Hazardous particulates and volatiles produced by incense burning accumulate in the indoor atmosphere, where they pose a health risk, entering the human body via the respiratory system. Yet, few studies have focused on the effects of the total particulate matter from incense burning on human health. Here, we evaluate the health risks associated with the total particulate matter generated from burning incense indoors for the first time. The total particulate matter and major chemical components of two types of incense smoke were characterized using an electrical low pressure impactor and gas chromatography coupled with mass spectrometry. Their genotoxicity and cytotoxicity were compared with mainstream tobacco smoke using in vitro assays. Our results show that both the particulate number and mass of incense smoke were dominated by ultrafine to fine particles. In addition, many aromatic, irritant, and toxic compounds were identified in the particulate fraction. In vitro assessments showed that the genotoxicity of the particulate matter from one particular incense sample was higher than the reference cigarette sample with the same dose. All particulate matter fractions from the incense investigated were found to possess greater cytotoxicity on Chinese hamster ovary cells than smoke from the reference cigarette. Collective assessment of these data will affect the evaluation of incense products and facilitate measures to reduce exposure to their smoke. Clearly, there needs to be greater awareness and management of the health risks associated with burning incense in indoor environments.

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Enzymatic activity is important characteristic of enzymes for industrial application, which can be improved by protein engineering. PLA1 is a biocatalyst applied in phospholipid modification for its phospholipase activity and had obtained board attention for its application in oil degumming. Bioinformatics analysis suggested that three charged residues, R81, R84, and E87 located in the lid of the protein, may affect the conformational change of lid thus influence the activity of the enzyme. In the current study, mutagenesis of these residues was conducted with protein engineering. Five mutants such as R81A, R84A, R84M, R84K, and E87Q with higher phospholipase activity were screened out. Biochemical properties analysis showed that all of them had identical optimal pH value with wild‐type, while the optimal temperature was decreased to be 50°C and the kcat/KM was improved. Degumming soybean oil, three of five mutants, R81A, R84M, and E87Q, decreased phosphorous content lower than 8.3 mg/kg within 3 h, which was highly improved compared with wild‐type. R84M decrease phosphorus content less than 5 mg/kg within 5 h. These findings not only permit optimization of enzyme performance in degumming but also shed light on the application of bioinformatics techniques and protein engineering techniques on industry application. Practical applications: The results support that design proteins according to bioinformatics and protein engineering is desirable and the phospholipase with higher activity is more suitable for oil degumming. The phospholipase activity of PLA1 can be improved by protein engineering based on bioinformatics analysis. With its properties of hydrolyzing sn‐1 position ester bond of phospholipids, nonhydratable phospholipids were converted into their hydratable forms, PLA1 can be applied in oil degumming. PLA1 with higher phospholipase activity is more likely to suitable for oil degumming since it could decrease the phosphorous content of oil lower than 10 mg/kg within shorter reaction, which showed great potencial for degumming application.