Optimisation and comparative study on the addition of shrimp protein hydrolysate and shrimp powder on physicochemical properties of extruded snack

The effect of an addition of shrimp protein hydrolysate and shrimp powder on the physicochemical properties of extruded snack was studied. Rice flour and cornflour were used as base materials, and extrusion was done using corotating twin‐screw extruder. A mixture response surface methodology was used to study the effect of ingredient mixture on the physical, functional and sensory properties of extrudates. Linear and quadratic mixture response regression model was fitted to the response variables, and it was evaluated using R² values. Based on the desirability function score, the optimum combination of ingredient was 47.75% rice flour, 38.64% cornflour, 5.95% hydrolysate and 7.67% shrimp protein powder. It was observed that an addition of shrimp hydrolysate more than 5% (7.5%) improved the crispiness. Sensory evaluation revealed that shrimp hydrolysate and shrimp powder can be used at 5–7.5% level for developing protein‐rich extruded products without affecting sensory characteristics.     

大豆蛋白的酶水解产物研究

大豆蛋白含有多种蛋白成分,其酶水解物非常复杂.为探索其中规律,采用Protamex酶对大豆蛋白进行有限水解,测定了水解液中氨基氮含量、三氯乙酸中可溶性氮含量随水解度的变化曲线,并采用凝胶层析过滤色谱分析了不同水解时间水解物分子量的变化,发现大豆分离蛋白中存在一些Protamex不容易水解成分,大豆分离蛋白的Protamex水解过程是一个不均匀的过程.     

乳蛋白胶粒的稳定性研究及应用

根据蛋白质一级结构原理,选用了一种碱性蛋白质—鱼精蛋白,研究了牛乳蛋白胶粒在适口酸性条件下的稳定性问题。确定出乳蛋白饮料的最佳工艺条件:牛奶含量(v/v)35%,白砂糖12.0%(m/v),柠檬酸含量0.2%(m/v),调酸温度在20℃之内,去离子水定容;以及鱼精蛋白的添加顺序和含量:在调酸前添加稳定效果最佳,含量(m/v)在0.3%即可达到稳定效果。     

菜籽蛋白水解物的分离纯化及抗肿瘤活性研究

本研究将菜籽蛋白通过碱性蛋白酶-风味蛋白酶分步酶解制备得到菜籽蛋白水解物(RPH),在经过超滤、葡聚糖凝胶柱(Sephadex G-15)以及半制备液相(RP-HPLC)分离纯化得到各级分离组分。采用MTT比色法分析菜籽蛋白水解物各组分RPHs(MW1 ku)对人体肝癌细胞HepG2、乳腺癌细胞MBA-MD-231及人体结肠癌细胞Caco-2的体外抗增殖活性。当RPHs质量浓度为50～1 000μg/mL时,RPHs对HepG2细胞、MBA-MD-231细胞及Caco-2细胞均有一定的抑制作用,且抑制效果与样品浓度之间呈现出剂量依赖性;其中,HepG2细胞对RPHs的作用最为敏感。经Sephadex G-15凝胶柱分离后得到2个洗脱峰,收集并测定其活性,发现组分RPHs-F2具有更强的抗肿瘤细胞增殖活性;再进一步对其经半制备液相分离得到的组分进行体外抗增殖活性分析发现,除组分RPHs-F2-4外,其他3个分离组分都具有显著的抑制作用,而组分RPHs-F2-3对HepG2细胞具有最高的体外增殖抑制率,当作用质量浓度为1 000μg/mL时,抑制率为(51.53±5.59)%。因此认为菜籽蛋白酶解物分离组分RPHs-F2-3具有较好的抗肿瘤活性,可以作为功能性成分用于抗肿瘤相关的功能食品及保健品的开发。     

Antihypertensive activity of fish protein hydrolysates and its peptides

ABSTRACT

The rising interest to utilize nutritionally exorbitant fish proteins has instigated research activities in fish waste utilization. The development of newer technologies to utilize fish waste has fostered use of bioactive value-added products for specific health benefits. Enzymatically obtained Fish Protein Hydrolysate (FPH) is a rich source of biologically active peptides possessing anti-oxidant, anticancer, antimicrobial and anti-hypertensive activity. Isolating natural remedies to combat alarming negative consequences of synthetic drugs has been the new trend in current research promoting identification of antihypertensive peptides from FPH. In this review, we aim to culminate data available to produce antihypertensive peptides from FPH, its composition and potential to be used as a therapeutic agent. These purified peptides are known to be rich in arginine, valine and leucine. Reports reveal peptides with low molecular weight (<1 kDa) and shorter chain length (<20 amino acids) exhibited higher antihypertensive activity. As these peptides have proven Angiotensin Converting Enzyme – I inhibitory activity in vitro and in vivo, their potential to be used as antihypertensive drugs is outrageous. However, current focus on research in the field of molecular docking is necessary to have improved understanding of interaction of the peptides with the enzyme.     

大马哈鱼鱼精蛋白的提取及抑菌作用的研究

对从大马哈鱼精巢中提取鱼精蛋白的工艺条件及其抑菌活性进行了研究。采用正交试验法筛选提取鱼精蛋白的最佳工艺条件,其条件为:H2SO4浓度为7.5%,用量为鱼精的3.5倍,提取时间2h,95%乙醇用量为鱼精的3倍。对鱼精蛋白进行分析,其蛋白质含量达到89.7%,且精氨酸含量较高。该鱼精蛋白对革兰氏阴性菌、革兰氏阳性菌和酵母菌均具有较强的抑菌活性,可作为一种天然防腐剂。     

改性大豆蛋白的凝胶流变性

研究了大豆蛋白水解物的凝胶流变学特性。研究结果表明,在pH7.6和pH5.2时,与大豆蛋白相比,大豆蛋白水解物的凝胶化温度升高、凝胶化时间延长;但凝胶的储能模量降低了。     

鱿鱼肝脏蛋白水解液及ACE 抑制肽的制备

为高效利用鱿鱼及其下脚料肝脏蛋白水解物,采用酶解技术和凝胶过滤分离等技术对鱿鱼肝脏蛋白水解液中抑制肽进行研究。结果表明：胃蛋白酶为鱿鱼肝脏蛋白水解的最佳酶类,同时以水解度和ACE 抑制活性为指标,得出胃蛋白酶水解的最佳条件：在36℃条件下酶解22h,酶与底物的质量比2%,底物质量分数2.5%。经过上述条件处理的水解液再经超滤处理(截留分子质量为20kD)后,用Sephadex G-50 进行分离,洗脱得到5 个峰,其中组分B 的ACE 抑制活性最高,其半抑制浓度(IC50)达到1.80mg/mL。     

Impact of ultrafiltration and nanofiltration of an industrial fish protein hydrolysate on its bioactive properties

BACKGROUND: Numerous studies have demonstrated that in vitro controlled enzymatic hydrolysis of fish and shellfish proteins leads to bioactive peptides. Ultrafiltration (UF) and/or nanofiltration (NF) can be used to refine hydrolysates and also to fractionate them in order to obtain a peptide population enriched in selected sizes. This study was designed to highlight the impact of controlled UF and NF on the stability of biological activities of an industrial fish protein hydrolysate (FPH) and to understand whether fractionation could improve its content in bioactive peptides. RESULTS: The starting fish protein hydrolysate exhibited a balanced amino acid composition, a reproducible molecular weight (MW) profile, and a low sodium chloride content, allowing the study of its biological activity. Successive fractionation on UF and NF membranes allowed concentration of peptides of selected sizes, without, however, carrying out sharp separations, some MW classes being found in several fractions. Peptides containing Pro, Hyp, Asp and Glu were concentrated in the UF and NF retentates compared to the unfractionated hydrolysate and UF permeate, respectively. Gastrin/cholecystokinin‐like peptides were present in the starting FPH, UF and NF fractions, but fractionation did not increase their concentration. In contrast, quantification of calcitonin gene‐related peptide (CGRP)‐like peptides demonstrated an increase in CGRP‐like activities in the UF permeate, relative to the starting FPH. The starting hydrolysate also showed a potent antioxidant and radical scavenging activity, and a moderate angiotensin‐converting enzyme (ACE)‐1 inhibitory activity, which were not increased by UF and NF fractionation. CONCLUSION: Fractionation of an FPH using membrane separation, with a molecular weight cut‐off adapted to the peptide composition, may provide an effective means to concentrate CGRP‐like peptides and peptides enriched in selected amino acids. The peptide size distribution observed after UF and NF fractionation demonstrates that it is misleading to characterize the fractions obtained by membrane filtration according to the MW cut‐off of the membrane only, as is currently done in the literature. Copyright © 2010 Society of Chemical Industry     

Thermal stability of soy protein isolate and hydrolysate ingredients

The objective of this study was to characterize the effects of pH, protein concentration and calcium supplementation on thermal stability, at 140 °C, of soy protein isolate (SPI) and soy protein hydrolysate (SPH) ingredients. Increasing pH between 6.4 and 7.5 led to significantly (p < 0.05) higher mean heat coagulation times (HCTs) at 140 °C, for all soy protein ingredients at 1.8, and 3.6% (w/v) protein. Increasing protein concentration from 1.8 to 7.2% (w/v) led to shorter HCTs for protein dispersions. Calcium supplementation up to 850 mg/L, except in the case of supplementation of SPI 1 with calcium citrate (CaCit), decreased HCT for soy protein ingredient dispersions, at pH 6.4 – 7.5. No significant differences (p < 0.05) were found in mean HCT for dispersions supplemented with calcium chloride (CaCl₂) and those supplemented with CaCit at 450, 650 and 850 mg/L Ca²⁺, in the pH range 6.4–7.5.