An automatically progressed computer-controlled simulated digestion system to predict digestible and metabolizable energy of unconventional plant protein meals for growing pigs

The objective of this experimentwas to develop a new computer-controlled simulated digestion system to predict the digestible energy(DE)and metabolizable energy(ME)of unconventional plant protein meals for growing pigs.Nine meals tested included 1 source of rapeseed meal,4 sources of cottonseed meal,2 sources of sunflower meal,and 2 sources of peanut meal.Twenty growing pigs(Duroc[LandraceLarge White])with an initial body weight(BW)of 41.7±2.6 kg were allotted to a replicated 103 incomplete Latin square design to determine the DE and ME of 1 basal diet and 9 experimental diets formulated with 9 unconventional plant protein meals.The DE andMEvalues of unconventional plant protein meals were calculated by the difference method.The in vitro digestible energy(IVDE)of 1 basal diet,9 experimental diets,and 9 unconventional plant protein meals were determined with 5 replicates of each sample in a complete randomized arrangement.The IVDE/DE or IVDE/ME ranged from 0.96 to 0.98 or 1.00 to 1.01,and the correlation coefficient between IVDE and DE or MEwas 0.97 or 0.98 in 10 experimental diets.Accordingly,the IVDE/DE or IVDE/ME ranged from 0.86 to 1.05 or 0.96 to 1.20,and the correlation coefficient between IVDE and DE orME was 0.92 or 0.91 in 9 unconventional plant protein meals.The coefficient of variation(CV)of IVDE was less than that of DE and ME in the experimental diets(0.43%,0.80%,and 0.97%for CV of IVDE,DE and ME,respectively)and unconventional plant protein meals(0.92%,4.84%,and 6.33%for CV of IVDE,DE and ME,respectively).The regression equations to predict DE from IVDE in 10 experimental diets and 9 unconventional plant protein meals were DE=0.8851IVDE t539(R^(2)=0.9411,residual standard deviation[RSD]=23 kcal/kg DM,P<0.01)and DE=0.9880IVDE t 166(R^(2)=0.8428,RSD=182 kcal/kg DM,P<0.01),respectively.Therewas no statistical difference in the slopes(P=0.82)or intercepts(P=1.00)of these 2 equations.Thus,10 diets and 9 unconventional plant protein meals were pooled to establish the regression equation of DE on IVDE as:DE=0.9813IVDE t187(R^(2)=0.9120,RSD=118 kcal/kg DM,P<0.01).The regression equations to predictME from IVDE in 10 experimental diets and 9 unconventional plant protein meals were ME=0.9559IVDE t146(R^(2)=0.9697,RSD=18 kcal/kg DM,P<0.01)and ME=0.9388IVDEt3(R^(2)=0.8282,RSD=182 kcal/kg DM,P<0.01),respectively.Therewas no statistical difference in slopes(P=0.97)but significant difference between the intercepts(P=0.02)of these 2 equations.Our results indicate IVDE has similar response to the DE but different response to the ME in 10 experimental diets and 9 unconventional plant protein meals.Therefore,IVDE is moresuitable to predict DE than ME of diets and unconventional plant protein meals for growing pigs.

Simultaneous determination of typical toxic aldehydes formed during food frying and digestion using isotope dilution UHPLC-QqQ-MS/MS

An isotope dilution ultra-performance liquid chromatography-triple quadrupole mass spectrometry method was developed to simultaneously detect two typical kinds ofα,β-unsaturated aldehydes,namely 4-hydroxy-2-hexenal(4-HHE)and 4-hydroxy-2-nonenal(4-HNE),in foods.The proposed method exhibited a linear range of 10-1000 ng/mL with a limit of detection of 0.1-2.0 ng/g and a limit of quantification of 0.3-5.0 ng/g.The recovery rates of these typical toxic aldehydes(i.e.,4-HHE,4-HNE)and their d3-labeled analogues were 91.54%-105.12%with a low matrix effect.Furthermore,this proposed method was successfully applied to a real frying system and a simulated digestion system,wherein the contents of 4-HHE and 4-HNE were determined for both.Overall,the obtained results provide strong support for further research into the production of 4-HHE and 4-HNE resulting from foods during oil digestion and frying.

Impact of particle size of pulverized citrus peel tissue on changes in antioxidant properties of digested fluids during simulated in vitro digestion

To examine the effect of mechanical processing for plant-based materials on antioxidant properties during digestion,relationships between the size of pulverized plant tissue and changes in antioxidant activities during simulated in vitro digestion were investigated.The citrus peel tissue was pulverized and classified into four powder fractions followed their particle size distributions as 125−180m,180−355m,355−500m and 500−710m.These fractions were regarded as a plant tissue model with various degrees of cell damages.Powder samples were collected during the digestion and measured their particle sizes and colors.Besides,total phenolic content and antioxidant activities of digested fluid were also evaluated.The results showed that the powder color of smaller particles were significantly changed than the bigger ones.The bio-properties of digested fluid for the bigger particle sizes comparatively retained more than smaller ones at the simulated gastric stage.It also showed mostly stable during simulated gastric or small intestinal digestion stage.This suggested that the release of bioactive compounds from plant tissues during digestion could be related to their structural attributes such as degrees of cell damages which could be affected by processing methods and conditions.

Herba Epimedii′s biotransformation in vitro simulated gastrointestinal digestion and faecal fermentation systems

OBJECTIVE Epimedium is rich in a variety of beneficial active ingredients,and has been widely used in the ethnopharmacological practices,however,its biotransformation in gastrointestinal digestions remain unclear.This study aimed to investigate the dynamic changes of components and biological activity of Epimedium in the in vitro simulated digestion and subsequent human faecal fermentation.METHODS The models of in vitro simulated saliva,gastric and intestinal digestion,as well as colonic fermentation were constructed to simulate the digestion process of Epimedium.The dynamic changes of components of Epimedium during the simulated digestions in vitro and subsequent human faecal fermentation were investigated by UPLC-MS,HPLC-DAD combined with principal component analysis(PCA)and multi-ingredient quantitative analysis.RESULTS A variety of metabolites with high contents were produced after 0.5 h of intestinal digestion and colonic fermentation 0.5 h.Application of PCA to HPLC data showed the obvious separation of colonic fermentation 0.5 h stage samples from other colonic fermentation stages samples(24,48 and 72 h).Additionally,non-digestion and saliva digestion stage samples clustered together,and there was obvious separation between intestinal digestion samples and gastric digestion samples.The contents of epimedium C,icariin and baohuside I all increased significantly after intestinal digestion[58.70±7.08,47.15±5.68 and(12.78±0.55)mg·g^(-1)]compared with gastric digestion[29.00±5.65,17.40±4.55 and(2.77±0.19)mg·g^(-1)].There were significant differences between sample after 0.5 h of colonic fermentation[64.22±9.32,51.26±6.33 and(16.68±3.19)mg·g^(-1)]and other time points(24,48 and 72 h)in components and the contents of active ingredient,and the content of these components all decreased with the fermentation time.The ability of scavenging ABTS free radicals[IC50=(0.29±0.02)g·L^(-1)]increased significantly compared with gastric digestion[(1.57±0.02)g·L^(-1)],and after 0.5 h of colonic fermentation,the ability also increased significantly.CONCLUSION Gastrointestinal digestion had a significant impact on the contents of active components in Epimedium,and the metabolism of these components mainly occurred in the colon.The intestinal digestion and colonic fermentation significantly improved the anti-ABTS activity of epimedium.

Changes in Antioxidant Activity of Alcalase-Hydrolyzed Soybean Hydrolysate under Simulated Gastrointestinal Digestion and Transepithelial Transport

Peptides from Alcalase-hydrolyzed soybean protein hydrolysate(SPH)may hold the potential as natural antioxidants.In addition,the effect of human gastrointestinal(GI)tract on peptide bioavailability needs to be explored.In this study,the impact of simulated GI digestion and transepithelial transport on various antioxidant properties of SPH were investigated.SPH displayed DPPH radical scavenging(IC50=4.22 mg/m L),ABTS·+radical scavenging(IC50=2.93 mg/m L),reducing power and metal ion-chelating activities(IC50=0.67 mg/m L).Furthermore,SPH significantly(P<0.05)inhibited the generation of intracellular reactive oxygen species(ROS)in Caco-2 cells.After simulated GI digestion,the antioxidant properties of SPH were enhanced,except for a decrease in ABTS·+radical scavenging activity.After transepithelial transport,the permeates maintained partial antioxidant activity and the LC-MS/MS data further identified the absorbed soybean peptides.These results suggest that SPH contains the antioxidant peptides that are potentially bioavailable and can be regarded as a promising source of functional food ingredients.

Adsorption,in vitro digestion and human gut microbiota regulation characteristics of three Poria cocos polysaccharides

Poria cocos(PC)is a famous traditional Chinese medicine(TCM)and a widely used healthcare ingredient,which has antiobesity,enhancing immunity and improving sleep effects.Traditionally,only water-soluble poria polysaccharide(WSP)is extracted and applied for clinical application,while insoluble polysaccharide(alkali-soluble poria polysaccharide,ASP)is discarded as herb residue.However,the whole PC has also been historically utilized as functional herbal food.Considering the beneficial role of dietary fiber and the traditional use of PC,ASP may also contribute substantially to the therapy function of PC.Compared to WSP,little attention has been paid to ASP and ASP modified product carboxymethyl poria polysaccharide(CMP)which has been used as an antitumor adjuvant drug.In this study,the oil,cholesterol,metal ions and polyphenols adsorption ability,in vitro simulated digestive and the gut microbiota fermentation characteristics of WSP,ASP and CMP were studied to evaluate the functional values of three P.cocos polysaccharides(PCPs).The results showed that all three PCPs had good adsorption capacity on cholesterol,polyphenols and metal ions(Cd^(2+)/Zn^(2+)/Mg^(2+)),among which ASP showed the highest capacity than WSP and CMP.The adsorption capacity of all three PCPs on heavy metal ions(Cd^(2+)/Zn^(2+))was stronger than that of non-heavy metal ions(Mg^(2+));The in vitro digestibility of all three PCPs was very low,but WSP was slightly higher than ASP and CMP;Moreover,the indigestible residue of all three PCPs could improve the richness and diversity of gut microbiota,among which ASP had the greatest influence.In general,ASP and CMP could significantly promote the proliferation of some probiotics and inhibit the growth of some harmful bacteria.The gut microbiota diversity of CMP was reduced,but the richness of probiotics,especially Parabacteroides distasonis was significantly enhanced compared with the ASP group,and the growth of harmful bacteria Klebsiella pneumoniae was inhibited after CMP treatment.The short-chain fatty acids(SCFAs)analysis results showed that all three PCPs could significantly promote the production of acetic acid,propionic acid and the total acid content compared with blank control group,and SCFAs producing activity was positively correlated with the proliferative capacity of probiotics.Taken together,the good adsorption characteristics and gut microbiota regulatory activity of ASP may lay foundation for its lipid-lowering and immune-improving function.Additionally,the probiotic effect of CMP and ASP indicated that except for only use the water extract of PC in clinic,CMP and ASP also can be used in healthcare to take full advantage of this valuable medicine.

Digestion mechanism and crystal simulation of roasted low-grade high-sulfur bauxite

Low-grade high-sulfur bauxite was pretreated via suspension roasting and muffle furnace roasting to remove sulfur and enhance digestion properties.The results show that sulfur can be efficiently removed,and the alumina digestion properties are significantly improved after suspension roasting.Under optimal conditions(t=70 min,T=280°C,w(CaO)=8%and Nk=245 g/L),the digestion ratios are 94.45%and 92.08%for the suspension-roasted and muffle-roasted ore,respectively,and the apparent activation energies are 63.26 and 64.24 kJ/mol,respectively.Two crystal models were established by Materials Studio based on the XRD patterns.The DFT simulation shows that the existing Al—O bands after suspension roasting can improve alumina digestion.The(104)and(113)planes of Al2O3 after suspension roasting are found to combine with NaOH more easily than those of Al2O3 treated in a muffle furnace.

还原剂对挤压蛋白消化率的影响

该研究阐明了3种不同抗氧化剂(抗氧化肽、迷迭香提取物以及维生素C)的添加对大豆浓缩蛋白-麦麸蛋白复合体系挤压拉丝蛋白的氨基酸组成、质构和消化率的影响。结果表明,添加迷迭香水提物会显著改变颜色并降低内部纤维化程度,大豆还原肽的添加使得拉丝蛋白的纤维化程度有显著性提升。同时3种还原剂的添加使氨基酸留存率增加,说明减少了挤压过程中美拉德反应造成的氨基酸损失。模拟消化发现在胃消化阶段均无显著性变化,胰消化阶段大豆还原肽添加组对消化率有显著提升,说明大豆还原肽抑制了美拉德反应从而提升了拉丝蛋白的消化性质。研究结果可为有效提升挤压组织化产物和植物基模拟肉产物的营养价值和质构等提供理论基础。

体外模拟消化环境中乳清浓缩蛋白对5-甲基四氢叶酸钙生物可及性及微观结构的影响

生物可及性是5-甲基四氢叶酸钙(5-methyltetrahydrocalcium folate,5-MTHF)发挥生物功能的前提,易受到食品组分的影响。该文以乳清浓缩蛋白(whey protein concentrate,WPC)和5-MTHF为研究对象,利用体外消化系统,探究WPC在不同条件下(浓度、加工方式、胃肠pH、消化时间)对5-MTHF生物可及性的影响,并采用胶体粒径电位仪与激光共聚焦观察消化前后粒子微观结构的变化。结果表明,在胃消化阶段,WPC可将5-MTHF紧密包裹,较好地保护了5-MTHF,并成功转运至肠消化阶段完成释放,提高了5-MTHF的生物可及性。同时,WPC浓度、WPC加工方式、胃肠pH、消化时间等均不同程度影响5-MTHF的生物可及性和粒径、电位。其中,在胃消化阶段,各WPC-5-MTHF组均未检测出5-MTHF,生物可及性为0。在肠消化阶段,WPC-5-MTHF组的生物可及性随WPC浓度的增加而提高,较5-MTHF组的生物可及性提高了11.1%~19.61%;超声处理组、高压均质组、加热处理组的生物可及性较未加工处理组分别减少了8.49%、9.52%、8.75%;在肠pH为7、消化时间为5 h时,WPC-5-MTHF组拥有最佳生物可及性,分别为45.17%、42.32%,与5-MTHF组相比,提高到2倍左右。粒径和电位的结果显示,WPC-5-MTHF组较WPC拥有更小的粒径,更大的电位绝对值,并且WPC-5-MTHF结构的变化会引起消化特性的改变,该研究为5-甲基四氢叶酸钙在乳制品中的应用提供理论指导。

再造型黄花脆片品质及类黄酮生物利用度

以感官评价、色泽、质构、玻璃化转变温度及微观结构为评价指标,研究不同原辅料对再造型黄花脆片品质的影响。采用体外模拟消化试验法,分析新鲜(F)、粉质(P)、干制(D)3种黄花菜原料分别加工的脆片产品的类黄酮生物利用度。结果表明,不同原辅料的再造型黄花脆片品质及类黄酮生物利用度均存在差异。F-脆片、P-脆片、D-脆片的感官评分依次为86.3、70.8、63.5。3种黄花原料和4种辅料对脆片的色泽、质构、玻璃化转变温度(Tg)等均存在显著影响。F-脆片的L^(*)值最大,P-脆片的硬度和脆度最大,F-脆片的Tg最低。鲜黄花菜、小麦粉(flour,FL)、大豆(soybean,So)、花生米(peanut,Pe)、白芝麻(sesame,Se)、蔗糖(sucrose,Su)复合制脆片(F/FL/So/Pe/Se/Su)的L^(*)值最大,F/FL/So、F/FL/Pe、F/FL/Su、F/FL/So/Pe/Se/Su脆片的硬度与F/FL具有显著差异(P<0.05),其他5种脆片的脆度与F/FL相比均存在显著差异(P<0.05),除F/FL/Se外,其余脆片的Tg与F/FL差异显著(P<0.05)。3种脆片的消化液平均粒径与类黄酮含量均有显著差异(P<0.05),P-脆片的类黄酮生物利用度最高。综合感官品质及类黄酮生物利用度,F-脆片和大豆、花生米、白芝麻、蔗糖制作的脆片整体品质较好。

Microencapsulation of immunoglobulin Y: optimization with response surface morphology and controlled release during simulated gastrointestinal digestion

Immunoglobulin Y(Ig Y)is an effective orally administered antibody used to protect against various intestinal pathogens,but which cannot tolerate the acidic gastric environment.In this study,Ig Y was microencapsulated by alginate(ALG)and coated with chitooligosaccharide(COS).A response surface methodology was used to optimize the formulation,and a simulated gastrointestinal(GI)digestion(SGID)system to evaluate the controlled release of microencapsulated Ig Y.The microcapsule formulation was optimized as an ALG concentration of 1.56%(15.6 g/L),COS level of 0.61%(6.1 g/L),and Ig Y/ALG ratio of 62.44%(mass ratio).The microcapsules prepared following this formulation had an encapsulation efficiency of 65.19%,a loading capacity of 33.75%,and an average particle size of 588.75μm.Under this optimum formulation,the coating of COS provided a less porous and more continuous microstructure by filling the cracks on the surface,and thus the GI release rate of encapsulated Ig Y was significantly reduced.The release of encapsulated Ig Y during simulated gastric and intestinal digestion well fitted the zero-order and first-order kinetics functions,respectively.The microcapsule also allowed the Ig Y to retain 84.37%immune-activity after 4 h simulated GI digestion,significantly higher than that for unprotected Ig Y(5.33%).This approach could provide an efficient way to preserve Ig Y and improve its performance in the GI tract.

Impact of simulated in vitro gastrointestinal digestion on bioactive compounds,bioactivity and cytotoxicity of melon (Cucumis melo L. inodorus) peel juice powder

The objectives of this research work were to evaluate the effect of in vitro gastrointestinal digestion (GIT) on melon peel juice (MPJ) powder from fruit processing industry by-products,considering (i) the recovery and accessibility indexes,(ii) the changes on antioxidant activity,and (iii) the prebiotic effect.Throughout exposition to GIT conditions a decrease on the total phenolic content (TPC = 65.31%) and antioxidant activity by ABTS = 39.77% and DPPH = 45.91% were observed.However,these both parameters exhibited stable accessibility,accounting with 81.89%,76.55%,and 54.07% for TPC,ABTS and DPPH,respectively.After gastrointestinal digestion,the non-absorbed fraction exhibited a positive impact on the growth of Bifidobacterium and Lactobacillus strains,possibly associated with the high content of simple sugar (glucose and fructose).This fraction also showed to be safe on Caco-2 intestinal cells.These findings suggest that MPJ might be used as a potential food functional ingredient.

In vitro Evaluating the Influence of Grape Seed Polyphenol Extract on the Digestibility of Macronutrients

Interaction between dietary polyphenol and proteins including digestive enzymes may result in reduced digestibility of food macronutrients, thus lowering absorption of nutrients that contributing to high energy accumulation in human body. The objective of this study was to investigate the effect of grape seed polyphenol extract （GSPE） on the digestibility of starch, food lipid and food protein by digestive enzymes such as u-amylase, lipase, pepsin and trypsin. The digestion of each substrate was conducted at the optimal pH and temperature of specific enzyme. Bread containing different amount of grape pomace was used as a real food model and its digestion was conducted under simulated digestion condition. Concentrations of reducing sugar, fatty acid and amino acids in enzyme digested mixtures were determined as indicators of starch, lipid and protein digestions, respectively. Results indicate that GSPE significantly inhibited the digestion of starch, cooking oil and casein, but did not inhibit digestion of whey protein and egg white protein. Instead, the digestion of egg white and whey protein by trypsin was moderately enhanced in the presence of GSPE. However, under simulated human digestion condition, the grape pomace in the bread significantly reduced the digestibility of bread starch and protein.

Influence of fatty acids in edible oils on lutein micellization and permeation in a simulated digestion model

Lutein is a nutraceutical compound that promotes human eye health and prevents neurodegenerative diseases.The oral bioavailability of lutein is affected by both extrinsic and intrinsic factors in the host.Although hydrophobicity of the compound is further challenging,its lipophilicity can be utilized to micellize and thereby improve its oral bioavailability.Currently,available data on the effects of dietary fats on lutein micellization and permeation is limited and needs further exploration.In this study,the influence of 17 carrier type edible oils on lutein micellization and permeation,was investigated in a simulated digestion model.The overall effectiveness of these oils to permeate micellized lutein was attributed to its Fatty Acid(FA)profile.While 94%of the edible oils exhibited a positive influence on the permeation of micellized lutein,the micellization and permeation efficiency of these oils were significantly(p≤0.05)modulated by the saturation of FA in the order Saturated(SFA)>Mono-Unsaturated(MUFA)>Poly-Unsaturated(PUFA).The highest apparent permeability coefficient was exhibited by lutein micellized in ghee(3.01×10^(-6) cm/s)and butter(2.93×10^(-6) cm/s),which was 1.28 and 1.24 folds higher than lutein alone(2.35×10^(-6) cm/s)respectively.Exceptionally MUFA rich olive oil and PUFA rich flaxseed oil improved lutein permeation by 1.19(2.80×10^(-6) cm/s)and 1.14 folds(2.69×10^(-6) cm/s)respectively.This study is the first to report the influence of saturated fatty acids on micellization and permeation of lutein.Furthermore,the outcomes of this study offer the field of lutein delivery systems a fresh perspective.

蓝莓多酚微胶囊的制备及体外消化特性研究

【目的】旨在研究蓝莓多酚的提取纯化及微胶囊制备工艺,为研发具有缓释功能的蓝莓多酚微胶囊提供科学依据。【方法】以酶解渣汁分离后的蓝莓皮渣为试验材料,通过比较不同提取方法和不同大孔树脂在蓝莓多酚纯化上的作用,确定蓝莓多酚的提取纯化工艺,在此基础上通过均质和冷冻干燥的方法制备蓝莓多酚微胶囊,以包埋效率为主要指标,结合颜色和结构表征明确蓝莓多酚微胶囊的最佳制备工艺,并进一步分析微胶囊的体外胃肠消化特性。【结果】(1)分别比较园蓝、巴尔德温和寨选4号3个品种蓝莓果渣和果汁提取物,发现果渣提取物的总多酚含量均高于果汁提取物,寨选4号最高达2倍以上;(2)通过比较10种大孔树脂对蓝莓多酚吸附和解吸附的性能,优选出HPD-300、HPD-100B和HPD-1003种树脂,并比较不同乙醇体积分数对蓝莓多酚的解吸附效率,确定选用80%的乙醇溶液对蓝莓多酚进行解吸附;(3)选择HPD-100B大孔树脂进行提取和纯化的扩大试验,获得纯度达71.4%的蓝莓多酚提取物;(4)在此基础上比较麦芽糊精、大豆蛋白和乳清蛋白3种壁材对蓝莓多酚的包埋率,发现大豆蛋白的包埋率最高,并且复配阿拉伯胶能够进一步提高多酚的包埋率;(5)通过色差的比较发现,相比多酚提取物,微胶囊产品的L*降低,a*、b*升高,即微胶囊的明度降低,红色增强,蓝色减弱;(6)扫描电镜结果显示与片层结构的多酚提取物相比,微胶囊呈现交联状的圆球形;(7)体外消化试验发现,多酚提取物在胃液和肠液中的释放率均达到99.8%,而多酚微胶囊在胃液和肠液中的释放率分别为65.77%和74.31%。【结论】蓝莓多酚的最优制备工艺为蓝莓皮渣粗提物水液上样HPD-100B、HPD-300或HPD-100大孔树脂,5倍柱体积的水冲洗,80%的乙醇收集蓝莓多酚,且经减压浓缩和冷冻干燥制备得到蓝莓多酚提取物,纯度达71.4%。蓝莓多酚微胶囊的最优制备工艺为阿拉伯胶与大豆蛋白比例为3∶7,壁材溶液质量分数10%,芯壁比1∶5,芯壁混合液pH 2.0,4000 r/min均质10 min,冷冻干燥。所制备的蓝莓多酚大豆蛋白+阿拉伯胶微胶囊的包埋率97.6%,颜色为带有红、蓝色调的低明度粉末,结构为交联状的圆球形,具有一定的缓释特性。

牛血红蛋白肽的酶解工艺优化及其亚铁螯合物结构、稳定性研究

本研究以牛血为原料,提取牛血红蛋白进行酶解,筛选最适的酶解蛋白酶,采用单因素结合响应面试验探究最佳酶解工艺,通过扫描紫外光谱,傅里叶红外光谱,扫描电镜和全自动氨基酸分析仪等技术对制备的牛血红蛋白肽铁螯合物(Bovine Hemoglobin Peptide Iron Chelate,BHP-Fe)进行结构表征,并通过热重分析和体外模拟胃肠道消化探究其体外稳定性。结果表明:胃蛋白酶和碱性蛋白酶分步酶解为最适酶解方法。在胃蛋白酶初步酶解的基础上,得到碱性蛋白酶最佳酶解条件:料液比1:3,酶解pH9.8,酶解温度41℃,酶添加量5900 U/g,酶解时间2 h。在此条件下,酶解得到牛血红蛋白肽(Bovine Hemoglobin Peptide,BHP)的Fe^(2+)螯合能力达72.11%,牛血红蛋白水解度达35.07%。紫外光谱和傅里叶红外光谱结果显示,Fe^(2+)与BHP肽链上的羧基氧和氨基氮发生螯合反应生成了不同于多肽的新物质;扫描电镜结果显示,多肽与Fe^(2+)螯合后从表面光滑的碎片状变成表面粗糙的块状,两者存在明显差异;氨基酸含量变化显示天冬氨酸、谷氨酸、赖氨酸为多肽与金属离子的结合提供结合位点;热重分析结果表明,BHP与BHP-Fe在300℃高温状态下依然能保持较好的稳定性;体外模拟消化稳定性分析结果表明,BHP-Fe相较于其它铁补充剂在胃肠道中能保持较高的稳定性。本实验制备的多肽源性补铁剂螯合力强、消化稳定性好、具有广阔应用前景,可为牛血副产物的高效利用和新型多肽源补铁剂的未来发展前景提供建设性参考。

臭氧水处理对罗非鱼鱼糜品质及体外消化特性的影响

将臭氧水漂洗的罗非鱼鱼片制成鱼糜,研究漂洗质量浓度和漂洗时间对鱼糜品质和体外消化特性的影响,并通过分析肌原纤维蛋白氧化程度探讨臭氧水漂洗提高罗非鱼鱼糜品质的原因。结果表明,臭氧水漂洗后鱼糜白度、硬度和胶着度显著提高(P<0.05),10 mg/L臭氧水漂洗10 min时鱼糜的凝胶特性最佳。随着臭氧水漂洗质量浓度的增加和漂洗时间的延长,鱼糜硫代巴比妥酸反应物值呈上升趋势,肌原纤维蛋白的羰基含量上升、总巯基含量逐渐降低。感官评价结果显示10 g/mL臭氧水漂洗10 min时感官品质最佳。十二烷基硫酸钠-聚丙烯酰胺凝胶电泳图谱显示,10~18 mg/L臭氧水漂洗使蛋白交联形成较小的可溶性聚集体,大于18 mg/L臭氧水漂洗后蛋白形成较大的不溶性聚集体。根据拉曼光谱结果可知,10~18 mg/L臭氧水漂洗使肌原纤维蛋白二级结构逐渐展开,α-螺旋逐渐转化为β-折叠和无规卷曲。体外消化结果表明,臭氧水漂洗提高了鱼糜在消化过程中的水解程度,其中10 mg/mL臭氧水漂洗10 min时水解程度最高,消化后小分子肽(100~1000 Da)含量显著高于其他实验组(P<0.05)。综上所述,肌原纤维蛋白适度氧化能提高罗非鱼鱼糜的品质,10 mg/mL臭氧水漂洗10 min时,鱼糜感官品质最好,凝胶特性及体外消化特性最佳。

荞麦蜂花粉多糖的纯化、表征及其在体外消化过程中抗氧化活性的变化

本论文旨在研究荞麦蜂花粉多糖(BWPP)在模拟体外胃肠消化过程中的抗氧化活性。采用DEAE-52纤维素柱对粗多糖进行分级纯化,经体外模拟胃、肠消化研究其在体外消化过程中的抗氧化活性的变化规律。结果表明经DEAE-52纤维素柱层析洗脱纯化后得到总糖含量最高组分BWPP-1,其主要由Glc、Xyl、Ara等组成,且红外光谱显示BWPP-1具有明显的多糖特征吸收峰。BWPP和BWPP-1在进行体外模拟胃肠消化时,模拟胃液消化60 min时,BWPP和BWPP-1的ABTS^(+)·清除率均达到最大值,分别为86.39%±1.28%、90.38%±2.78%,与其他消化时间的存在显著差异(P<0.05);60 min时对DPPH·清除率达到最大值,分别为86.86%±0.11%、89.58%±1.67%,且二者差异不显著(P>0.05);模拟肠液消化时,BWPP和BWPP-1对ABTS^(+)·清除率在60 min时达到最大值为88.67%±0.40%和91.82%±2.77%,且二者差异不显著(P>0.05);对DPPH·清除率在240 min时达到最大值57.11%±0.06%和65.67%±3.67%,二者差异显著(P<0.05);而在消化过程中,对铁离子还原能力均较弱。由此可得,BWPP和BWPP-1具有较好的ABTS^(+)·和DPPH·清除能力,且胃液消化时DPPH·清除能力略高于肠液消化,而肠液消化时的ABTS^(+)·清除能力略高于胃液消化。本研究为以荞麦蜂花粉为基料的功能性产品的开发提供理论依据。

模拟消化中小扁豆活性物质释放和抗氧化能力变化

为了解小扁豆中活性物质在消化过程的变化规律,以白、红、黑、绿4种颜色小扁豆为原料,采用体外模拟消化模型研究口腔、胃和肠消化过程中多酚、黄酮和花青素等活性物质释放和抗氧化能力变化。结果表明:4种颜色小扁豆多酚在消化过程中逐渐释放,肠消化阶段释放量最大,模拟消化结束时,白、红、黑、绿小扁豆多酚释放量分别为1.76、1.91、1.94、2.56 mg GAE/g;黄酮和花青素在胃消化阶段释放量最大,模拟消化结束时,黄酮释放量分别为0.82、1.75、4.15、3.92 mg R/g,花青素释放量分别为0.06、0.15、0.19、0.20 mg/g;黑、绿小扁豆活性物质释放量高于红、白小扁豆。模拟消化过程中,不同消化阶段小扁豆消化产物抗氧化能力具有显著差异(P<0.05),胃消化阶段4种颜色小扁豆清除DPPH·能力较强,进入肠消化后,DPPH·清除能力显著减弱(P<0.05),绿色小扁豆消化产物对DPPH·清除能力和铁离子还原力最强。相关性分析表明黄酮释放量和小扁豆抗氧化能力相关性更强,黄酮是小扁豆的主要抗氧化物质。

英国红芸豆抗氧化肽营养价值评价及体外模拟消化分析

为了提高英国红芸豆的经济效益,开发高附加值的功能性产品,以英国红芸豆蛋白抗氧化肽组分(BRKBPAPC)为研究对象,对其营养价值和粒径分布进行分析,并采用体外模拟消化法评价BRKBPAPC消化过程中抗氧化活性的变化。结果表明:BRKBPAPC含有8种必需氨基酸,与抗氧化活性相关的氨基酸含量较高;BRKBPAPC的氨基酸比值系数分(SRCAA)为66.01,必需氨基酸指数(EAAI)为86.13,生物价(BV)为82.18,必需氨基酸组成符合FAO/WHO标准模式,是一种良好的植物源多肽;BRKBPAPC的粒径分布均匀且只有一个峰,在400~800nm之间。体外模拟消化结果表明,与未超滤肽相比,BRKBPAPC的抗氧化活性和稳定性显著提高(P<0.05);BRKBPAPC消化物对DPPH自由基清除率最高可达81.83%,对羟自由基清除率最高可达82.76%,对ABTS自由基清除率最高可达48.84%。研究为英国红芸豆产品开发提供了理论依据。