Editorial on “Measurement of protein digestibility in humans by a dual tracer method”—a key limiting factor of protein quality

Abstract Objectives The measurement of amino acid (AA) digestibility of protein through direct ileal sampling is highly invasive and inappropriate for vulnerable populations, such as children or elderly. The new dual tracer method relies on comparing meal and plasma isotopic ratios of 1/a test protein 2/a reference protein (or AA mix) of known digestibility, each one being labelled with a different isotope. The aim of this study was to compare this new indirect dual tracer method to standard ileal method, for the determination of AA digestibility of pea protein and milk casein. Methods Fifteen healthy adult volunteers completed the study and were equipped with a naso-ileal tube. They were given 9 portions of mashed potatoes containing either pea protein or casein isolates that were intrinsically labelled with 15N and 2H. A 13C algal free AA mix was added in the meals as the reference for dual tracer method. Plasma samples were collected regularly from before the first ingestion to 8-h later, while ileal digesta were collected continuously. For ileal sampling method, the AA digestibility (RIDAA) was determined using the recovery a non-absorbable marker (PEG-4000) perfused in the ileum, and the measurement of 15N enrichment of the digesta. For the dual tracer method, the amount of AA absorbed (AbAA) was calculated by the ratio of 2H/13C enrichments in plasma and in meals. The isotopic enrichments were evaluated in digesta, plasma samples and meals by GC-C-IRMS. The AA content was measured in digesta and meals by U-HPLC. Results Mean AbAA and RIDAA of pea protein were 102.2 ± 3.1% and 94.3 ± 1.5%, respectively. Mean AbAA and RIDAA of casein were 91.9 ± 2.0% and 97.1 ± 0.8%, respectively. The dual tracer method overestimated by 10% and 5% the AA digestibility of pea protein and casein, respectively, and the variability was high. The mean ileal AA digestibility of the 13C free AA mix was high (98.1 ± 1.1%), which validated our choice to use it as the reference ‘protein’ in the dual tracer method. Conclusions Several AA digestibilities obtained with dual tracer method were in the same range as the digestibilities from ileal sampling method. The variability was high and the effect of the protein source was inconsistent. After further research and validation, the dual tracer method could lead to notable advances in the determination of protein quality in humans. Funding Sources Roquette.

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Measurement of protein digestibility in humans by a dual-tracer method

American Journal of Clinical Nutrition ◽

10.1093/ajcn/nqy062 ◽

2018 ◽

Vol 107 (6) ◽

pp. 984-991 ◽

Cited By ~ 25

Author(s):

Sarita Devi ◽

Aneesia Varkey ◽

M S Sheshshayee ◽

Thomas Preston ◽

Anura V Kurpad

Keyword(s):

Protein Digestibility ◽

Tracer Method ◽

Dual Tracer

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Evaluation of Changes in Protein Quality of High-Pressure Treated Aqueous Aquafaba

Molecules ◽

10.3390/molecules26010234 ◽

2021 ◽

Vol 26 (1) ◽

pp. 234

Author(s):

Fatemah B. Alsalman ◽

Hosahalli S. Ramaswamy

Keyword(s):

High Pressure ◽

Protein Quality ◽

Treatment Time ◽

Control Sample ◽

Thermal Characteristics ◽

Protein Digestibility ◽

Foaming Properties ◽

Freeze Dried ◽

Cooking Water

Chickpea cooking water (CCW), known as aquafaba, has potential as a replacement for egg whites due to its emulsion and foaming properties which come from the proteins and starch that leach out from chickpeas into the cooking water. High pressure (HP) processing has the ability to modify the functional characteristics of proteins. It is hypothesized that HP processing could favorably affect the functional properties of CCW proteins by influencing their structure. The objective of this study to evaluate the effect of HP treatment on the associated secondary structure, emulsion properties and thermal characteristics of CCW proteins. A central composite rotatable design is used with pressure level (227–573 MPa) and treatment time (6–24 min) as HP variables, and concentration of freeze dried CCW aquafaba powder (11–29%) as product variable, and compared to untreated CCW powder. HP improves aquafaba emulsion properties compared to control sample. HP reduces protein aggregates by 33.3%, while β-sheets decreases by 4.2–87.6% in which both correlated to increasing protein digestibility. α-helices drops by 50%. It affects the intensity of some HP treated samples, but not the trend of bands in most of them. HP treatment decreases Td and enthalpy because of increasing the degree of denaturation.

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Effect of Time and Legume Type on Germination-Induced Proteolysis of Lentils and Faba Beans

Proceedings ◽

10.3390/foods_2020-07823 ◽

2020 ◽

Vol 70 (1) ◽

pp. 4

Author(s):

Sara Bautista-Expósito ◽

Elena Peñas ◽

Albert Vanderberg ◽

Juana Frias ◽

Cristina Martínez-Villaluenga

Keyword(s):

Amino Acids ◽

Protease Activity ◽

Protein Quality ◽

Principal Component ◽

Fold Increase ◽

Protein Digestibility ◽

Essential Amino Acids ◽

Seedling Development ◽

Positive Effects ◽

Faba Beans

Legumes are alternative protein sources that have been successfully used to develop diverse meatless foods. Although these plant-based products have a lower impact on the environment than equivalent animal-based products, they have lower protein digestibility. Germination could be a useful bioprocess to enhance protein digestibility in legumes, although its effect at different times of seedling development has been little studied in lentils and faba beans. This work investigated the effect of germination time (4 and 6 days after full seed imbibition) on the proteins of three types of Canadian lentils (“gray zero tannin”, G; “caviar black”, B; and “red dehulled”, D) and faba beans (“zero vicin/convicin”, F). Germination increased total nitrogen (4–14% increase) and total levels of some amino acids: Asp in all the sprouts studied; Ser, Pro, Ala, Cys, His and Lys in G; and Met and Tyr in B. A concurrent degradation of the 7S and 11S globulin subunits, the accumulation of peptides below 20 kDa and free essential and non-essential amino acids (4- to 6-fold increase) were observed after germination in all the legumes studied. These effects were attributable to the increased protease activity observed after sprouting. Trypsin inhibitory activity was lower in legume sprouts, except for D, where a small increase was detected. Time, legume type and their interaction showed significant effects on the parameters studied. Germination effects were generally more remarkable at longer stages of seedling development. Among the legumes studied, D showed a differential behavior characterized by a faster protein degradation and release of small peptides, probably due to its higher protease activity as indicated by principal component analysis. These results evidence the positive effects of germination on the protein digestibility of different lentil types and faba beans. The protein quality of plant-based foods could be improved through the selection of legume species with higher germination-induced proteolytic rates and optimized germination times.

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Dietary Protein Quality in Humans—An Overview

Journal of AOAC International ◽

10.1093/jaoac/88.3.874 ◽

2005 ◽

Vol 88 (3) ◽

pp. 874-876 ◽

Cited By ~ 15

Author(s):

Paul J Moughan

Keyword(s):

Amino Acid ◽

Nutritive Value ◽

Protein Quality ◽

Current Method ◽

Protein Digestibility ◽

Food Protein ◽

Amino Acid Utilization ◽

Dietary Amino Acid ◽

Amino Acid Requirements ◽

Amino Acid Score

Abstract The first objective in evaluating protein quality is to permit a ranking of proteins according to their potential nutritive value and to permit detection of changes in nutritive value due to processing and/or storage. The second objective is to permit prediction of the contribution a food protein, or mixture of food proteins, makes toward meeting nitrogen and amino acid requirements for growth or maintenance. Different approaches are used in meeting these distinct aims. The preferred current method to meet the second aim is the protein digestibility corrected amino acid score (PDCAAS). This article introduces the concept of PDCAAS and places it in the context of the series of papers published in this Special Guest Editor Section addressing aspects of dietary amino acid utilization.

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Biofortified Maize Can Improve Quality Protein Intakes among Young Children in Southern Ethiopia

Nutrients ◽

10.3390/nu11010192 ◽

2019 ◽

Vol 11 (1) ◽

pp. 192 ◽

Cited By ~ 5

Author(s):

Nilupa Gunaratna ◽

Debebe Moges ◽

Hugo De Groote

Keyword(s):

Young Children ◽

Food Insecurity ◽

Protein Quality ◽

Protein Digestibility ◽

Southern Ethiopia ◽

Home Production ◽

Dietary Intakes ◽

Food Records ◽

Amino Acid Score ◽

Potential Impact

Quality protein maize (QPM) varieties are biofortified, or nutritionally improved, to have higher lysine and tryptophan levels to increase quality protein intakes particularly among young children. This study assesses adequacy of children’s protein intakes in Ethiopia, where QPM is being promoted, accounting for protein quality and seasonal dietary changes, and estimates potential increases in intakes if QPM replaced conventional maize in diets. Diets of randomly sampled children aged 12–36 months in rural southern Ethiopia (n = 218) were assessed after harvest during relative food security and 3–4 months later during relative food insecurity using 24-h weighed food records. Diets were analyzed for protein adequacy, accounting for protein quality using the protein digestibility corrected amino acid score (PDCAAS) method, and potential improvements from QPM substitution were estimated. Stunting was prevalent (38%) at the first assessment. Across seasons, 95–96% of children consumed maize, which provided 59–61% of energy and 51–55% of total protein in 24 h. Dietary intakes decreased in the food insecure season, though children were older. Among children no longer breastfeeding, QPM was estimated to reduce inadequacy of utilizable protein intakes from 17% to 13% in the food secure season and from 34% to 19% in the food insecure season. However, breastfed children had only 4–6% inadequate intakes of utilizable protein, limiting QPM’s potential impact. Due to small farm sizes, maize stores from home production lasted a median of three months. Young Ethiopian children are at risk of inadequate quality protein intakes, particularly after breastfeeding has ceased and during food insecurity. QPM could reduce this risk; however, reliance on access through home production may result in only short-term benefits given the limited quantities of maize produced and stored.

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Digestible Indispensable Amino Acid Score (DIAAS) better Estimates the Protein Value of Pistachios than Digestibility Corrected Amino Acid Score (PDCAAS)

Proceedings of The Nutrition Society ◽

10.1017/s0029665120005224 ◽

2020 ◽

Vol 79 (OCE2) ◽

Author(s):

Hannah Marie Bailey ◽

Arianna Carughi ◽

Hans-Henrik Stein

Keyword(s):

Amino Acid ◽

Unsaturated Fatty Acids ◽

Protein Quality ◽

Protein Digestibility ◽

Growing Pigs ◽

Ileal Digestibility ◽

Indispensable Amino Acid ◽

Older Adolescents ◽

Adolescents And Adults ◽

Amino Acid Score

AbstractPistachios (Pistacia Vera) are nutrient-dense foods with a healthy nutritional profile that contains fiber, unsaturated fatty acids, essential nutrients, phytochemicals and protein. However, the nutritional quality of the protein has not been characterized to date. Therefore, the objective of this study was to determine the Protein Digestibility Corrected Amino Acid Score (PDCAAS) and Digestible Indispensable Amino Acid Score (DIAAS) for raw and roasted American pistachio nuts in growing pigs. The values for apparent ileal digestibility (AID) of crude protein (CP) and the standard ileal digestibility (SID) where calculated for these proteins. The CP content was greater for raw pistachios (27.1%) compared with roasted pistachios (25.1%). The amino acid (AA) in greatest concentrations for both types of pistachio were arginine followed by leucine. The AA in the lowest concentration were tryptophan followed by methionine. The AID of CP was greater (P < 0.05) for raw pistachios than for roasted pistachios, and the AID of most indispensable AA (IAA), except arginine, isoleucine, and phenylalanine, was greater (P < 0.05) for raw pistachios. The SID of CP was greater (P < 0.05) for raw than for roasted pistachios, and the SID of all IAA, except phenylalanine, was greater (P < 0.05) for raw than for roasted pistachios. The PDCAAS value calculated for both types of pistachios was based on the requirement for children from 2 to 5 years old (FAO, 1991), whereas the DIAAS value was calculated based on the requirement for children 3 years and older, adolescents, and adults (FAO, 2013). Both raw and roasted pistachios had a PDCAAS value of 75. In contrast, the DIAAS was numerically greater for raw pistachios than for roasted pistachios with values of 86 and 83, respectively. For PDCAAS, the first limiting AA in both raw and roasted pistachios when compared with the AA requirements for children 2 to 5 years was threonine. For DIAAS, lysine was the first limiting AA in both raw and roasted pistachios when compared with the AA requirements for children 3 years and older, adolescents, and adults. Based on the DIAAS cut-off values describing protein quality (FAO, 2013), raw pistachios and roasted pistachios can both be considered a ‘Good’ quality protein if consumed by children older than 3 year, adolescents, and adults.

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Protein Digestibility of Cereal Products

Foods ◽

10.3390/foods8060199 ◽

2019 ◽

Vol 8 (6) ◽

pp. 199 ◽

Cited By ~ 22

Author(s):

Iris Joye

Keyword(s):

Amino Acid ◽

Protein Quality ◽

Intact Cell ◽

Protein Digestibility ◽

Amino Acid Profile ◽

Antinutritional Factors ◽

Internal Factors ◽

Cereal Products ◽

Low Protein ◽

Cell Structures

Protein digestibility is currently a hot research topic and is of big interest to the food industry. Different scoring methods have been developed to describe protein quality. Cereal protein scores are typically low due to a suboptimal amino acid profile and low protein digestibility. Protein digestibility is a result of both external and internal factors. Examples of external factors are physical inaccessibility due to entrapment in e.g., intact cell structures and the presence of antinutritional factors. The main internal factors are the amino acid sequence of the proteins and protein folding and crosslinking. Processing of food is generally designed to increase the overall digestibility through affecting these external and internal factors. However, with proteins, processing may eventually also lead to a decrease in digestibility. In this review, protein digestion and digestibility are discussed with emphasis on the proteins of (pseudo)cereals.

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Ribosomal mistranslation leads to silencing of the unfolded protein response and increased mitochondrial biogenesis

Communications Biology ◽

10.1038/s42003-019-0626-9 ◽

2019 ◽

Vol 2 (1) ◽

Cited By ~ 9

Author(s):

Dmitri Shcherbakov ◽

Youjin Teo ◽

Heithem Boukari ◽

Adrian Cortes-Sanchon ◽

Matilde Mantovani ◽

...

Keyword(s):

Unfolded Protein Response ◽

Mitochondrial Biogenesis ◽

Protein Quality ◽

Genetic Manipulation ◽

Ubiquitin Proteasome System ◽

Limiting Factor ◽

Unfolded Protein ◽

Comprehensive Picture ◽

The Unfolded Protein Response ◽

Protein Response

Abstract Translation fidelity is the limiting factor in the accuracy of gene expression. With an estimated frequency of 10−4, errors in mRNA decoding occur in a mostly stochastic manner. Little is known about the response of higher eukaryotes to chronic loss of ribosomal accuracy as per an increase in the random error rate of mRNA decoding. Here, we present a global and comprehensive picture of the cellular changes in response to translational accuracy in mammalian ribosomes impaired by genetic manipulation. In addition to affecting established protein quality control pathways, such as elevated transcript levels for cytosolic chaperones, activation of the ubiquitin-proteasome system, and translational slowdown, ribosomal mistranslation led to unexpected responses. In particular, we observed increased mitochondrial biogenesis associated with import of misfolded proteins into the mitochondria and silencing of the unfolded protein response in the endoplasmic reticulum.

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Biological protein quality and phytic acid content of domesticallyprocessed kidney beans (Phaseolus Vulgaris)

Asian Journal of Dairy and Food Research ◽

10.18805/ajdfr.v35i4.6631 ◽

2016 ◽

Vol 35 (4) ◽

Cited By ~ 1

Author(s):

Rajni Modgil ◽

K. Mankotia ◽

Ranjana Verma ◽

Anupama Sandal

Keyword(s):

Phaseolus Vulgaris ◽

Phytic Acid ◽

Phosphorus Content ◽

Protein Quality ◽

Protein Digestibility ◽

Efficiency Ratio ◽

Phytate Phosphorus ◽

Kidney Beans ◽

Net Protein

Effect of domestic processing techniques i.e. soaking, sprouting and cooking was seen on the anti nutrient constituents of kidney beans (Phaseolus vulgaris). Biological protein quality of sprouted and cooked grains was also estimated. Anti nutrient analyzed was phytic acid. Phytate phosphorus and non phytate phosphorus content was also estimated. Rats were fed on domestically processed kidney beans for estimation of protein efficiency ratio(PER), food efficiency ratio(FER) ,apparent protein digestibility(APD), true protein digestibility(TPD), Biological value(BV), net protein utilization(NPU) and net protein retention (NPR). Cooking of kidney beans resulted in a significant decrease in phytic acid and phytate phosphorus content as compared to sprouting. Sprouting and cooking resulted in an increase in FER and PER. Cooking resulted in an increase in biological protein quality of kidney beans. Domestically processed kidney beans have better biological protein quality.

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