Taste modification of amino acids and protein hydrolysate by α-cyclodextrin

Investigation on adaptations of broiler chickens to high dietary free amino acid levels in nitrogen utilisation and plasma amino acid concentrations

1. A reduction in crude protein (CP) in feed for broiler chickens necessitates elevated free amino acid (AA) levels to meet the requirement of each AA. This study investigated adaptations following a change to diets with increasing free AA concentrations and possible reasons for the limitation caused by the inclusion of more free AA.2. Male Ross 308 broiler hatchlings received a starter diet (164 g CP/kg containing 80 g/kg soy protein isolate (SPI)) until d 7. From d 7-22, birds received a diet almost identical to the starter diet or two other diets, where 50% or 100% of digestible AA in SPI were substituted with a free AA mixture. Birds were allocated to metabolism units located in the same barn to determine performance (n = 7 units) and blood traits (n = 14 birds). Total excreta collection was performed on d 7-8, 8-9, 9-10, 11-12, 14-15 and 21-22. Blood samples were collected on d 7, 8, 9, 11, 14 and 21.3. Average daily weight gain (ADG) and average daily feed intake (ADFI) was unaffected at 50% AA substitution but decreased at 100% AA substitution on d 7-22 (p ≤ 0.001). The 100% substitution led to a decline in ADG and ADFI consistently on all days (p ≤ 0.037) except on d 11-12. A 50% AA substitution resulted in lower ADFI on d 7-8 and 14-15 (p ≤ 0.032). Nitrogen utilisation efficiency (NUE) was on a level of ~ 0.74 and was only affected by treatment up to d 11-12 (p ≤ 0.008). Concentrations of 10, 9, 8, 10 and 4 plasma free AA were affected on d 8, 9, 11, 14 and 21, respectively (p ≤ 0.037).4. Following a change to diets containing high levels of free AA, NUE and free AA concentrations in the circulation became more balanced within 3 to 7 d. The results suggested that peptide-bound and free AA did not cause different NUE, particularly 3 and 7 d after the diet change.

Enzymes for production of whey protein hydrolysates and other value-added products

Whey is a byproduct of dairy industries, the aqueous portion which separates from cheese during the coagulation of milk. It represents approximately 85-95% of milk's volume and retains much of its nutrients, including functional proteins and peptides, lipids, lactose, minerals, and vitamins. Due to its composition, mainly proteins and lactose, it can be considered a raw material for value-added products. Whey-derived products are often used to supplement food, as they have shown several physiological effects on the body. Whey protein hydrolysates are reported to have different activities, including antihypertensive, antioxidant, antithrombotic, opioid, antimicrobial, cytomodulatory, and immuno-modulatory. On the other hand, galactooligosaccharides obtained from lactose can be used as prebiotic for beneficial microorganisms for the human gastrointestinal tract. All these compounds can be obtained through physicochemical, microbial, or enzymatic treatments. Particularly, enzymatic processes have the advantage of being highly selective, more stable than chemical transformations, and less polluting, making that the global enzyme market grow at accelerated rates. The sources and different products associated with the most used enzymes are particularly highlighted in this review. Moreover, we discuss metagenomics as a tool to identify novel proteolytic enzymes, from both cultivable and uncultivable microorganisms, which are expected to have new interesting activities. Finally enzymes for the transformation of whey sugar are reviewed. In this sense, carbozymes with ß-galactosidase activity are capable of lactose hydrolysis, to obtain free monomers, and transgalactosylation for prebiotics production. KEY POINTS: • Whey can be used to obtain value-added products efficiently through enzymatic treatments • Proteases transform whey proteins into biopeptides with physiological activities • Lactose can be transformed into prebiotic compounds using ß-galactosidases.

Influence of Complexation with β- and γ-Cyclodextrin on Bioactivity of Whey and Colostrum Peptides

Dairy protein hydrolysates possess a broad spectrum of bioactivity and hypoallergenic properties, as well as pronounced bitter taste. The bitterness is reduced by complexing the proteolysis products with cyclodextrins (CDs), and it is also important to study the bioactivity of the peptides in inclusion complexes. Hydrolysates of whey and colostrum proteins with extensive hydrolysis degree and their complexes with β/γ-CD were obtained in the present study, and comprehensive comparative analysis of the experimental samples was performed. The interaction of CD with peptides was confirmed via different methods. Bioactivity of the initial hydrolysates and their complexes were evaluated. Antioxidant activity (AOA) was determined by fluorescence reduction of fluorescein in the Fenton system. Antigenic properties were studied by competitive enzyme immunoassay. Antimutagenic effect was estimated in the Ames test. According to the experimental data, a 2.17/2.78-fold and 1.45/2.14-fold increase in the AOA was found in the β/γ-CD interaction with whey and colostrum hydrolysates, respectively. A 5.6/5.3-fold decrease in the antigenicity of whey peptides in complex with β/γ-CD was detected, while the antimutagenic effect in the host-guest systems was comparable to the initial hydrolysates. Thus, bioactive CD complexes with dairy peptides were obtained. Complexes are applicable as a component of specialized foods (sports, diet).

Bitter Peptides in Fermented Soybean Foods - A Review

Fermented soybean foods with a long history are popular worldwide because of rich nutrition. However, many traditional fermented soybean foods have unacceptable bitterness, which mostly comes from the bitter peptides produced from the hydrolysis of soybean proteins. In this review, the bitter peptides in fermented soybean foods is briefly reviewed. The structural properties of bitter receptors and bitter peptides were reviewed. Bitterness is perceived through the binding between bitter compounds and specific sites of bitter receptors (25 hTAS2Rs), which further activate the downstream signal pathway mediated by G-protein. And it converts chemical signals into electrical signals, and transmit them to the brain. In addition, the influencing factors of bitter peptides in fermented soybean foods were summarized. The bitterness of fermented soybean foods primarily results from the raw materials, microbial metabolism during fermentation, unique techniques, and interactions of various flavor compounds. Moreover, the structure-bitterness relationship of bitter peptides was also discussed in this review. The bitterness degree of the bitter peptide is related to the polypeptide hydrophobicity, amino acids in the peptide, peptide molecular weight and polypeptide spatial structure. Studying the bitter peptides and their bitter characteristics in fermented soybean foods is beneficial for improving the sensory quality of fermented soybean foods and prompting more consumers accept them.

Computational Methods for the Interaction between Cyclodextrins and Natural Compounds: Technology, Benefits, Limitations, and Trends

Cyclodextrins (CDs) have a hollow structure with a hydrophobic interior and hydrophilic exterior. Forming inclusion complexes with CDs will maximize the bioavailability of natural compounds and enable active components to be processed into functional foods, medicines, additives, and so forth. However, experimental methods cannot explain CD-guest binding at the atomic level. Different models have been recently developed to simulate the interaction between CDs and guests to study the binding conformation and analyze noncovalent forces. This review paper summarizes modeling methods of CD-natural compound complexes. The methods include quantitative structure-activity relationships, molecular docking, molecular dynamics simulations, and quantum-chemical calculations. The applications of these methods to enhance the solubility and bioactivities of guest molecules, assist material transportation, and promote compound extraction are also discussed. The purpose of this review is to explore interaction mechanisms of CDs and guests and to help expand new applications of CDs.

OUP accepted manuscript

Oligosaccharides, a subclass of complex carbohydrates, occur both naturally in foods and as a result of oral starch digestion. We have previously shown that humans can taste maltooligosaccharides (MOS) and that their detection is independent of the canonical sweet taste receptor. While MOSs most commonly occur in a linear form, they can also exist in cyclic structures, referred to as cyclodextrins (CD). The aim of this study was to investigate how the structure of the MOS backbone (i.e. cyclic form) and the size (i.e. degree of polymerization; DP) affect their taste perception. We tested taste detection of cyclodextrins with DP of 6, 7, and 8 (i.e. α-, β-, and γ-CD, respectively) in the presence and absence of lactisole, a sweet receptor antagonist. We found that subjects could detect the taste of cyclodextrins in aqueous solutions at a significant level (P < 0.05), but were not able to detect them in the presence of lactisole (P > 0.05). These findings suggest that the cyclodextrins, unlike their linear analogs, are ligands of the human sweet taste receptor, hT1R2/hT1R3. Study findings are discussed in terms of how chemical structures may contribute to tastes of saccharides.

Main Applications of Cyclodextrins in the Food Industry as the Compounds of Choice to Form Host-Guest Complexes

Cyclodextrins (CDs) are cyclic oligomers broadly used in food manufacturing as food additives for different purposes, e.g., to improve sensorial qualities, shelf life, and sequestration of components. In this review, the latest advancements of their applications along with the characteristics of the uses of the different CDs (α, β, γ and their derivatives) were reviewed. Their beneficial effects can be achieved by mixing small amounts of CDs with the target material to be stabilized. Essentially, they have the capacity to form stable inclusion complexes with sensitive lipophilic nutrients and constituents of flavor and taste. Their toxicity has been also studied, showing that CDs are innocuous in oral administration. A review of the current legislation was also carried out, showing a general trend towards a wider acceptance of CDs as food additives. Suitable and cost-effective procedures for the manufacture of CDs have progressed, and nowadays it is possible to obtain realistic prices and used them in foods. Therefore, CDs have a promising future due to consumer demand for healthy and functional products.

Characterization of fish sausage manufactured with combination of sunflower oil and fish oil stabilized with fish roe protein hydrolysates

The present study aimed to determine the effect of adding protein hydrolysates obtained after 30, 60, and 90 min enzymatic hydrolysis of fish roe on properties of silver carp sausages enriched with fish oil during storage at 4 °C for 30 days. Properties of the fortified sausages were determined by assessment of primary and secondary oxidation, fatty acid composition, microbial spoilage, texture, and organoleptic properties. The results indicated that the hydrolysates could retard oil oxidation and microbial spoilage and preserve n - 3 fatty acids in fish sausages during the refrigerated storage. Also, they rendered firmer microstructure with smaller oil droplets to the sausages. Fish sausages fortified with the hydrolysates were lighter and exhibited better textural and sensory properties. It can be concluded that enzymatic hydrolysates from discarded fish roe can be added to fish sausages containing fish oil to retard oil oxidation and microbial spoilage and improve sausage properties.

Bitterness of fish protein hydrolysate and its debittering prospects

Fish processing by-products often generated as discard can enzymatically be processed into a product known as fish protein hydrolysates (FPH). FPH is a good source of amino acid and peptides with bioactivities. FPH can be added to foods to improve nutritive values and bioactivities. However, bitterness in FPH, associated with hydrophobicity, degree of hydrolysis, molecular weight, proline residues, type of enzymes, and amino acid sequences has limited its uses in foods. Thus, FPH is used in foods at low levels. Numerous procedures such as extraction with alcohol, activated carbon treatment, Maillard reaction, cyclodextrin, chromatographic separation, and enzymatic hydrolysis with exopeptidase and plastein reaction have been explored to remove the bitterness of FPH. These methods can lower bitterness and improve its taste. However, changes in structure and loss of some peptides may occur. FPH with less or no bitterness can therefore be used at higher levels to alleviate nutrition deficiencies in foods. PRACTICAL APPLICATIONS: Fish protein hydrolysate (FPH) is a nutritive ingredient, which can be produced from fish processing by-products. However, bitterness in FPH has limited its potential use as a nutritive ingredient. As a result, it is incorporated into foods at low levels. Nevertheless, application of several reported debittering processes could assist to solve the problem of bitterness in FPH. The debittering can improve sensory property of FPH, thus widening its utilization.

Difference in microbial community and taste compounds between Mucor-type and Aspergillus-type Douchi during koji-making

Douchi has attracted people's attention because of its unique taste and rich health function. The microbes participated in the koji-making process contribute to taste compounds of Douchi. However, the majority of studies on Douchi focused on their functional components and the microbial community in single type of Douchi during koji-making so far. In the present study, the taste components of Mucor-type and Aspergillus-type Douchi were measured initially and the results showed that the amino acid and organic acid levels as well as the percentage of unsaturated fatty acids in Mucor-type Douchi were significantly higher than those in Aspergillus-type. The investigation of the microbial composition in two types of Douchi showed that Aspergillus, Candida, Meyerozyma and Lecanicillium were shared by >50% of samples during koji-making. Comparison of the microbial community between the two types of Douchi revealed that Meyerozyma and Lecanicillium were the main microbial community with significant difference during the initial stage of koji-making, while Candida was significantly different during the later stage of koji-making. When supplemented with Meyerozyma and Candida in Aspergillus-type Douchi, the level of all amino acid and organic acids as well as the percentage of unsaturated fatty acid was significant improved, which further validated the importance roles of the two microorganisms in enhancing the taste components of Douchi during koji-making. The results provide useful information on optimizing the microbial community structure of Douchi during the process of koji-making and improving the product quality.

Bitter taste masking of enzyme-treated soy protein in water and bread

BACKGROUND

Bioactive protein hydrolysates are often very bitter. To overcome this challenge, xylitol, sucrose, α-cyclodextrin, maltodextrin and combinations of these were tested systematically as bitter-masking agents of an enzyme-treated soy protein in an aqueous model and in a bread model. Sensory descriptive analysis was used to reveal the bitter-masking effect of the taste-masking blends on the enzyme-treated soy protein.

RESULTS

In water, xylitol, sucrose and maltodextrin reduced bitterness significantly, whereas α-cyclodextrin did not. No significant difference was observed in bitterness reduction between xylitol and sucrose. Both reduced bitterness significantly more than maltodextrin. No interactions between the taste-masking agents affecting bitterness reduction were found. Clearer bitter-masking effects were seen in the aqueous model compared with the bread model. The bitter-masking effects of α-cyclodextrin and maltodextrin were similar between water and bread. The effect of xylitol and sucrose on bitterness suppression varied between the systems. In water, bitterness was negatively correlated with sweetness. In bread, bitterness was negatively correlated with freshness, and maltodextrin significantly reduced bitterness of the enzyme-treated soy protein and increased freshness.

CONCLUSION

Bitter-masking effects were generally more discernible in the aqueous model compared with the bread model. © 2018 Society of Chemical Industry.

Peptides: Production, bioactivity, functionality, and applications

Production of peptides with various effects from proteins of different sources continues to receive academic attention. Researchers of different disciplines are putting increasing efforts to produce bioactive and functional peptides from different sources such as plants, animals, and food industry by-products. The aim of this review is to introduce production methods of hydrolysates and peptides and provide a comprehensive overview of their bioactivity in terms of their effects on immune, cardiovascular, nervous, and gastrointestinal systems. Moreover, functional and antioxidant properties of hydrolysates and isolated peptides are reviewed. Finally, industrial and commercial applications of bioactive peptides including their use in nutrition and production of pharmaceuticals and nutraceuticals are discussed.

Enhancement of umami taste of hydrolyzed protein from wheat gluten by β-cyclodextrin

BACKGROUND

Wheat gluten was hydrolyzed by Flavourzyme and Neutrase at pH 7.0 and 50 °C for 8 h with β-cyclodextrin (β-CD) employed in the reaction. The hydrolysates were enzyme deactivated, cooled and centrifuged at 1500 × g for 15 min.

RESULTS

Sensory and chemical characterization of wheat gluten hydrolysates WGH-1 (reaction conducted without β-CD), WGH-2 (reaction conducted with β-CD) and WGH-3 (β-CD added to WGH-1) was performed. WGH-2 revealed enhanced umami taste and higher hydrolyzing degree, total free amino acid amount, protein yield and umami taste amino acid (Glu + Asp) amount. High-performance liquid chromatography showed that the proportion of molecular weight 180-500 Da in WGH-2 was 11.5% higher than that in WGH-1. Further research indicated that β-CD had multiple effects on the hydrolysis. It could not only increase the solubility of wheat gluten but also form inclusion complexes with resultants. This can both promote the hydrolysis and protect oligopeptides from degradation.

CONCLUSION

β-CD was found to have the ability to increase the umami taste of enzyme-hydrolyzed vegetable protein from wheat gluten. The reasons analyzed were that β-CD could take part in the hydrolysis process by improving the solubility of wheat gluten and form inclusion complexes with resultants. © 2016 Society of Chemical Industry.

Evaluating the Reduced Hydrophobic Taste Sensor Response of Dipeptides by Theasinensin A by Using NMR and Quantum Mechanical Analyses

The current study demonstrated that theasinensin A (TSA) had a potential to form the complex with hydrophobic Trp-containing dipeptides, and to reduce their membrane potential by artificial-lipid membrane taste sensor. At a 1:3 molar ratio of the 6 Trp-containing dipeptides together with TSA, we observed a significant chemical shift of the protons of the dipeptides (Δδ) to a high magnetic field, when analyzed using ¹H-nuclear-magnetic resonance (NMR) spectroscopy. The Δδ values were correlated with the hydrophobicity (log P) of the dipeptides and significant correlations were obtained (P = 0.022, R² = 0.77); e.g., Trp-Leu with the highest log P value of 1.623 among the tested dipeptides showed the highest Δδ value of 0.105 ppm for the H7 proton of Trp-Leu, while less chemical shifts were observed in theasinensin B and epigallocatechin-3-O-gallate. Diffusion-ordered NMR spectroscopy revealed that the diffusion coefficient of 3 mM of Trp-Leu (7.6 × 10⁻¹¹ m²/s) at a pulse field gradient in the range 0.05–0.3 T/m decreased in the presence of 3 mM TSA (6.6 × 10⁻¹¹ m²/s), suggesting that Trp-Leu forms a complex with TSA. Quantum mechanical calculations and rotating frame nuclear Overhauser effect-NMR spectroscopy provided configuration information on the geometry of the complex that Trp-Leu formed with TSA (1:1 complex) with a ΔG energy of –8.7 kJ/mol. A sensor analysis using artificial-lipid membranes demonstrated that the changes in membrane potential of 1 mM Trp-Leu (21.8 ± 1.3 mV) and Leu-Trp (5.3 ± 0.9 mV) were significantly (P < 0.001) reduced by 1 mM TSA (Trp-Leu, 13.1 ± 2.4 mV; Leu-Trp, 3.5 ± 0.5 mV; TSA alone, 0.2 ± 0.01 mV), indicating the effective suppression of hydrophobicity of dipeptides by TSA-formed complex.

Physical approaches to masking bitter taste: lessons from food and pharmaceuticals

Many drugs and desirable phytochemicals are bitter, and bitter tastes are aversive. Food and pharmaceutical manufacturers share a common need for bitterness-masking strategies that allow them to deliver useful quantities of the active compounds in an acceptable form and in this review we compare and contrast the challenges and approaches by researchers in both fields. We focus on physical approaches, i.e., micro- or nano-structures to bind bitter compounds in the mouth, yet break down to allow release after they are swallowed. In all of these methods, the assumption is the degree of bitterness suppression depends on the concentration of bitterant in the saliva and hence the proportion that is bound. Surprisingly, this hypothesis has only rarely been fully tested using a combination of adequate human sensory trials and measurements of binding. This is especially true in pharmaceutical systems, perhaps due to the greater experimental challenges in sensory analysis of drugs.

Optimization of debittering of soybean antioxidant hydrolysates with β-cyclodextrins using response surface methodology

Antioxidant hydrolysates from soybean have the potential as the new antioxidants, but the bitterness limites their application. A study on the debittering of the soybean antioxidant hydrolysates with β-cyclodextrins and the effects of the debittering conditions on the reducing power of the peptides was conducted using response surface methodology (RSM). The coefficient of determination, R (2) values for bitterness and reducing power were 0.883 and 0.902 respectively. Reducing power of the soybean hydrolysates varied curvilinearly with increase of temperature, mass fraction of β-cyclodextrin, and incubation time. The optimum conditions to obtain the hydrolysates with the minimum bitterness and the maximum reducing power were: temperature 38.50 °C, the mass fraction of β-cyclodextrin 2.00%, and incubation time 12 min, The resulting response functions under this conditions were the reducing power (OD700 nm) of 0.453 and bitterness of 0.290, which was under the threshold for the detection of bitterness taste.