplementation. In all cases, cell counts were 108–109 CFU ml−1 after 24 hours of fermentation. The highest lactic acid and acetic acid productions were observed in the case of strain L. plantarum 01. The L. plantarum 01 and L. fermentum D13 strains prefer glucose over fructose and sucrose, whereas fructose was the most favoured sugar for L. rhamnosus B01725 and B. bifidum B7.5. At the end of the fermentation process, antioxidant activity and total polyphenol content of grapefruit juice decreased in all cases, but the changes were not significant. Significant decrease of naringin was observed in the case of L. plantarum 01, 28% naringin in grapefruit juice was removed after fermentation. This result is promising for development of technology for production of probiotic grapefruit juice.

β-Galactosidase was covalently immobilized on the chitosan-coated magnetic nanoparticles activated with glutaraldehyde. The effect of three factors including protein content, pH and time on the yield of immobilization was investigated, and the optimum values were 0.45 mg/ml, 4.9 and 4.9 h, respectively. The maximum yield of immobilization reached 98.8% in term of enzyme activity. The stability of β-galactosidase significantly was improved after immobilization from 2.5 days to over 6 days of half-life at 60 °C and was active in wider ranges of temperature (45–60 °C), and pH (4.0–5.5) compared to soluble form. The activity of immobilized enzyme remained 85% of origin after eight recycles (at 60 °C, pH 4.5 for 4 h). Different initial lactulose concentrations (0.58–2.34 M) were applied for synthesis of galactooligosaccharides. The maximum yield of galactooligosaccharides was 17% mol/mol at the initial lactulose concentration of 2.34 M at 36 h of reaction. It showed that both hydrolytic and trans-galactosylation activities of β-galactosidase remained well after immobilization. The kinetic model of immobilized enzyme was determined. These results revealed that immobilized enzyme on chitosan-coated magnetic nanoparticles has application potentials in the production of prebiotic lactulose-based galactooligosaccharides.

The electrical conducting bacterial cellulose/polyaniline (BC/PANI) based composites were synthesized over in situ polymerization of aniline onto BC with ammonium-persulphate (APS) and chloride hexahydrate of iron (III) as oxidant (FeCl3·6H2O). The conductivity of synthesized BC was improved in the presence of a titanium-dioxide (TiO2) coating. The conductivity of BC/PANI/TiO2/APS was 3.7 S/m compare 2.9 S/m and 2.67 S/m with BC/PANI/TiO2/FeCl3·6H2O and BC/PANI/APS, respectively. Moreover, when using the BC/PANI/TiO2/APS as anode with the immobilization of Shewanella xiamenensis, an improved efficiency of microbial fuel cell was observed. The power-density maximized 38.89 W/m3 with BC/PANI/TiO2/APS anode compared with 2.57 W/m3 in the case of bare BC anode. These results will serve as a good base for the development of compact microbial fuel cell with high power density.

Oligosaccharides especially prebiotics take high attention in the development of foods because of their physiological properties in human health. They are generally synthetized enzymatically via transferases or hydrolases from mold or bacteria. The fact is that such oligosaccharides synthetized by probiotic bacteria, should be utilized by these microorganisms. This study focused on the production of oligosaccharides with prebiotic potential by crude enzyme preparation from bifidobacteria. Both monosubstrates and bisubstrates systems together with TLC and HPLC techniques, were applied. The crude enzyme preparation has different hydrolase activities such as α-glucosidase (2U/mL), β-glucosidase (0.3 U/mL), α-galactosidase (1.2 U/mL), β-galactosidase (0.4 U/mL), β-fructosidase (11.5 U/mL). Additionally, it also has transglycosylation activities on lactose, lactulose, maltose and sucrose substrates. Two or three types of oligosaccharides were detected. The glycosyltransferase activity peaked at 45 °C, pH 6.6 and 30 g/100 mL substrate concentration. Significant high amount of oligosaccharides were formed in the case of lactose:sucrose combination than others. Both glucooligosaccharides and galactooligosaccharides are detected in the reaction mixtures of bisubstrate. When the lactose is present, the galactosyltransferation is predominated. One-one new types of oligosaccharides were detected in the reaction mixture of bioconversion. Among newly synthetized oligosaccharides, the fraction namely OS4 was utilized by probiotic bifidobacteria only. In conclusion, new types of galacto- and glucooligosaccharides with high prebiotic potentials were synthetized by the crude enzyme from probiotic Bifidobacterium strains.

The commercial enzymatic preparation, Pectinex Ultra SP-L, was successfully immobilized on activated chitosan particles for production of lactulose-based galacto-oligosaccharide (LuOS). The main degrees of polymerization (DP) of LuOS produced in this bioreactor were DP3 and DP4. The immobilization yield in term of expressed activity and recovery activity were 71% and 36.05%, respectively. The optimum temperature (60° C) was not affected by immobilization process, while the optimum pH was shifted from pH 5.5 to pH 4.5. In addition, a thermal stability of the immobilized enzyme was better than that of free enzyme. The half-life time of hydrolytic activity increased from 2.5 days (free enzyme) to 14 days (immobilized enzyme). Hydrolytic KM values were 651.3 mM and 187.9 mM lactulose for free enzyme and immobilized enzyme, respectively. Furthermore, the immobilized enzyme showed high reusability. The yield of LuOS formation was more than 60% after 33 cycles of reuses. In the case of trans-galactosylation, a model with 8 reaction rates was build using five-step reaction pathways with different initial lactulose concentrations. This catalytic model was validated well for a long-term period (27 days). These results strongly support to develop a continuous bioconversion to synthesize functional food ingredients, prebiotic LuOS.

The deinking ability of chitosan-based particles in the pretreatment of recycling paper was studied. All these polymers were able to adsorb carbon black as ink pigment. Amount of adsorbents, contact time, solution pH and temperature were optimized to estimate maximum sorption capacity of polymers. The optimum condition of carbon black adsorption was achieved using chitosan-coated Ca-alginate beads at 30 min, 35 °C, pH 6.5 and 220 rpm of agitation speed. The adsorption capacity was more than 80%. Packed-bed reactor filled with chitosan-coated alginate beads was conducted and operated under the optimal conditions. More than 95% of ink was adsorbed onto carriers after 20 h. Saccharification with industrial enzyme preparation of deinked paper pulp was carried out and sugars released were converted into ethanol. The results of alcoholic fermentation confirmed the success of the deinking process. Our results are very promising in the development of pretreatment technology to enhance the efficiency of the utilization of recycling paper.