Hydrolysis Of Sodium Caseinate Research Articles

Caseinophosphopeptides Overcome Calcium Phytate Inhibition on Zinc Bioavailability by Retaining Zinc from Coprecipitation as Zinc/Calcium Phytate Nanocomplexes.

Caseinophosphopeptides have shown great potential to increase zinc bioavailability from phytate-rich diets, but the mechanism of action remains unclear. Here, caseinophosphopeptides from a sodium caseinate hydrolysate dose-dependently retained zinc in solution against calcium phytate coprecipitation under physiologically relevant conditions. The 3 kDa ultrafiltration separation unveiled no added low-molecular-weight chelates of zinc and calcium by caseinophosphopeptides. Tyndall effect, dynamic light scattering measurements, transmission electron microscopy observation, electron diffraction pattern, X-ray diffraction spectrum, and energy-dispersive X-ray analysis demonstrated the caseinophosphopeptides-mediated formation of single-crystal zinc/calcium phytate nanocomplexes (Zn/CaPA-NCs) with a size and ζ-potential of 10-30 nm and -25 mV, respectively. Caseinophosphopeptides-stabilized Zn/CaPA-NCs were found to deliver bioavailable nanoparticulate zinc in mouse jejunal loop ex vivo model and polarized Caco-2 cells, and the treatments with specific inhibitors revealed that intestinal zinc absorption from Zn/CaPA-NCs invoked macropinocytosis, lysosomal release into the cytosol, and transcytosis. Overall, our study proposes a new paradigm for the benefit of caseinophosphopeptides for zinc bioaccessibility and bioavailability in phytate-rich diets.

OBTAINING AND CHARACTERISTICS OF MANNAN-PEPTIDE NANOHYBRID

Bioactive peptides belong to a new generation of biologically active regulators with a wide range of important physiological effects. This determines the prospects for their use in functional foods as dietary supplements and medicine. The main source of such bioactive peptides is cow's milk. It contains proteins, which include 80% caseins. Like other bioactive compounds, they are exposed to unwanted changes in technological processes and during transit along the gastrointestinal tract. In order to improve their stability and increase bioavailability, conjugates obtained by the Maillard reaction have recently been used. Currently, it is positioned as a promising way to prevent the destructive impact of external factors. This article highlights the results of studies designed to determine the feasibility of casein fragmentation with papain to obtain bioactive peptides and the subsequent creation on their basis of a nanohybrid with a mannan component by the Maillard reaction. Enzymatic hydrolysis of sodium caseinate with papain was carried out with varying the duration of the hydrolysis process (30, 60, 120, 180, 240 min). The yield of protein proteolysis products depending on the duration of the process ranged from 77.8% to 83.9%.Enzymatic hydrolysis of sodium caseinate contributed to a significant increase in the products of its fragmentation mass fraction of amine Nitrogen – from 4561.4 to 5687.5 mg/100 g (4.6–5.7%), which is 3.5–4.4 times more than the content of free amino groups in the original sodium caseinate. Among them, almost 1/2 arebioactive peptidescontaining up to 20 amino acid residues.The mannan-peptide nanohybrid was incubated with biopeptides with modified coffee mannan, which had the ability to dissolve in water.The reaction mixture was exposed to 60 oC for 6 h. The yield of lyophilized product was 38.1%, the mass fraction of mannan reached 10.6-10.9%, and peptides, respectively, – 89.1–89.4%. The protective effect of the polysaccharide component against the peptide component was evaluated in vitro in a pepsin-trypsin system. It was found that the stability of peptides in the nanohybrid is much higher than in the original hydrolyzate. The use of the created nanohybrid is possible both to obtain protective shells of labile biologically active substances and to increase the bioavailability of peptides when they are included in dietary supplements and functional foods.

PVOH/protein blend films embedded with lactic acid bacteria and their antilisterial activity in pasteurized milk

PVOH-based polymer matrices in the form of films were evaluated as carriers of living Lactococcus lactis subsp. Lactis. These lactic acid bacteria are capable of producing nisin, which is an effective antilisterial peptide. A low percentage (1:0.125 w/w) of yeast extract, gelatin, sodium caseinate, gelatin, or casein hydrolysates was incorporated in PVOH matrices with the aim of increasing the viability of bacteria in the film. The films were obtained by casting after incorporating L. lactis. Then they were evaluated for antilisterial activity in liquid medium at 37 °C for 24 h, and also at 4 °C for 21 days in order to simulate the storage of liquid foods in refrigeration conditions. The survival of the lactic acid bacteria was also evaluated at both temperatures during the experiment. L. lactis remained viable in all the films tested at 37 and 4 °C. The antimicrobial activity of the films was greater at 4 °C than at 37 °C. With regard to the effect of the film composition, the activity of the films was higher when protein hydrolysates and sodium caseinate were incorporated in the formulation. Films supplemented with protein hydrolysates or sodium caseinate inhibited growth of the pathogen during the 21 days of storage at 4 °C. At 37 °C, after 24 h the films had slowed the growth of the inoculated pathogen by between 2 and 4 log CFU/mL.Finally, as the films developed are intended to be used in the design of active packaging of foods, they were tested in pasteurized milk inoculated with 4 log CFU/mL of Listeria monocytogenes and stored at 4 °C for 21 days. The pathogen began to grow after the second day of storage with or without film, but when the films were added to the medium the growth of the pathogen was slowed down, without reaching >6 log CFU, whereas the control reached a maximum growth of 8.5 log CFU. The pH of the milk was monitored throughout the experiment, and it decreased with time. This was due to the generation of organic acids by the lactic bacteria. Buffering the food stabilized the pH without modifying the activity of the films. Thus, the current study shows that PVOH films supplemented with nutrients can act as carriers of L. lactis, and they can help to increase the safety of refrigerated dairy beverages and sauces.

An innovative two-step enzymatic membrane bioreactor approach for the continuous production of antioxidative casein hydrolysates with reduced bitterness

Enzymatic batch processes bear some disadvantages, such as the high quantity of enzyme, energy and labor needed and, consequently, high production costs. The aim of this study was the production of a sodium caseinate hydrolysate with improved antioxidative capacity and reduced bitterness in a continuous system to avoid such drawbacks. Therefore, a novel, food-grade, two-step enzymatic membrane bioreactor (EMBR) process was designed in which a functional improved permeate with a 33% increased antioxidativity compared to sodium caseinate was produced with the endopeptidases Sternzym BP 25201. This bitter permeate was subsequently debittered in a second EMBR step with commercial Flavourzyme, which was reduced in its endopeptidase activity. This resulted in a linear production of 7.5 gProduct h−1 of antioxidative (antioxidativity: +39% compared to sodium caseinate), debittered peptides. The influence of the peptidases on each other was excluded by separating the endo- and exopeptidases in two EMBR steps and a product with consistent properties like degree of hydrolysis, antioxidativity and taste was obtained. The process conditions chosen were optimal regarding a stable product formation for three days. Therefore, the process was superior in its productivity, enzyme usage and run time compared to an equivalent batch process.

Satiating effect of a sodium caseinate hydrolysate and its fate in the upper gastrointestinal tract

Previously we identified a sodium caseinate (NaCas) hydrolysate, LFC25, which significantly increased secretion of satiety hormone glucagon-like peptide-1 (GLP-1) in vitro and reduced food intake in mice when administered intraperitoneally. This study investigates whether LFC25, administered orally, promotes GLP-1 secretion and/or reduces food intake in vivo. Over an 8-hour period, mice received LFC25 by oral gavage had similar food intake to mice received NaCas. Postprandial blood glucose, plasma active GLP-1, amino acids, insulin and food consumed at the next meal were not significantly different in pigs that consumed LFC25 compared to NaCas in a dairy beverage, at a dosage relevant for human consumption. Simulated in vitro gastro-duodenal digestion of LFC25 revealed a significant reduction in bioactivity. In contrast, the harsh conditions of the upper gut appear to functionalize intact NaCas as a GLP-1 secretagogue. In conclusion, LFC25 will need enteric protection to be used as a food ingredient for satiety.

Development and application of a biocatalyst-filter reactor for the continuous production of caseinate hydrolysate surfactants

Abstract A novel continuous process for enzymatic production of sodium caseinate hydrolysates with a low degree of hydrolysis (DH) and increased interfacial behaviour was developed. Retention of free peptidase in the reactor (separation of the peptidase from the product via an ultra-filtration membrane) was not possible because the peptidase used (thermolysin-like peptidase from Geobacillus stearothermophilus; Sternzym BP 25201; 34 kDa, approximately 4.3 nm) was smaller than the hydrolysate product (up to 90 μm). Thus, the peptidase was immobilized on macroporous particles (Sepabeads EC-EP/M; 200–500 μm) and applied for the process consisting of a stirred reactor vessel and a metal filter (150 μm) as the separation unit. A consistent DH of 2.2–2.6% was obtained by adding about 1/3 of the initial peptidase activity per day or adjusting the residence time. This DH resulted in improved foam and emulsion behaviours (foam stability increased to 139 ± 2.3%; emulsion stability increased to 162 ± 9%) of the filtrate compared to substrate and was like a hydrolysate produced in a batch hydrolysis using the free enzyme. However, the continuous process was superior to the batch process because it resulted in an increased space-time yield (155%) and enzyme productivity (695%).

Peptidomic screening of bitter and nonbitter casein hydrolysate fractions for insulinogenic peptides

Sodium caseinate hydrolysates (NaCaH) contain biologically active peptides that can positively influence human health. However, their intense bitterness hinders their inclusion in food products. To our knowledge, no studies have investigated whether a correlation between bitterness and bioactivity exists in NaCaH, so it is not yet known what effect selective removal of bitterness has on NaCaH bioactivity. A deeper understanding of the physicochemical characteristics affecting both bitterness and bioactivity is therefore needed. The aim of this study was to use in silico analysis to elucidate the relationship between bitterness and bioactivity of the insulinogenic NaCaH. The NaCaH fractions were generated by membrane filtration and flash chromatography and were subsequently evaluated for bitterness by a sensory panel. In this present study, peptidomic and bioinformatic processing of these NaCaH fractions allowed for the identification of insulinogenic peptides as well as other literature-identified peptides in each of the fractions. The results showed that the most bitter fraction contained the highest abundance of insulinogenic peptides, whereas another bitter fraction contained the highest abundance of other literature-identified bioactive peptides exhibiting angiotensin-converting enzyme-inhibition activity. Although some bioactive peptides were identified in the least bitter fractions, the abundance of these peptides was very low. These observations show a correlation between bitter taste and bioactivity, highlighting potential complications in removing bitterness while maintaining bioactivity. However, as the most bitter fraction contained the highest abundance of insulinogenic peptides, there is potential for using a lower dose of this enriched bioactive fraction to exert health benefits. The second most bitter fraction contained a very low abundance of insulinogenic peptides and other bioactive peptides. Therefore, removal of this fraction could reduce the NaCaH product's bitterness without significantly altering overall bioactive potential.

A casein hydrolysate increases GLP-1 secretion and reduces food intake

In an effort to control weight gain, much attention has focused on the identification of bioactive peptides from food sources that induce satiety hormone secretion and increase the feeling of fullness. In this study, a screening platform identified a sodium caseinate hydrolysate, LFC25, that significantly increased calcium signalling in the enteroendocrine cell line, STC-1, and as a result increased secretion of the satiety hormone, GLP-1, in a dose-dependent manner. Administration of this hydrolysate to mice reduced the cumulative food intake over an eight hour period. To determine the feasibility of LFC25 as a food ingredient, production was scaled up to 10 L and spray-dried or freeze-dried without loss of bioactivity.

Angiotensin converting enzyme and dipeptidyl peptidase-IV inhibitory activities of transglutaminase treated sodium caseinate hydrolysates

Angiotensin converting enzyme (ACE) and dipeptidyl peptidase-IV (DPP-IV) inhibitory activities of cross-linked and non-cross-linked sodium caseinate (NaCN) hydrolysates were studied. Three different samples were generated: NaCN hydrolysed with Prolyve 1000™ (Prolyve), NaCN cross-linked with transglutaminase (TGase) pre-Prolyve hydrolysis and NaCN cross-linked post-Prolyve hydrolysis. Gel filtration and reverse phase HPLC analysis of the resulting samples indicated that the hydrolysates had similar peptide profiles. Hydrolysates showed higher (p < 0.05) ACE and DPP-IV inhibitory activity compared with intact protein, but no significant (p > 0.05) differences in activity were found between cross-linked and non-cross-linked hydrolysate samples. Hydrolysate IC50 values for ACE and DPP-IV inhibition ranged from 0.10 to 0.17 mg mL−1 and 0.85–1.18 mg mL−1, respectively. Simulated gastrointestinal digestion had no significant (p > 0.05) effect on the bioactivities of the hydrolysates. The results demonstrated that incubation with TGase before or after NaCN hydrolysis with Prolyve had no effect on ACE or DPP-IV inhibitory activities.

Comparison of conventional heat treatment with selected non-thermal technologies for the inactivation of the commercial protease Protamex™

Preparation of protein hydrolysates for food use requires the elimination of residual enzyme activity after the hydrolysis reaction, which is usually achieved by thermal inactivation. However, precise data on inactivation of commonly used enzymes is still not readily available. Sodium-caseinate hydrolysates were produced with the commercial protease Protamex™. A conventional thermal method to terminate enzymatic hydrolysis was evaluated and complete inactivation of Protamex™ was attained at 95°C for 20s. High intensity light pulses (HILP), Pulsed Electric Fields (PEF), and ultrasound (US) were evaluated as methods to terminate enzymatic hydrolysis. HILP was effective in inactivating Protamex™ in solutions with high optical transmittance particularly in the UV region. A 90% reduction in Protamex™ activity was achieved after a 1min treatment with no significant temperature increase. A PEF treatment (18.2kV/cm, 500 pulses) gave a 70% decrease in Protamex™ activity in a hydrolysate solution while sample temperatures remained below the range for thermal inactivation. Thermosonication did not decrease enzyme activity at temperatures <60°C and at temperatures >60°C any inactivation observed was most likely due to thermal effects. Despite the promising results, further optimisation would be required before these technologies could be considered as alternatives to conventional heat treatments.

Intact sodium caseinate and a sodium caseinate hydrolysate have potential to resolve inflammation through the cessation of proinflammatory signaling

Overweight metabolically unhealthy individuals are characterised by an unresolving chronic low‐grade inflammation which contributes to diseases such as insulin resistance and type‐2 diabetes (T2D) [1]. Dairy proteins have previously demonstrated potent anti‐inflammatory effects resulting in improved glycaemic management, however mechanistic perspectives are lacking [2, 3]. Our study investigates the anti‐inflammatory effects of sodium caseinate (NaCas) and a sodium caseinate hydrolysate (CasH) on cytokine production and inflammatory signalling pathways in an in vitro mouse macrophage cell model. J774.2 macrophages were treated with NaCas or CasH before stimulation with lipopolysaccharide (LPS). TNFα, IL‐1β, IL‐6 and IL‐10 cytokine secretion was determined by ELISA. NF‐κB and MAPK pathway proteins were analysed by western blot. NF‐κB activity in NIH‐3T3/NF‐κB‐luc cells was determined by luciferase assay. Both NaCas and CasH significantly reduced LPS and LPS/ATP induced TNFα and IL‐1β cytokine secretion in J774 macrophages without affecting cell viability. NaCas, and to a lesser extent CasH significantly reduces TNFα and IL‐1β cytokine secretion from BMDMs treated and stimulated with LPS ex vivo, but not TNFα secretion with LPS/IFN in combination. NaCas and CasH significantly reduce LPS induced NFκB transcription factor activity in a dose dependent manner. NaCas and CasH reduce IL‐6 cytokine secretion, with no reduction in IL‐10 with NaCas, but not CasH. Both NaCas and CasH reduced IκBα degradation and NFκBp65 phosphorylation. CasH significantly reduces the phosphorylation of ERK1/2 and p38, but not JNK. Thus, intact NaCas or hydrolysed CasH are potential new anti‐inflammatory ingredients with potential to prevent diseases of unresolved systemic inflammation, however further work is on‐going in terms of defining potential efficacy.Support or Funding InformationThis work was supported by Food for Health Ireland (Enterprise Ireland Grant: CC20080001).

Bitterness in sodium caseinate hydrolysates: role of enzyme preparation and degree of hydrolysis.

Enzymatic hydrolysis of sodium caseinate (NaCas) may lead to the development of bitterness. Careful selection of hydrolysis conditions (i.e. enzyme preparation and duration) yielding different degrees of hydrolysis (DH) may aid in the development of low bitterness. Eighteen NaCas hydrolysates were generated with four enzyme preparations (Alcalase 2.4L, Prolyve 1000, FlavorPro Whey and pepsin) to different DH values. Hydrolysate bitterness score, assessed using a trained panel (ten assessors), generally increased at higher DH values for Alcalase, Prolyve and pepsin hydrolysates. However, all FlavorPro Whey hydrolysates (DH 0.38-10.62%) displayed low bitterness score values (<26.0%) comparable to that of intact NaCas (13.8 ± 2.0%, P > 0.05). Enzyme preparation and DH affect the bitterness of NaCas hydrolysates. The results are relevant for the generation of NaCas hydrolysates with reduced bitterness. © 2017 Society of Chemical Industry.

Impact of enzyme preparation and degree of hydrolysis on peptide profile and nitrogen solubility of sodium caseinate hydrolysates

SummaryThe solubility of casein ingredients is limited under certain pH conditions. Therefore, sodium caseinate (NaCN) was hydrolysed at laboratory scale with four enzyme preparations (Alcalase, Prolyve, FlavorPro Whey and pepsin) yielding hydrolysates having degree of hydrolysis (DH) values between 0.19 ± 0.11 and 19.25 ± 0.73%. The nitrogen solubility index (NSI) over the pH range 2.0–8.0 was affected by (i) the specificity of the enzyme preparation, (ii) the DH and (iii) the presence of unhydrolysed NaCN within the hydrolysate. The trends observed at laboratory scale (&lt;5 L) were also seen with the semi‐pilot‐scale (300 L) hydrolysates generated with Alcalase and FlavorPro Whey. Removal of unhydrolysed NaCN from the FlavorPro Whey hydrolysate using a 5‐kDa ultrafiltration (UF) membrane increased NSI. This study has highlighted the importance of carefully selecting the proteolytic preparation along with the DH to design casein‐based ingredients with enhanced technofunctional properties.

Response surface methodology applied to the generation of casein hydrolysates with antioxidant and dipeptidyl peptidase IV inhibitory properties.

Hydrolysis parameters affecting the release of dipeptidyl peptidase IV (DPP-IV) inhibitory and antioxidant peptides from milk proteins have not been extensively studied. Therefore, a multifactorial (i.e. pH, temperature and hydrolysis time) composite design was used to optimise the release of bioactive peptides (BAPs) with DPP-IV inhibitory and antioxidant [oxygen radical absorbance capacity (ORAC)] properties from sodium caseinate. Fifteen sodium caseinate hydrolysates (H1-H15) were generated with ProtamexTM , a bacillus proteinase activity. Hydrolysis time (1 to 5 h) had the highest influence on both DPP-IV inhibitory properties and ORAC activity (P < 0.05). Alteration of incubation temperature (40 to 60 °C) and pH (6.5 to 8.0) had an effect on the DPP-IV inhibitory properties but not the ORAC activity of the Protamex sodium caseinate hydrolysates. A multi-functional hydrolysate, H12, was identified having DPP-IV inhibitory (actual: 0.82 ± 0.24 vs. predicted optimum: 0.68 mg mL-1 ) and ORAC (actual: 639 ± 66 vs. predicted optimum: 639 µmol TE g-1 ) activity of the same order (P > 0.05) as the response surface methodology (RSM) predicted optimum bioactivities. Generation of milk protein hydrolysates through multifactorial design approaches may aid in the optimal enzymatic release of BAPs with serum glucose lowering and antioxidant properties. © 2016 Society of Chemical Industry.

In silico, in vitro and in vivo analyses of dipeptidyl peptidase IV inhibitory activity and the antidiabetic effect of sodium caseinate hydrolysate.

The frequency (A), a novel in silico parameter, was developed by calculating the ratio of the number of truncated peptides with Xaa-proline and Xaa-alanine to all peptide fragments from a protein hydrolyzed with a specific protease. The highest in vitro DPP-IV inhibitory activity (72.7%) was observed in the hydrolysate of sodium caseinate by bromelain (Cas/BRO), and the constituent proteins of bovine casein also had relatively high A values (0.10-0.17) with BRO hydrolysis. 1CBR (the <1 kDa fraction of Cas/BRO) showed the greatest in vitro DPP-IV inhibitory activity of 77.5% and was used for in vivo test by high-fat diet-fed and low-dose streptozotocin-induced diabetic rats. The daily administration of 1CBR for 6 weeks was effective to improve glycaemic control in diabetic rats. The results indicate that the novel in silico method has the potential as a screening tool to predict dietary proteins to generate DPP-IV inhibitory and antidiabetic peptides.

Masking of bitterness in dairy protein hydrolysates: Comparison of an electronic tongue and a trained sensory panel as means of directing the masking strategy

Sodium caseinate hydrolysates (NaCaHs) are known to be a rich source of bioactive peptides but are also known to have a bitter taste which can make them difficult to incorporate into foods. The objective of the study was to identify whether a commercially available electronic tongue (e-tongue) could be used to identify sweeteners and flavours which reduce bitterness perception in model beverages containing NaCaHs. The two NaCaHs analysed in this study were found to be strongly bitter, the sensory panel found sucralose to be the most effective sweetener, reducing bitterness by a minimum of 39% at the lowest concentration assessed, 0.017% w/w, and the flavour vanilla was the most effective flavouring for further reducing bitterness in a sweetened model beverage. The e-tongue was found to be an effective tool for measuring the reduction of bitterness in of NaCaHs due to different sweeteners but not for evaluating the effect of flavourings in the model beverage. The results also showed good agreement between the e-tongue and sensory panel in the measurement of bitterness and sweetness in sweetened NaCaHs suggesting that the e-tongue maybe a useful device for the selection of sweeteners as bitterness masking agents in NaCaHs.

Biological and physicochemical properties of bovine sodium caseinate hydrolysates obtained by a bacterial protease preparation

In this work, we aimed at the production of bovine sodium caseinate (NaCAS) hydrolysates by means of an extracellular protease from Bacillus sp. P7. Mass spectrometry was carried out to evaluate peptide mass distribution and identified sequences of peptides with a signal/noise ratio higher than 10. Antioxidant and antimicrobial properties of hydrolysates were evaluated. An acid-induced aggregation process of the hydrolysates and their corresponding mixtures with NaCAS were also analyzed. The results showed that the enzymatic hydrolysis produced peptides, mostly lower than 3 kDa, with different bioactivities depending on the time of hydrolysis (ti). These hydrolysates lost their ability to aggregate by addition of glucono-δ-lactone, and their incorporation into NaCAS solutions alter the kinetics of the process. Also, the degree of compactness of the NaCAS aggregates, estimated by the fractal dimension of aggregates, was not significantly altered by the incorporation of hydrolysates. However, at higher protein concentrations, when the decrease in pH leads to the formation of NaCAS acid gels, the presence of hydrolysates alters the microstructure and rheological behavior of these gels.

Characterisation of the physicochemical, residual antigenicity and cell activity properties of transglutaminase cross-linked sodium caseinate hydrolysates

Sodium caseinate (NaCN) was hydrolysed with Prolyve 1000, a Bacillus licheniformis derived proteolytic preparation to a degree of hydrolysis of 21.57 ± 1.2%. An aliquot of this hydrolysate was cross-linked with transglutaminase (TGase). Furthermore, TGase cross-linked NaCN was also hydrolysed with Prolyve 1000. These three hydrolysate samples had broadly similar peptide and molecular mass distribution profiles while the reduction in residual antigenicity was not statistically significant (P > 0.05) between the hydrolysates. Jurkat T cell viability studies showed that the hydrolysate cross-linked prior to hydrolysis was the most cytotoxic of the three hydrolysates studied. There was no significant difference (P > 0.05) between the hydrolysates in catalase activity and glutathione content in Jurkat T cells following 24 h incubation. However, the production of interleukin-2 and interleukin-10 in Con-A stimulated Jurkat T cells was significantly decreased (P < 0.05) in cells incubated with the NaCN hydrolysate that was cross-linked prior to hydrolysis.

Effects of hydrolysis on solid-state relaxation and stickiness behavior of sodium caseinate-lactose powders

Hydrolyzed or nonhydrolyzed sodium caseinate-lactose dispersions were spray dried, at a protein: lactose ratio of 0.5, to examine the effects of protein hydrolysis on relaxation behavior and stickiness of model powders. Sodium caseinate (NC) used included a nonhydrolyzed control (DH 0) and 2 hydrolyzed variants (DH 8.3 and DH 15), where DH = degree of hydrolysis (%). Prior to spray drying, apparent viscosities of liquid feeds (at 70°C) at a shear rate of 20/s were 37.6, 3.14, and 3.19 mPa·s, respectively, for DH 0, DH 8, and DH 15 dispersions. Powders containing hydrolyzed casein were more susceptible to sticking than those containing intact NC. The former had also lower bulk densities and powder particle sizes. Scanning electron microscopy showed that hydrolyzed powders had thinner particle walls and were more friable than powders containing intact NC. Secondary structure of caseinates, determined by Fourier transform infrared spectroscopy, was affected by the relative humidity of storage and the presence of lactose as co-solvent rather than its physical state. Glass transition temperatures and lactose crystallization temperatures, determined by differential scanning calorimetry were not affected by caseinate hydrolysis, although the effects of protein hydrolysis on glass-rubber transitions (Tgr) could be determined by thermo-mechanical analysis. Powders containing hydrolyzed NC had lower Tgr values (∼30°C) following storage at a higher subcrystallization relative humidity (33%) compared with powder with nonhydrolyzed NC (Tgr value of ∼40°C), an effect that reflects more extensive plasticization of powder matrices by moisture. Results support that sodium caseinate-lactose interactions were weak but that relaxation behavior, as determined by the susceptibility of powder to sticking, was affected by hydrolysis of sodium caseinate.

Physicochemical and antioxidant properties of bovine caseinate hydrolysates obtained through microbial protease treatment

It is currently possible to obtain bioactive nutritional components through enzyme hydrolysis under well‐controlled and moderate conditions of pH and temperature. In this work, we aimed for the production and characterisation of bovine sodium caseinate (NaCAS) hydrolysates by means of an extracellular protease from Bacillus sp. P45. Antioxidant properties were evaluated through 2,2‐diphenyl‐1‐picrylhydrazyl and thiobarbituric acid reactive substances assays. A glucono‐δ‐lactone acid‐induced aggregation and gelation processes of the hydrolysates and their corresponding mixtures with NaCAS were also analysed. Hereby, we demonstrate that the presence of hydrolysates affects the kinetics of NaCAS aggregation processes but does not significantly alters the final state of the acid aggregates obtained.