Antioxidant and emulsifying properties of potato protein hydrolysate in soybean oil-in-water emulsions

The efficacy of a previously developed antioxidative potato protein hydrolysate (PPH) for the stabilisation of oil droplets and inhibition of lipid oxidation in soybean oil-in-water (O/W) emulsions was investigated. Emulsions (10% lipid, pH 7.0) with PPH-coated oil droplets were less stable than those produced with Tween 20 (P < 0.05). However, the presence of PPH, whether added before or after homogenisation with Tween 20, retarded emulsion oxidation, showing reduced formation of peroxides up to 53.4% and malonaldehyde-equivalent substances up to 70.8% after 7-d storage at 37 °C (P < 0.05), when compared with PPH-free emulsions. In the emulsions stabilised by PPH + Tween 20, 8–15% of PPH was distributed at the interface. Adjustment of the pH from 3 to 7 markedly increased ζ-potential of such emulsions (P < 0.05). Inhibition of lipid oxidation by PPH in soybean O/W emulsions can be attributed to both chemical and physical (shielding) actions.     

马铃薯蛋白水解物对不同乳化剂制备O/W乳状液氧化稳定性的影响

用Fenton催化氧化体系模拟氧化,催化剂FeCl3,H2O2,VC的浓度分别为5、5、0.1mmol/L,以脂肪氧化产物丙二醛为指标,考察了马铃薯蛋白和不同乳化剂(非离子乳化剂Tween20、阴离子乳化剂卵磷脂和大分子乳化剂酪蛋白酸钠)共乳化制备得到的乳状液的氧化稳定性,并测定了相应乳状液的乳化稳定性。酪蛋白酸钠和马铃薯水解蛋白作为乳化剂得到的乳状液氧化稳定性较好,而Tween20和马铃薯蛋白水解物作为乳化剂得到的乳状液物理稳定性较高。     

Oxidation and oxidative stability in emulsions

Emulsions are implemented in the fabrication of a wide array of foods and therefore are of great importance in food science. However, the application of emulsions in food production is restricted by two main obstacles, that is, physical and oxidative stability. The former has been comprehensively reviewed somewhere else, but our literature review indicated that there is a prominent ground for reviewing the latter across all kinds of emulsions. Therefore, the present study was formulated in order to review oxidation and oxidative stability in emulsions. In doing so, different measures to render oxidative stability to emulsions are reviewed after introducing lipid oxidation reactions and methods to measure lipid oxidation. These strategies are scrutinized in four main categories, namely storage conditions, emulsifiers, optimization of production methods, and antioxidants. Afterward, oxidation in all types of emulsions, including conventional ones (oil-in-water and water-in-oil) and uncommon emulsions in food production (oil-in-oil), is reviewed. Furthermore, the oxidation and oxidative stability of multiple emulsions, nanoemulsions, and Pickering emulsions are taken into account. Finally, oxidative processes across different parent and food emulsions were explained taking a comparative approach.     

乳化体系中花生油氧化稳定性的研究

主要探讨花生油乳化体系中乳化剂类型、用量、pH值、EDTA、温度等对花生油氧化稳定性的影响,结果显示:乳化剂种类和pH对于乳状液体系的氧化稳定性有显著影响,阴离子乳化剂SDS稳定的乳化液,pH4.0的氧化速率最快;非离子乳化剂Tween20稳定的乳化液,pH的影响不是很显著;阳离子乳化剂CTAB稳定的乳化液,随着pH的升高,氧化速率变快。乳化液体系中微量金属离子对于体系也有相当大的影响,随着金属离子螯合剂EDTA浓度的增加,其乳化体系中花生油的氧化速率显著降低。乳化剂用量也会影响体系的氧化稳定性,随着乳化剂用量的增加,乳化乳化体系中花生油的氧化稳定性降低。     

水解蛋白来源的抗氧化肽研究进展

采用水解技术制备抗氧化肽可大大拓宽其来源。本文介绍了影响水解技术制备抗氧化肽的因素，综述了国内外在这一领域的研究进展，并展望了此种方法制备抗氧化肽产业化的可能性。     

葵花籽蛋白水解物对水包油型乳状液物理和氧化稳定性的影响

利用碱性蛋白酶对葵花籽蛋白进行适度水解后,将葵花籽蛋白水解物(SSH)添加到以单甘酯作为乳化剂制备的乳状液中,通过测定乳状液的乳化活性、乳化稳定性、粒径、絮凝指数、凝结指数以及乳状液贮藏14 d过氧化值和丙二醛含量的变化,评价SSH对乳状液物理和氧化稳定性的影响。结果表明:添加SSH可显著提高乳状液的乳化活性、乳化稳定性、絮凝和凝结稳定性,显著降低乳状液的粒径;SSH添加量为1.0%时,乳状液具有较好的物理稳定性,同时又具有较好的氧化稳定性。     

玉米醇溶蛋白抗氧化肽耐消化性研究

主要研究了玉米蛋白水解物的抗氧化性和耐消化性。通过（胃蛋白酶1h,胰蛋白酶2h）两阶段消化实验,探讨了抗氧化玉米水解物的耐消化性,以ABTS+.自由基清除能力和Cu2+螯合能力为抗氧化指标,并利用高效凝胶排阻色谱（HPSEC）来测定消化产物的分子量分布。研究表明,分子量小于500Da的产物几乎占总消化产物的70%,经过胃蛋白酶消化,ABTS+.自由基清除能力下降了近20%（P<0.05）,但在随后的胰蛋白酶消化过程中活性逐步提高,最后完全恢复;Cu2+螯合能力具有与ABTS+.自由基清除能力相似的变化趋势。虽然玉米水解产物的抗氧化性随着阶段性消化而发生改变,但仍然可以作为一种较好的自由基稳定剂、金属螯合剂和人体健康促进剂应用于食品体系。      

猪血浆蛋白水解物对水包油型乳状液氧化稳定性的影响

本实验主要研究了猪血浆蛋白水解物（Porcine plasma protein hydrolysate,PPPH）对水包油型（O/W型）乳状液储藏过程氧化稳定性的影响。分别将PPPH以0、2.5、5、10和20 mg/m L的浓度添加到以Tween-20为乳化剂的菜籽油O/W型乳状液中,测定乳状液在37℃条件下储藏10 d时间内的荧光光谱分析、共轭二烯（Conjugated diene,CD）和硫代巴比妥酸值（Thiobarbituric acid reactive substances,TBARS）的变化趋势。研究结果表明,色氨酸的氧化降解发生在蛋白氧化的初级阶段,而荧光蛋白氧化产物（Fluorescent protein oxidation products,FP）的形成是蛋白氧化第二阶段的产物。另外,在乳化体系储藏期间,与对照组相比,添加2.5 mg/m L PPPH的处理组具有最高的色氨酸荧光强度和FP（p<0.05）,同时具有最低的CD和TBARS值（p<0.05）。与此同时,色氨酸荧光强度与CD含量和TBARS值之间呈现显著的负相关关系。总之,PPPH的添加能够显著提高O/W型乳状液的氧化稳定性,为其作为抗氧化剂在乳状液食品中的潜在应用奠定了理论基础。      

Effects of skipjack roe protein hydrolysate on properties and oxidative stability of fish emulsion sausage

Effects of skipjack roe protein hydrolysate (SRPH) at various levels (0–3 g/100 g) on properties and oxidative stability of emulsion sausage from broadhead catfish (Clarias macrocephalus) fortified with skipjack tuna roe lipids were investigated. The addition of SRPH increased hardness, cohesiveness and resilience of sausage (p < 0.05). Finer fat globules were visualised in the sample added with SRPH at higher amounts. Nevertheless, the incorporation of SRPH at all levels had no impact on likeness of sausages. SRPH was shown to retard lipid oxidation of sausage during extended storage of 12 days as evidenced by the lower peroxide value (PV) and thiobarbituric acid-reactive substances (TBARS), in comparison with the control. After 12 days, the sausage with 3 g/100 g SRPH had the retained docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), accounting more than 80%. Addition of SRPH had no effect on the organoleptic properties but could prevent the development of rancidity. Nevertheless, it showed no pronounced impact on microbial growth. SRPH could therefore be used as a natural antioxidative emulsifier in cooked fish emulsion sausage.     

大米蛋白抗氧化肽的活性以及组成鉴定研究

采用碱性蛋白酶酶解大米蛋白制备大米蛋白抗氧化肽。研究表明大米蛋白酶解产物具有螯合金属铁离子、清除H2O2、羟自由基、DPPH自由基、抑制亚油酸自然氧化的作用。通过应用高解析离子淌度质谱（HD-MS）分析鉴定米蛋白抗氧化肽的序列主要为Met-Pro-Pro-Ser-Ser-Pro-His（376.68u）,Leu-Ala-Gly-Pro-Lys-Phe-Ala-Leu（408.75u）和Met-Pro-Arg-His-Asp-Pro-Gln（440.70u）。      

Characterisation of antioxidant peptides from enzymatic hydrolysate of golden melon seeds protein

The purpose of present research was to study novel antioxidant peptides from Golden melon seeds. Alkaline protease was used to hydrolyse the Golden melon seeds protein to obtain the hydrolysed peptides. These antioxidant peptides were purified and identified by ultrafiltration, gel filtration chromatography and RP-HPLC-ESI-MS/MS. Results showed that the peptide fraction (GMSHp3) with molecular weight (MW) <3 kDa obtained by ultrafiltration had the highest antioxidant capacity. This fraction was further purified via gel filtration chromatography into six sub-fractions, among which GMSHp3-3 exhibited the highest hydroxyl radical scavenging effect. Fraction GMSHp3-3 was further purified via RP-HPLC-ESI-MS/MS and sequenced as six potential antioxidant peptides with amino acids sequences of RMSFPVMCRN, LMRVLAQLG, ALAPLVALPAA, LVGKPAPD, LPAAHKA and AHAAGYGG, among which LMRVLAQLG, LPAAHKA and AHAAGYGG possessed effective ferric reducing power. These results indicated that novel antioxidant peptides from golden melon seeds protein hydrolysates might be potential antioxidant source of functional foods or nutraceutical supplements.     

花生蛋白水解物对色拉酱贮藏稳定性的影响

该文将花生蛋白水解物以不同的添加量(0.25％、0.5％、1％,质量分数)添加到色拉酱中,探索花生蛋白水解物对色拉酱贮藏稳定性的影响,测定了离心乳析率、离心破乳时间、黏度、过氧化物生成量(peroxide val-ue,POV)、硫代巴比妥酸(thiobarbituric acid,TBA)值以及蛋白水解物的分布等指标...     

Chemical and physical stability of protein and gum arabic-stabilized oil-in-water emulsions containing limonene

ABSTRACT:  An important flavor component of citrus oils is limonene. Since limonene is lipid soluble, it is often added to foods as an oil-in-water emulsion. However, limonene-containing oil-in-water emulsions are susceptible to both physical instability and oxidative degradation, leading to loss of aroma and formation of off-flavors. Proteins have been found to produce both oxidatively and physically stable emulsions containing triacylglycerols. The objective of this research was to determine if whey protein isolate (WPI) could protect limonene in oil-in-water emulsion droplets more effectively than gum arabic (GA). Limonene degradation and formation of the limonene oxidation products, limonene oxide and carvone, were less in the WPI- than GA-stabilized emulsions at both pHs 3.0 and 7.0. These data suggest that WPI was able to inhibit the oxidative deterioration of limonene in oil-in-water emulsions. The ability of WPI to decrease oxidative reactions could be due to the formation of a cationic emulsion droplet interface at pH 3.0, which can repel prooxidative metals, and/or the ability of amino acids in WPI to scavenge free radical and chelate prooxidative metals.     

Purification and identification of kokumi-enhancing peptides from chicken protein hydrolysate

The Maillard reaction products (MRPs) from chicken protein hydrolysate were demonstrated to have intense umami and kokumi-enhancing effects. To find the main flavour-enhancing compounds in the chicken protein hydrolysate, the fractions with different molecular weights were obtained by ultrafitration. The evaluation of taste characteristics revealed that the fractions with molecular weights ranging from 1000 to 5000 Da predominantly contributed to the umami and kokumi-enhancing effects. After further purification by using ultrafiltration, gel filtration chromatography, and ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) in combination with sensory evaluation, three peptides were identified, an octapeptide (WVNEEDHL), a nonapeptide (NSLEGEFKG) and a decapeptide (KDLFDPVIQD). Sensory evaluation results showed that all three peptides could significantly enhance the meat flavour, umami taste and thickness of the chicken powder solution. The results indicate that the peptides have potential application as effective chicken flavour-enhancing ingredients in the food industry.     

马铃薯蛋白ACE抑制肽的Plastein反应修饰研究

以马铃薯为原料提取马铃薯蛋白,采用胰蛋白酶水解马铃薯蛋白,制备ACE抑制肽,利用类蛋白反应(Plastein反应)修饰获得ACE抑制肽。研究添加氨基酸的种类、酶与底物浓度比([E]/[S])、反应pH、温度和时间5个因素对ACE抑制肽抑制率的影响。结果表明,Plastein反应修饰的最佳条件为:底物浓度30.0%,反应温度43.68℃、pH值8.05、加酶量3 565.05U/g,反应时间3.0h。经Plastein反应修饰,产物的ACE抑制率可以达到(82.89±0.05)%,较未经修饰的提高了1.35倍。     

Isolation and identification of antioxidative peptides from rice endosperm protein enzymatic hydrolysate by consecutive chromatography and MALDI-TOF/TOF MS/MS

The defatted rice endosperm protein (REP) was, respectively, digested by five different protease treatments (Alcalase, Chymotrypsin, Neutrase, Papain and Flavorase), and Neutrase appears to be the most desirable for producing high quality antioxidant peptides from REP. Specially, the DPPH and hydroxyl radical scavenging activities of NHREP were higher than its superoxide radical scavenging activity, and the percentage inhibition of autooxidation of NHREP (80.09%) was similar to that of α-tocopherol (86.59%) on day 5. Furthermore, NHREP was purified consecutively, and the antioxidant peptides were identified to be Phe-Arg-Asp-Glu-His-Lys-Lys (FRDEHKK, 959.5 Da) and Lys-His-Asp-Arg-Gly-Asp-Glu-Phe (1002.5 Da) by MALDI-TOF/TOF MS/MS. Lastly, FRDEHKK was chemically synthesised. It significantly inhibited lipid peroxidation in an linoleic acid emulsion system more effectively than α-tocopherol, and enhanced the viability of t-BHP induced cytotoxicity up to 74.38% (for MRC-5) and 78.39% (for RAW264.7) at 80 μg/ml. Conclusively, it was feasible to produce natural antioxidants from REP.