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Extraction And Purification Of Polyphenol From Hull Of Water Chestnut And Its Application In Fresh Meat Preservation

Posted on:2024-02-21Degree:MasterType:Thesis
Country:ChinaCandidate:J ZhaoFull Text:PDF
GTID:2531306938990099Subject:Food processing and safety
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Trapa natans,also known as water caltrop,sand horns,have been widely planted as food in our country.Trapa natans pericarp is the outer skin of the Trapa natans fruit,which is usually discarded during the processing of the Trapa natans fruit.Due to the ineffective development and utilization of Trapa natans pericarp,it has resulted in resource waste and environmental pollution.Existing studies have shown that there are antioxidant,antibacterial,hypoglycemic and other active substances in Trapa natans pericarp,but there are few application studies on Trapa natans pericarp.If the active polyphenols in Trapa natans pericarp can be efficiently extracted and applied to the field of chilled meat preservation,the comprehensive utilization rate of Trapa natans pericarp will be greatly improved.In this paper,Trapa bispinosa Roxb.pericarps was used as raw material for extraction of dictyostelium polyphenol by ultrasonically assisted solvent,and the extraction ability of low eutectic solvent and ethanol were compared in terms of polyphenol content and ABTS radical scavenging ability,and response surface optimization was performed for the extraction conditions of the screened low eutectic solvent of choline chloride-lactic acid type.Then the obtained polyphenols were further purified by macroporous resin,and static and dynamic adsorption-desorption studies were performed on the screened AB-8 type macroporous resin to enhance the polyphenol concentration.The obtained polyphenols were applied in the preservation of cold pork,and the preservation ability of lozenge polyphenols was evaluated by physicochemical and microbiological indices.The detailed methods and results can be summarized as follows:(1)Optimization of extraction conditions for polyphenol of Trapa natans.①Screening for low eutectic solvents:six kinds of DES and 60%ethanol were used to extract polyphenols from Trapa natans,and the extraction rate of polyphenols and the scavenging rate of ABTS free radicals were used as evaluation indexes,which the best extraction reagent was selected as DES2(ChCl:Lac).Its extract had the highest total phenolic content(145.17±1.55 mg GAE/g)and the strongest free radical scavenging capacity,with a IC50 of 7.99±0.051 μg/ml.② Based on the results of the single-factor test of the screened DES,responding surface optimization was performed:analyzed the effects of material-liquid ratio,DES water content and temperature on the total phenol extraction and ABTS radical scavenging rate.The results showed that the optimal extraction process of polyphenols were as follows:material-liquid ratio 1:25 g/mL,temperature 57℃,water content 27%.Under this extraction condition,the extraction amount of polyphenols was(150.83 ± 1.262)mg GAE/g,and the ABTS radical scavenging rate of the extract was(68.17±0.633)%.(2)The isolation and purification of polyphenols from Trapa natans.With Trapa natans polyphenol extract as raw material,we compared the adsorption and desorption rates of seven types of macroporous resins and selected AB-8 as more suitable for adsorption of Trapa natans polyphenols.The purification process of water caltrop polyphenols was explored by examining several factors in static adsorption-desorption and dynamic adsorption-desorption.Meanwhile,the kinetics and thermodynamics of AB-8 adsorption of rhodopsin polyphenols were also explored,and it was shown that the quasi-secondary kinetic model in kinetics was more appropriate for description of the adsorption process of polyphenols by AB-8 resin,and the intraparticle diffusion model revealed that the adsorption process was influenced by both the intraparticle diffusion process and diffusion through the liquid film.Thermodynamically,the process of adsorption was more consistent to the Freundlich thermodynamic model,which suggested that the adsorption process was exothermic and more favorable to the adsorption of water caltrop polyphenols by the macroporous resin when the experimental temperature was 25℃.The final purification parameters were as follows:the extract was diluted 4 times,the desorption solvent was 70%ethanol solution,the loading volume and elution volume were 3BV and 4BV,and both the loading and elution flow rates were 2 mL/min.Under the process parameters,the purification of polyphenols from Trapa natans could reach 143.79%and the recovery was 61.76%.The results of the experiments proved that this method is practical and could be used as the purification process conditions for polyphenols in Trapa natans.(3)Application of polyphenols of Trapa natans to chilled meat preservation study.The freshness preservation effect of chilled meat was investigated by four groups:blank group,Trapa natans polyphenols group,chitosan group and Trapa natans polyphenolschitosan compound group.The results showed that the compound group had the best fresh-keeping effect,followed by the chitosan group.At 12 d,the pH of the compound group reached 6.64,the drip loss rate was 8.24%,the total volatile basic nitrogen(TVBN)was 21.45 mg/100g,the thio barbituric acid reactive substance(TBARS)was 1.21 mg/kg,and the total bacterial count was 6.03 log CFU/g,which means that the meat samples had started to decay at this time.In contrast,the indexes of the blank group pointed out that the meat samples had spoiled by the 8th day.Accordingly,the Trapa natans polyphenols-chitosan compound group can extend the shelf life of cold meat by about 4 days.The results of this study will lay a certain theoretical foundation for the rational development and comprehensive utilization of Trapa natans resources in the future.
Keywords/Search Tags:Trapa natans pericarp, Polyphenols, Deep eutectic solvent(DES), Macroporous resin, Chilled meat preservation
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