The effect of high solid concentrations on enzymatic hydrolysis of soya bean protein isolate and antioxidant activity of the resulting hydrolysates

This study investigated the effect of high solid concentrations on the enzymatic hydrolysis and antioxidant activities of soya bean protein isolate hydrolysates (SPIHs). The soya bean protein isolate at the concentration of 8%, 16%, 24% and 32% was hydrolysed to obtain SPIH with 21.5% degree of hydrolysis (DH), respectively. Results showed that, for the same DH, significant increases in reaction time and decrease in protein recovery were observed as solid concentrations increased. There was no significant difference in molecular weight distribution, but different amino acid compositions in supernatants of SPIH hydrolysed at different solid concentrations. The level of antioxidant amino acids in high solid concentration (32%) was higher than that in low solid concentration group, and antioxidant activity of SPIH increased with the solid concentration increased. Thus, increasing solid concentrations could increase the antioxidant activities and functional properties with low water costs.     

板栗淀粉酶水解工艺条件研究

为探索板栗淀粉酶水解特性及工艺条件,采用中温α-淀粉酶对板栗淀粉进行水解,并在水解温度、pH、底物浓度及酶用量等单因素试验的基础上进行二次回归正交旋转试验,确定板栗淀粉酶解工艺条件.结果表明:对α-淀粉酶水解板栗淀粉影响程度大小依次为pH＞水解温度＞酶用量＞底物浓度;α-淀粉酶水解板栗淀粉的适宜工艺条件为:水解温度70.2 ℃,pH 5.83,底物浓度73.10 g/L,酶用量122.45 U/g,水解时间为75 min.在此工艺条件下板栗淀粉酶水解度为27.476% .     

Enzymatic hydrolysis of wheat gluten by proteases and properties of the resulting hydrolysates

The insolubility of gluten in aqueous solutions is one of the major limitations for its more extensive use in food processing. Wheat gluten was enzymatically hydrolyzed by several commercially available proteases (Alcalase 2.4L, PTN 6.0S, Pepsin, Pancreatin, Neutrase and Protamex™) with protein recovery of 81.3%, 42.5%, 53.3%, 61.6%, 46.3% and 43.8%, respectively. The hydrolytic efficiency of these proteases on wheat gluten was also compared. Alcalase served best for the preparation of wheat gluten hydrolysates with the maximum degree of hydrolysis (DH) 15.8%. Subsequently, the solubility of wheat gluten hydrolysates (WGHs) obtained with those enzymes was comparably evaluated. The products had excellent solubility (>60%) over a pH range of 2–12. The molecular weight distribution of WGHs was further determined by SDS-PAGE and size exclusion chromatography on Sephadex G-15. The results showed that with the increasing of DH values, there occurred a large amount of smaller polypeptides.     

Evaluation of bitterness in enzymatic hydrolysates of soy protein isolate by taste dilution analysis

ABSTRACT:  Although enzymatic hydrolysates of soy protein isolate (SPI) have physiological functionality, partially hydrolyzed SPI exhibits bitter taste depending on proteases and degree of hydrolysis (DH). To determine proteolysis conditions for SPI, it is important to evaluate bitterness during enzymatic hydrolysis. Taste dilution analysis (TDA) has been developed for the screening technique of taste-active compounds in foods. The objectives of the present study were to evaluate bitterness of enzyme-hydrolyzed SPI by TDA and to compare bitterness of SPI hydrolysates with respect to kinds of proteases and DH. SPI was hydrolyzed at 50 °C and pH 6.8 to 7.1 to obtain various DH with commercial proteases (flavourzyme, alcalase, neutrase, protamex, papain, and bromelain) at E/S ratios of 0.5%, 1%, and 2%. The DH of enzymatic hydrolysates was measured by trinitrobenzenesulfonic acid method. The bitterness of enzymatic hydrolysates was evaluated by TDA, which is based on threshold detection in serially diluted samples. Taste dilution (TD) factor was defined as the dilution at which a taste difference between the diluted sample and 2 blanks could be detected. As DH increased, the bitterness increased for all proteases evaluated. Alcalase showed the highest TD factor at the same DH, followed by neutrase. Flavourzyme showed the lowest TD factor at the entire DH ranges. At the DH of 10%, TD factor of hydrolysate by flavourzyme was 0 whereas those by protamex and alcalase were 4 and 16, respectively. These results suggest that TDA could be applied for the alternative of bitterness evaluation to the hedonic scale sensory evaluation.     

Antioxidant and antihypertensive protein hydrolysates produced from tuna liver by enzymatic hydrolysis

In order to better utilize a fish by-product, the enzymatic hydrolysis of tuna liver was performed using commercially available proteases such as Flavourzyme, Alcalase, Protamex, and Neutrase. The hydrolysates were prepared as both first step hydrolysates and second step hydrolysates. The molecular weight distribution of the hydrolysates was determined by size exclusion chromatography and matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry, which analyzed a representative hydrolysate type with a weight range of 1000–3000 Da. The antioxidant activities of the tuna liver hydrolysates against 2,2-diphenyl-1-picrylhydrazyl (DPPH), hydroxyl radical, and hydrogen peroxide, along with a reducing power assay, showed that the second step hydrolysates had more potent antioxidant activity than the first step hydrolysates. However, the first step hydrolysates exhibited more effective chelating activity. Furthermore, the protection ability of the hydrolysates toward hydroxyl radical-induced oxidative DNA damage was evaluated by measuring the conversion of supercoiled pBR322 plasmid DNA to the open circular form. In addition, an angiotensin I-converting enzyme (ACE) inhibition assay revealed that all hydrolysates had similar ACE-inhibitory properties. These findings suggest that tuna liver hydrolysates may be a beneficial ingredient to use in functional foods.     

鲢鱼酶解产物对酵母菌的抗冻保护作用

优选酵母抗冻剂对改善冷冻面团品质具有重要意义。通过酶法制备了系列鲢鱼酶解产物,分析其基本组成和电泳图谱变化,并考察酶解时间及其浓度对面包酵母冻融过程中存活率的影响。结果表明:面包酵母耐冻性差,1个冻融循环后存活率仅为0.69%;不同酶解时间的鲢鱼酶解产物基本组成相差不大,但酶解15,30min的酶解产物对酵母菌的抗冻保护效果最好;添加4%的30min酶解产物使酵母菌的冷冻存活率提高到90.73%,较8%的甘油提高了42.88%。Tricine-SDS-PAGE分析发现,酶解产物的蛋白条带分布基本相似,但信号随着酶解时间的延长逐渐减弱,其中新增约13kDa的蛋白可能与酶解产物的抗冻保护活性有重要关系。     

Effects of enzymatic hydrolysis on lentil allergenicity

Enzymatic hydrolysis and further processing are commonly used to produce hypoallergenic dietary products derived from different protein sources, such as cow's milk. Lentils and chickpeas seem to be an important cause of IgE‐mediated hypersensitivity in the Mediterranean area and India. Some studies have investigated the effects of enzymatic treatments on the in vitro immunological reactivity of members of the Leguminosae family, such as soybean, chickpea, lentil, and lupine. Nevertheless, there are only a few studies carried out to evaluate the effect on IgE reactivity of these food‐hydrolysis products with sera from patients with well‐documented allergy to these foods. In this study, lentil protein extract was hydrolyzed by sequential action of an endoprotease (Alcalase) and an exoprotease (Flavourzyme). Immunoreactivity to raw and hydrolyzed lentil extract was evaluated by means of IgE immunoblotting and ELISA using sera from five patients with clinical allergy to lentil. The results indicated that sequential hydrolysis of lentil results in an important proteolytic destruction of IgE‐binding epitopes shown by in vitro experiments. However, some allergenic proteins were still detected by sera from four out of five patients in the last step of sequential hydrolyzation.     

Hemoglobin hydrolysates from porcine blood obtained through enzymatic hydrolysis assisted by high hydrostatic pressure processing

The purpose of this work was to obtain discoloured hemoglobin (Hb) hydrolysates from porcine red blood cells fraction by combining enzymatic hydrolysis and high hydrostatic pressure (HHP) treatments. Samples of Hb were submitted to treatments of enzymatic hydrolysis by trypsin (EC 3.4.21.4) or pepsin (EC 3.4.23.1), under controlled conditions of temperature and pH, for 2, 6 and 24 h, and pressurization at 400 MPa, at 20 °C for 15 min, after the addition of the proteases. To evaluate the effects of the proteolysis reactions, the effectiveness of discolouration, the extent of hydrolysis as the percentage of non-protein nitrogen, and the SDS-PAGE electrophoretic profiles of the hydrolysates were determined. The results showed that HHP had a significant influence on enzymatic hydrolysis of Hb by trypsin, whereas did not improve the extent of proteolysis in the case of pepsin. The main conclusion derived from this study is that pressurization of Hb samples after the addition of trypsin enhanced enzymatic hydrolysis of the Hb, hence permitting a decrease in the incubation time.

Industrial relevance

The present study is focussed on assessing the effects of enzymatic hydrolysis with trypsin or pepsin assisted by HHP treatment on the discolouration of Hb from porcine blood. HHP treatment was able to increase the activity of trypsin and to enhance discolouration effectiveness of Hb with pepsin. The results from this work corroborate the potential of the application of HHP processing combined with enzymatic treatments on the development of food ingredients from porcine blood.     

复合酶对壳聚糖的降解作用研究

研究由胃蛋白酶、果胶酶、纤维素酶、木瓜蛋白酶组合而成的复合酶对壳聚糖的降解作用.着重探讨反应温度、pH、酶底比和不同脱乙酰化度的原料对多种复合酶水解作用的影响.结果表明：复合酶E2对壳聚糖具有最高的水解活力,水解产物的DE值最高.结合酸预处理,以酶底比1∶10,可使壳聚糖的水解产物分子量低于4000.     

湿热及酶解处理对糯米粉体外消化特性和血糖生成指数的影响

目的 研究酶解处理、湿热处理和湿热复合酶解处理对糯米粉体外消化特性和血糖生成指数(glycemic index, GI)的影响。方法 采用体外消化法测定了不同处理糯米粉的水解度和血糖生成指数值, 并通过X-射线衍射和激光共焦拉曼光谱实验测定了不同处理糯米的淀粉晶体结构。结果 3种处理的水解度和抗性淀粉(resistant starch, RS)相对含量增加, 慢消化淀粉(slowly digestible starch, SDS)相对含量降低; 其中湿热复合酶解处理条件下, RS相对含量最高, 为71.31%; 酶解处理条件下, RS相对含量最低, 为67.66%。酶解处理、湿热处理和湿热复合酶解处理的GI值分别为79.1、76.0和70.6。3种处理后糯米淀粉的晶体结构发生改变, 3种处理均使分子短程有序度与结晶度增加, 其中湿热复合酶解处理条件下, 结晶度最高, 为34.41%。 结论 湿热复合酶解处理后的糯米粉抗消化特性增强且GI值降低, 湿热复合酶解工艺可能通过影响糯米粉的体外消化率来降低GI值。     

The effect of enzymatic hydrolysis time and temperature on the properties of protein hydrolysates from Persian sturgeon (Acipenser persicus) viscera

Protein hydrolysate was prepared from the viscera of Persian sturgeon (Acipenser persicus), a major sturgeon species in the Caspian Sea. Hydrolysis was performed at three different temperatures (35, 45 and 55 °C), pH 8.5, using commercially available Alcalase^® and an enzyme to substrate ratio of 0.1 AU/g viscera protein over a 205 min incubation period. Protein and lipid content of the hydrolysate were 65.82%, and 0.18%, respectively. Protein recovery and degree of hydrolysis ranged from 34.97% to 61.96% and 13.32% to 46.13%, respectively. The highest degree of hydrolysis was observed at 55 °C after 205 min (p < 0.05). The amino acid score of the hydrolysates was similar to that of the FAO/WHO reference protein. It is revealed that Persian sturgeon visceral protein hydrolysate amino acid fulfils adult human requirements. Based on National Research Council guidelines, phenylalanine is the first limiting amino acid in the hydrolysate. However, the hydrolysate has the potential for application as an ingredient in formulated diets.     

沙蚕不同蛋白酶酶解产物滋味特征及聚类分析研究

摘要：目的 研究沙蚕不同酶解产物中氨基酸和呈味核苷酸的含量、组成和呈味效果差异。方法 以酱油粉为对照,采用味道强度值、味精当量、主成分分析法、聚类分析法进行分析和综合评价。结果 沙蚕不同蛋白酶解产物中游离氨基酸含量在90.84±1.12~151.25±0.95 mg/g之间;风味蛋白酶酶解产物的游离氨基酸和呈味氨基酸含量最高;胰蛋白酶组的味精当量值远高于酱油粉组;各组氨基酸对滋味有较大贡献,风味、胰蛋白酶组中谷氨酸的味道强度值值与酱油粉组中该值接近,分别为37.13和35.40 mg/g。提取了4个主成分,累计方差贡献率达95.372%,较好地反应了酶解产物中游离氨基酸的综合信息,风味蛋白酶组综合得分最高,基于电子舌的滋味轮廓也支撑了这一结论。采用聚类分析将实验组分为4类,较直观地反映了不同酶解产物间的差异。结论 风味蛋白酶和胰蛋白酶酶解沙蚕的产物游离氨基酸品质较好,且鲜味氨基酸含量和呈味核苷酸含量较高,可开发呈味基料。     

牡蛎酶解过程的成分变化及脱腥初步研究

对牡蛎原浆液、酶解液及其浓缩液的基本营养成分进行分析比较,分别采用了活性炭吸附、β-环状糊精包埋法和酵母发酵法对牡蛎酶解液进行脱腥,研究了温度,时间,pH和脱腥剂用量等对脱腥效果的影响. 结果表明:牡蛎蛋白质、水分含量分别为9. 46%和81. 42%:酶解后,蛋白质和水分含量分别为7. 36%和83. 18%;酶解液浓缩后,蛋白质含量高达52. 55%. 活性炭脱腥效果最优:用量为0. 5%,在pH7. 0、30℃条件下吸附0. 5 h,酶解液基本无腥味,蛋白质回收率可达84. 65%. 促进牡蛎酶解液的推广应用.     

Enhancing enzymatic hydrolysis of food proteins and production of bioactive peptides using high hydrostatic pressure technology

BackgroundBioactive peptides (BPs) generated by hydrolysis of food proteins exhibit a broad spectrum of biological properties (antihypertensive, hypocholesterolemic, antimicrobial, antioxidant, etc.) in both in vitro and in vivo models. Initially obtained from milk and egg products, BPs have now largely been obtained from food byproducts such as marine, animal and plant biomasses. Amongst the various strategies being developed for BPs production, enzymatic hydrolysis (EH) is the most widely preferred due to its GRAS nature. However, the main challenge of EH is to decrease the time and quantity of enzyme, and improve yield and bioactivity of BPs.Scope and approachConsequently, innovative and efficient food technologies have been developed to satisfy these needs. High hydrostatic pressure (HHP) processing, a non-thermal technology, initially developed to extend food shelf-life, is being considered as a promising tool to improve the efficiency of EH and generate high value-added peptide fractions from various complex biomasses.Findings and conclusionsThis innovative and emerging technology enhances EH by inducing protein unfolding/denaturation, as well as activating the enzymes used while maintaining their nutritional and functional properties. This review discusses the state of the art of HHP technique, its applications in combination with EH, and potential challenges for the production of BPs from food-derived protein sources.     

酶水解法提高大豆蛋白水解度的研究

用蛋白酶水解方法提高大豆分离蛋白水解度.通过对多种蛋白酶的对比分析可知,风味蛋白酶的水解效果好于其它蛋白酶,但正交试验结果表明,即使在优化条件下水解,单一的风味蛋白酶水解所得大豆分离蛋白水解度最高只达到43.12%.若先用胃蛋白酶水解再用风味蛋白酶水解则水解度最高可达68.81%,而风味蛋白酶与其它酶的联合应用效果略差;若先使用风味蛋白酶后使用胃酶则水解度只有47.89%.表明不同酶对大豆蛋白分子具有不同的水解特点.     

马铃薯蛋白酶抑制剂酶解产物超滤组分的抗氧化活性与结构特征

本实验以马铃薯蛋白酶抑制剂为原料,通过超声联合蛋白酶K酶解处理后,对其酶解产物(PPIHs)的理化性质、抗氧化稳定性及其超滤后各组分的抗氧化活性及结构特性进行分析。结果表明,超声联合酶解处理后,PPIHs的溶解度增加,乳化性和乳化稳定性增强;进一步研究发现,其在80 °C以下的抗氧化稳定性较好,超过80 °C时,有下降趋势;在酸性或中性环境下,除了对ABTS自由基的抗氧化稳定性较差,PPIHs对其他自由基的抗氧化稳定性较好。PPIHs经过超滤得到PPIHs-I(> 10 kDa)、PPIHs-II(3-10 kDa)和PPIHs-III(< 3 kDa)的三种超滤产物,PPIHs-I对ABTS自由基的清除能力最强,Zeta电位的绝对值显著增大;PPIHs-II的油脂氧化抑制能力以及对-OH和DPPH自由基的清除能力较强,粒径均显著减小。通过紫外吸收光谱、傅里叶变换红外光谱和荧光光谱中可以看出,酶解产物的结构发生明显改变,如无规卷曲和β-转角相对含量提高,β-折叠含量和 α-螺旋相对减少,疏水性增强等,进而改善其抗氧化活性。     

Effects of ultrasound-assisted enzymatic hydrolysis and monosaccharides on structural,antioxidant and flavour characteristics of Maillard reaction products from sweet potato protein hydrolysates

Effects of ultrasound (US)-assisted enzymatic hydrolysis and different monosaccharides (arabinose; xylose, XY; galactose and glucose) on peptide structure, antioxidant activities and flavour characteristics of Maillard reaction products (MRP) from sweet potato protein hydrolysates were investigated. US markedly enhanced the MR progress, and USXY showed the lowest pH value of 5.04, the highest browning intensity and fluorescence intensity (P < 0.05). FTIR results revealed significant peptide structure changes in USXY, USAR and USGA compared to other samples. USXY exhibited the highest Oxygen radical absorbance capacity (ORAC) value of 109.15 µg TE/mL, followed by USGA and USAR (94.07 and 93.41 µg TE/mL), respectively (P < 0.05). USXY and USAR showed different aroma features as compared to other MRP (P < 0.05). In addition, US enhanced umami, sweetness and sourness attributes and reduced bitterness of all MRP. USXY exhibited the highest umami intensity score (7.4), followed by USGA (7.3) and USAR (7.2), respectively. Partial least square regression analysis showed that the stronger umami taste was strongly correlated to aldehydes, thiophenes, MW 1000–3000 and 500–1000 Da peptides. Thus, US-assisted enzymatic hydrolysis and MR with xylose (XY) could be a promising way to produce natural flavouring with improved antioxidant activity.     

虾夷扇贝活力变化对其呈味特性的影响研究

目的 研究虾夷扇贝活力变化对于呈味特性的影响。方法 将活品虾夷扇贝在4℃干藏0、6、24 h后,其分别处于不同的活力状态。通过扇贝组织形态、扇贝闭壳肌中三磷酸腺苷（Adenosine triphosphate,ATP）及其关联化合物、腺苷酸能荷（Adenylate energy charge,AEC值）、线粒体活性、能量代谢物水平等指标分析活力;对加热熟制后的各样品进行感官评价,测定呈味化合物含量、计算味觉活度值;最后分析扇贝活力变化对呈味特性的影响。结果 干藏期间扇贝外套膜收缩,活力轻微下降,但ATP及其关联化合物、AEC值均无显著变化。线粒体活性由85.59%显著下降至59.21%,线粒体功能下降。另外,干藏导致糖酵解代谢物糖原由4.32 g/100 g下降至3.14 g/100 g,同时葡萄糖1-磷酸、果糖6-磷酸、磷酸二羟丙酮等代谢物含量显著上升,三羧酸循环（Tricarboxylic acid,TCA）代谢物丙氨酸含量由0.44 mg/g增加至0.71 mg/g。干藏导致扇贝中呈味化合物谷氨酸含量由0.93 mg/g下降至0.51 mg/g,精氨酸含量由9.05mg/g上升至10.56 mg/g,滋味中鲜味降低、苦味上升。结论 虾夷扇贝活力下降导致了谷氨酸含量的下降和精氨酸含量的上升,进而造成扇贝滋味中鲜味的下降和苦味的上升。     

不同酶制剂对银杏浊汁品质的影响

以银杏为原料，通过酶法制备银杏混浊汁，考察不同的淀粉酶和蛋白酶对银杏浊汁品质的影响。结果表明：不同的酶制剂对银杏浊汁的品质有不同的影响，采用组合酶系较使用单一酶制剂效果更好，其中，使用中温α-淀粉酶和Alcalase蛋白酶制备的银杏浊汁悬浮稳定性最好，品质较佳。     

酵母抽提物对原酿黄豆酱呈味物质的影响研究

通过自动电位滴定、高效凝胶过滤色谱等方法研究了1%添加量的3款纯品型和3款5'肌苷酸二钠＋5'鸟苷酸二钠（I+G）型酵母抽提物（YE）对原酿黄豆酱中游离氨基酸、5'-呈味核苷酸、小分子肽等呈味物质和感官评价的影响。结果表明,1%添加量的纯品型酵母抽提物YE3、I+G型YE4以及I+G型YE5分别能明显提升原酿黄豆酱的丙氨酸、谷氨酸、5'-呈味核苷酸等鲜味物质的含量,提升效果分别为90%、27%、63倍;纯品型YE2可使分子质量为400～1 000 Da的小分子肽提升64%,并在口感上对应的体现出提鲜、淡咸、抑苦、增厚和协调整体口感等应用效果,应用效果较好的是3款I+G型酵母抽提物。