Study On Antimicrobial Activity Of Camellia Meal

Oil-tea meal is the residue of camellia seed after oil extraction. As a major residue in oil-tea camellia processing, it contains a variety of biologically active substances, such as protein, sugar, crude fiber, saponin and alkaloids, etc.. Therefore, it has the potential to become food ingredients and animal feed. China’s annual output of camellia seed reaches over 1 billion kilograms, producing over 600 million kilograms oil-tea meal. However, the residue, oil-tea meal, has not been used efficiently and rationally, only a small part used as fuel or extracted for tea saponin. Currently, the research on the biological activity of oil-tea meal is little, let alone the research on the antibacterial activity from the perspective of food safety preservation.In the research, the author uses the Camellia seed processing byproduct, oil-tea meal, as test material, common food bacteria as tested bacteria and the diameter of inhibition zone as index. The thesis has systematically studied the technological conditions of antibacterial substances extraction of oil-tea meal, its antibacterial properties and its application in terms of fruit and vegetable preservation. The research will provides theoretical and technical basis for further utilization of oil-tea meal. The main findings are as follows:(1) The preliminary findings of crude extract antibacterial activity show that ethanol has the strongest antibacterial effect on the tested strains. The antibacterial effect on gram-negative bacterial is stronger than on gram-positive bacteria. It possesses broad spectrum antibacterial effect. In respect of antibacterial effect, the order from strong to weak is Coli, Salmonella, Staphylococcus aureus, Bacillus subtilis, Beer yeast, and Aspergillus flavus.(2) Study on the extraction technology of antibacterial substances. This test adopts ultrasound assisted extraction method. Based on the results of single factor experiments, the test conducts the extraction process parameters optimization through orthogonal combination design. The result shows that extraction effect is the best in such extraction condition:twice ultrasonic processing (each for 20 minutes),1:25 solid-liquid ratio and 60% ethanol solution.The bacteriostatic diameter is 16.1 mm.(3) Study on antibacterial properties of oil-tea crude extract. This test adopts the Oxford Cup antibacterial method to measure the inhibitory effect of crude extracts on six kinds of common microorganism. The bacteriostasis experiment results show that the antimicrobial spectrum of optimized crude extract is similar to ethanol extracts, but the inhibition effect is better. E. coli is the most sensitive to crude extract of Camellia, both the MIC and MBC value reaching 3.125 mg/ml. The order of the inhibiting ability of crude extract on six microorganism is:S. aureus> Bacillus subtilis> Salmonella> E. coli> Aflatoxin> Beer yeast. With good thermal stability, the antibacterial activity of crude extract is relatively stable under light and ultraviolet radiation. It has in the highest biological activity in the pH 7.(4) Preliminary study of crude extract on fruit and vegetable coating preservation aspects. The test studies separately the preservation effect of single oil-tea meal crude extract fluid and oil-tea meal chitosan coating liquid on strawberry by measuring the rate of decay, weight loss, vitamin C content, soluble solids and titratable acid content of strawberry after coating. It also studies the preservation effect difference of different coating liquid. The conclusions are that suitable concentration of single oil-tea meal crude extract fluid has a positive effect on strawberry preservation. It can extend the storage period of strawberries to a certain extent, which is conducive to maintaining the commodity value of strawberries. Compound preservative solutions of oil-tea meal crude extract and chitosan has better preservation effect on strawberries than single oil-tea meal crude extract fluid. It is more conducive to reducing decay rate and water loss, delaying the decrease of strawberries vitamin C, soluble solids and titratable acid content of strawberries.(4) The preservation effect of crude Camellia oleifera Abel meal crude extracts and Camellia oleifera Abel meal-chitosan composite film on strawberry preservation was evaluated separately by measuring the rotting rate, weight loss, vitamin C level, soluble solids and titratable acid content in strawberry. The conclusions revel that the former present a positive effect on strawberry preservation. It can prolonged the storage period of strawberries to a certain extent, which is conducive to maintaining the commodity value of strawberries. Compared with crude Camellia oleifera Abel meal extracts, Camellia oleifera Abel meal-chitosan composite film possess better preservation effect on strawberries. It is more conducive to reducing decay rate and water loss, delaying the decrease of strawberries vitamin C, soluble solids and titratable acid content of strawberries.