Functional and bioactive properties of fish protein hydolysates and peptides: A comprehensive review

Global fish processing industries dispose of fish wastes that account for more than 60% of processed fish biomass. In lieu of environmental pollution and disposal problems, these wastes are used to produce fish silage, fishmeal and sauce. They are also utilized for the production of value added products such as proteins, hydrolysates, bioactive peptides, collagen and gelatin. Research on the production of fish protein hydroysates (FPHs) presently focuses on maximizing the industrial potential of fish wastes. Since bioactive peptides containing amino acids hold properties of great interest, this paper reviews current research on the functional and bioactive properties of FPHs with an additional focus on gaps between fish and other hydrolysates, as well as current and future trends for the productive utilization of FPHs.     

Fish protein hydrolysates: production, biochemical, and functional properties

Considerable amounts of fish processing byproducts are discarded each year. By developing enzyme technologies for protein recovery and modification, production of a broad spectrum of food ingredients and industrial products may be possible. Hydrolyzed vegetable and milk proteins are widely used food ingredients. There are few hydrolyzed fish protein foods with the exception of East Asian condiments and sauces. This review describes various manufacturing techniques for fish protein hydrolysates using acid, base, endogenous enzymes, and added bacterial or digestive proteases. The chemical and biochemical characteristics of hydrolyzed fish proteins are discussed. In addition, functional properties of fish protein hydrolysates are described, including solubility, water-holding capacity, emulsification, and foam-forming ability. Possible applications of fish protein hydrolysates in food systems are provided, and comparison with other food protein hydrolysates where pertinent.     

蛋白质酶解物苦味形成机理及控制研究

蛋白质酶解后产生不同程度苦味主要是由产物中含疏水性氨基酸低分子肽所形成,这些苦味严重影响蛋白质水解产物在食品工业中应用。该文综述不同食物蛋白质酶解物中苦味肽形成机理及蛋白质酶解物苦味的降低、去除及控制方法研究最新进展,主要包括选择性分离、苦味掩盖、酶法及微生物脱苦等。     

A Mini‐Review on Brewer's Spent Grain Protein: Isolation,Physicochemical Properties,Application of Protein,and Functional Properties of Hydrolysates

There is a growing demand in reusing agro‐industrial waste to enrich food proteins and develop new protein‐related products. Brewer's spent grain (BSG), the byproducts generated from the processing of beer‐brewing industry, is rich in abundant protein (26 to 30%) with good physicochemical properties and nutritional benefits. BSG is mainly composed of four proteins including hordein, gluten, globulin, and albumin. The methods for extracting protein from BSG mainly include alkali extraction, ultrasonic‐assisted extraction, and organic solvent extraction, among others. However, little researches have described the functional properties of Brewer's spent grain protein (BSGP) and how it can be improved by enzymatic modification. Additionally, BSG protein hydrolysates (BSGPHs) have good bioactivities, mainly including antioxidant, antiinflammatory, and angiotensin‐I–converting enzyme inhibitory activities, among others. Based on the above situation, this review provides a comprehensive overview about the isolation, physicochemical features, application of the BSGP. In addition, the functional properties and biological activities of BSGPHs are also emphasized. The purpose of this review is to provide an up‐to‐date summary of BSGP research, and to broaden the market potential of this emerging protein in food industry. Besides, this review provides a reference to study the use of BSGP or hydrolysates for a variety of purposes in‐depth, including pharmaceutical, food, and industrial applications.     

Enzymatic hydrolysates from tuna backbone and the subsequent Maillard reaction with different ketohexoses

Enzymatic hydrolysates from tuna backbone were prepared, and the subsequent Maillard reaction with rare sugars (d ‐psicose, d ‐sorbose and d ‐tagatose) was investigated. The hydrolysates were found to contain a large number of short peptides under 1000 Da and were good sources of essential amino acids. In assays of free radical scavenging activity and reducing power, the Maillard reaction products from rare sugars, especially d ‐tagatose, performed better than that from d ‐fructose. After heating at 55 °C for 48 h, the scavenging capacity of the hydrolysates for 1,1‐diphenyl‐2‐picryl‐hydrazyl radicals improved by 8.9‐ and 16‐fold in the presence of d ‐fructose and d ‐tagatose. Hence, hydrolysates with high nutrient contents could be prepared from fish by‐products via proteolysis, and the Maillard reaction of rare sugars may greatly promote the antioxidant activity of the hydrolysates.     

大孔吸附树脂静态吸附草鱼蛋白水解物中氨基酸的研究

研究了4种大孔吸附树脂对草鱼蛋白水解物中氨基酸的吸附情况,结果表明,树脂最大静态吸附量由大到小排序为XDA-200>LSA-800C>XDA-5>LSA-8B,树脂吸附后酶解液的颜色和风味有所改善;进一步研究表明,XDA200型树脂除吸附游离氨基酸外,对肽分子也有较强的吸附力;芳香氨基酸主要以游离态形式吸附,其中色氨酸因与其他不易被树脂吸附的氨基酸结合而导致总色氨酸吸附量不高;支链氨基酸也主要以游离态形式吸附;从营养价值角度分析,除色氨酸含量稍偏高外,其他氨基酸含量变化情况均表明草鱼蛋白酶解物经大孔树脂吸附有望实现“高支低芳”的氨基酸组成特点。     

食源蛋白水解物/多肽与糖类物质美拉德反应产物在食品应用中的研究进展

食源蛋白水解物/多肽和糖类物质是极具开发利用价值的食物资源，两者经美拉德反应得到的共价复合物结构和营养功能优势突出，美拉德反应被广泛用于改善蛋白水解物功能特性，已成为当前食品科学研究领域关注的热点。本文综述了食源蛋白水解物/多肽与糖类物质美拉德反应产物的原料来源、反应机制、制备方法、结构表征、功能性质、营养生物活性以及在食品医药领域应用的最新研究进展和展望，可为推动食源蛋白水解物/多肽与糖类物质美拉德反应产物功能产品开发提供新思路，也为其健康效应的深入研究提供理论参考。     

Sweet potato protein hydrolysates: antioxidant activity and protective effects on oxidative DNA damage

In this study, sweet potato protein (SPP) hydrolysates were prepared by six enzymes (alcalase, proleather FG‐F, AS1.398, neutrase, papain and pepsin). The antioxidant activities and protective effect against oxidative DNA damage of SPP hydrolysates were investigated. Alcalase hydrolysates exhibited the highest hydroxyl radical‐scavenging activity (IC₅₀ 1.74 mg mL^?1) and Fe²⁺‐chelating ability (IC₅₀ 1.54 mg mL^?1) (P < 0.05). Compared with other five hydrolysates, the hydrolysates obtained by alcalase had the most abundant <3‐kDa fractions. In addition, below 3‐kDa fractions of alcalase hydrolysates showed the highest antioxidant activities and protective effects against DNA damage through both scavenging hydroxyl radicals and chelating Fe²⁺, which was probably because of the increase in several antioxidant amino acids, such as His, Met, Cys, Tyr and Phe, as well as the hydrophobic amino acids. The results suggested that enzymatic hydrolysis could be used as an effective technique to produce high value‐added peptides products from SPP.     

Protein hydrolysates from meriga (Cirrhinus mrigala) egg and evaluation of their functional properties

Protein hydrolysates from underutilised meriga (Cirrhinus mrigala) fish egg were prepared by using commercial Alcalase and papain enzymes. The degree of hydrolysis was 62% for Alcalase and 17.1% for papain, after 90 min digestion at 50–55 and 60–65 °C, respectively. The protein content of Alcalase-produced hydrolysate was higher (85%) than that of papain hydrolysate (70%) (p < 0.05). Hydrolysis by both enzymes increased protein solubility of fish egg protein hydrolysates to above 72.4% over a wide pH range (2–12). Results showed that the hydrolysates had good fat absorption capacity (0.9 and 1.0 g/g sample), foam capacity (70% and 25%) and emulsifying capacity (4.25 and 5.98 ml/g hydrolysate), respectively for Alcalase and papain protein hydrolysates. Gel filtration chromatograms and SDS–PAGE analysis indicated the distribution of smaller peptides. These results suggested that fish egg protein hydrolysates could be useful in the food industry.     

The effect of natural antioxidants on haemoglobin-mediated lipid oxidation during enzymatic hydrolysis of cod protein

Heating and changes in pH often practised during fish protein hydrolysis can cause lipid oxidation. The effect of natural antioxidants towards haemoglobin-mediated lipid oxidation during enzymatic hydrolysis of cod proteins was investigated. Different variants of a washed cod model system, containing different combinations of haemoglobin and natural antioxidants (l-ascorbic acid and Fuscus vesiculosus extract), were hydrolysed using Protease P “Amano” 6 at pH 8 and 36 °C to achieve 20% degree of hydrolysis. Lipid hydroperoxides and thiobarbituric acid reactive substances (TBARS) were analysed periodically during the hydrolysis process. The in vitro antioxidant activity of the final products was investigated. Results indicate that oxidation can develop rapidly during hydrolysis and antioxidant strategies are preferable to produce good quality products. Oxidation products did not have an impact on the in vitro antioxidant activity of the hydrolysates. The natural antioxidants inhibited oxidation during hydrolysis and contributed to the antioxidant activity of the final product.     

Properties of hydrolysed saithe protein isolates prepared via pH shift process with and without dewatering

Fish protein hydrolysates (FPH) possess various bioactivities making them a desirable ingredient in health foods. Saithe is an underutilized fish species and an excellent candidate for FPH. To produce high quality FPH removing undesirable components prior to the hydrolysis process is preferred and possible via the pH-shift process. The objective was to produce and investigate the properties of hydrolyzed protein isolates produced from minced saithe trimmings. Saithe trimmings were minced, homogenized in water and subjected to two variations of a pH shift process with (A) and without (B) dewatering. The latter process has the advantage of being less complicated and less expensive which is beneficial to the industry. Both systems were adjusted to 3% protein, pH 8 and 45 °C and subjected to enzyme hydrolysis. Both hydrolysis processes led to almost identical SDS-page peptide makeup. Both FPHs had similar antioxidative activities evaluated using oxygen radical absorbance capacity (ORAC), iron chelation ability and (DPPH) radical scavenging ability assays. FPH from process A had significantly higher ACE inhibition ability compared to FPH from process B.These results demonstrate that saithe FPH has good antioxidative activities and a strong ability to inhibit ACE, and may thus have a potential as a bioactive food ingredient.     

Bioactive peptides from marine processing waste and shellfish: A review

Marine organisms such as fish and shellfish are rich sources of structurally diverse bioactive nitrogenous components. Based on emerging evidence of potential health benefits, these components show significant promise as functional food ingredients. Activities including antihypertensive, antioxidant, anti-microbial, anti-coagulant, anti-diabetic, anti-cancer, immunostimulatory, calcium-binding, hypocholesteremic and appetite suppression have been reported. Fish and shellfish waste components contain significant levels of high quality protein (10–23% (w/w)) which represents a source for biofunctional peptide mining. This review summarises the protein-derived bioactive peptides identified in marine processing waste, molluscs and crustaceans. Moreover, it highlights the potential of proteins derived from these marine organisms as substrates for the generation of biofunctional peptides. It outlines current technologies used in the production, fractionation and purification of marine protein-derived peptides and lists some commercially available products containing marine derived bioactive protein hydrolysates and peptides. Finally, bioactive proteins, non-protein peptides and amino acids found in fish and shellfish are briefly discussed.     

鲣鱼蛋白肽谱效关系研究

采用鲣鱼为原料,以蛋白质回收率为指标,酶解制备不同工艺条件的样品。通过测定其黄嘌呤氧化酶(XOD)抑制活性、ORAC值、分子质量分布图谱和总氨基酸含量,构建鲣鱼蛋白肽体外化学活性与其分子质量分布图谱、总氨基酸含量图谱之间的谱效关系。结合超高效液相-质谱联用(LC-MS/MS)方法研究其降尿酸肽和抗氧化肽的分布。研究表明,鲣鱼蛋白肽的XOD抑制活性与其ORAC值具有显著的相关性。由多肽分子质量<1ku所占含量的分布区段和脂肪族氨基酸的含量可初步预测鲣鱼蛋白肽的化学活性。质谱分析表明,纯化组分的质谱基峰图在不同时间段的信号强度与鲣鱼蛋白肽的降尿酸活性和抗氧化活性具有明显的相关性。     

Enzymatic production of bioactive protein hydrolysates from tuna liver: effects of enzymes and molecular weight on bioactivity

Tuna liver is fish by‐product, which is normally discarded and/or used as fish meal and animal feed because of poor functionality. In this study, we attempt to recover functional peptides from tuna liver protein by enzymatic hydrolysis using various proteases, and further hydrolysates were fractionated into four categories base on their molecular weight (MW) by ultrafiltration membranes. All fractionated hydrolysates produced by Alcalase, Neutrase and Protamex following Flavourzyme hydrolysis showed excellent antioxidant activities against DPPH, hydrogen peroxide and hydroxyl radical scavenging, and reducing power. Their bioactivity was dependent on treated enzymes, and antioxidant activities of fractions dependent on employing bioassay. Moreover, they confirmed antioxidant ability toward the protection effects on hydroxyl radical‐induced DNA damage by the measuring the conversion of supercoiled pBR322 plasmid DNA to the open circular form. In addition, all fractionated hydrolysates inhibited acetylcholinesterase activity, which is involved in Alzheimer’s diseases, and high MW fractions showed high AChE inhibition activity than those of low MW fractions.     

Characterization and ACE-Inhibitory Activity of Amaranth Proteins

ABSTRACT:  Amaranth seeds have been considered as an excellent alternative or complementary source of food protein due to their balanced amino acid composition. However, their potential as a source of bioactive peptides has not been explored. The present study is aimed at characterizing and evaluating the activity of the angiotensin converting enzyme inhibitor of the amaranth protein concentrate and of hydrolysates produced with Alcalase. The protein concentrate, after simulated gastrointestinal digestion, showed lower angiotensin converting enzyme-inhibitory activity (IC₅₀ of 0.439 ± 0.018 mg protein/mL and 0.475 ± 0.021 mg protein/mL, for untreated and heat treated protein concentrate, respectively) than the hydrolysates produced with Alcalase, before and after simulated gastrointestinal digestion (IC₅₀ 0.118 ± 0.009, 0.123 ± 0.007, 0.137 ± 0.002, and 0.176 ± 0.014 mg protein/mL, respectively). The simulated gastrointestinal digestion (pepsin–pancreatin) did not significantly alter the angiotensin-converting enzyme inhibiting activity of the Alcalase hydrolysates, suggesting that the peptides of the hydrolysates were resistant to gastrointestinal hydrolysis. These results highlight the angiotensin converting enzyme-inhibitory potential of amaranth proteins, which is an indication of their health-promoting potential.     

Influence of degree of hydrolysis on functional properties and angiotensin I‐converting enzyme‐inhibitory activity of protein hydrolysates from cuttlefish (Sepia officinalis) by‐products

BACKGROUND: In Tunisia the cuttlefish‐processing industry generates large amounts of solid wastes. These wastes, which may represent 35% of the original material and constitute an important source of proteins, are discarded without any attempt at recovery. This paper describes some functional properties and the angiotensin I‐converting enzyme (ACE)‐inhibitory activity of protein hydrolysates prepared by hydrolysis of cuttlefish (Sepia officinalis) by‐products with crude enzyme extract from Bacillus licheniformis NH1. RESULTS: Cuttlefish by‐product protein hydrolysates (CPHs) with different degrees of hydrolysis (DH 5, 10 and 13.5%) were prepared. All CPHs contained 750–790 g kg^?1 proteins. Solubility, emulsifying capacity and water‐holding capacity increased while fat absorption and foaming capacity decreased with increasing DH. All hydrolysates showed greater fat absorption than the water‐soluble fraction from undigested cuttlefish by‐product proteins and casein. CPHs were also analysed for their ACE‐inhibitory activity. CPH3 (DH 13.5%) displayed the highest ACE inhibition (79%), with an IC₅₀ value of 1 mg mL^?1. CONCLUSION: Hydrolysis of cuttlefish by‐product proteins with alkaline proteases from B. licheniformis resulted in a product with excellent solubility over a wide pH range and high ACE‐inhibitory activity. This study suggests that CPHs could be utilised to develop functional foods for prevention of hypertension. Copyright © 2010 Society of Chemical Industry     

Angiotensin-I converting enzyme inhibitory and antioxidant activities of egg protein hydrolysates produced with gastrointestinal and nongastrointestinal enzymes

Egg is a well-known rich source of bioactive peptides. In this study, egg protein (egg white and egg yolk proteins) hydrolysates were produced with gastrointestinal enzymes (pepsin and pancreatin) or nongastrointestinal enzymes (thermolysin and alcalase), and fractionated by ultrafiltration and cation exchange chromatography. Angiotensin-I converting enzyme (ACE) inhibitory and antioxidant activities, amino acid composition and molecular weight distribution were studied, and the physicochemical properties were related with the bioactivities. Our results showed that egg protein hydrolysates produced with non-GI enzymes (thermolysin and alcalase) showed significantly higher ACE inhibitory activity, whereas similar or even lower antioxidative activities, than those of hydrolysates produced with GI enzymes. ACE-inhibitory activity significantly correlated with the amino acid composition, especially the proportion of positively charged amino acid, whereas antioxidant activities correlated with the proportion of low molecular weight peptides under 500 Da. Understanding the relationship between the bioactivities and physicochemical properties of the hydrolysates/fractions is important to facilitate the development technologies for preparing fractions with improved bioactivities.     

棉粕蛋白及其枯草蛋白酶酶解产物的组分分析

通过常规测定、凝胶层析、高效液相色谱等3种方法，测定和分析了棉粕蛋白及其枯草蛋白酶酶解产物的组份，并进行比较研究。结果表明，棉粕经过枯草杆菌蛋白酶酶解之后，可溶性蛋白比例比原来增加了1倍，游离氨基酸的含量增加了2.9倍；棉粕原料和酶解后的蛋白质产物经过SephadexG-50凝胶层析分离后均得到2个主要蛋白峰，并且它们相对分子质量分别为16300u和7950u左右，而酶解物2个峰的蛋白质含量比棉粕原料中的少；通过高效液相色谱分析，棉粕蛋白含有较多大分子蛋白，酶解之后大分子蛋白含量下降了7.71％，小分子肽的种类与含量明显增加，含量由16.36％增加至63.27％，游离氨基酸的含量由4.9％增加至19.4％。     

Prediction of short peptides composition by RP-HPLC coupled to ESI mass spectrometry

The combination of reversed-phase chromatography and electrospray mass spectrometry was used to predict the amino acid composition of low molar weight peptides present in a complex mixture of rapeseed protein hydrolysates. First, amino acid retention times on a hydrophobic stationary phase were evaluated to determine hydrophobicity coefficients for each amino acid and then global hydrophobicity coefficients were established for standard peptides. In this way, a correlation between peptide hydrophobicity coefficients and retention time was established. Then, a C language program was developed to calculate all potential amino acid combinations from the mass of a peptide (molar mass < 1000 Da) and determine theoretical hydrophobicity coefficients corresponding to these combinations. Comparison between the theoretical retention time determined by the model and the experimental retention time resulted in the establishment of a sorted potential composition table. This methodology has been applied to two different rapeseed protein hydrolysates peptides that have been purified and sequenced.     

Protein hydrolysates from animal processing by-products as a source of bioactive molecules with interest in animal feeding: A review

Industrial processing of livestock, poultry and fish produces a large amount of waste in a solid or liquid form that can either be destroyed or be used to make compost, biogas or other low-added value products. However, the by-products from animal processing industries have a potential for conversion into useful products of higher value, such as protein hydrolysates, with interesting applications in animal feed. Low amounts of animal protein hydrolysates included in aqua-feeds may enhance growth rate and feed conversion of farmed fish and crustacean. Animal protein hydrolysates may also be incorporated in diets to enhance the nonspecific immunity of fish. As well, these hydrolysates can be used as a good source of amino acids for newly weaned animals. Protein hydrolysates from animal by-products including antimicrobials, antioxidants, opioid-like and/or other interesting bioactive molecules have promising and interesting applications on companion and production animals. By-products from animal processing industries are therefore a promising source of bioactive peptides of considerable interest for animal care, always within the framework of the existing legislation. Possible drawbacks and future trends of the use of animal by-products and/or production of protein hydrolysates from those materials are also discussed.