Variable Glycemic Responses to Intact and Hydrolyzed Milk Proteins in Overweight and Obese Adults Reveal the Need for Precision Nutrition

peer-reviewedBackground Dietary modifications can contribute to improved pancreatic β cell function and enhance glycemic control. Objectives The objectives of this study were as follows: 1) to investigate the potential of milk protein hydrolysates to modulate postprandial glucose response; 2) to assess individual responses; and 3) to explore the inter- and intraindividual reproducibility of the response. Methods A 14-d randomized crossover study investigated interstitial glucose levels of participants in response to 12% w/v milk protein drinks (intact caseinate and casein hydrolysate A and B) consumed in random order with a 2-d washout between treatments. Milk protein drinks were consumed immediately prior to study breakfast and evening meals. Twenty participants (11 men, 9 women) aged 50 ± 8 y with a body mass index (in kg/m2) of 30.2 ± 3.1 were recruited. Primary outcome was glucose levels assessed at 15-min intervals with the use of glucose monitors. Results Repeated-measures ANOVA revealed that for breakfast there was a significant difference across the 3 treatment groups (P = 0.037). The ability to reduce postprandial glucose was specific to casein hydrolysate B in comparison with intact caseinate (P = 0.039). However, despite this significant difference, further examination revealed that only 3 out of 18 individuals were classified as responders (P < 0.05). High intraclass correlation coefficients were obtained for glucose response to study meals (intraclass correlation coefficient: 0.892 for breakfast with intact caseinate). The interindividual CVs were higher than the intraindividual CVs. Mean inter- and intraindividual CVs were 19.4% and 5.7%, respectively, for breakfast with intact caseinate. Conclusion Ingestion of a specific casein hydrolysate successfully reduced the postprandial glucose response; however, at an individual level only 3 participants were classified as responders, highlighting the need for precision nutrition. Exploration of high interindividual responses to nutrition interventions is needed, in combination with the development of precision nutrition, potentially through an n-of-1 approach. This clinical trial was registered as ISRCTN61079365 (https://www.isrctn.com/).Food for Health Irelan

Improved short peptide identification using HILIC-MS/MS: retention time prediction model based on the impact of amino acid position in the peptide sequence

Short peptides can have interesting beneficial effects but they are difficult to identify in complex mixtures. We developed a method to improve short peptide identification based on HILIC-MS/MS. The apparent hydrophilicity of peptides was determined as a function of amino acid position in the sequence. This allowed the differentiation of peptides with the same amino acid composition but with a different sequence (homologous peptides). A retention time prediction model was established using the hydrophilicity and peptide length of 153 di- to tetrapeptides. This model was proven to be reliable (R-2 = 0.992), it was validated using statistical methods and a mixture of 14 synthetic peptides. A whey protein hydrolysate was analysed to assess the ability of the model to identify unknown peptides. In parallel to milk protein database and de nova searches, the retention time prediction model permitted reduction and ranking of potential short peptides, including homologous peptides, present in the hydrolysate. (C) 2014 Elsevier Ltd. All rights reserved

ÔØ Å ÒÙ× Ö ÔØ Identification of short peptide sequences in the nanofiltration permeate of a bioactive whey protein hydrolysate Identification of short peptide sequences in the nanofiltration permeate of a bioactive whey protein hydrolysate

Abstract Short peptides in food protein hydrolysates are of significant interest as they may be highly bioactive whilst also being bioavailable. A dipeptidyl peptidase IV (DPP-IV) inhibitory whey protein hydrolysate (WPH) was fractionated using nanofiltratio

Peptide composition and dipeptidyl peptidase IV inhibitory properties of beta-lactoglobulin hydrolysates having similar extents of hydrolysis while generated using different enzyme-to-substrate ratios

β-Lactoglobulin hydrolysates (βlgHs) were generated using elastase at enzyme-to-substrate ratios (E:S) of 0.5, 1.0 and 1.5% in order to reach target degree of hydrolysis (DH) values of 9 and 13%. The impact of different E:S during manufacture on hydrolysates having similar DHs was assessed. Samples with similar DHs generated with different E:S showed comparable molecular mass distribution profiles and in vitro dipeptidyl peptidase IV (DPP-IV) inhibitory activities (p > 0.05). Liquid-chromatography tandem mass spectrometry (LC-MS/MS) analysis showed that 62 and 84% of the peptides identified were common within hydrolysates having a similar DH of 9 or 13%, respectively. Differences in the peptides identified within hydrolysates having similar DHs may be due to E:S dependent modifications in specificity and enzyme kinetics. Overall, this study showed that reduction in E:S while targeting the development of a similar DH for βlgHs may be employed to reduce the cost of hydrolysate production without having an adverse impact on the bioactivity and physicochemical properties studied herei

Impact of enzyme inactivation conditions during the generation of whey protein hydrolysates on their physicochemical and bioactive properties

The thermal inactivation conditions (75 degrees Cx35min, 80 degrees Cx10min, 85 degrees Cx5min and 90 degrees Cx5min) for Protamex following bovine whey protein concentrate (WPC) hydrolysis was studied with the view to limiting WPC hydrolysate (WPH) aggregation while maintaining bioactivity. A decrease in the amount of large WPH aggregates formed was observed at inactivation temperatures 85 degrees C. However, the WPC appeared to be more hydrolysed on heating at 75 degrees Cx35min, as Protamex was active for longer under these heating conditions. Significantly (P0.05). A reduction in thermal treatment from 90 degrees Cx5min to 85 degrees Cx5min was sufficient to decrease the amount of large aggregates formed in the hydrolysate without altering its bioactive properties

Complexes between linoleate and native or aggregated β-lactoglobulin: Interaction parameters and in vitro cytotoxic effect.

peer-reviewedIron is essential for human health, but it sometimes causes an unpleasant taste, rusty colour and a decrease in the stability of food products. Previously, we found that ethanol-treated yeast (ETY) cells could remove iron from wine and juice, and reduce the fishy aftertaste induced by iron in wine–seafood pairings. However, the mechanism of iron sorption by ETY cells is undefined; thus, there is no indicator that can be used to estimate the iron sorption capacity of these cells. In this study, we showed that cell wall components are not mainly associated with iron sorption by investigating ETY cells with the cell wall removed. Moreover, plasma membrane permeability was correlated with the iron sorbing capacity of the cells. Microscopic analysis showed that iron accumulated within ETY cells. Proteinase-treated ETY cells had no iron sorbing capacity. On the basis of these results, we conclude that intracellular proteins are involved in iron sorption by ETY cells.S. Le Maux is currently supported by a Teagasc Walsh Fellowship and the Department of Agriculture, Fisheries and Food (FIRM project 08/RD/TMFRC/650). We also acknowledge funding from IRCSET-Ulysses Travel Grant

Enzymatic generation of whey protein hydrolysates under pH-controlled and non pH-controlled conditions: Impact on physicochemical and bioactive properties

Enzymatic hydrolysis of whey protein (WP) was carried out under pH-controlled and non pH-controlled conditions using papain and a microbial-derived alternative (papain-like activity). The impact of such conditions on physicochemical and bioactive properties was assessed. WP hydrolysates (WPH) generated with the same enzyme displayed similar degree of hydrolysis. However, their reverse-phase liquid chromatograph mass spectrometry peptide profiles differed. A significantly higher oxygen radical absorbance capacity (ORAC) value was obtained for WP hydrolysed with papain at constant pH of 7.0 compared to the associated WPH generated without pH regulation. In contrast, there was no significant effect of pH regulation on dipeptidyl peptidase IV (DPP-IV) properties. WP hydrolysed with papain-like activity under pH regulation at 7.0 displayed higher ORAC activity and DPP-IV inhibitory properties compared to the associated WPH generated without pH regulation. This study has demonstrated that pH conditions during WPH generation may impact on peptide release and therefore on WPH bioactive properties. (c) 2015 Elsevier Ltd. All rights reserved

Strategies for the release of dipeptidyl peptidase IV (DPP-IV) inhibitory peptides in an enzymatic hydrolyzate of alpha-lactalbumin

Bovine α-lactalbumin (α-La) contains numerous dipeptidyl peptidase IV (DPP-IV) inhibitory peptides sequences within its primary structure. In silico analysis indicated that the targeted hydrolysis of α-La with elastase should release DPP-IV inhibitory peptide sequences. An α-La isolate was hydrolysed with elastase under different conditions using an experimental design approach incorporating 3 factors (temperature, pH and enzyme to substrate ratio (E:S) ratio) at 2 levels. The hydrolyzate generated at pH 8.5, 50C, E:S 2.0% (w/w) (H9) displayed the lowest half maximal DPP-IV inhibitory concentration (IC50 = 1.20 ± 0.12 mg mL-1). Five α-La-derived DPP-IV inhibitory peptides (GY, GL, GI, NY and WL) predicted to be released in silico were identified by liquid-chromatography tandem mass spectrometry (LC-MS/MS) within H9 and its simulated gastrointestinal digestion (SGID) sample. This proof of concept study demonstrated the benefit of using a targeted approach combined with an experimental design in the generation of dietary protein hydrolyzates with DPP-IV inhibitory properties

Quinoa (Chenopodium quinoa Willd.) protein hydrolysates with in vitro dipeptidyl peptidase IV (DPP-IV) inhibitory and antioxidant properties

The potential of quinoa to act as a source of dipeptidyl peptidase IV (DPP-IV) inhibitory and antioxidant peptides was studied. A quinoa protein isolate (QPI) with a purity of 40.73 ± 0.90% was prepared. The QPI was hydrolysed at 50 °C for 3 h with two enzyme preparations: papain (P) and a microbial papain-like enzyme (PL) to yield quinoa protein hydrolysates (QPHs). The hydrolysates were evaluated for their DPP-IV inhibitory and oxygen radical absorbance capacity (ORAC) activities. Protein hydrolysis was observed in the QPI control, possibly due to the activity of quinoa endogenous proteinases. The QPI control had significantly higher DPP-IV half maximal inhibitory concentrations (IC50) and lower ORAC values than QPH-P and QPH-PL (P < 0.05). Both QPH-P and QPH-PL had similar DPP-IV IC50 and ORAC values. QPH-P had a DPP-IV IC50 value of 0.88 ± 0.05 mg mL−1 and an ORAC activity of 501.60 ± 77.34 μmol Trolox equivalent (T.E.) g−1. To our understanding, this is the first study demonstrating the in vitro DPP-IV inhibitory properties of quinoa protein hydrolysates. QPHs may have potential as functional ingredients with serum glucose lowering properties