Spent coffee ground (SCG) is a residue released during coffee brewing. Disposal of SCG is able to lead to a loss of bioactive constituents and have a negative impact upon the environment. This study aimed to explore fatty acids, bioactive phenolics, antioxidant and anti-aging potentials of SCG samples obtained from coffee shops in Ho Chi Minh city, Vietnam. The oil content of the SCG samples ranged from 6.3 to 10.5%, and linoleic (43%), palmitic (33.4%) and oleic (11%) acids were identified as major constituents of the oil. Chlorogenic acid was the most abundant phenolic acid examined (832.9-7657.7 μg/g of dry weight), followed by ferulic acid (40.5-1041.7 μg/ g). Through anti-collagenase and anti-elastase assays, SCG showed a promising anti-aging activity, with IC 50 values comparable with those of epigallocatechin gallate. The correlation analysis revealed gallic acid positively correlated with the free radical scavenging potential evaluated by DPPH (2,2-diphenyl-1-picrylhydrazyl) assay and the inhibitory effect on elastase. The results demonstrated that utilization of SCG prepared from Vietnamese coffee could open new avenues for food and cosmeceutical industry.

The aim of the present study was to determine the phenolics, carotenoids, B-vitamins, and antioxidant activity of nuts and seeds grown in Vietnam. The concentrations of carotenoids and B-vitamins may vary among the nuts and seeds. Watermelon seed contained the highest level of lutein while pumpkin seed was the β-carotene richest sample. Sachi inchi and sunflower seed comprised considerable levels of vitamin B1, B6, and B9. The phenolic analysis revealed that cashew contained the highest total amount of flavonoids (466.04 μg/g), with catechin, epicatechin, and procyanidin B2 predominating over the other flavonoids. Likewise, chlorogenic and neochlorogenic acids made up the highest total amount of phenolic acids in sunflower seed (1870.41 μg/g). Walnut appeared to possess the highest antioxidant activity evaluated by DPPH, ABTS, FRAP, and reducing power assays. The correlation analysis indicated strong positive correlations between total phenolic content with DPPH and FRAP values. Principal component analysis graphically showed the distant positioning of cashew and sunflower seed, highlighting their significantly higher levels of phenolics. The findings of the study would be useful to improve nutrient database contents for flavonoids and phenolic acids as well as to promote the consumption of nut and seed products in Vietnam.

Limited information about exposure to volatile organic compounds (VOCs) in primary schools in Vietnam is available. In this study, we aimed to characterize indoor VOCs in four primary schools situated in Ho Chi Minh City, a metropolis in the south of Vietnam and assess health risks linked to the students’ exposure to VOCs. Indoor and outdoor air samples were collected in the schools and analyzed for volatile composition using gas chromatography coupled with mass spectrometry. Different classes of VOCs, including aromatic hydrocarbons, alkanes, aldehydes, esters, cyclic terpenes, and chlorinated hydrocarbons, were identified and quantified in classrooms of the schools. The results showed that the concentrations of the VOCs differed significantly among the schools and between ground-floor and first floor classrooms. In addition, VOC profiles differed considerably between air-conditioned and non-air-conditioned classrooms. Limonene, a compound associated with fragrance products, was the most abundant VOC, with the median (range) concentration of 26.12 (10.29, 50.08) μg/m3. The concentrations of the compounds examined in the study were in general found to be higher indoors compared with outdoors, signifying indoor emission sources. Potential harmful effects are expected as a result of exposure to benzene, ethylbenzene, naphthalene, 1,4-dichlorobenzene and tetrachloroethylene in the investigated schools. Further research is needed to fully assess the health risks to students, teachers, and staff in these educational environments.

Rambutan (Nephelium lappaceum) production is growing worldwide so the treatment and utilization of Rambutan by-products has become a concern of manufacturers. The objective of this study was to evaluate the potential application of rhizobacteria to decompose Rambutan peel for organic fertilizer production. After the rhizospheric soil samples were selectively proliferated and preadded on agar medium containing only Rambutan peel, the rhizobacterial colony isolates were screened based on their ability to grow on this agar medium and then to degrade cellulose in Rambutan peel. The LD7.3 isolate from the Rambutan rhizosphere showed the highest efficiency in degrading Rambutan peel with 5.6% degraded cellulose content and was identified by the MALDI-TOF technique as belonging to Klebsiella. Klebsiella sp. LD7.3 grew well and maintained the same degrading activity after three times of subculturing in liquid medium. Notably, the supplementation of grinded Rambutan fruit peel to the liquid medium had a positive effect on the growth and the degrading activity of Klebsiella sp. LD7.3. This was the primary report on the application of rhizobacteria to degrade Rambutan peel and the results showed that this was a potential approach to reuse this waste source.

Plant-based media have recently been of interest as potential natural media for microbial culture. This study was conducted to apply inexpensive and available fruits to culture Bacillus antagonizing three fungal phytopathogens including Phytophthora capsici GTC 2.6.1, Rhizoctonia solani GTC 2.7.1, and Sclerotium rolfsii GTC 2.9.1. The results showed that the juice media of dragon fruit, Cavendish banana, watermelon, pineapple, and MT1 seedless guava could all be used to culture two screened antagonistic Bacillus strains including B08 and B18. Surveys on the media from watermelon juice indicated that juice concentration (based on mass of fruit pulp), initial pH, concentration of traditional medium added to the juice medium had different effects on the growth of two strains of Bacillus sp. B08 and B18. These preliminary results demonstrated the potential application of the juice in biomass production of antagonistic Bacillus strains. This approach is certainly safe for the environment and has the potential to improve fruit consumption and reduce the cost of microbial fertilizer production, so it needs more research attention.