Search

Background: Various methodologies have been employed for the therapeutic interpolation of the progressive brain disorder Alzheimer’s disease. Thus, β-secretase inhibition is significant to prevent disease progression in the early stages. Objective: This study seeks to purify and characterize a novel β-secretase inhibitory peptide from Pacific hake enzymatic hydrolysate. Methods: A potent β-secretase inhibitory peptide was isolated by sequential purifications using Sephadex G-25 column chromatography and octadecylsilane (ODS) C18 reversed-phase HPLC. A total of seven peptides were synthesized using the isolated peptide sequences. SH-SY5Y cells stably transfected with the human ‘‘Swedish’’ amyloid precursor protein (APP) mutation APP695 (SH-SY5YAPP695swe) were used as an in-vitro model system to investigate the effect of Leu-Asn peptide on APP processing. Results: The β-secretase inhibitory activity (IC50) of the purified peptide (Ser-Leu-Ala-Phe-Val-Asp- Asp-Val-Leu-Asn) from fish protein hydrolysate was 18.65 μM and dipeptide Leu-Asn was the most potent β-secretase inhibitor (IC50 value = 8.82 µM). When comparing all the seven peptides, the inhibition pattern of Leu-Asn dipeptide was found to be competitive by Lineweaver-Burk plot and Dixon plot (Ki value = 4.24 µM). The 24 h treatment with Leu-Asn peptide in SH-SY5Y cells resulted in reducing the β-amyloid (Aβ) production in a dose-dependent manner. Conclusion: Therefore, the results of this study suggest that β-secretase inhibitory peptides derived from marine organisms could be potential candidates to develop nutraceuticals or pharmaceuticals as antidementia agents.

Permeability of angiotensin I-converting enzyme (ACE) inhibitory peptides (KPLLCS, ELFTT, and KPLL) identified from the in vitro gastrointestinal digest of cooked chicken breast was investigated using the Caco-2 cell model system. KPLLCS was originally the most effective ACE inhibitor (IC50 0.37 μM), but it was degraded during permeation through Caco-2 cells. Among these peptides, KPLL showed the highest permeability in intact form, and partially degraded to KP and LL, which still showed ACE inhibitory activity after permeation. ACE inhibitory activity of permeated KPLL was highest of 56%. KPLL and KP possessed a mixed inhibitor characteristic, while LL was a non-competitive inhibitor. Based on molecular docking, K at N-terminus of KPLL is a key structure contributing to ACE inhibition as it can occupy the active site of ACE. Determining the structural stability and degree of peptide transport across epithelial cell is required to confirm their potential as ACE inhibitors.

The objectives of this study were to apply response surface methodology to optimize fat-soluble vitamin loading in re-assembled casein micelles, and to evaluate vitamin D stability of dry formulations during ambient or accelerated storage and in fortified fluid skim milk stored under refrigeration. Optimal loading of vitamin A (1.46-1.48mg/100mgcasein) was found at 9.7mM phosphate, 5.5mM citrate and 30.0mM calcium, while optimal loading of vitamin D (1.38-1.46mg/100mg casein) was found at 4.9mM phosphate, 4.0mM citrate and 26.1mM calcium. In general, more vitamin D was retained in vitamin D-re-assembled casein micelles than control powders during storage, while vitamin D loss was not different for vitamin D-re-assembled casein micelles and control fortified milks after 21days of refrigerated storage with light exposure. In conclusion, re-assembled casein micelles with high loading efficiency show promise for improving vitamin D stability during dry storage.

In recent years, peptides derived from a variety of dietary proteins have been reported to exhibit inhibitory activity against the dipeptidyl-peptidase IV (DPP-IV) enzyme, a target in the management of type 2 diabetes. While much attention has been given to the production and identification of peptides with DPP-IV inhibitory activity from food proteins, particularly dairy proteins, little is known on the bioavailability of these molecules. In this study, the stability and transport of five previously identified milk-derived peptides (LKPTPEGDL, LPYPY, IPIQY, IPI and WR) and a whey protein isolate (WPI) digest with DPP-IV-inhibitory activity were investigated using Caco-2 cell monolayers as a model system for human intestinal absorption. Even though a small percentage (ranging from 0.05% for LPYPY to 0.47% for WR) of the bioactive peptides added to the apical side was able to cross the monolayer intact, all five peptides investigated were susceptible to peptidase action during the transport study. Conversely, only minor changes to the WPI digest composition were observed. Determination of the DPP-IV inhibitory activity of the peptides and amino acids identified in the apical and basolateral solutions showed that most degradation products were less effective at inhibiting DPP-IV than the peptide they originated from. Findings from this research suggest that the susceptibility of food-derived DPP-IV inhibitory peptides to degradation by intestinal brush border membrane enzymes may alter their biological activity in vivo. Further research should be conducted to enhance the bioavailability of DPP-IV inhibitory peptides.

Background Diabetes, which currently affects 1 in 11 adults, is considered one of the biggest worldwide health crises of the 21st century. Over the last decade, synthetic inhibitors of the enzyme dipeptidyl-peptidase IV (DPP-IV) have emerged as an effective pharmaceutical approach for the management of type 2 diabetes. These molecules exert their beneficial effect by preventing the inactivation of gut-derived hormones that play a pivotal role in glycemic regulation. More recently, food components have been suggested as sources of DPP-IV inhibitors with the potential to help manage blood glucose levels. Scope and approach This review examines the sources, production, molecular characteristics and modes of action of food-derived DPP-IV inhibitors. Insights into the needs for future research to validate their efficacy and to establish their application in the management of type 2 diabetes are also discussed. Key findings and conclusions To date, hydrolysates of protein from a variety of food commodities, including both plant and animal sources, have been shown to be able to inhibit the activity of the DPP-IV enzyme. Moreover, a number of peptides, either isolated from these hydrolysates or synthetically produced, as well as non-protein-derived compounds such as polyphenols, have also been identified as DPP-IV inhibitors. These food-derived constituents present different degrees of potency and modes of action on the DPP-IV enzyme. While their effectiveness in humans is currently unknown, findings from in vitro and animal studies conducted to date warrant further research to evaluate their potential as functional food ingredients for glycemic regulation.

The effects of high intensity ultrasound (HIU, 105-110 W/cm(2) for 5 or 40 min) pre-treatment of soy protein isolate (SPI) on the physicochemical properties of ensuing transglutaminase-catalyzed soy protein isolate cold set gel (TSCG) were investigated in this study. The gel strength of TSCG increased remarkably from 34.5 to 207.1 g for TSCG produced from SPI with 40 min HIU pre-treatment. Moreover, gel yield and water holding capacity also increased after HIU pre-treatments. Scanning electron microscopy showed that HIU of SPI resulted in a more uniform and denser microstructure of TSCG. The content of free sulfhydryl (SH) groups was higher in HIU TSCG than non-HIU TSG, even though greater decrease of the SH groups present in HIU treated SPI was observed when the TSCG was formed, suggesting the involvement of disulfide bonds in gel formation. Protein solubility of TSCG in both denaturing and non-denaturing solvents was higher after HIU pretreatment, and changes in hydrophobic amino acid residues as well as in polypeptide backbone conformation and secondary structure of TSCG were demonstrated by Raman spectroscopy. These results suggest that increased inter-molecular ε-(γ-glutamyl) lysine isopeptide bonds, disulfide bonds and hydrophobic interactions might have contributed to the HIU TSCG gel network. In conclusion, HIU changed physicochemical and structural properties of SPI, producing better substrates for TGase. The resulting TSCG network structure was formed with greater involvement of covalent and non-covalent interactions between SPI molecules and aggregates than in the TSCG from non-HIU SPI.

High intensity ultrasound (HIU) treated soy protein isolate (SPI) and non-HIU-treated SPI were cross-linked by transglutaminase to form hydrogels. SDS-PAGE showed that HIU increased the amount of high molecular weight aggregates, likely due to the formation of e-(γ-glutamyl) lysine bonds. Moreover, HIU pretreatment increased the hydrophobic nature of transglutaminase gels as demonstrated by FT-Raman. HIU changed the 3D-network structure of transglutaminase induced SPI gel with riboflavin (TSGR). Furthermore, 40 min HIU increased gel yield, riboflavin encapsulation efficiency and gel strength of TSGR. HIU decreased swelling and protein erosion of TSGR in simulated gastrointestinal fluids. It also resulted in reduced riboflavin release rate and altered the release mechanism in simulated gastrointestinal fluids both in the absence and presence of digestive enzymes. In conclusion, HIU may facilitate covalent cross-linking, increase hydrophobicity and change the 3D network of TSGR, leading to differences in hydrogel stability, as well as riboflavin encapsulation and release profiles.

Sudan I is a carcinogenic and mutagenic azo-compound that has been utilized as a common adulterant in spice and spice blends to impart a desirable red color to foods. A novel biosensor combining molecularly imprinted polymers (MIPs), thin layer chromatography (TLC) and surface enhanced Raman spectroscopy (SERS) could determine Sudan I levels in paprika powder to 1 ppm (or 2 ng/spot). Sudan I spiked paprika extracts (spiking levels: 0, 1, 5, 10, 40, 70 and 100 ppm) were prepared. Sudan I imprinted polymers were synthesized by employing the interaction between Sudan I (template) and methacrylic acid (functional monomer), followed by washing to remove Sudan I leaving the Sudan I-binding sites exposed. MIPs were used as a stationary phase for TLC and could selectively retain Sudan I at the original spot with little interference. A gold colloid SERS substrate could enhance Raman intensity for Sudan I in this MIP-TLC system. Principal component analysis plot and partial least squares regression (R(2)=0.978) models were constructed and a linear regression model (R(2)=0.983) correlated spiking levels (5, 10, 40, 70 and 100 ppm) with the peak intensities (721 cm(-1)) of Sudan I SERS spectra. Both separation (30-40s) and detection (1s or 0.1s) were extremely fast by using both commercial bench-top and custom made portable Raman spectrometers. This biosensor can be applied as a rapid, low-cost and reliable tool for screening Sudan I adulteration in foods.

Proteins play a fundamental role not only in sustaining life, but also in foods derived from plants and animals. Foods vary in their protein content, and even more so in the properties of those proteins. In addition to their contribution to the nutritional properties of foods through the provision of amino acids that are essential to human growth and maintenance, proteins impart the structural basis for various functional properties of foods. This chapter provides an introduction to the basic chemical and physical properties of proteins and their amino acid building blocks. It then provides an overview of the molecular forces involved in protein structure, and the various factors that can influence the properties of proteins in food systems, including interactions with food constituents, food processes, and external conditions, chemical derivatizations, and enzymatic modifications. Finally, it highlights the current trends in food protein research.

Background: Thiamin deficiency in infancy is the underlying cause of beriberi, which can be fatal without rapid treatment. Reports of thiamin deficiency are common in Cambodia; however, population representative data are unavailable. Because B-complex vitamin deficiencies commonly occur in combination, riboflavin was also investigated. Objective: We determined the biomarker status of thiamin and riboflavin in women of childbearing age in rural and urban Cambodia. Methods: We measured thiamin (erythrocyte thiamin diphosphate; TDP) and riboflavin (erythrocyte glutathione reductase activity coefficient; EGRac) status in a representative sample of Cambodian women (aged 20‐45 y) in urban Phnom Penh (n = 146) and rural Prey Veng (n = 156), Cambodia, and, for comparison purposes, in a convenience sample of women in urban Vancouver, British Columbia, Canada (n = 49). Results: Thiamin insufficiency (TDP # 90nmol/L) was common among both urban (39%) and rural (59%) Cambodian women (P < 0.001), whereas

The effects of high intensity ultrasound treatment (HUS; 20 kHz at 400 W for 5, 20 or 40 min) on aggregated soybean β-conglycinin (7S) and glycinin (11S) fractions were investigated in this study. HUS decreased turbidity and particle size of 7S in 0.05 M Tris–HCl buffer at pH 7.0, while it increased surface hydrophobicity (H0), solubility, emulsifying activity (EAI) and emulsion stability (ESI). Similarly, HUS of soybean 11S decreased turbidity while increasing EAI but it had minimal effects on particle size and ESI. The SH groups of both 7S and 11S fractions decreased after HUS. HUS did not change 7S or 11S secondary structure, but it slightly increased the percentage of high molecular-weight aggregates under non-reducing SDS-PAGE, and changed the microenvironment of aromatic and aliphatic side chains as observed by Raman spectroscopy of freeze-dried samples. These findings on physicochemical changes of 11S and especially of 7S proteins induced by HUS treatment may contribute to improved applications of soy proteins in food products.

The past decade has seen a burgeoning of literature on food-derived peptides and protein hydrolysates with diverse biological activities, but to date, empirical and bioinformatics studies have provided primarily in vitro data and limited clinical evidence to justify the development of these bioactive peptides and hydrolysates as nutraceuticals and functional foods for promoting health. Several obstacles must be overcome on the road to commercialization of these products. In conjunction with the need to implement efficient and cost-effective strategies for industrial scale production, the successful transfer of the technology to market requires standardization of analytical methods for assurance of product quality, assessment of sensory properties for consumer acceptance, and most importantly, well-designed clinical trials to provide robust evidence for supporting health claims.

Korat-chicken breast and thigh were subjected to heating at 70, 100 or 121 °C for 30 min and simulated in vitro gastrointestinal digestion. At 70 or 100 °C heating, digests of breast possessed higher ACE inhibitory activity than those of thigh. The highest ACE inhibitory activity was found in the digest of breast cooked at 70 °C (B/H-70), whereas breast heated at 121 °C (B/H-121) exhibited the lowest. The 1-kDa permeate of the B/H-70 digest revealed higher permeability through colorectal adenocarcinoma monolayers and ACE inhibitory activity than did B/H-121. Among nine transported peptides, APP derived from myosin showed the highest ACE inhibition, with a non-competitive characteristic (Ki 0.93 μM). Molecular docking showed that APP interacts with ACE via hydrogen bonds, electrostatic and van der Waals interactions. In conclusion, mild thermal treatment of chicken breast resulted in a higher amount of transported peptides, exerting higher ACE inhibitory activity, which could lead to potential health benefits.

We integrated molecularly imprinted polymers with surface-enhanced Raman spectroscopy (MIPs-SERS) to develop an innovative nano-biosensor for the determination of chloramphenicol (CAP) in milk and honey products. Template molecule (CAP), functional monomer (acrylamide), cross-linking agent (ethylene glycol dimethacrylate), initiator (2,2'-azobis(isobutyronitrile)), and porogen (methanol) were employed to form MIPs via "dummy" precipitation polymerization. Static and kinetic studies validated the specific selectivity of MIPs toward CAP over nonimprinted polymers (imprinting factor >4). Canadian penny-based silver nano-structure was synthesized as SERS-active substrate for determination of CAP in food matrices. Collected spectra were processed by principal component analysis to differentiate various concentrations of CAP in foods. Partial least squares regression models showed good prediction values (R > 0.9) of actual spiked contents (0, 0.1, 0.5, 1, 5 ppm) of CAP in milk and honey. This developed nano-biosensor is low cost, requires little sample pretreatment, and can provide reliable detection of trace level of chemical hazards in food systems within a total of 15 min.

The inhibition of the enzyme dipeptidyl-peptidase IV (DPP-IV) is an effective pharmacotherapeutic approach for the management of type 2 diabetes. Recent findings have suggested that dietary proteins, including bovine α-lactalbumin, could be precursors of peptides able to inhibit DPP-IV. However, information on the location of active peptide sequences within the proteins is far from being comprehensive. Moreover, the traditional approach to identify bioactive peptides from foods can be tedious and long. Therefore, the objective of this study was to use peptide arrays to screen α-lactalbumin-derived peptides for their interaction with DPP-IV. Deca-peptides spanning the entire α-lactalbumin sequence, with a frame shift of 1 amino acid between successive sequences, were synthesized on cellulose membranes using “SPOT” technology, and their binding to and inhibition of DPP-IV was studied. Among the 114 α-lactalbumin-derived decamers investigated, the peptides ⁶⁰WCKDDQNPHS⁶⁹ (αKi = 76 µM), ¹⁰⁵LAHKALCSEK¹¹⁴ (Ki = 217 µM) and ¹¹⁰LCSEKLDQWL¹¹⁹ (Ki = 217 µM) were among the strongest DPP-IV inhibitors. While the SPOT- and traditionally-synthesized peptides showed consistent trends in DPP-IV inhibitory activity, the cellulose-bound peptides’ binding behavior was not correlated to their ability to inhibit the enzyme. This research showed, for the first time, that peptide arrays are useful screening tools to identify DPP-IV inhibitory peptides from dietary proteins.

The objective of this study was to purify and characterize the β-secretase inhibitor from enzymatic hydrolysates of skate skin, for the development of a novel antidementia agent that may be utilized in the drug or functional food industries. β-secretase inhibitory peptide was purified from various enzymatic hydrolysates of skate skin. Among six enzymatic hydrolysates, the Neutrase hydrolysate showed the highest β-secretase inhibitory activity. Consecutive purification of the skate skin hydrolysate using Sephadex G-25 column chromatography and octadecylsilane C18 reversed phase HPLC techniques was used to isolate a potent β-secretase inhibitory peptide composed of 12 amino acids, Gln–Gly–Try–Arg–Pro–Leu–Arg–Gly–Pro–Glu–Phe–Leu (MW: 1,391 Da). The purified peptide had strong β-secretase inhibitory activity, with IC50 value of 24.26 μM, and displayed a non-competitive mode of inhibition. Among the synthesized β-secretase inhibitory peptides, the tetrapeptide Pro–Glu–Phe–Leu had the highest β-secretase inhibitory activity. The result of this study suggests that the β-secretase inhibitory peptide derived from skate skin could be potential candidates to develop nutraceuticals and pharmaceuticals.

The objective of this work was to examine the texture, viscosity, rheological properties and meltability of processed cheese analogues prepared using only acid casein (AC) or rennet casein (RC) at 11, 12 or 13% concentration, or using 10% AC or RC plus 1, 2 or 3% whey protein concentrate 80 or isolate. Hardness, adhesiveness and viscosity generally increased while meltability decreased with protein concentration. RC samples were harder but less cohesive than AC samples, and adding whey proteins to RC samples caused greater adhesiveness compared with AC samples. The temperature of decreasing loss tangent and the transition temperature differed between AC and RC samples. All AC samples but only 11% RC samples exhibited good meltability. These distinct properties observed in the current study may provide an approach to control textural/rheological properties and meltability by using the appropriate casein and whey preparations at the proper concentration.

UNLABELLED Sarcoplasmic proteins from 3 fish species were fractionated by 50% to 70% ammonium sulfate precipitation. Lyophilized fractionated sarcoplasmic proteins of threadfin bream (TB-SP), bigeye snapper (BS-SP), and yellow croaker (YC-SP) showed 80% to 92% trypsin inhibitory activity. Trypsin inhibitory activity staining gel electrophoresis revealed bands at 32, 33, 37, 45, 48, and 50 kDa for the 3 species, and a band at 95 kDa was observed for TB-SP and YC-SP. Alpha-1-antitrypsin with molecular mass of 45 to 50 kDa was identified in YC-SP by gel-based liquid chromatography-tandem mass spectrometry (GeLC-MS/MS). Other major protein bands appeared on trypsin activity staining included phosphorylase, glyceraldehyde-3-phosphate dehydrogenase, and creatine kinase with molecular mass of 95 and 35 to 40 kDa, respectively. But, these 3 proteins did not show true trypsin inhibitory activity. Trypsin inhibitory activity of fractionated sarcoplasmic proteins showed good stability, with >80% activity retained at 60 °C and up to 0.6 M NaCl. TB-SP showed the highest inhibitory activity against autolysis of washed threadfin bream mince at 65 °C. Addition of 0.5% or 1% TB-SP improved textural properties of threadfin bream surimi gels preincubated at 37 or 65 °C followed by heating at 90 °C. Therefore, TB-SP could be a promising protein ingredient for enhancing surimi gel texture. PRACTICAL APPLICATION Threadfin bream, bigeye snapper, and yellow croaker are the main species used as raw material for tropical surimi production. Sarcoplasmic proteins from 3 species contain trypsin inhibitor(s) that can minimize proteolytic activity and improve gel texture of proteinase-laden fish muscle. Therefore, sarcoplasmic proteins that are byproducts from surimi processing of these species could be recovered, fractionated, and utilized as a functional protein ingredient.

Inhibition of the enzyme dipeptidyl peptidase (DPP)-IV is one of the strategies used for the treatment of type 2 diabetes. In the present study, pepsin-treated whey protein isolate (WPI) and α-lactalbumin displaying DPP-IV inhibitory activity were fractionated by successive chromatographic steps and the resulting active fractions analyzed for their constituent peptides by liquid chromatography-electrospray ionization-tandem mass spectrometry. Among the identified sequences, 24 peptides derived from α-lactalbumin and 11 from β-lactoglobulin were synthesized and their effects on DPP-IV activity assessed. The most potent fragments, LKPTPEGDL and LKPTPEGDLEIL (IC50=45 and 57 μM, respectively), were found to inhibit DPP-IV in an un-competitive manner. Although several of the peptides tested showed some inhibitory activity, only two were as effective as the un-fractionated WPI hydrolysate and none were as potent as the un-fractionated α-lactalbumin hydrolysate. The peptides' structural features, including length and amino acid composition, were found to impact their inhibitory activity. This study provides new insights on the active components responsible for the DPP-IV inhibitory activity of pepsin-treated whey proteins.

High-intensity ultrasound (HUS; 20 kHz at 400 W for 5, 20 or 40 min) pre-treatments of soy protein isolate (SPI) changed the particle distribution and reduced particle size of SPI dispersions. Surface hydrophobicity and free sulfhydryl (SH) content of SPI increased with HUS time. Free SH content of CaSO 4 -induced SPI gels (CISGs) and protein solubility in the presence of SDS and urea decreased after HUS pretreatments, suggesting HUS facilitated disulfide bond formation during CISG formation. HUS resulted in more uniform and denser gel network, water holding capacity (WHC) and gel strength of CISG. Furthermore, WHC and gel strength were positively correlated with free SH content of heated SPI and surface hydrophobicity of unheated SPI, and negatively correlated with particle size of heated SPI and free SH content of CISG. In conclusion, HUS induced structural changes in SPI molecules, leading to different microstructure and improved WHC and gel strength of CISG.

Inhibitors of the enzymes dipeptidyl peptidase (DPP)-IV and α-glucosidase are two classes of pharmacotherapeutic agents used for the treatment of type 2 diabetes. In the present study, whey protein isolate (WPI), α-lactalbumin, β-lactoglobulin, serum albumin, and lactoferrin hydrolysates obtained by peptic digestion were investigated for their potential to serve as natural sources of DPP-IV and α-glucosidase inhibitors. Although inhibition of DPP-IV activity was observed in all pepsin-treated whey proteins studied, the α-lactalbumin hydrolysate showed the greatest potency with an IC50 value of 0.036 mg/mL. Conversely, only WPI, β-lactoglobulin, and α-lactalbumin hydrolysates displayed some inhibitory activity against α-glucosidase. This study suggests that peptides generated from whey proteins may have dual beneficial effects on glycemia regulation and could be used as functional food ingredients for the management of type 2 diabetes.

The aim of this study was to investigate application of fish protein hydrolysates (FPHs) as cryoprotectants for cod fish mince subjected to freeze-thaw abuse. Response surface methodology revealed little difference in cryoprotectant ability between FPHs produced from Pacific hake muscle within the range of conditions studied, namely Flavourzyme® enzyme/substrate ratio (E/S 1-4%), time (1-6h) and pH (5-7). When added at 4% or higher concentrations, FPH minimized expressible moisture and cook loss, while maximizing salt extractable protein from freeze-thaw abused fish mince, providing similar or better cryoprotection compared to an 8% sucrose-sorbitol blend, and a stabilizing effect of FPH on myosin was observed by differential scanning calorimetry. Sensory evaluation showed that addition of 8% FPH in fish ball products increased the perception of fishiness, saltiness, bitterness and firmness while decreasing moistness. FPH could be a viable alternative to the sugar-based cryoprotectants currently used for frozen fish products.

The effects of low-frequency (20 kHz) ultrasonication at varying power (200, 400 or 600 W) and time (15 or 30 min) on functional and structural properties of reconstituted soy protein isolate (SPI) dispersions were examined. Ultrasonic treatments reduced both the storage modulus and loss modulus of SPI dispersions and formed more viscous SPI dispersions (fluid character). Moreover, ultrasound treatment significantly decreased the consistency coefficients and increased the flow behaviour index of SPI dispersions. Scanning electron microscopy of lyophilized ultrasonicated SPI showed different microstructure with larger aggregates compared to non-treated SPI. No significant change was observed in the protein electrophoretic patterns by SDS-PAGE. However, free sulfhydryl content, surface hydrophobicity and protein solubility of SPI dispersions were all increased with ultrasonic treatment. Differences in solubility profiles in the presence versus absence of denaturing (0.5% sodium dodecyl sulphate and 6 M urea) and reducing (mercaptoethanol) agents suggested a decrease in non-covalent interactions of SPI in dispersion after ultrasonic treatment. Secondary structure analysis by circular dichroism indicated lower α-helix and random coil in SPI treated at lower power, in contrast to higher α-helix and lower β-sheet in SPI treated with higher power (600 W). In conclusion, under the conditions investigated in this study, ultrasonic treatment resulted in partial unfolding and reduction of intermolecular interactions as demonstrated by increases in free sulfhydryl groups and surface hydrophobicity, leading to improved solubility and fluid character of SPI dispersions, while larger aggregates of ultrasonic-treated SPI in the dry state were formed after lyophilization.

Infantile beriberi, a potentially fatal disease caused by thiamine deficiency, remains a public health concern in Cambodia and regions where thiamine-poor white rice is a staple food. Low maternal thiamine intake reduces breast milk thiamine concentrations, placing breastfed infants at risk of beriberi.To determine if consumption of thiamine-fortified fish sauce yields higher erythrocyte thiamine diphosphate concentrations (eTDP) among lactating women and newborn infants and higher breast milk thiamine concentrations compared with a control sauce.In this double-blind randomized clinical trial, 90 pregnant women were recruited in the Prey Veng province, Cambodia. The study took place between October 2014 and April 2015.Women were randomized to 1 of 3 groups (n = 30) for ad libitum fish sauce consumption for 6 months: control (no thiamine), low-concentration (2 g/L), or high-concentration (8 g/L) fish sauce.Maternal eTDP was assessed at baseline (October 2014) and endline (April 2015). Secondary outcomes, breast milk thiamine concentration and infant eTDP, were measured at endline.Women's mean (SD) age and gestational stage were 26 (5) years and 23 (7) weeks, respectively. April 2015 eTDP was measured among 28 women (93%), 29 women (97%), and 23 women (77%) in the control, low-concentration, and high-concentration groups, respectively. In modified intent-to-treat analysis, mean baseline-adjusted endline eTDP was higher among women in the low-concentration (282nM; 95% CI, 235nM to 310nM) and high-concentration (254nM; 95% CI, 225nM to 284nM) groups compared with the control group (193nM; 95% CI, 164nM to 222M; P .05); low-concentration and high-concentration groups did not differ (P = .19). Breast milk total thiamine concentrations were 14.4 μg/dL for the control group (95% CI, 12.3 μg/dL to 16.5 μg/dL) (to convert to nanomoles per liter, multiply by 29.6); 20.7 μg/dL for the low-concentration group (95% CI, 18.6 μg/dL to 22.7 μg/dL ); and 17.7 μg/dL for the high-concentration group (95% CI, 15.6 μg/dL to 19.9 μg/dL). Mean (SD) infant age at endline was 16 (8) weeks for the control group, 17 (7) weeks for the low-concentration group, and 14 (8) for the high-concentration group. Infant eTDP was higher among those in the high-concentration group (257nM; 95% CI, 222nM to 291nM; P .05) compared with the low-concentration (212nM; 95% CI, 181nM to 244nM) and control (187nM; 95% CI, 155nM to 218nM) groups.Compared with women in the control group, women who consumed thiamine-fortified fish sauce through pregnancy and early lactation had higher eTDP and breast milk thiamine concentrations and their infants had higher eTDP, which was more pronounced in the high group. Thiamine-fortified fish sauce has the potential to prevent infantile beriberi in this population.Clinicaltrials.gov Identifier: NCT02221063.

Soybean meal (SBM) inclusion in salmonid diets can lower feed cost, but dramatically reduces growth and feed utilization, and increases mortality in juvenile chinook salmon Oncorhynchus tshawytscha, due to diminished diet palatability and/or other adverse physiological effects exerted by antinutritional factors in SBM. The objective of this study was to investigate whether commercial Antarctic krill meal Euphausia superba or hydrolysates enzymatically produced from Pacific hake Merluccius productus could reverse the negative palatability effects of SBM inclusion in juvenile chinook salmon diets. Diets without SBM or with SBM and no added feed attractant were used as positive and negative control diets respectively. Incorporation of 2% krill meal or Alcalase®-produced hydrolysates into SBM-containing diets (20% of dry matter by isonitrogenous replacement of fishmeal) significantly (P

Dipeptidyl peptidase (DPP)-IV inhibitors are promising new therapies for type 2 diabetes. Currently, these inhibitors are only available as synthetic drugs. Therefore, the aim of the present study was to investigate dairy protein hydrolysates as natural sources of DPP-IV inhibitors. While the DPP-IV inhibitory activity of sodium caseinate, skim milk powder and milk protein concentrate hydrolysates increased over the course of in vitro pepsin-pancreatin digestion, whey protein isolate (WPI) hydrolysate showed highest inhibitory activity following peptic digestion. Hydrolysates produced from sodium caseinate using 11 different proteases displayed higher inhibitory activity than most WPI hydrolysates. However, among all enzymatic treatments investigated, peptic digestion of WPI resulted in the greatest DPP-IV inhibitory activity (IC 50 of 0.075 mg mL −1 ). Fractionation of the hydrolysates by size generally improved the inhibitory activity. This study shows that peptides with DPP-IV inhibitory activity can be generated from dairy ingredients.

To produce and identify antiproliferative peptides, two commercial enzymes, papain (PA) and Protease XXIII (PR) were used to hydrolyse tuna dark muscle byproduct, and the protein hydrolysates were purified, before being evaluated for antiproliferative activities against human breast cancer cell line MCF-7. The results showed that the peptide fractions with the molecular weight ranging from 390 to 1400 Da possessed the greatest antiproliferative activity. The amino acid sequences of the two antiproliferative peptides isolated from PA and PR hydrolysates were Leu-Pro-His-Val-Leu-Thr-Pro-Glu-Ala-Gly-Ala-Thr (1206 Da) and Pro-Thr-Ala-Glu-Gly-Gly-Val-Tyr-Met-Val-Thr (1124 Da), whilst they show the dose-dependent inhibition effect of the MCF-7 cells with IC50 values of 8.1 and 8.8 μM, respectively. We thus conclude that antiproliferative hydrolysates from tuna dark muscle byproduct may be useful ingredients in food and nutraceutical applications.

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 L 16 (4 5 ) experimental design. Protease type significantly ( p IC 50 = 100–200 μg/ml and 70 μg/ml, respectively), accompanied by high yield, high DH and strong bitterness. Furthermore, ACE inhibition was positively correlated ( r 2 = 0.87) with bitterness of the hydrolysates. Fractionation by size-exclusion chromatography revealed that the bitter substances, which also showed strong ACE inhibition, were

Pacific hake fish protein hydrolysate (FPH) with promising chemical assay based antioxidative capacity was studied for in vitro angiotensin-I-converting enzyme (ACE)-inhibitory potential, intestinal cell permeability characteristics, and intracellular antioxidative potential using the Caco-2 cell model system. FPH showed substrate-type inhibition of ACE with IC(50) of 161 microg of peptides/mL. HPLC analysis revealed that different peptides were responsible for antioxidative and ACE-inhibitory activity. FPH inhibited 2,2'-azobis(2-amidinopropane) dihydrochloride-induced oxidation in Caco-2 cells at noncytotoxic concentrations. In vitro simulated gastrointestinal digestion increased (P < 0.05) antioxidative capacity; ACE-inhibitory activity of FPH remained unchanged, although individual peptide fractions showed decreased or no activity after digestion. Some FPH peptides passed through Caco-2 cells: the permeates showed 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) radical scavenging activity but no ACE-inhibitory activity. These results suggest the potential for application of Pacific hake FPH to reduce oxidative processes in vivo. Further studies are needed to assess prospective antihypertensive effects.

Fish protein hydrolysates produced by proteolysis of Pacific hake (Merluccius productus) with Alcalase® (FPH-A) or Flavourzyme® (FPH-F) were investigated as a potential alternative to the 1 : 1 blend of sucrose–sorbitol (SuSo) commonly used for cryoprotection of frozen fish mince. The physicochemical properties of cod mince samples in the absence (control) or presence of 8% FPH-A, FPH-F, or SuSo were evaluated before and after 6 freeze–thaw cycles, with differences noted at the 5% significance level. Freeze–thawing of control sample increased expressible moisture (from 22% to 33%) and cook loss (from 3% to 16%). These poor water retention properties were improved in samples containing FPH or SuSo. Differential scanning calorimetry showed higher proportion of unfrozen water in freeze–thawed samples containing FPH-F or FPH-A (0.36 g/g) compared to SuSo (0.33 g/g) and control (0.24 g/g) samples. Textural analysis of cooked mince from unfrozen samples indicated greater hardness for FPH than SuSo and control samples, while freeze–thawing resulted in decreased hardness for FPH and SuSo samples. Content and surface hydrophobicity of extractable natural actomyosin (NAM) were maintained after freeze–thawing of samples containing FPH-F or SuSo, compared to 50% decrease in extractable NAM and a significant increase in surface hydrophobicity for the control. The presence of oligopeptides in both hydrolysates and the high levels of free amino acids including Asp, Glu, Arg, and Lys in FPH-F might be responsible for their cryoprotective action. This study provides strong evidence to support development of FPH as a new generation cryoprotectant to maintain quality of frozen fish.

The cross-linking of β-lactoglobulin (BLG) was efficiently catalysed by microbial transglutaminase (MTG) but not by fish (threadfin bream) liver transglutaminase (FTG). BLG cross-linking was inhibited by 2 mM 5-(biotinamido) pentylamine (BPNH2) and MTG incorporated BPNH2 into BLG ∼5 times more than was FTG. The glutaminyl sites for the incorporation of BPNH2 into BLG by FTG and MTG were identified using matrix-assisted laser desorption/ionisation-time of flight mass spectrometry (MALDI-TOF MS). MALDI-TOF MS analyses showed that MTG and FTG incorporated 4 and 1 residues of BPNH2 per molecule of BLG, respectively. The BPNH2-tagged BLG was digested by trypsin and BPNH2-tagged peptides were selectively purified by avidin-affinity chromatography. Amino acid sequences of BPNH2-tagged peptides were identified by comparing their MALDI-TOF mass spectra with the theoretical mass profiles from the MASCOT database. The BPNH2-modification sites catalysed by MTG were glutamine (Q)13, Q68, Q15 or Q20, Q155 or Q159, whilst FTG only incorporated BPNH2 into BLG at Q68. The different reactivities between FTG and MTG might be due to the different accessibilities of these TGases to the Q residues as well as to differences in substrate specificities.

Tail muscle tissue free amino acids (FAA) concentration is reported for subadult (4.3 g) Litopenaeus vannamei fed diets containing only protein-bound amino acids, crystalline lysine as a supplement to protein-bound lysine, and only crystalline amino acids (CAA). FAA were determined in shrimp at 0.00, 0.25, 0.5, 1, 2, 4, and 8 h postfeeding. Highest total tissue concentrations of essential amino acids and individual amino acids were typically observed 4 h postfeeding for shrimp fed intact and crystalline lysine-supplemented feeds. Those shrimp offered diets containing only CAA showed no tissue maxima. Similar uptake patterns for lysine shown by shrimp fed the intact and crystalline lysine-supplemented diet indicate the potential use of small amounts of crystalline lysine in shrimp feeds.

The effects of Kudoa infection of Pacific hake (Merluccius productus) on endogenous protease activity and on cooked mince texture were investigated. Texture was significantly (p

Fish protein hydrolysates (FPH) with antioxidative properties were prepared using Pacific hake fish with high endogenous proteolytic activity from Kudoa paniformis parasitic infection. Infection level of ∼107 K. paniformis spores/g fish mince or higher yielded FPH with high antioxidant potential by autolysis and/or Validase® BNP or Flavourzyme® 500L. Autolyzing fish mince containing 30 × 106 spores/g for 1 h at 52 °C and pH 5.50 produced FPH (named E-1h) with Trolox equivalent antioxidant capacity (TEAC) in the 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulphonic acid) radical assay of 262 ± 2 μmol/g and oxygen radical absorbing capacity (ORAC) of 225 ± 17 μmol Trolox equivalents/g freeze-dried sample. E-1h FPH also exhibited a marked concentration-dependent scavenging activity on 1,1-diphenyl-2-picrylhydrazyl radical. Antioxidant activity of E-1h FPH was higher (p < 0.05) than BHA and α-tocopherol in a linoleic acid peroxidation system over prolonged storage (∼162 h). Antioxidative FPH from Pacific hake may be useful ingredients in food and nutraceutical applications.

Fish protein hydrolysate (FPH) produced by incubation of Pacific hake fillet with 3.00% Protamex at pH 6.5 and 40 degrees C for 125 min demonstrated in vitro ACE-inhibitory activity (IC50 = 165 microg/mL), which was enhanced by ultrafiltration through a 10 kDa molecular weight cutoff membrane (IC50 = 44 microg/mL). However, after simulated gastrointestinal digestion, FPH and ultrafiltrate had similar ACE-inhibitory activity (IC 50 = 90 microg/mL), indicating that FPH peptides act as "pro-drug type" inhibitors and that enrichment by ultrafiltration may be unnecessary. Matrix-assisted laser desorption/ionization-time of flight mass spectrometry confirmed that the molecular weights of major peaks were1 kDa regardless of ultrafiltration. ACE-inhibitory activities of digested hydrolysates were not significantly affected by preincubation with ACE ( P0.05) and exhibited a competitive inhibitory mode. A permeability assay using fully differentiated colorectal adenocarcinoma (Caco-2) cells showed an apical to basolateral transport of peptides that ranged from approximately 2 to 20% after 2 h at 37 degrees C. Pacific hake fillet hydrolysates are a potentially bioavailable source of ACE-inhibitory peptides awaiting further in vivo study.

Descriptive sensory analysis (DA) and gas chromatography (GC) analysis were conducted to investigate changes in aroma characteristics of simulated beef flavour (SBF) upon addition of soy protein isolate (SPI). Five attributes (beefy, roasted, yeasty, soymilk-like and cereal) were selected to assess various mixtures of SBF and SPI. The results of DA confirmed that “roasted”, “beefy” and “yeasty” notes were highly positively correlated with SBF concentration, and the beefy related notes were substantially suppressed by increasing SPI content. Fifteen peaks from GC analysis were selected as indicator peaks to represent beefy attribute based on their odour-active properties assessed by GC–olfactometry and correlation of their peak areas with beefy intensity in mixtures of SPI and SBF assessed by DA. The indicator peaks may form the basis of further research to explicate the nature of SPI–SBF interactions to explain the suppression of perceived intensity of beef flavour in soy protein products.

The influence of ingredients such as glucosamine, sucrose, ascorbic acid, and/or polyethylene glycol, on the release of beefy aroma components of simulated beef flavour (SBF) in the presence of soy protein isolate (SPI), were investigated. Conformational changes of SPI protein structure induced by the added ingredients were also detected. Addition of ascorbic acid alone or with polyethylene glycol resulted in reduction of disulfide bonds, increase in surface hydrophobicity and increase in unordered structure of SPI. The SPI–SBF mixtures containing ascorbic acid alone or with polyethylene glycol showed increased GC peak areas of indicator peaks, which were associated with an increase in the perceived beef characteristic attributes in descriptive analysis, as expressed by enhancement of roasted note and diminishing of soymilk-like and cereal notes. These results provide the basis for further research to elucidate strategies to maximize perception of beefy aroma in soy based products.

The in vitro angiotensin I-converting enyzme (ACE) inhibitory activity of Pacific hake hydrolysates was investigated as a function of hydrolysis conditions, starting material variability, and ultrafiltration. Hake fillets were hydrolyzed using Protamex protease under various conditions of pH, hydrolysis time, and enzyme-to-substrate ratio (% E/S) according to a response surface methodology (RSM) central composite design. The hydrolysate produced at pH 6.5, 125 min, and 3.0% E/S had an IC 50 of 165 +/- 9 microg of total solids/mL. ACE-inhibitory activity was not significantly different (P < 0.05) for hydrolysates produced using higher time-enzyme combinations within the model or from fish of different catches. Ultrafiltration (10 kDa molecular mass cutoff) resulted in an IC50 value of 44 +/- 7 microg of peptides/mL, 2.5 times more potent than the commercial product PeptACE Peptides (IC50 = 114 +/- 8 microg of peptides/mL). These results suggest that hydrolysates prepared with minimal fractionation from Pacific hake, an undervalued fish, may be a commercially competitive source of ACE-inhibitory peptides.

La spectroscopie vibrationnelle est un outil adequat pour l'analyse des aliments, dont des produits laitiers. Cet article presente une revue des techniques qui peuvent etre utiles pour etudier les proprietes structurales et les interactions entre proteines laitieres. Des exemples specifiques de recherches recentes conduites dans notre laboratoire utilisant la spectroscopie Raman, micro-Raman et FT-Raman sont decrites pour illustrer leurs applications dans l'etude des interactions proteines/proteines, proteines/lipides et proteines/polysaccharides, et dans l'elucidation des relations structure/fonction des proteines et peptides du lactoserum. La spectroscopie Raman a ete utilisee pour faire la distinction entre les changements de structure de gels de β-lactoglobuline filamenteux ou particulaires. La formation de structures de gel particulaire conduisait a un microenvironnement plus hydrophile ou expose autour des residus tryptophane compare a un microenvironnement plus hydrophobe dans les gels translucides. Une diminution du contenu en helices a etait plus prononcee dans les gels translucides, alors que les deux types de gels retenaient une proportion importante de structures en feuillets β, en accord avec la thermoresistance connue de ces structures dans la β-lactoglobuline. L'analyse en composante principale a demontre que les facteurs traitement thermique et traitement thermique + interactions K-carraghenane etaient ceux qui influaient le plus sur la structure des proteines de lactoserum, comme montre par le suivi des changements de spectre. La spectroscopie micro-Raman a ete utilisee pour etudier les interactions serum-albumine bovine/lipides dans une interface huile-eau. Alors qu'a partir des bandes Raman attribuees aux residus aromatiques ou aliphatiques on pouvait conclure a l'implication des interactions hydrophobes a l'interface huile-eau, la structure secondaire n'etait pas significativement modifiee. Les changements temperature-dependants relatifs a la region C-H du spectre Raman de liposomes composes de differents phospholipides etaient influences par la presence de lactoferricine bovine. Cette approche peut etre utile pour elucider les interactions entre peptides antimicrobiens cationiques et bacteries ou membrane cellulaire de l'hote. Une large gamme d'autres applications ainsi que de nouveaux developpements dans les techniques emergent dans la litterature, montrant les potentialites accrues d'usage de la spectroscopie vibrationnelle pour l'analyse du lait et des produits laitiers.