鲜食水稻蛋白质提取工艺优化及结构分析

为促进稻米深加工的进程,分别对乳熟(前、中、后)期、蜡熟期、完熟期五个不同时期鲜食水稻进行蛋白质含量的测定,以蛋白质含量最高的乳熟中期为实验原料,进行鲜食水稻蛋白质提取工艺的优化。本实验通过单因素实验考察了液料比、pH、提取温度及提取时间对鲜食水稻蛋白质提取率的影响,并用响应面法优化了鲜食水稻的提取工艺。结果表明,蛋白质最佳提取工艺为:液料比8∶1、pH 9、提取温度52℃、提取时间118min,在此条件下,提取率的理论最大值为69.51%,实验验证值为69.82%,得到的鲜食水稻蛋白质提取工艺参数准确可靠,经红外测得鲜食水稻蛋白质与其他大米蛋白质结构基本一致,为鲜食水稻的进一步应用提供一定技术参考。     

鲜食水稻籽粒成熟过程中多糖组成及抗氧化活性分析

以不同成熟时期的鲜食水稻籽粒为原料,采用超声—微波协同萃取法提取多糖,同时利用HPLC法分析了多糖的组成,并通过体外抗氧化试验测定其抗氧化活性。试验结果表明,乳熟后期,鲜食水稻中多糖含量最高,达46.89mg/g;此时的多糖组分主要为甘露糖、鼠李糖、葡萄糖醛酸、半乳糖醛酸、葡萄糖、半乳糖、木糖、阿拉伯糖和岩藻糖等,而完熟期鲜食水稻的多糖组分中并未检出甘露糖和岩藻糖;通过对不同时期鲜食水稻中多糖的抗氧化能力研究发现,乳熟后期的鲜食水稻籽粒中,多糖对ABTS+自由基、DPPH自由基、羟基自由基、超氧阴离子清除率分别为86.18%,56.81%,75.62%,41.69%,均强于其他时期。     

鲜食水稻水溶性膳食纤维理化性质和抗氧化活性研究

为探索鲜食水稻开发与应用,采用不同生长时期鲜食水稻的叶片、茎、壳、籽粒为原料,研究其水溶性膳食纤维(soluble dietary fiber,SDF)的理化结构特性和抗氧化活性,以拓展水稻深加工和营养利用前景。结果表明:乳熟中期的鲜食水稻茎、叶、壳、籽粒中的SDF含量均显著高于相同部位的其他各成熟时期(p<0.05),随着生长时间的延长则SDF含量逐渐降低,乳熟中期茎SDF含量最高为3.40%,成熟期籽粒最低为0.50%。成熟期壳中的鲜食水稻SDF持水力最达到3.54 g/g,成熟期茎中SDF持油力为1.98 g/g,乳熟中期叶片中SDF结合水力最强且显著高于籽粒,成熟期茎中SDF膨胀力为2.28 mL/g。鲜食水稻叶片SDF的阳离子交换能力最强。傅里叶变换红外光谱分析表明,鲜食水稻SDF缔合的氢键较多,且多处出现糖类特征峰。体外抗氧化活性测定结果显示,鲜食水稻叶片和茎清除自由基能力较强,籽粒较弱,鲜食水稻叶片总抗氧化能力最强为1.87 U/mg,籽粒总抗氧化最弱为籽粒为0.52 U/mg。     

母乳和不同婴儿配方乳粉中蛋白质消化性研究

以母乳为对照,模拟婴儿胃肠消化环境对两种普通婴儿配方乳粉和一种适度水解蛋白婴儿配方乳粉中的蛋白质进行体外模拟消化研究,测定其体外胃、肠以及胃肠总消化率和消化液中的氨基酸含量。结果表明体外胃消化率、肠消化率及胃肠总消化率从高到低依次均为:母乳>适度水解蛋白婴儿配方乳粉>婴儿配方乳粉B>婴儿配方乳粉A,且母乳中蛋白质的体外消化率均显著高于适度水解蛋白婴儿配方乳粉和两种普通婴儿配方乳粉(p<0.05)。此外,在体外胃肠总消化液中,适度水解蛋白婴儿配方乳粉中的必需氨基酸总量显著高于母乳和婴儿配方乳粉A、B(p<0.05),母乳和适度水解蛋白婴儿配方乳粉中的氨基酸总量显著高于婴儿配方乳粉A、B(p<0.05)。与两种普通婴儿配方乳粉相比,适度水解蛋白婴儿配方乳粉中蛋白质能更好的被机体消化利用,营养价值更高。      

海参内脏酶解粉主要成分的分析

为了评价海参内脏酶解粉的营养功效,对海参内脏酶解粉基本成分、氨基酸组成、脂肪酸组成、蛋白质分子量、体外模拟胃肠总消化试验进行分析和计算。结果表明,海参内脏酶解粉蛋白质含量为51.03%,脂肪及糖含量分别达到总质量的9.84%和6.7%。酶解粉中必需氨基酸含量占氨基酸总量的36.87%,不饱和脂肪酸含量占脂肪酸总量的75.64%,多不饱和脂肪酸中二十碳五烯酸(EPA),二十碳六烯酸(DHA),花生四烯酸(AA)含量丰富,占多不饱和脂肪酸总量的59.10%。海参内脏酶解粉中约76.03%的蛋白质的分子量分布在1 000~2 000 Da。体外模拟肠胃总消化试验结果显示,20 min后酶解粉肠胃总消化率趋于稳定,达88.76%。海参肠酶解粉含有丰富蛋白质、必需氨基酸、DHA、EPA等营养成分,具有较高的食用价值和保健功效,可作为一种优质的营养品供消费者食用。     

鹰嘴豆蛋白质的营养学评价

采用碱溶酸沉法制备鹰嘴豆蛋白,测定体外消化率、分析氨基酸组成,并计算氨基酸评分,对鹰嘴豆蛋白质的营养学价值进行综合评价。鹰嘴豆蛋白体外模拟消化率为97.9%。鹰嘴豆蛋白含有18种氨基酸,总氨基酸含量为868.7 mg/g,必需氨基酸含量为353.1 mg/g,接近WHO/FAO推荐的理想蛋白质氨基酸组成(360 mg/g)。鹰嘴豆蛋白质氨基酸评分为60.5,蛋白质总体营养价值高于常见的谷薯类及杂豆类植物蛋白,营养价值较高,是仅次于大豆蛋白的杂豆类植物蛋白来源。     

苡仁营养成分的研究

对苡仁营养成分的测定结果表明,苡仁含蛋白质17.5%、必需氨基酸占氨基酸总量的35%、支链氨基酸占17.0%;总脂肪含量为5.9%,其中不饱和脂肪酸含量为85%;富含多种矿质元素、多糖以及抗氧化活性物质.揭示苡仁是一种营养丰富的药食两用原料.     

中华鳖腿肉蛋白质体内外消化研究

通过测定氨基酸组成、体内外蛋白质消化率及经蛋白质消化率校正的氨基酸评分（protein digestibilitycorrectedamino acid scores,PDCAAS）等指标,评价热处理前后中华鳖腿肉蛋白质的营养价值。结果表明：中华鳖腿肉热处理前后必需氨基酸含量分别为36.84%、34.55%（以干质量计）,占氨基酸总量的41.12%、40.20%,其构成符合联合国粮农组织/世界卫生组织推荐的理想模式。热处理前,测得中华鳖腿肉蛋白质体外消化率为83.68%,体内消化率为95.05%;热处理后,测得其体外消化率为87.04%,体内消化率为96.18%,热处理后消化率显著提高（P＜0.05）。结合氨基酸评分及真实消化率,计算得到热处理前其PDCAAS为100%,由于蒸煮过程营养物质的流失,测得热处理后Trp氨基酸评分最低为80,热处理后其PDCAAS为76.94%。     

体外模拟消化对酸枣仁蛋白酶解产物抗氧化活性的影响

目的：以具有良好抗氧化活性的酸枣仁蛋白酶解产物（SZPHs）为研究对象,探究体外模拟胃肠消化对其氨基酸组成及抗氧化活性的影响。方法：通过体外模拟胃肠消化,得到酸枣仁蛋白酶解产物消化物（SZPHs-GD）,并分析SZPHs消化前后的氨基酸组成以及体外抗氧化活性。结果：体外模拟胃肠消化后,SZPHs-GD中疏水性氨基酸含量降低了1.51%,亲水性氨基酸和带负电荷氨基酸含量分别升高了0.83%和2.11%,必需氨基酸含量无显著变化;分子量分布结果表明,SZPHs及SZPHs-GD分子量主要分布在5 kDa以下,且体外模拟消化后<5 kDa组分比例增加;经体外模拟胃肠消化后,SZPHs-GD对DPPH自由基清除率最高可达81.25%,对ABTS⁺自由基清除率最高可达90.40%,对超氧阴离子自由基清除率最高可达47.51%,对羟基自由基清除率最高可达32.66%。结论：经模拟体外胃肠消化后,SZPHs-GD仍具有较好的氨基酸组成以及较高的体外抗氧化活性。     

纸型海藻食品的氨基酸构成和模拟胃肠消化特性的研究

研究纸型紫菜食品和纸型海带食品的氨基酸构成特点及2种海藻食品模拟胃肠消化的特性。分别以紫菜和海带为原料,制作纸型紫菜和纸型海带,通过氨基酸分析、模拟胃消化、模拟肠消化分析纸型海藻食品的营养成分和消化特性。纸型紫菜和纸型海带均含有人体必需的8种氨基酸,2种半必需氨基酸及8种其他氨基酸。纸型紫菜的氨基酸含量为19.62g/100g,纸型紫菜和纸型海带的鲜味氨基酸占氨基酸的总量超过20%。纸型紫菜经5h模拟胃消化的消化率为57%,高于非纸型紫菜消化率(36%),纸型海带经5h模拟胃消化的消化率为18%,高于非纸型海带消化率(13%)。纸型紫菜和纸型海带经5h模拟肠消化的消化率分别为78%和28%,均显著高于非纸型海藻模拟肠消化的消化率。纸型紫菜和纸型海带具有合乎FAO/WHO的氨基酸参考模式,具有优良的胃消化特性和肠消化特性。     

体外模拟胃肠消化对缢蛏抗氧化活性的影响

目的 基于体外模拟消化系统探究胃肠模拟消化对缢蛏的抗氧化活性的影响以及氨基酸含量的变化。方法 以新鲜缢蛏为原料,向体外模拟消化系统加入胃蛋白酶和胰蛋白酶,模拟在胃液和肠液下的胃消化、十二指肠消化和小肠消化过程,研究缢蛏在消化过程中的羟基自由基(·OH)清除率、二苯代苦味酰基自由基(2,2-diphenyl-1-picrylhydrazyl radical, DPPH·)清除率、还原力、水解度、游离氨基态氮及游离氨基酸含量的变化。结果 整个胃肠消化阶段,加酶组的·OH清除率、DPPH·清除率、还原力均高于对照组。肠消化产物的·OH清除率、DPPH·清除率、还原能力及水解度均高于胃消化产物,并且肠消化产物中的总游离氨基酸含量及具有抗氧化特征的氨基酸含量均显著高于胃消化产物(P<0.05)。在十二指肠消化阶段,·OH清除率、DPPH·清除率、还原力值达到最高。结论 体外模拟消化处理能够提高缢蛏的抗氧化活性,其中十二指肠消化阶段产物抗氧化活性最高。     

Microstructure and chemical changes in Twarog cheese made from ultrafiltrated milk and from lactose-hydrolysed milk

Twarog cheese was manufactured from fresh milk, lactose-hydrolysed milk and retentate. Microstructure, chemical composition, protein breakdown, amino acid distribution and organoleptic properties were studied during ripening.Inoculation of the milk with β-galactosidase, before cheese processing, reduced the clotting time, enhanced the protein breakdown and enhanced amino acid accumulation during ripening. Concentrating the milk, by ultrafiltration, prolonged the coagulation time and resulted in a cheese with greater amounts of moisture, fat, total nitrogen and higher pH than other cheeses.Essential free amino acids are considered to constitute more than half of the total free amino acids of Twarog cheese and glutamic acid, leucine and phenylalanine are the major free amino acids in the ripened cheese.Quality of the cheese was improved either by ultrafiltration or by lactose hydrolysis and the acceptable flavour was more pronounced in β-galactosidase-treated cheese.Microstructure of the protein in young cheeses does not differ in all treatments. The disintegration and fusion of casein advanced during ripening in the outer protein matrix more than internally. The appearance of the cheese matrix was similar in both control and ultrafiltrated cheeses while the casein in β-galactosidase-treated cheese fused faster than in other treatments.     

基于模拟胃肠道消化的云南民族乳制品蛋白肽研究

乳扇、乳饼和奶渣是云南民族传统乳制品,具有历史悠久、特色鲜明、蛋白质含量高等特点.本研究基于模拟胃肠道消化,采用液相色谱-串联质谱、氨基酸分析仪研究乳扇、乳饼和奶渣的肽谱及游离氨基酸含量,并借助蛋白肽数据库分析潜在的生物活性肽.结果表明,乳扇蛋白肽221条,分子质量集中在500～750Da,潜在的功能活性肽包括血管紧张...     

Ripening time estimation of Kariesh cheese

Kariesh cheese is a popular cheese in Egypt produced by acid coagulation of milk. It can be consumed fresh or after ripening. Proteolysis in cheese was measured by determining soluble nitrogen (SN), amino acid nitrogen (AAN), total amino acids (TAA) and free amino acids (FAA). SN, AAN and FAA increased during ripening. Free amino acids profile revealed in total 16 amino acids and the same distribution of free amino acids. Cheese ripening was influenced by the type of milk and the method of production. The mildly acid sweet flavour was attributed to the concentration of glutamic acid, aspartic acid, proline and valine. Linear regression analysis was carried out to estimate the ripening time of this cheese. A positive correlation between the accumulation of amino acid and ripening time was established. The highest coefficient of determination near one resulted from glutamic acid (R² = 0.99) followed by lysine (R² = 0.97–0.99), then aspartic acid (0.90–0.98). From the linear regression equation for glutamic acid, lysine, aspartic acid or proline, the ripening time of Kariesh cheese in weeks was determined as follows: Time of ripening [weeks] = mg amino acid 100 g cheese-a/b where b = slope and a = intercept of regression straight line at 0 time.     

Evolution of free amino acids during ripening of Caciocavallo cheeses made with different milks

The evolution of free amino acids (FAA) in Caciocavallo cheeses, made with cow milk (CC) and cow milk mixed with ewe (CE) and goat (CG) milk, was studied throughout ripening. In all Caciocavallo cheeses produced, the total free amino acid (TFAA) content increased during ripening. In general, the highest TFAA content was found in cow cheeses, and the lowest in CG cheeses, whereas CE cheeses ranged over an intermediate level. In all the analyzed samples, during ripening, the content of the individual FAA increased with the exception of arginine. Tyrosine and histidine were found only in CE samples from the middle to the end of ripening. The major FAA found throughout the whole ripening period, in all types of cheese, were leucine, phenylalanine, lysine, valine, asparagine, γ-aminobutyric acid, and ornithine. The TFAA and several AA showed significant differences in ripening time, whereas tyrosine and histidine showed significant differences in kinds of milk.     

Proteolytic and lipolytic changes during the ripening of León raw cow's milk cheese, a Spanish traditional variety

Proteolytic and lipolytic changes were studied throughout ripening of five batches of León cow's milk cheese, a traditional variety made in the north of Spain. Total soluble nitrogen, non-protein nitrogen, oligopeptides nitrogen, amino nitrogen and ammonia nitrogen fractions increased slightly during the ripening process. The final values of these nitrogen fractions indicate that this cheese undergoes a very slight proteolysis as much in extent as in depth. This weak protein degradation is corroborated when the caseins and their degradation products were quantified by electrophoresis. β-Casein stayed practically intact throughout the ripening process and only 10% of α_s-casein became degraded. The content of total free amino acids increased progressively but in a slightly increased way during ripening, reaching final average values of 592 mg (100 g)⁻¹ of total solids. The most abundant free amino acid at the end of ripening was lysine, followed by leucine, glutamic acid, tryptophan, valine and phenylalanine. The acidity index of the fat values increased during ripening by a factor of 4.39. The final values of this parameter are in the range of those observed in other cow's milk cheeses ripened by bacteria. The content in total free fatty acids underwent an increase throughout ripening reaching final average values of 6669 ppm. The most abundant free fatty acid at the end of ripening was oleic acid followed by butyric and palmitic acids. The high content of short-chain fatty acids is outstanding, specially that of butyric acid.     

多宝鱼不同水解物肽段组成及体外抗氧化活性比较

为研究熟化、模拟消化和酶解对多宝鱼肉水解物抗氧化活性的影响,本研究分别采用碱性蛋白酶和胃蛋白酶-胰蛋白酶水解多宝鱼生肉和熟肉,制备生肉碱性蛋白酶水解物、熟肉碱性蛋白酶水解物、生肉体外模拟消化产物和熟肉模拟消化产物,并评价其水解度、相对分子质量分布、氨基酸组成、肽段组成和体外抗氧化活性的差异。结果表明:生肉碱性蛋白酶水解物的水解度最高,为20.18%;4种水解物的分子质量分布差异明显,共有肽段仅有1条,但氨基酸组成没有显著性差异;碱性蛋白酶水解物以肽段小于1000 Da的组分为主,2～4肽的含量达64.57%～51.73%,而模拟消化产物中1000～3000 Da的组分占比超过50%,以多肽(>10)为主,熟化过程会减少小肽(<6)的比例;体外抗氧化活性分析显示,碱性蛋白酶水解物的抗氧化活性均高于模拟消化样品,熟化会降低生肉碱性蛋白酶水解物的抗氧化能力,生肉碱性蛋白酶水解物具有最高的超氧阴离子和羟基自由基清除能力,以及最佳的铁离子还原能力。因此,碱性蛋白酶是优于模拟消化的多宝鱼蛋白水解方式,鱼肉的熟化总体上会降低水解物的抗氧化能力。     

氨基酸均衡小米复合粉制备及发酵乳体外消化分析

将小米与乳清分离蛋白粉和大豆分离蛋白粉复配,通过正交实验确定最优氨基酸均衡小米复合粉的质量配方;评价体外胃肠消化过程对小米浓浆未发酵组和小米发酵乳组的多酚、黄酮及抗氧化性的影响。结果表明：小米复合粉最佳质量配方为：小米粉66.8%,乳清分离蛋白粉16.6%,大豆分离蛋白粉16.6%;未发酵组和发酵乳组的多酚含量、DPPH、ABTS和羟基自由基清除率在胃、肠消化的各个阶段都显著增加。黄酮含量和铁还原力在胃消化阶段呈正增长而在肠消化时略微减少。发酵乳组的抗氧化能力在消化的每个时间段都要强于未发酵组,说明发酵工艺可以提升产品的抗氧化性。     

Changes of liposome and antioxidant activity in immature rice during seed development

For the past several decades, only a few studies were conducted on the change in immature rice liposomes during seed development. To evaluate and compare the lipid material of different degrees of developing rice grains, this paper focused on fresh rice seeds from only one most popular species of Dasan divided into five growth periods. The lipid components of fresh rice, especially γ-oryzanol and fatty acids equipped with extremely beneficial phytonutrients, were investigated. The results illustrated that the level of extracted liposome increased gradually along with the development of rice and in the third stage of development, the level of liposome achieved maximum. And then, instead of increasing, it was decreased at later stages of development. Moreover, the antioxidant activity of fresh edible rice (FER) was also evaluated by DPPH and ABTS assay. It was shown that FER has the higher antioxidant activity than the ripened rice seed on lipids, which will improve FER using on the functional foods and help provide certainly theoretical basis in food processing industry.