Calculation of Nitrogen‐to‐Protein Conversion Factors: A Review with a Focus on Soy Protein

Krul, Elaine S.

doi:10.1002/aocs.12196

Cited by 88 publications

(46 citation statements)

References 86 publications

(196 reference statements)

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“…The protein contents of the DFSM and SPCs were determined by using a nitrogen analyzer (Flash EA 1112 series Dumas, Thermo Scientific, Breda, The Netherlands). A nitrogen-to-protein conversion factor of 5.7 was used [ 13 ]. The oil content was determined by using petroleum ether as an extraction solvent with a Buchi extraction system B-811LSV (Buchi Labortechnik AG, Flawil, Switzerland).…”

Section: Methodsmentioning

confidence: 99%

Characteristics of Soy Protein Prepared Using an Aqueous Ethanol Washing Process

Kyriakopoulou

Ndiaye³

et al. 2021

Foods

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Currently, the predominant process for soy protein concentrate (SPC) production is aqueous ethanol washing of hexane-extracted soy meal. However, the use of hexane is less desired, which explains the increased interest in cold pressing for oil removal. In this study, cold-pressed soy meal was used as the starting material, and a range of water/ethanol ratios was applied for the washing process to produce SPCs. Washing enriched the protein content for the SPCs, regardless of the solvent used. However, we conclude that washing with water (0% ethanol) or solvents with a high water/ethanol ratio (60% and above) can be more advantageous. Washing with a high water/ethanol ratio resulted in the highest yield, and SPCs with the highest protein solubility and water holding capacity. The water-only washed SPC showed the highest viscosity, and formed gels with the highest gel strength and hardness among all the SPCs at a similar protein concentration. The variations in the functionality among the SPCs were attributed to protein changes, although the effects of non-protein constituents such as sugar and oil might also be important. Overall, the aqueous ethanol washing process combined with cold-pressed soy meal created SPCs comparable to commercial SPC in terms of composition, but with varied functionalities that are relevant for novel soy-food developments.

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Section: Methodsmentioning

confidence: 99%

Characteristics of Soy Protein Prepared Using an Aqueous Ethanol Washing Process

Kyriakopoulou

Ndiaye³

et al. 2021

Foods

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“…Nitrogen content (%N) was quantified using the Dumas combustion method by a Nitrogen/Protein Analyzer (CN628; LECO Corp.), which was converted to protein content (%N × 6.25 for pulses and %N × 5.7 for wheat) following AACC Method 46‐30.01 (AACC, ). For the composite flours, the %protein was calculated as: %N × 6.25 × 0.1 + %N × 5.7 × 0.9 for 10:90 ratio and %N × 6.25 × 0.2 + %N × 5.7 × 0.8 for 20:80 ratio, respectively (Krul, ). The moisture, crude fat and ash contents were performed following AOAC Method 925.10, 920.85, and 923.03, respectively (AOAC, ).…”

Section: Methodsmentioning

confidence: 99%

Properties and bread‐baking performance of wheat flour composited with germinated pulse flours

et al. 2020

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Background and objectives Germination of pulse seeds can effectively improve the functional and nutritional properties of resultant flours for broader food applications to deliver multiple health benefits. However, there is a lack of understanding on the performance of germinated pulse flours in bakery goods, particularly in bread. This study aimed to determine the flour quality, dough properties, and baking performance of composite flours prepared by blending raw or germinated pulse flours and hard wheat flour at 10:90 and 20:80 ratios (w/w). Findings The incorporation of both raw and germinated yellow pea and faba bean flours reduced the starch level but increased the protein level of the flours. The inclusion of the pulse flours progressively decreased the pasting viscosities of the composite flours—with more noticeable changes being observed with the germinated samples, corresponding well with the decreases in their falling numbers. The incorporation of the raw and germinated pulse flours diminished the solvent retention capacity with 5% lactic acid and gluten performance index, and thus, the generated doughs showed shortened dough development time, poorer dough stability, and less elastic structure than the control. The breads baked from the wheat–pulse flour blends—despite the addition of 2% wheat gluten—exhibited decreased loaf volumes and smaller numbers of cells per slice but greater crumb firmness, and the use of 20% germinated pulse flours showed the most significant impact. Conclusions The inclusion of germinated yellow pea and faba bean flours into hard wheat flour weakened the dough structure and caused poorer bread‐baking performance. Significance and novelty The findings from this research greatly advanced our understanding of the roles that germinated pulse flours played in the flour and dough systems after being composited with hard wheat flour as well as their influence on the quality attributes of the baked bread products.

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“…AAA is considered a more accurate quantification method than the indirect alternatives, hence is increasingly used as a species‐specific CP calibration method (Mæhre et al., 2018). As abovementioned, AAA also suffers from several biases mostly due to amino acid degradation or imperfect breakdown of peptide bonds in the hydrolysis phase (Krul, 2019; Mariotti et al., 2008; Mosse, 1990; Rutherfurd & Gilani, 2009). Yet even if we assume high accuracy, intra‐specific variation in non‐protein nitrogenous compounds may hinder attempts to develop species‐specific conversion factors.…”

Section: Discussionmentioning

confidence: 99%

Protein quantification in ecological studies: A literature review and empirical comparisons of standard methodologies

et al. 2021

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Protein quantification is a routine procedure in ecological studies despite the inherent limitations of well‐acknowledged protein determination methods which have been largely overlooked by ecologists. Thus, we want to bridge this knowledge gap, in hopes of improving the way ecologists quantify proteins and interpret findings. We surveyed the ecological literature to determine how and why ecologists quantify proteins. To determine whether different quantification methods produce comparable results across taxa, and between populations of a single species, we estimated the protein content of eight phylogenetically diverse taxa, and of desert isopods fed different diets, using various derived protocols of the 'crude protein', Bradford and bicinchoninic acid approach (BCA) methods. We found that ecologists use many protein quantification procedures, often without reporting the crucial information needed to evaluate and repeat their methods. Our empirical work demonstrated that the three quantification methods examined, and their derived protocols, resulted in highly divergent protein estimations that were inconsistent in rank across taxa, preventing conversion between methods. We also found that different quantification methods yielded different answers to whether isopod protein content is affected by diet. We conclude that commonly used quantification techniques yield distinct protein estimations with varying precision, and no single method is likely to be more accurate than another across taxa which may lead to inconsistent results across taxa and between conspecifics. Inaccurate protein quantification may explain the observed mismatch between organismal N and protein that has plagued some recent studies and that contradicts the principles of ecological stoichiometry. We recommend using a single BCA protocol to reduce inconsistencies across studies, until the promising amino acid analysis becomes more affordable, accurate and accessible to ecologists. Until then, ecologists should consider the abovementioned drawbacks of protein quantification methods and interpret their results accordingly.

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Calculation of Nitrogen‐to‐Protein Conversion Factors: A Review with a Focus on Soy Protein

Cited by 88 publications

References 86 publications

Characteristics of Soy Protein Prepared Using an Aqueous Ethanol Washing Process

Characteristics of Soy Protein Prepared Using an Aqueous Ethanol Washing Process

Properties and bread‐baking performance of wheat flour composited with germinated pulse flours

Protein quantification in ecological studies: A literature review and empirical comparisons of standard methodologies

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