Effect of Moisture, Lipids, and Select Amino Acid Blocking Agents on the Formation and Stability of Metastable Radicals in Powdered Soy Proteins

Boatright, W.L.; Lei, Q.; Jahan, M. S.

doi:10.1111/j.1750-3841.2012.02722.x

Cited by 3 publications

(3 citation statements)

References 31 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Levels of these radicals are initially lower right after the isolated soy protein (ISP) is prepared, and then the level of radicals gradually increases during storage of the powdered protein, especially when exposed to oxygen at 40 °C (Boatright and others ). ISP prepared from defatted soybean flour that had approximately 96% of the native lipids removed, exhibited an initial rate of radical accumulation similar to the control ISP, indicating that the reactions contributing to the formation of metastable radicals in the powdered ISP are not strongly dependent on associated lipids (Boatright and others ). The central singlet EPR signal at g = 2.0049 exhibited a P1/2 power saturation at approximately 2 mW and was located in a manganese EPR signal that was strongest in laboratory‐prepared ISP samples.…”

Section: Introductionmentioning

confidence: 96%

Effect of Sequestering Intrinsic Iron on the Electron Paramagnetic Resonance Signals in Powdered Soy Proteins

Boatright

Jahan

2013

Journal of Food Science

View full text Add to dashboard Cite

This investigation examined iron in powdered soy protein products using electron paramagnetic resonance (EPR) spectroscopy, and the effect that selectively binding free iron in isolated soy protein (ISP) had on the occurrence of metastable radicals in powdered soy proteins. EPR analyses of soybean defatted flour, commercial ISP and laboratory ISP samples revealed a peak at g = 4.3 characteristic of high-spin ferric iron in a rhombic-coordinated environment. Commercial ISP samples examined contained higher levels of the rhombic ferric iron than laboratory-prepared ISP samples. During the first 6 wk of storage the primary singlet EPR signal at g = 2.0049 in the commercial ISP samples approximately doubled, and the laboratory prepared samples increased by about 9-fold. The EPR signal was initially about 4-times higher in the freshly prepared commercial samples compared to the corresponding laboratory ISP. Laboratory ISP samples prepared with added deferoxamine to sequester endogenous iron exhibited a large increase in the high-spin ferric iron EPR signal at g = 4.3. ISP treated with deferoxamine also exhibited a multiple-line EPR signal at about g = 2.007, instead of the typical singlet signal at g = 2.0049. The power at which the signal amplitude was half-saturated also changed from about 1 mW in the control ISP to about 20 mW in the deferoxamine treated ISP. The multiple-line EPR spectrum from the ISP treated with deferoxamine increased during storage over a 6-wk period by about 6-fold. The observed changes in EPR line-shape, g-value, and power saturation with the deferoxamine treatment indicate that the primary free-radical signal in powdered ISP samples may be from stabilized tyrosine radicals with spin densities distributed over the aromatic ring.

show abstract

Section: Introductionmentioning

confidence: 96%

Effect of Sequestering Intrinsic Iron on the Electron Paramagnetic Resonance Signals in Powdered Soy Proteins

Boatright

Jahan

2013

Journal of Food Science

View full text Add to dashboard Cite

show abstract

“…Examples of metastable carbon radicals in several different food protein sources have been shown using solid phase electron paramagnetic resonance (EPR) spectroscopy (Boatright, Lei, & Jahan, 2009;Boatright et al, 2008;Fan et al, 2016). In the powdered form, the type and level of metastable radicals in soy proteins, once formed, were reported to be relatively stable over a 2-year period (Boatright, Lei, & Jahan, 2012). Once the powdered food proteins are hydrated, the metastable radicals are released and can catalyze oxidative reactions such as protein carbonylation, fragmentation, dimerization, and cross-linking (Stadtman & Levine, 2003;Zhao, Xiong, & McNear, 2013).…”

Section: Introductionmentioning

confidence: 99%

Chemically stimulated luminescence from food proteins

2018

View full text Add to dashboard Cite

Background and objectives: Protein powders contain metastable radicals that are released upon hydration. The influence of protein source, free radical content, and hydration condition on luminescence was investigated. Findings: Hydration of rice, soy, pea, and egg albumin generated a burst of luminescence in the absence of added enhancers/stimulates. Rice proteins were generated from 3 to 10 times more luminescence than other protein samples. Hydrating proteins with 25 mM H 2 O 2 increased the luminescence intensities from all food proteins. Luminescence maximums occurred between 550-600 nm for rice protein, 500-600 nm for soy protein, and two peaks from egg albumin (500-550 nm and <450 nm). Carbon-centered metastable radicals were most abundant in rice protein which contained between 3.87 × 10 16 -53.44 × 10 16 spins per gram. Plotting intrinsic luminescence versus spins per gram (including all types of proteins examined) revealed an r-square of 0.771. Conclusions: Based on peak shape, g-value (2.0050 ± 0.0003) and power saturation (4-8 mW), metastable radicals in proteins were identified as carbon-centered. Both intrinsic and added sources of oxidative stimuli strongly correlate with the generation of chemically stimulated luminescence from hydrated proteins. Significance and novelty: These findings are the first to correlate the quantity of metastable radicals in rice proteins with intrinsic luminescence generated upon hydration and provide spectral characterization of luminescence from these proteins. K E Y W O R D Scarbon-centered metastable radicals, chemically stimulated luminescence, electron paramagnetic resonance spectroscopy, rice protein concentrates

show abstract

“…Interestingly, it was previously reported that SPI flours have more carbon-centered radicals than animal protein ingredients such as WPI (Boatright et al, 2008;Boatright et al, 2012;Boatright et al, 2009;Lei et al, 2010). The release of those radicals increased during storage (Boatright et al, 2009) and upon hydration (Boatright et al, 2008).…”

Section: Introductionmentioning

confidence: 99%

Protein oxidation as an integrated aspect of plant protein-based food

Duque-Estrada¹

View full text Add to dashboard Cite

the protein and extracting soluble components (Johnson et al., 2008). The preparation of soy protein isolate (SPI) from the defatted flour involves separation steps under alkaline or acidic conditions (Alibhai et al., 2006;Lawhon et al., 1981).The final step to prepare both SPC and SPI is spray or freeze drying. About 80% of the proteins in SPI are storage globulin proteins: β-conglycinin, formed by three subunits α, α′ and β; and glycinin, composed of acid and basic subunits linked by disulfide bonds (Nishinari et al., 2017). Typically, the protein yield is around 60% of the protein present in the original soybeans (Johnson et al., 2008). Clearly, the isolation process requires a large amount of water and chemicals (van der Goot et al., 2016). Further, the process conditions applied to isolate proteins generally cause protein denaturation and loss of solubility (Jafari et al., 2016;Schutyser & van der Goot, 2011).Given the inefficiency of current fractionation route, there is an interest arising to develop more energy-efficient methods under less severe conditions, such as aqueous or dry fractionation (Geerts et al., 2018;Xing et al., 2018). Such methods do not yield high protein purity, however, some native components and structures are still present in protein-enriched fractions. Fractions obtained under such mild condition can be beneficial for structuring purposes, for instance when making meat analogues with a soy protein ingredient that intrinsically contains fat (Geerts et al., 2018).Recent research has focused on the use of alternative plant protein sources, such as starch-or oil-rich plants (Schreuders et al., 2019). The use of alternatives could increase the variety of food products on the market, in terms of sensory properties and nutritional value. In addition, the use of alternatives would add value to these other crops. Storage stability Bioavailability Water-insoluble iron Water-soluble iron EncapsulationChapter 1 Jacobsen, 2016;Promeyrat et al., 2011). It has been shown that protein oxidation in meat depends on the temperature and time of the treatment. Some related findings are summarized in Table 1. Protein oxidation increased with temperatures above 100 °C for all meat types. Noticeably, cooking bacon led to higher protein oxidation than other meat products and raw bacon already had a substantial level of oxidation.Protein oxidation often leads to changes in the secondary and tertiary structures of proteins, altering their physical properties, such as solubility and hydrophobicity (Santé-Lhoutellier et al., 2007). Table 1, outline studies showing that cooking meat increased hydrophobicity, due to protein denaturation. In meat products, protein oxidation has been associated with a loss of water-holding and gelling capacities, modification in color and flavor, altered texture, loss of essential amino acids and impaired digestion (

show abstract

Effect of Moisture, Lipids, and Select Amino Acid Blocking Agents on the Formation and Stability of Metastable Radicals in Powdered Soy Proteins

Cited by 3 publications

References 31 publications

Effect of Sequestering Intrinsic Iron on the Electron Paramagnetic Resonance Signals in Powdered Soy Proteins

Effect of Sequestering Intrinsic Iron on the Electron Paramagnetic Resonance Signals in Powdered Soy Proteins

Chemically stimulated luminescence from food proteins

Protein oxidation as an integrated aspect of plant protein-based food

Contact Info

Product

Resources

About