苦味肽和苦味受体研究进展

苦味肽是通常在发酵、老化及水解食品中产生的寡聚肽。人类通过一种包含25种苦味受体的T2Rs苦味受体组感受苦味肽的苦味。文章综述了酶法水解获得的苦味肽的氨基酸序列结构特征。通过对苦味受体的胞外结构域的结构特征及T2Rs基因的单核苷酸多态性的研究有助于理解苦味感知的机制,为开发具有生理活性功能的苦味肽提供依据,同时介绍了苦味抑制研究的进展。     

蛋白质酶法水解物苦味的控制

蛋白质酶法水解物的苦味问题，曾经在很长一段时间内困扰着食品科学家们，并阻碍了蛋白质水解物在食品工业中的应用。本文回顾了蛋白质水解物的苦味问题及其控制，包括苦味物质的化学结构和蛋白质酶法水解过程中苦味的控制及苦味的去除。     

酶解大豆分离蛋白及脱苦技术的研究

本试验对酶法水解大豆分离蛋白及其水解液苦味脱出进行了研究,结果表明,ASI.398中性蛋白酶水解度和水解液苦味值较好,最佳水解条件为pH为7.0,温度50℃,底物浓度5%,酶浓度8%,水解时间6h。大豆蛋白水解液采用1%粉末状活性炭,0.8%β-环状糊精和0.08%柠檬酸,三者联合脱苦风味较好。     

大豆蛋白水解液脱苦的研究

大豆蛋白酶解常常会产生苦味,蛋白质水解物苦味肽的苦味是长期困扰其应用的问题。本文研究了酶法与微生物法对大豆蛋白水解液脱苦的效果。结果表明:采用端肽酶黑曲霉酸性蛋白酶(3000u/g)与内切酶枯草杆菌碱性蛋白酶(Alcalase 2.4L)协同作用水解大豆蛋白可有效降低水解液苦味,并且由酿酒酵母对水解液进一步处理后,大豆蛋白水解液的苦味降至更低。     

大豆蛋白水解液脱苦的研究

大豆蛋白酶解常常会产生苦味，蛋白质水解物苦味肽的苦味是长期困扰其应用的问题。本文研究了酶法与微生物法对大豆蛋白水解液脱苦的效果。结果表明：采用端肽酶黑曲霉酸性蛋白酶(3000u／g)与内切酶枯草杆菌碱性蛋白酶(Alcalase 2．4L)协同作用水解大豆蛋白可有效降低水解液苦味，并且由酿酒酵母对水解液进一步处理后，大豆蛋白水解液的苦味降至更低。     

蛋白酶脱除大豆蛋白水解物苦味的研究进展

主要概述大豆蛋白水解研究的起源,蛋白水解物的苦味以及苦味形成理论的研究进展。从蛋白酶催化特性的角度阐述了蛋白水解物苦味形成的直接根源,以及蛋白酶酶法脱苦的理论及研究概况,并对这一领域的研究前沿提出了自己的设想。     

大豆蛋白水解物的苦肽以及脱除方法进展

详细地论述了苦肽的结构与苦味相关理论,包括其苦味与疏水度和空间结构的关系以及苦肽的呈味机,在此基础上,总结并探讨了大豆蛋白不同酶水解物所含有的苦肽以及脱除方法,后者包括有选择分离法、掩盖法、膜分离法、“类蛋白反应”法以及酶法等。重点综述了酶法脱除大豆蛋白水解的研究进展。     

酶法水解谷朊生产生物活性肽

生物酶法改性食品蛋白是提高蛋白功能的重要途径。采用酶法水解谷朊制备生物活性肽 ,对蛋白酶的选择、酶水解工艺参数、多肽苦味的去除及酶解后产品性能进行了系统研究 ,并提出可行性生产工艺路线。     

多酶水解棉籽分离蛋白制备低苦味肽的研究

以水解度为指标,采用酶法水解制备棉籽生物活性肽,在单酶水解的基础上探讨双酶水解工艺.确定碱性蛋白酶和胰蛋白酶为最佳的双酶组合,其最佳酶解条件为:温度50℃,pH8.2,底物浓度5%,水解时间3.5h.酶活添加量6000μ/g(蛋白),酶活比3:1,进行验证实验水解度能达到26.67%,肽得率为87.35%.采用风味酶继续水解,有效降低了苦味,肽得卒为85.26%.     

苦味肽的形成及其脱苦研究进展

蛋白质水解后会产生各种多肽和氨基酸,可以有效地改善蛋白质的溶解性、起泡性、乳化性、吸水性,还能生成各种生物活性肽。但蛋白质水解后产生的苦味肽又限制了水解产物在食品中的应用。综述了蛋白质水解产生苦味的原因及脱苦方法,以期对酶水解产物的苦味脱除研究提供依据。     

乙醇对谷朊粉酶解产物的苦味影响研究

为了探寻降低谷朊粉酶解产物苦味的方法,通过添加不同浓度的乙醇(5%、10%和15%),研究其对碱性蛋白酶酶解产物苦味值、游离氨基酸和相对分子质量分布的影响,以及在乙醇存在下碱性蛋白酶、中性蛋白酶以及风味蛋白酶3种复配酶解体系所制得的酶解产物的苦味值和相对分子质量分布变化。结果表明:加入乙醇后,在相同的水解度下(DH),碱性蛋白酶的酶解产物苦味值降低,并与加入乙醇的浓度呈负相关。添加乙醇后,相对分子质量小于1 000的组分含量显著(P0.05)降低,游离疏水性氨基酸(Pro,Ile,Phe和Met)显著(P0.05)增加。添加乙醇后,3种复配酶解体系酶解产物苦味降低,相对分子质量小于1 000的组分含量显著(P0.05)降低。与添加碱性蛋白酶单一酶解相比,在相同的水解度下3种酶复配酶解产物的苦味值进一步降低。添加低浓度乙醇对3种酶的活性影响较小。     

高钙奶苦味原因分析

通过有苦味的高钙奶样品中的细菌总数、蛋白质水解度、寡肽含量、游离氨基酸含量、蛋白酶活性等指标的测定,对高钙奶在保质期末出现苦味的原因进行分析。结果表明苦味高钙奶和无苦味牛奶样品中的细菌总数无显著差异(p≥0.05),苦味高钙奶中的寡肽、游离氨基酸含量,特别是苦味氨基酸含量显著高于无苦味牛奶样品(p<0.05),苦味牛奶样品中的蛋白酶活性显著高于无苦味牛奶样品(p<0.05),同时高钙奶中添加的碳酸钙和稳定剂中的蛋白酶也有较高活性。高钙奶苦味主要是由于牛奶中的内源或外源性蛋白酶水解酪蛋白,生成苦味的游离氨基酸、寡肽等造成的,针对这一原因,可通过提高原料乳和添加剂的卫生质量、控制生产加工过程中的卫生、调整和改进杀菌工艺等方法,以避免高钙奶的苦味问题。     

Enzymatic Production,Bioactivity, and Bitterness of Chickpea (Cicer arietinum) Peptides

Chickpeas are inexpensive, protein rich (approximately 20% dry mass) pulses available worldwide whose consumption has been correlated with positive health outcomes. Dietary peptides are important molecules derived from dietary proteins, but a comprehensive analysis of the peptides that can be produced from chickpea proteins is missing in the literature. This review provides information from the past 20 years on the enzymatic production of peptides from chickpea proteins, the reported bioactivities of chickpea protein hydrolysates and peptides, and the potential bitterness of chickpea peptides in food products. Chickpea peptides have been enzymatically produced with pepsin, trypsin, chymotrypsin, alcalase, flavorzyme, and papain either alone or in combination, but the sequences of many of the peptides in chickpea protein hydrolysates remain unknown. In addition, a theoretical hydrolysis of chickpea legumin by stem bromelain and ficin was performed by the authors to highlight the potential use of these enzymes to produce bioactive chickpea peptides. Antioxidant activity, hypocholesterolemic, and angiotensin 1‐converting enzyme inhibition are the most studied bioactivities of chickpea protein hydrolysates and peptides, but anticarcinogenic, antimicrobial, and anti‐inflammatory effects have also been reported for chickpea protein hydrolysates and peptides. Chickpea bioactive peptides are not currently commercialized, but their bitterness could be a major impediment to their incorporation in food products. Use of flavorzyme in the production of chickpea protein hydrolysates has been proposed to decrease their bitterness. Future research should focus on the optimization of chickpea bioactive peptide enzymatic production, studying the bioactivity of chickpea peptides in humans, and systematically analyzing chickpea peptide bitterness.     

Sensory Flavor Characteristics of Water-Extracted Soluble Orange Solids Produced in Florida

Commercial Florida-packed water-extracted soluble orange solids (PESOS) had poor flavor quality and varied widely within an unacceptable flavor range. Major problems were bitterness, processed off-flavor and spoilage. WESOS flavor was inferior to orange juice made from the same lots of fruit. As little as 10% of a poor-flavored, bitter WESOS sample or about 50% addition of better-flavored WESOS added to good orange juice resulted in unacceptably flavored product. Late season fruit within a single season made betterflavored WESOS than did early-midseason fruit. WESOS flavor and bitterness varied from plant-to-plant; generally plants that produced the best-flavored WESOS had the least amounts of product bitterness.     

苦瓜系列产品的研制

苦瓜具有良好的食用和药用价值,但由于其带有明显的苦味,而不容易被消费者所接受。采用新鲜苦瓜为原料,通过控制苦瓜成熟度及采用酶处理、调配、热烫等加工方法,解决了苦瓜明显苦味所带来的口感缺陷,保持了苦瓜特有的清香,研制出多种风味独特的苦瓜系列产品。     

Angiotensin-I-converting enzyme inhibitory activity and bitterness of enzymatically-produced hydrolysates of shrimp (Pandalopsis dispar) processing byproducts investigated by Taguchi design

The importance of water-to-substrate ratio, protease type, percent enzyme and incubation time on hydrolysates produced from shrimp processing byproducts was investigated using Taguchi’s L₁₆ (4⁵) experimental design. Protease type significantly (p < 0.05) influenced soluble yield, degree of hydrolysis (DH), angiotensin-I-converting enzyme (ACE) inhibitory activity and bitterness of hydrolysates, while percent enzyme only affected the DH. Hydrolysates produced by Alcalase and Protamex possessed strong ACE inhibitory activity (IC₅₀ = 100–200 μg/ml and 70 μg/ml, respectively), accompanied by high yield, high DH and strong bitterness. Furthermore, ACE inhibition was positively correlated (r² = 0.87) with bitterness of the hydrolysates. Fractionation by size-exclusion chromatography revealed that the bitter substances, which also showed strong ACE inhibition, were <3 kDa in size and contained many hydrophobic residues, including Tyr, Phe, Leu, Ile, Val and Lys. Despite the bitterness, these hydrolysates may have potential health benefits, arising from their potent ACE inhibitory activity.     

Modification of perceived beer bitterness intensity,character and temporal profile by hop aroma extract

The effect of hop aroma on perceived bitterness intensity, character and temporal profile of beer was investigated. A hop aroma extract was added at 3 levels (0, 245, 490 mg/L) to beers at low, medium and high bitterness. Beers were evaluated for perceived bitterness intensity, harshness, roundedness and linger by a trained panel using a rank-rating technique at each bitterness level, with and without nose clips. The use of nose clips enabled the olfactory aspect to be decoupled from taste and mouthfeel aspects of bitterness perception. Results showed significant modification of perceived bitterness in beer by hop aroma depending on the inherent level of bitterness. These modifications were mainly driven by olfaction – in an example of taste-aroma interactions, as well as certain tactile sensations elicited by the hop aroma extract in the oral cavity. At low bitterness, beers with hop aroma added were perceived as more bitter, and of ‘rounded’ bitterness character relative to those without hop aroma. When judges used nose clips, this effect was completely eliminated but the sample was perceived to have a ‘harsh’ bitterness character. Conversely, at high bitterness, even when nose clips were used, judges still perceived beers containing hop aroma to be more bitter. These increases in bitterness perception with nose clips indicates the stimulating of other receptors, e.g. trigeminal receptors by hop aroma extract, which in tandem with the high bitterness, cause perceptual interactions enhancing bitterness intensity and also affecting bitterness character. Bitterness character attributes such as ‘round’ and ‘harsh’ were found to significantly depend on bitterness and aroma levels, with the second level of aroma addition (245 mg/L) giving a ‘rounded’ bitterness in low bitterness beers but ‘harsh’ bitterness in high bitterness beers. The impact of aroma on temporal bitterness was also confirmed with time-intensity measurements, and found to be mostly significant at the highest level of hop aroma addition (490 mg/L) in low bitterness beers. These findings represent a significant step forward in terms of understanding bitterness flavour perception and the wider impact of hop compounds on sensory perception.     

Protein hydrolysate from salmon frame debittered by plastein reaction: amino acid composition,characteristics and antioxidant activities

Impacts of plastein reaction on bitterness, physicochemical and antioxidant properties of salmon frame hydrolysate with the aid of various proteases (alcalase and papain) at different concentrations and varying reaction temperatures were investigated. Plastein was produced from hydrolysate by papain at 40°C, which had 30% degree of hydrolysis (30DHP). Rearrangement of peptides in hydrolysate was performed by 1% papain at 40°C for 10 h, yielding plastein namely ‘30DHP-P1’. It showed the lowest bitterness (P < 0.05) than other plasteins and hydrolysates. Surface hydrophobicity was not related well with bitterness. Therefore, the size of peptides also determines the bitterness. 30DHP-P1 had augmented solubility; however, its antioxidant activities (DPPH and ABTS radical scavenging activities and ferric reducing antioxidant power) were slightly lower (P < 0.05) than those of hydrolysates. Bitterness of hydrolysate was markedly debittered via plastein reaction under optimal condition. Plastein generally had lighter colour and still possessed antioxidant activity.     

Ultrafiltered milk reduces bitterness in reduced-fat Cheddar cheese made with an exopolysaccharide-producing culture

The objectives were to reduce bitterness in reduced-fat Cheddar cheese made with an exopolysaccharide (EPS)-producing culture and study relationships among ultra-filtration (UF), residual chymosin activity (RCA), and cheese bitterness. In previous studies, EPS-producing cultures improved the textural, melting, and viscoelastic properties of reduced-fat Cheddar cheese. However, the EPS-positive cheese developed bitterness after 2 to 3 mo of ripening due to increased RCA. We hypothesized that the reduced amount of chymosin needed to coagulate UF milk might result in reduced RCA and bitterness in cheese. Reduced-fat Cheddar cheeses were manufactured with EPS-producing and nonproducing cultures using skim milk or UF milk (1.2×) adjusted to a casein:fat ratio of 1.35. The EPS-producing culture increased moisture and RCA in reduced-fat Cheddar cheese. Lower RCA was found in cheese made from UF milk compared with that in cheese made from control milk. Ultrafiltration at a low concentration rate (1.2×) produced EPS-positive, reduced-fat cheese with similar RCA to that in the EPS-negative cheese. Slower proteolysis was observed in UF cheeses compared with non-UF cheeses. Panelists reported that UF EPS-positive cheese was less bitter than EPS-positive cheese made from control milk. This study showed that UF at a low concentration factor (1.2×) could successfully reduce bitterness in cheese containing a high moisture level. Because this technology reduced the RCA level (per g of protein) to a level similar to that in the control cheeses, the contribution of chymosin to cheese proteolysis would be similar in both cheeses.