Study on Antibacterial Effect of Aloe Extract: Material and Method
Wang Jinxu, Wang Xin, Ye Jingbo, Zhu Yiping, Guan Zhanwen, He Yanming (National Biology Experimental Teaching Center, Zhongshan Institute of Life Science, Guangzhou 510275, China)
[Objective] To provide a theoretical basis for the development and utilization of aloe in the food industry.
[Method] With sodium benzoate as control, the filter paper method was used to study the resistance of the extracts from the roots, middle leaves and tip of Aloe vera in the United States to various common strains and their thermal stability.
[Result] Different parts of aloe extract showed certain antibacterial activity against Staphylococcus aureus, Escherichia coli and aflatoxin, which was comparable to sodium benzoate. The antibacterial effect on Saccharomyces cerevisiae was not obvious. In terms of strains, the aloe extract has good thermal stability against bacteriostasis, and retains good antibacterial ability even after heat treatment.
[Capability] Aloe extract has strong antibacterial activity against various bacteria and molds, but has no inhibitory effect on Saccharomyces cerevisiae.
Aloe, Liliaceae Aloe is a perennial evergreen succulent herb native to Africa, widely distributed in tropical and subtropical regions. Aloe vera has many functions such as medical treatment, beauty, health care, food consumption and viewing. Studies have shown that aloe vera has antibacterial and bactericidal action, and terpenoids are the main antibacterial substances in aloe. The author extracted aloe vera juice from the roots, middle leaves and tips of Aloe vera, and used sodium benzoate (pH=3 and PH=6) as control to study the antibacterial effect and thermal stability of aloe extract. Research provides a basis for the development and utilization of aloe in the food industry.
1. Materials and methods
1.1 Materials: Aloe vera from the United States: Staphylococcus aureus, Escherichia coli, Aspergillus niger, Saccharomyces cerevisiae; medium with beef extract peptone medium (bacterial medium), LB medium (yeast medium), Potato medium (mold medium); all provided by the Microbiology Laboratory of the School of Life Sciences, Sun Yat-sen University.
1.2.1 Preparation of aloe vera juice. After washing the fresh American Aloe vera, it is disinfected with 0.11% KMhO4 and then rinsed with running water. The roots, middle leaves and tips of the leaves are taken separately, and the light green method is squeezed out with the fruit and vegetable juicer. Filter with 4 layers of gauze.
1.2.2 Preparation of bacterial suspension. The above four test bacteria (S. aureus, Escherichia coli, Aspergillus niger, Saccharomyces cerevisiae) were activated with a suitable bevel and formulated into a bacterial solution of 106-107 cfu/ml with sterile weight saline.
1.2.3 Prepare aloe extract instead of water medium. The aloe vera was diluted 10 times to prepare an aloe solution, and the solution was prepared by replacing the distilled water with the solution.
1.2.4 Determination of bacteriostasis by filter paper method. The sterilized filter paper with a diameter of 7 mm was placed in aloe juice for 24 hours, and 0.5 ml of each suspension of the test bacteria was prepared, and the corresponding solid medium was used to prepare a bacteria-containing plate, and the filter paper containing the aloe method was taken with sterile forceps. Attached to the bacteria-containing plate, 3 pieces per dish, repeated 3 times per bacteria. The bacteria were cultured at (37±1)0C for 18-24 hours, and the fungi were observed after 280C culture for 48 hours. In addition, sodium benzoate (pH = 3 and PH = 6) was used as a control. The size of the inhibition zone of the filter paper was measured to compare the bacteriostatic effect.
1.2.5 Determination of aloe juice resistance. Various test bacteria were inoculated separately in a medium in which various aloe extracts were used instead of water, and the corresponding medium prepared in distilled water was inoculated as a control. Warm culture and observe the growth.
(The research on the antibacterial effect of aloe extract is not yet to be continued)