Decoupling Macronutrient Interactions during Heating of Model Infant Milk Formulas

Murphy, Eoin G.; Fenelon, Mark A.; Roos, Yrjö H.; Hogan, Sean A.

doi:10.1021/jf503620r

Cited by 39 publications

(28 citation statements)

References 49 publications

(93 reference statements)

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“…For pre-heated solutions, a decrease in denaturation temperature occurred, although the decrease occurred at a lower denaturation temperature and was not statistically significant. It has previously been observed that increasing the protein concentration of β-LG results in a decrease in its denaturation temperature (Qi et al, 1995), with comparable results also observed in mixed whey protein systems (Boyle and Alli, 2000;Murphy et al, 2014).…”

Section: Protein Denaturationsupporting

confidence: 73%

Pilot-scale formation of whey protein aggregates determine the stability of heat-treated whey protein solutions—Effect of pH and protein concentration

Buggy

McManus

Brodkorb

et al. 2018

Journal of Dairy Science

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Denaturation and consequent aggregation in whey protein solutions is critical to product functionality during processing. Solutions of whey protein isolate (WPI) prepared at 1, 4, 8, and 12% (wt/wt) and pH 6.2, 6.7, or 7.2 were subjected to heat treatment (85°C × 30 s) using a pilot-scale heat exchanger. The effects of heat treatment on whey protein denaturation and aggregation were determined by chromatography, particle size, turbidity, and rheological analyses. The influence of pH and WPI concentration during heat treatment on the thermal stability of the resulting dispersions was also investigated. Whey protein isolate solutions heated at pH 6.2 were more extensively denatured, had a greater proportion of insoluble aggregates, higher particle size and turbidity, and were significantly less heat-stable than equivalent samples prepared at pH 6.7 and 7.2. The effects of WPI concentration on denaturation/aggregation behavior were more apparent at higher pH where the stabilizing effects of charge repulsion became increasingly influential. Solutions containing 12% (wt/ wt) WPI had significantly higher apparent viscosities, at each pH, compared with lower protein concentrations, with solutions prepared at pH 6.2 forming a gel. Smaller average particle size and a higher proportion of soluble aggregates in WPI solutions, pre-heated at pH 6.7 and 7.2, resulted in improved thermal stability on subsequent heating. Higher pH during secondary heating also increased thermal stability. This study offers insight into the interactive effects of pH and whey protein concentration during pilot-scale processing and demonstrates how protein functionality can be controlled through manipulation of these factors.

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Section: Protein Denaturationsupporting

confidence: 73%

Pilot-scale formation of whey protein aggregates determine the stability of heat-treated whey protein solutions—Effect of pH and protein concentration

Buggy

McManus

Brodkorb

et al. 2018

Journal of Dairy Science

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“…The presence of increased levels of lactose, which can provide some thermal protection to whey proteins (Murphy et al . ), in UF manufactured WPI was offset, in this case, by the dissimilar mineral composition (mono‐ and di‐valents) compared to ion‐exchange manufactured WPI.…”

Section: Resultsmentioning

confidence: 96%

Concentrated whey protein ingredients: A Fourier transformed infrared spectroscopy investigation of thermally induced denaturation

O’Loughlin

Kelly

Murray

et al. 2015

Int J of Dairy Tech

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Thermal denaturation of whey protein solutions was investigated from a structural perspective utilising attenuated total reflectance -Fourier transformed infrared spectroscopy (ATR-FTIR). Solutions (100 g protein/L, pH 7) of commercial whey protein isolate (WPI) powders and enriched protein fractions of b-lactoglobulin (b-lg) and a-lactalbumin (a-la) were heat-treated at temperatures of 50-90°C. Subsequent analysis by ATR-FTIR highlighted the structural changes occurring as a direct result of heat treatments. Molecularly, WPI dispersions exhibited pronounced differences in denaturation behaviour depending on their method of manufacture. ATR-FTIR is an informative tool to discern the structural molecular interactions not apparent through physical analysis of concentrated ingredients.

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“…In addition, surge in loading around 1620-1618 cm -1 had also been attributed to disruption of intramolecular hydrogen bonds within a secondary structure, leading to formation of new stronger intermolecular hydrogen bonds (Ngarize, et al, 2004). However, unlike previously reported (Murphy, Fenelon, Roos, & Hogan, 2014), increase in intermolecular β sheet (1686 and 1618 cm -1 ) in the current study was not followed with concomitant decline in α-helix (1653 cm -1 ) and intramolecular β sheet structure (1630−1627 cm -1 ). It appeared that though there was an enhancement in intermolecular interactions leading to the aggregation, it was not at expense of intramolecular interactions.…”

Section: Region III Protein (Amide I and Amide Ii) 1700-1500 Cm -1mentioning

confidence: 92%

Fourier transform infrared spectroscopy analysis of physicochemical changes in UHT milk during accelerated storage

Grewal

Chandrapala

Donkor

et al. 2017

International Dairy Journal

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Ultra high temperature (UHT) treated milk undergoes substantial physicochemical changes during processing and storage which may lead to sedimentation. Physio-chemical changes leading to sedimentation primarily involve changes in secondary structure of proteins, protein-protein and protein-fat interactions. The study explored feasibility of FTIR to detect these changes. Moreover, accelerated shelf life testing method involving use of high storage temperature was used as an alternative to long realtime analysis to monitor these changes. UHT whole and skim milk were stored at 20, 30, 40 and 50 °C for a period of 28 days. FTIR was able to detect changes leading to increased sedimentation in skim milk and whole milk at higher temperatures (≥40 °C) in a short period of 14 days. Milk samples stored at 40 and 50 °C showed marked changes in the bands corresponding to confirmation of milk lipids and formation of intermolecular β sheet, suggesting protein-lipid interactions and aggregation. Dried sediment contained fat, further evidencing protein-lipid involvement in sedimentation. However, FTIR was not able to detect changes that led to increased sedimentation in skim milk at temperatures lower than 40 °C. A full length study at 20 and 30 °C might enable detection of changes leading to increase in sedimentation at these temperatures. Furthermore, more extensive analysis will be required to establish marker changes in FTIR spectra which could be used for rapid prediction of shelf life of UHT milk.

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Decoupling Macronutrient Interactions during Heating of Model Infant Milk Formulas

Cited by 39 publications

References 49 publications

Pilot-scale formation of whey protein aggregates determine the stability of heat-treated whey protein solutions—Effect of pH and protein concentration

Pilot-scale formation of whey protein aggregates determine the stability of heat-treated whey protein solutions—Effect of pH and protein concentration

Concentrated whey protein ingredients: A Fourier transformed infrared spectroscopy investigation of thermally induced denaturation

Fourier transform infrared spectroscopy analysis of physicochemical changes in UHT milk during accelerated storage

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