Objective To explore the antioxidant effects and fatty acid content of walnut oil derived from different substrates. Methods Gas chromatography-mass spectrometry (GC-MS) was used to analyze the fatty acid content in walnut oil and unqualified walnut oil at different pressing temperatures. Single variable control method was used to study the antioxidant effects of walnut oil with different air content. After adding a complex of natural antioxidants, fat soluble rosemary at 0.04 g/100 g and vitamin E at 0.1 g/100 g, 2 sets of experiments were conducted. The first set contained 100, 200, 300, 400 and 500 mL oil samples in 500 mL glass bottles, while the second set contained 100 mL oil samples in 100, 250 and 500 mL glass bottles. The samples were rapidly oxidized in a constant temperature drying oven at 63 ℃±1 ℃ and kept at that temperature for 70 days. The aroma, taste, peroxide value and acid value of the oil samples were measured every 10 days. Results The fatty acids in walnut oil were palmitic acid, linoleic acid, stearic acid and oleic acid. The content of fatty acids varies with storage time and pressing temperature, and the unqualified oil sample didn’t contain oleic acid. The walnut oil pressure pressing temperature of 130-140 ℃ had the best quality. The 2 sets of experiments had confirmed that walnut oil with lower air content could be stored for a longer period of time, up to a maximum of 100 days. Conclusion The less contact with air during storage or the decrease in the ratio of initial air volume to initial oil sample volume, the longer the shelf life. The conduct of this study provides a reference for the storage conditions of walnut oil.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |