| Zanthoxylum armatum DC. Prodr. belonging to Subgenus Zanthoxylum in the plant family Rutaceae is a very popular species in China. This species has a distinctive flavor that can be generally described as astringent, burning, numbing, fresh, aromatic, spicy and green. To make a better use of Zanthoxylum resources and establish the quality evaluation system of Zanthoxylum oil, in this paper, fresh Zanthoxylum armatum DC. Prodr. were collected from Hongya county, Sichuan province. Two methods were adopted, including cold pressing and organic solvent extraction. The sensory quality and physicochemical indexes of oil samples were analyzed. The volatile components and relative contents were determined by HS-SPME/GC/MS. The fatty acid compounds were detected by GC/MS. The antioxidant activities of oil samples were evaluated through building antioxidant experiment model in vitro. The antibacterial activities and antibacterial stabilities were tested at the same time. The results were as followed:1. Acid values of cold pressed oil and organic solvent extracted oil were 1.87mgKOH/g、3.16mgKOH/g, respectively, peroxide values were 1.69meq/kg、 5.23meq/kg, respectively, iodine values were 121gI2/100g、120gI2/100g, respectively, moisture and volatile matter content were 1.82%、2.19%, respectively, saponification values were 184.46mgKOH/g、192.09mgKOH/g, respectively. Acid value and peroxide value of cold pressed oil both met the national standard, and because of the high acid value of organic solvent extracted oil, it required further refining to meet the national standard.2. The volatile components and relative contents of oil samples were detected and analyzed by HS-SPME/GC/MS coupled with retention index. A total of 22 volatile compounds in the cold pressed oil were identified, and D-limonene (33.47%),.beta.-phellandrene (27.70%), linalool (24.99%),.beta.-myrcene (5.06%), a-pinene(2.08%) were the main components.42 components in the organic solvent extracted oil were identified, and linalool (38.70%), D-limonene (28.08%),.beta.-phellandrene (17.01%),.beta.-myrcene (4.52%), tricyclo[2.2.1.0(2,6)]heptane,1,7,7-trimethyl-(1.78%), germaerene D (1.19%) were the main components.3. Oil samples had different fatty acid compositions and relative contents. A total of 16 fatty acid compounds in both oil samples were identified, among which,8 fatty acid compounds were detected simultaneously. They were mainly composed of unsaturated fatty acids, which accounted for more than 84%(relative content) of the total amount. Oleic acid was revealed the highest relative content in cold pressed oil, with the relative content of 57.91%, followed by 9,12-Octadecadienoic acid (Z,Z)-, 9,12,15-Octadecatrienoic acid and Hexadecanoic acid. While (Z)-hexadec-9-enoate was revealed the highest relative content in organic solvent extracted oil, and the relative content was up to 45.55%, followed by 9,12,15-Octadecatrienoic acid, Hexadecanoic acid, (Z)-9-Octadecenoic acid and 9,12-Octadecadienoic acid (Z,Z)-4. Cold pressed oil and organic solvent extracted oil had certain effect on restraining the growth of Staphylococcus aureus, Escherichia coli, Bacillus subtilis, Rhodotorula mucilaginosa, Pichia galeiformis, Candida sake, Aspergillus niger and Aspergillus Jlavus. While the antibacterial effects of organic solvent extracted oil were stronger than cold pressed oil. Organic solvent extracted oil exhibited strong activity against Bacillus subtilis with MIC value of 0.7813mg/mL, while weaker effect against other bacteria and yeasts, and IC50 values against Aspergillus niger and Aspergillus flavus were 0.0829 and 0.5470mg/mL, respectively. Cold pressed oil had stronger activity against Bacillus subtilis and Rhodotorula mucilaginosa compared with other bacteria and yeasts. The MIC value of cold pressed oil against Bacillus subtilis was investigated to be 6.2500mg/mL, similar to that of Rhodotorula mucilaginosa, and IC50 values against Aspergillus niger and Aspergillus flavus were 1.0348 and 1.4437mg/mL, respectively. The antimicrobial activities of cold pressed oil and organic solvent extracted oil were stable under the conditions of heat and ultraviolet ray, while unstable under different pH values, and strong in base and stable in acid.5. To evaluate the antioxidant potentials of cold pressed oil and organic solvent extracted oil, the abilities of scavenging DPPH radicals, superoxide anion radicals, and hydroxyl free radicals, and reducing power were assayed, with vitamin C and BHT as the positive control. Results showed that oil samples had good antioxidant activity:the higher the concentration of oil, the stronger the antioxidant effect. The scavenging ability against hydroxyl free radicals and DPPH radicals of cold pressed oil was weaker than that of organic solvent extracted oil under the same concentration. IC50 values of cold pressed oil against hydroxyl free radicals, DPPH radicals, superoxide anion radicals were determined to be 4.0675mg/mL,10.3052mg/mL,0.5415mg/mL, respectively. While organic solvent extracted oil were determined to be 1.9606mg/mL,2.9465mg/mL,1.6053mg/mL, respectively. Organic solvent extracted oil showed a better hydroxyl free radical scavenging ability, with scavenging rate of 89.79% under 9mg/mL, which was equal with that of vitamin C under 1mg/mL. Organic solvent extracted oil showed a better DPPH radical scavenging ability, with scavenging rate of 86.87% under llmg/mL, which was better than BHT under lmg/mL. |
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