Inter- and Intra-laboratory Variability in Rat Growth Assays for Estimating Protein Quality of Foods

1984 ◽  
Vol 67 (5) ◽  
pp. 976-981 ◽  
Author(s):  
Ghulam Sarwar ◽  
Robert Blair ◽  
Mendel Friedman ◽  
Michael R Gumbmann ◽  
L Ross Hackler ◽  
...  
Keyword(s):  
Protein Quality ◽  
Protein S ◽  
Protein Ratio ◽  
Whole Wheat ◽  
Minced Beef ◽  
Test Protein ◽  
Coefficients Of Variation ◽  
Reference Protein ◽  
Rat Growth ◽  
Pea Flour

Abstract Protein efficiency ratio (PER), relative PER (RPER), net protein ratio (NPR), relative NPR (RNPR), and nitrogen utilization (NU) methods were investigated in an interlaboratory rat growth study. Six collaborating laboratories studied 7 protein sources (ANRC casein; minced beef; soya assay protein, SAP; pea flour; whole wheat flour, WW; rapeseed protein concentrate, RPC; and egg white solids, EW), and their 10 supplementary or complementary mixtures (casein + Met, SAP + Met, pea flour + Met, WW + Lys, WW + casein, WW + beef, WW + SAP, WW + pea flour, WW + RPC, WW + EW). Test protein(s) were added at the 8% level (N × 6.25). Casein + Met was used as the reference protein. Interlaboratory variation (estimated as between-laboratories coefficients of variation) of PER (up to 17.2%) was greater than that of RPER (up to 14.9%), NU (up to 9.5%), NPR (up to 7.0%), and RNPR, which had the lowest variability (up to 4.7%). In most cases, intralaboratory variation (estimated as within-Laboratories coefficients of variation) for all the methods was less than 5%.

Available Amino Acid Score for Evaluating Protein Quality of Foods

1984 ◽  
Vol 67 (3) ◽  
pp. 623-626
Author(s):  
Ghulam Sarwar
Keyword(s):  
Amino Acid ◽  
Protein Quality ◽  
Regression Line ◽  
Egg White ◽  
Protein Ratio ◽  
Whole Wheat ◽  
Rat Growth ◽  
Growth Method ◽  
Pea Flour ◽  
Amino Acid Score

Abstract Amino acid scores corrected for true digestibility of individual amino acids (as determined by rat balance method) were termed “available amino acid scores” in the present investigation. Available amino acid scores were calculated for 7 protein sources and their 10 supplementary or complementary mixtures which have been tested in collaborative amino acid and rat growth assays for evaluating protein quality. The available amino acid scores were as follows: casein + methionine (100); egg white (100); rapeseed protein concentrate, RPC (94); casein (93); beef (89); soya assay protein, SAP (62); pea flour (61); whole wheat flour, WW (38); SAP + methionine (88); pea flour + methionine (72); WW + lysine (67); WW + casein (84); WW + egg white (79); WW + RPC (65); WW + beef (77); WW + SAP (70); and WW + pea flour (75). These scores were similar to the collaborative relative NPR values; the differences were less than 10 units (2–9 units) in most cases. The positive correlation (r = 0.92) between available amino acid scores and relative net protein ratio (RNPR, a rat growth method) values was highly significant (P < 0.01) and the origin of the regression line (y = 0.92x + 1.88) was not significantly different from zero. Amino acid bioavailability has previously been a problem, preventing widespread acceptance of amino acid score. Available amino acid score solves this problem.

Assessment of Rat Growth Methods for Estimating Protein Quality: Interlaboratory Study

1980 ◽  
Vol 63 (3) ◽  
pp. 462-467 ◽  
Author(s):  
J Murray Mclaughlan ◽  
G Harvey Anderson ◽  
L Ross Hackler ◽  
Douglas C Hill ◽  
G Richard Jansen ◽  
...  
Keyword(s):  
Protein Efficiency Ratio ◽  
Protein Quality ◽  
Interlaboratory Study ◽  
Official Method ◽  
Efficiency Ratio ◽  
Protein Ratio ◽  
Reference Protein ◽  
Rat Growth ◽  
Growth Methods ◽  
Net Protein

Abstract An interlaboratory study involving protein efficiency ratio (PER), net protein ratio (NPR), relative NPR (RNPR) and relative nitrogen utilization (RNU) was carried out. Six collaborators assayed 6 samples, including casein plus methionine which was used as a reference protein. Collaborators prepared their own diets and analyzed the diets for nitrogen. Test proteins were added at the 8% level (N × 6.25). PER values varied more than NPR values which varied more than either RNPR or RNU. RNU and RNPR produced almost identical values, but RNPR remains the official method of choice, because it is a well established method.

The Relative Nitrogen Utilization Method for Evaluating Protein Quality

1976 ◽  
Vol 59 (1) ◽  
pp. 42-45 ◽  
Author(s):  
J Murray McLaughlan
Keyword(s):  
Protein Quality ◽  
Poor Quality ◽  
Nitrogen Utilization ◽  
The Other ◽  
Efficiency Ratio ◽  
Protein Ratio ◽  
Test Protein ◽  
Reference Protein ◽  
Net Protein

Abstract A single-dose rat assay for protein quality called relative nitrogen utilization (RNU) is described. The method includes a factor for the protein utilized for maintenance. The protein quality of the test protein is expressed as a per cent of the value for Iactalbumin, the reference protein. For good quality proteins RNU gives results that are similar to those obtained by net protein ratio and relative protein value; for poor quality proteins RNU results fall between values by the other 2 methods. The protein efficiency ratio (PER) gives much lower values for poor quality proteins than any of the other 3 aforementioned methods and is influenced more by both level of protein and lipid in the diet. RNU is a more precise assay than PER as judged by the coefficient of variation.

Comparison of Interlaboratory Variation in Amino Acid Analysis and Rat Growth Assays for Evaluating Protein Quality

1985 ◽  
Vol 68 (1) ◽  
pp. 52-56 ◽  
Author(s):  
Ghulam Sarwar ◽  
Robert Blair ◽  
Mendel Friedman ◽  
Michael R Gumbmann ◽  
Ross L Hackler ◽  
...  
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Amino Acid Analysis ◽  
Protein Quality ◽  
Essential Amino Acids ◽  
Quality Indices ◽  
Protein Ratio ◽  
Protein Sources ◽  
Rat Growth ◽  
Positive Correlations

Abstract Estimates of inter- and intralaboratory variation of protein efficiency ratio (PER), relative PER (RPER), net protein ratio (NPR), relative NPR (RNPR), and nitrogen utilization (NU) were compared with those of amino acid analysis in the same batches of 7 protein sources (ANRC casein, egg white solids, minced beef, soy assay protein, rapeseed protein concentrate, pea flour, and whole wheat flour). Interlaboratory variation (estimated as between-laboratories coefficients of variation, CV) of NPR and RNPR (up to 6.0%) was lower than that of PER (up to 20.2%) and RPER (up to 18.5%). The interlaboratory determination of NPR and RNPR was also more reproducible than that of most essential amino acids (CV up to 10.0%), especially tryptophan (CV up to 23.7%), cystine (CV up to 17.6%), and methionine (CV up to 16.1%). Intralaboratory variation (estimated as within-laboratories CV) of amino acid analysis (up to 4.7%), however, was comparable to that of protein quality indices in most protein sources (up to 6.0%). The significant (P <0.01) positive correlations (r = 0.68-0.74) between amino acid scores and protein quality indices based on rat growth were further improved when amino acid scores were corrected for digestibility of protein (r = 0.73-0.78) or individual amino acids (r = 0.79- 0.82).

Determination of bioavailability of some long-chain N-substituted derivatives of L-methionine and L-lysine

1980 ◽  
Vol 58 (7) ◽  
pp. 577-580 ◽  
Author(s):  
Alenka Paquet ◽  
Ghulam Sarwar
Keyword(s):  
Ethyl Ester ◽  
Sodium Salt ◽  
Tetrahymena Pyriformis ◽  
Fatty Acyl ◽  
Protein Ratio ◽  
Rat Growth ◽  
Growth Method ◽  
The Media ◽  
Derivatives Of

The bioavailability of N-acyl-L-methionine derivatives has been determined using microbiological assay with Tetrahymena pyriformis. It was found that palmitoyl- and stearoyl-L-methionine, stearoyl-L-methionine ethyl ester, and stearoyl-L-methionine sodium salt were partially utilized (14–38%) for growth of the microorganism. These compounds partially inhibited utilization of free methionine added to the media. The shorter derivatives, acetyl-, hexanoyl-, lauroyl-, and myristoyl-L-methionine completely inhibited the growth of T. pyriformis. This effect was not reversed when DL-methionine was added to the media. N6-fatty acyl L-lysine derivatives gave low availability values (3–18%) in microbiological assessment with T. pyriformis. N2-Acetyl- and N6-acetyl-lysine did not inhibit the utilization of the added parent amino acid.Nutritional evaluation of L-methionine derivatives by the rat growth method using net protein ratio (NPR) as the performance index indicated complete availability of stearoyl-L-methionine, stearoyl-L-methionine sodium salt, and partial availability of stearoyl-L-methionine ethyl ester (52%), stearoyl-L-methionylglycine (32%), and lauroyl-L-methionine (75%).

Quality characteristics of spent hen meat powder incorporated whole wheat breads

2018 ◽  
Vol 48 (4) ◽  
pp. 579-588 ◽  
Author(s):  
Pramila Umaraw ◽  
Geeta Chauhan
Keyword(s):  
Wheat Flour ◽  
Wheat Bread ◽  
Meat Industry ◽  
Protein Ratio ◽  
Variable Effect ◽  
Whole Wheat Flour ◽  
Content Type ◽  
Whole Wheat ◽  
Whole Wheat Bread ◽  
Spent Hen

Purpose This paper aims to standardize level of spent hen meat powder incorporation in whole wheat bread without affecting the bread structure. Design/methodology/approach Spent hen meat powder at 20, 30 and 40 per cent level was used for substitution of whole wheat flour. Findings The results revealed that increasing the level of meat powder brought about significant (p < 0.05) effect on physicochemical parameters, proximate composition, textural profile and instrumental colour values (except hue). The pH, baking loss, carbohydrate content, energy and moisture protein ratio decreased significantly (p < 0.05) with meat powder incorporation. Whereas, moisture, protein, fat, ash and moisture retention values increased significantly (p < 0.05) with whole wheat substitution. Meat powder addition increased all the textural profile parameters significantly (p < 0.05). Redness, yellowness and chroma values also increased significantly (p < 0.05) with replacement of whole wheat flour. Sensory evaluation showed variable effect of higher meat powder incorporation. The colour of crust, crumb and flavour evinced significant (p < 0.05) increase with level of incorporation, while porosity and texture decreased significantly (p < 0.05). The overall acceptability of 30 per cent replacement was the highest. Research limitations/implications Storage stability and preservation aspect can be further explored for better shelf life at ambient temperature. Practical implications The development of such a product would definitely be profitable to the poultry industry by opening new avenues for under-used spent hen meat and meat processors. Social implications Addition of meat not only channels better utilization of spent hen meat but also enhances economical return to farmers and the meat industry; it also helps in accomplishing protein requirement of consumers. Originality/value The addition of spent hen meat enhanced the physico-chemical and sensory attributes of the treated groups than control. It is a novel nutritionally rich alternative for regular breads.

scholarly journals Increased Protein S-Glutathionylation in Leber’s Hereditary Optic Neuropathy (LHON)

2020 ◽  
Vol 21 (8) ◽  
pp. 3027 ◽  
Author(s):  
Lei Zhou ◽  
James Chun Yip Chan ◽  
Stephanie Chupin ◽  
Naïg Gueguen ◽  
Valérie Desquiret-Dumas ◽  
...  
Keyword(s):  
Optic Neuropathy ◽  
Complex I ◽  
Protein Quality ◽  
3D Structure ◽  
Protein S ◽  
Cell Protein ◽  
Leber’S Hereditary Optic Neuropathy ◽  
Leber's Hereditary Optic Neuropathy ◽  
Complex I Deficiency ◽  
Hereditary Optic Neuropathy

Leber’s hereditary optic neuropathy (LHON, MIM#535000) is the most common form of inherited optic neuropathies and mitochondrial DNA-related diseases. The pathogenicity of mutations in genes encoding components of mitochondrial Complex I is well established, but the underlying pathomechanisms of the disease are still unclear. Hypothesizing that oxidative stress related to Complex I deficiency may increase protein S-glutathionylation, we investigated the proteome-wide S-glutathionylation profiles in LHON (n = 11) and control (n = 7) fibroblasts, using the GluICAT platform that we recently developed. Glutathionylation was also studied in healthy fibroblasts (n = 6) after experimental Complex I inhibition. The significantly increased reactive oxygen species (ROS) production in the LHON group by Complex I was shown experimentally. Among the 540 proteins which were globally identified as glutathionylated, 79 showed a significantly increased glutathionylation (p < 0.05) in LHON and 94 in Complex I-inhibited fibroblasts. Approximately 42% (33/79) of the altered proteins were shared by the two groups, suggesting that Complex I deficiency was the main cause of increased glutathionylation. Among the 79 affected proteins in LHON fibroblasts, 23% (18/79) were involved in energetic metabolism, 31% (24/79) exhibited catalytic activity, 73% (58/79) showed various non-mitochondrial localizations, and 38% (30/79) affected the cell protein quality control. Integrated proteo-metabolomic analysis using our previous metabolomic study of LHON fibroblasts also revealed similar alterations of protein metabolism and, in particular, of aminoacyl-tRNA synthetases. S-glutathionylation is mainly known to be responsible for protein loss of function, and molecular dynamics simulations and 3D structure predictions confirmed such deleterious impacts on adenine nucleotide translocator 2 (ANT2), by weakening its affinity to ATP/ADP. Our study reveals a broad impact throughout the cell of Complex I-related LHON pathogenesis, involving a generalized protein stress response, and provides a therapeutic rationale for targeting S-glutathionylation by antioxidative strategies.

Formulation and efficacy study of metabolic syndrome-specific ingredient mix

2018 ◽  
Vol 48 (2) ◽  
pp. 272-284
Author(s):  
Neetu Miglani ◽  
Kiran Bains ◽  
Simranpreet Kaur Bhathal
Keyword(s):  
Metabolic Syndrome ◽  
Amino Acid ◽  
Wheat Flour ◽  
Protein Quality ◽  
Fasting Blood Glucose ◽  
Essential Amino Acids ◽  
Protective Role ◽  
Whole Wheat Flour ◽  
Content Type ◽  
Whole Wheat

Purpose The study aims to design metabolic syndrome (MetS) ingredient mix with optimum amino acid makeup using key foods with reported functional properties and study the efficacy of this mix to alleviate the symptoms of MetS among adult men and women with MetS. Design/methodology/approach In total, 25 MetS-specific ingredient mixes that included wheat flour, common legumes, fenugreek and flaxseeds were formulated by correcting their amino acid score. The suitability of these mixes was tested for the preparation of chapati (an unleavened Indian bread). Owing to its highest lysine content, the ingredient mix of whole wheat flour, oat flour, soybean, flaxseeds and fenugreek seeds was selected for the 12-week supplementation trial among patients with MetS. Findings The sensory scores of chapatis made using nine ingredient mixes was comparable with those of chapati made from whole wheat flour (control). The test chapatis had a significantly (p = 0.05) higher protein, ash, fibre and fat content, and lysine was also higher (591-1,006 mg/100 g) than the control chapatis (314 mg). Positive and significant changes in the anthropometry, body composition, fasting blood glucose levels, blood pressure and lipid profile of the patients with MS was seen after consumption of the selected ingredient mix. Originality/value Keeping in view the traditional vegetarian Indian meals which usually take care of including foods from different sources to improve their protein quality, the concern for providing protein quality to prevent metabolic abnormalities is significant for a large lacto-vegetarian population in India which depends on plant foods for obtaining essential amino acids. Obtaining optimum protein quality from meals along with maintaining a physically active lifestyle may help people have the appropriate fat to lean mass proportion which may have a protective role against MetS.

PROTEIN QUALITY EVALUATIONS OF SELECTED CULTIVARS OF WHEAT, MEASURED BY CHEMICAL SCORES AND MOUSE BIOASSAYS

1984 ◽  
Vol 64 (1) ◽  
pp. 127-137
Author(s):  
J. M. BELL ◽  
D. M. ANDERSON
Keyword(s):  
Amino Acids ◽  
Crude Protein ◽  
Protein Quality ◽  
Growth Index ◽  
Wheat Cultivars ◽  
Protein Ratio ◽  
Relative Growth ◽  
Key Words Wheat ◽  
Limiting Amino Acid ◽  
Net Protein

Wheat cultivars, Glenlea, Inia-66, Neepawa, Pitic-62 and Twin, and Bonanza barley, were fed to mice in digestibility and protein quality evaluation trials. In the digestibility trial each diet contained 94.7% test grain, plus mineral and vitamin supplements and 0.55% chromic oxide fecal marker. Digestibility of energy ranged from 79.3% (Twin) to 83.4% (Neepawa). Digestibility of protein ranged from 71.0% (Twin) to 84.4% (Neepawa). Crude protein (CP) (N × 6.25) ranged from 11.8% (Twin) to 15.8% (Neepawa) and affected the protein apparent digestibility coefficients. In the 14-day growth trials the grains were compared in four ways: (a) as 94.7% of the diet, (b) in diets containing 9% CP, (c) in diets containing 9% CP plus amino acids to meet the requirements for growth of the mouse and (d) in diets containing 7% CP. Casein control diets were used. In (a) mice fed Twin wheat and Bonanza barley gained less than all others. In (b) all wheats resulted in slower growth than barley or casein but Twin had better protein than Inia-66 and Pitic-62, reflecting lysine contents. In (c) all wheats supplemented with amino acids equalled casein in terms of growth. In (d) the responses to 7% CP diets were inferior but parallel to those from 9% CP diets. In the protein quality evaluations barley ranked highest in relative growth index, protein efficiency ratio and net protein ratio. Twin wheat ranked second and Pitic-62 ranked last. Lysine was the first-limiting amino acid in all wheats, having from about 59 to 64% of the level required by 20- to 35-kg pigs. Isoleucine was second-limiting except for Glenlea with threonine. Key words: Wheat, cultivars, protein quality, mouse assays, digestibility

scholarly journals Influence of Flour Substitution and Sugar Replacement on the Physical, Proximate and Sensory Characteristics of Bread from Whole Wheat, Acha and Pigeon Pea Flour

2019 ◽  
pp. 309-320
Author(s):  
G. E. Liasu-Oni ◽  
S. O. Buraimoh
Keyword(s):  
Date Palm ◽  
Pigeon Pea ◽  
Sensory Characteristics ◽  
Raw Material ◽  
Palm Fruit ◽  
Whole Wheat ◽  
Composite Flours ◽  
Pea Flour ◽  
Bread Production ◽  
Sugar Replacement

Whole wheat was cleaned and milled into flour (WWF), acha was sorted, washed and milled into acha flour (AF), pigeon pea was soaked, dehulled, dried and milled into flour (PPF), date palm fruit was cleaned, deseeded, cut, dried and milled into flour (DPFS). The flours were combined in different ratios to obtain composite flours namely WAPC (100% WWF), WAPE (90% WWF and 10% AF), WAPG (80% WWF and 20% AF), WAPH (70% WWF and 30% AF), WAPJ (80% WWF, 10% AF and 10% PPF), WAPK (70% WWF, 10% AF and 10% PPF), WAPL (70% WWF, 15% AF and 15% PPF), WAPM (60% WWF, 20% AF and 20% PPF). The flours were used to bake bread, partial and total sugar replacement was carried out at 50% (WSDC, WSDE, WSDG, WSDH, WSDJ, WSDK, WSDL and WSDM) and 100% (WDPC, WDPE, WDPG, WDPH, WDPJ, WDPK, WDPL and WDPM). WAPC (100% sugar) was used as control. Physical, nutritional and consumer acceptability evaluation were carried out on the formulated bread samples using standard methods. The physical properties of the formulated bread from WWF and AF were comparable to WAPC in terms of the weight and volume. Loaf height, volume and specific volume of WAPC were higher (6.63cm, 1111.67cm3 and 1.82cm3/g respectively) than breads with 50% and 100% sugar substitution. However, the protein content of wheat-acha-pigeon pea composite bread increased significantly from 10.83% to 14.10% WDPH, WSDH were not significantly different from the WAPC in terms of its fibre, ash and fat content. The sensory characteristics of the formulated breads compared favourably with WAPC. Thus, substitution of WWF with AF and PPF may serve as potential raw material for bread production thereby reducing overdependence on wheat, increasing the utilization and cultivation of our local cereal (acha) and increasing nutrient composition of bread. Also, sugar replacement with date palm may increase the utilization of date palm and improve the nutritional value of the breads.

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