Protein Determination—Method Matters

Mæhre, Hanne K; Dalheim, Lars; Edvinsen, Guro Kristine; Elvevoll, Edel O.; Jensen, Ida‐Johanne

doi:10.3390/foods7010005

Cited by 418 publications

(217 citation statements)

References 28 publications

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“…Most methods of protein analysis tend to overestimate the amount of protein, and the Food and Agriculture Organisation of the United Nations (FAO) recommended that total protein is established by amino acid analysis [108]. Thus, the total amino acid content can be taken as a reasonable indication of total protein.…”

Section: Protein and Amino Acidsmentioning

confidence: 99%

Sargassum Inundations in Turks and Caicos: Methane Potential and Proximate, Ultimate, Lipid, Amino Acid, Metal and Metalloid Analyses

et al. 2020

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The Caribbean has been experiencing beach inundations of pelagic Sargassum, causing environmental, health and financial issues. This study showed variations in the composition and methane potential (MP) between the species of Sargassum. The MPs for S. natans VIII, S. natans I and S. fluitans (145, 66 and 113 mL CH4 g−1 Volatile Solids) were considerably below theoretical potentials, possibly due to the high levels of indigestible fibre and inhibitors. The mixed mats Sargassum composition was substantially different from the individual species, being higher in ash, calcium, iron, arsenic and phenolics. The mixed mats produced no methane, perhaps due to the high levels of phenolics. There was a strong correlation between MP and phenolic content. Heavy metals and metalloids were at levels that should not cause concern, except for arsenic (21–124 mg kg−1 dry weight). Further work on the speciation of arsenic in Sargassum is required to fully determine the risk to health and agriculture. Both protein and lipid levels were low. The ‘indispensable amino acid’ profile compares favourably with that recommended by the World Health Organisation. Lipids had a high proportion of Polyunsaturated Fatty Acids. The use of Sargassum for biogas production could be challenging, and further work is required.

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Section: Protein and Amino Acidsmentioning

confidence: 99%

Sargassum Inundations in Turks and Caicos: Methane Potential and Proximate, Ultimate, Lipid, Amino Acid, Metal and Metalloid Analyses

et al. 2020

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“…The Kjeldahl method is widely known and the most utilized method for total protein analysis in food (e.g. Moore et al 2010, Maehre et al 2018). There are numerous method standards for it and food and feed legislation often demands its use.…”

Section: Introductionmentioning

confidence: 99%

The nitrogen-to-protein conversion factor of two cricket species - Acheta domesticus and Gryllus bimaculatus

Ritvanen

Pastell

Welling

et al. 2020

AFSci

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The Kjeldahl method is the most utilized method for total protein content analysis in food. Using the universal nitrogen-to-protein conversion factor of 6.25, the protein content of insects is likely to be overestimated due to their chitin content. We have calculated nitrogen-to-protein conversion factors for two crickets, house cricket (Acheta domesticus) and field cricket (Gryllus bimaculatus), which are used for food and feed in Europe. By analyzing their nitrogen and amino acid content we were able to show that a conversion factor of 5.09 could be used for house cricket and 5.00 for field cricket in protein content calculation. Based on these results with a reservation about slight variation in farming conditions, we suggest a nitrogen conversion factor of 5.0 for both crickets.

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“…The Kjeldahl method is used to determine not only the protein component but also the relative nitrogen component, such as nitrate, ammonia, urea, nucleic acids, free amino acids, chlorophylls and alkaloids, all of which contain nitrogen [11]. The Bradford method is routinely used to determine the soluble protein content [21]. In the present study, the TNN content showed a weak negative correlation with the TSP content, and the TNN and TSP contents reached a peak in the tillering and booting stages, respectively.…”

Section: Discussionmentioning

confidence: 99%

Phytochemical Constituents and Antioxidant Enzyme Activity Profiles of Different Barley (Hordeum Vulgare L.) Cultivars at Different Developmental Stages

et al. 2019

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Barley grass possesses high nutritional value and antioxidant properties. In this study, the phytochemical constituents and antioxidant enzyme activities in six cultivars of barley grass were explored at three developmental stages: tillering, jointing, and booting stages. Total chlorophyll (Chl t) and carotenoid (Car) content, chlorophyll a/b (Chl a/b) ratio, total nitrogen nutrition (TNN), and total soluble protein (TSP) content, and superoxide dismutase (SOD), peroxidase (POD), and polyphenol oxidase (PPO) activities were assayed. The results indicated that the cultivar × development interaction was significant and that developmental stage was the main factor affecting the parameters studied. Cultivars had a negligible effect on these parameters, which varied with the developmental stages. In the tillering stage, Chl t and Car content, TNN, and POD activity achieved their highest value; in the jointing stage, SOD activity peaked; in the booting stage, Chl a/b ratio, TSP content, and PPO activity showed their highest values. TNN showed a negative correlation with TSP. Compared with those in the jointing, Chl t, Car, TSP, TNN content, Chl a/b ratio, and POD and PPO activities increased in the booting and the tillering stages, whereas SOD activity decreased. The differences in phytochemical constituents and antioxidant enzyme activities in barley grass were mainly correlated with the developmental stages. The aim of this study was to demonstrate the influence of developmental stages of barley grass on its phytochemical profile and antioxidant activities. Our results will help understand the mechanism of action of barley grass and provide theoretical support for the therapeutic application of barley grass.

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Protein Determination—Method Matters

Cited by 418 publications

References 28 publications

Sargassum Inundations in Turks and Caicos: Methane Potential and Proximate, Ultimate, Lipid, Amino Acid, Metal and Metalloid Analyses

Sargassum Inundations in Turks and Caicos: Methane Potential and Proximate, Ultimate, Lipid, Amino Acid, Metal and Metalloid Analyses

The nitrogen-to-protein conversion factor of two cricket species - Acheta domesticus and Gryllus bimaculatus

Phytochemical Constituents and Antioxidant Enzyme Activity Profiles of Different Barley (Hordeum Vulgare L.) Cultivars at Different Developmental Stages

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