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Daily consumption of chicken eggs produces a vast number of eggshells byproducts which are a rich source of calcium salt. This paper investigated the potential of eggshell powder from eggshell byproducts as an alternative coagulant in the tofu preparation process. The eggshell powder was successfully obtained and analyzed with calcium salt (CaCO3) of 74.7% followed by calcium of 17.48%. Liquid nigari as a coagulant was evaluated and showed better tofu yield (143.24 ± 1.68 g/ 100 g) at 2% of addition to the soybean milk. The tofu prepared with 2% liquid nigari and 0.25% eggshell powder showed a higher yield (154.79 ± 3.56 g/100 g) as well as the improvement of texture profile of resulting tofu with hardness of 19.1 ± 2.02 N, cohesiveness of 0.26, and springiness of 13.5 ± 0.06 mm. The studied tofu was obviously observed to have better textural characteristics than two samples of tofu prepared by traditional methods. The result suggested that eggshell powder could be a promising alternative coagulant for tofu preparation.

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.

Tobacco smoking is one of the most dangerous risk behaviors, leading to many adverse human health consequences. The aims of this study is to estimate the prevalence of tobacco smoking and related factor among adolescents aged 13–17 years in Vietnam. The data were from two rounds of the Vietnam Global School-based Student Health Survey (GSHS) that is the nationally representative survey conducted in 2013 and 2019. The logistic regressions were carried out to identify factors associated with tobacco smoking among study participants. We found the prevalence of current smoking (water pipe and cigarettes) reduced significantly from 5.4% (95% CI: 4.0–7.2) in 2013 to 2.8% (95% CI: 2.2–3.6) in 2019. In 2019, 2.6% of students used electronic cigarette products in the last 30 days. Factors associated with higher odds of current smoking status included study year, gender, parental monitoring, loneliness, suicide attempt, sexual intercourse, truancy, alcohol drinking. Similar patterns were found in e-cigarette use. Smoking among adolescents in Vietnam reduced between 2013 and 2019. Further follow-up studies are needed to confirm the causal factors of the reduction and e-cigarettes use.

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.