scholarly journals Determination of protein and reactive lysine in leaf-protein concentrates by dye-binding

1979 ◽  
Vol 42 (3) ◽  
pp. 445-454 ◽  
Author(s):  
Ann F. Walker
Keyword(s):  
Convenient Method ◽  
Nutritional Value ◽  
Tungstic Acid ◽  
Leaf Protein ◽  
Processing Conditions ◽  
Acid Orange ◽  
Protein Concentrates ◽  
Dye Binding ◽  
Available Lysine

1. Twenty leaf-protein concentrates (LPC), were produced from different crops and by different processes, the latter being designed to retain maximum nutritional value of the samples.2. The establishment of conditions for the use of CI Acid Orange 12 in a commercial dye-buffer reagent for the determination of protein and reactive (available) lysine in LPC was investigated.3. Values for protein by dye-binding correlated well with those for tungstic-acid-precipitated nitrogen (×6.25).4. Some LPC samples showed a loss of reactive lysine, the greatest loss being associated with the most severe processing conditions.5. For the LPC samples studied, dye-binding provided a convenient method for the concurrent determination of protein and reactive lysine.

Quantitative Determination of Coumestrol in Dried Alfalfa and Alfalfa Leaf Protein Concentrates Containing Chlorophyll

1975 ◽  
Vol 58 (5) ◽  
pp. 983-986
Author(s):  
Benny E Knuckles ◽  
Raymond E Miller ◽  
E M Bickoff
Keyword(s):  
Quantitative Determination ◽  
Analytical Method ◽  
Leaf Protein ◽  
Improved Method ◽  
Alcohol Extract ◽  
Protein Concentrates ◽  
Coefficients Of Variation ◽  
Lower Standard ◽  
Alfalfa Leaf

Abstract An improved analytical method for the determination of coumestrol in dried alfalfa and leaf protein concentrates is described. In this method, chlorophyll is removed from an alcohol extract prior to the paper chromatographic-fluorometric measurement of coumestrol. Ninety-eight per cent of the coumestrol added to alfalfa leaf protein concentrates is recovered by this method. This improved method gives replicate values with lower standard deviations and coefficients of variation than the literature method.

THE APPLICATION OF THE DYE-BINDING METHOD FOR MEASURING PROTEIN DENATURATION OF RAPESEED MEALS CAUSED BY AUTOCLAVE OR OVEN HEAT TREATMENTS FOR VARYING PERIODS OF TIME

1979 ◽  
Vol 59 (1) ◽  
pp. 189-194 ◽  
Author(s):  
Y. K. GOH ◽  
D. R. CLANDININ ◽  
A. R. ROBBLEE
Keyword(s):  
Nutritive Value ◽  
Protein Denaturation ◽  
Nitrogen Solubility ◽  
Binding Capacity ◽  
Protein Nitrogen ◽  
Acid Orange ◽  
Moisture Contents ◽  
Dye Binding ◽  
Similar Temperature ◽  
Available Lysine

Laboratory-prepared rapeseed meals (RSMs) with moisture contents ranging from 2 to 40% of the meal were heated in an autoclave or an oven at 121 °C from 15 min to 4 h. The degree of protein denaturation of the RSMs was estimated by nitrogen solubility (NS) in water and by dye-binding capacity of the protein (DBCP) with Acid Orange 12. The NS study indicated that heating RSM for 15 min to 1 h in an autoclave produced more severe denaturation than heating RSM at a similar temperature for the same periods of time in an oven. When heating in the autoclave was prolonged, the nitrogen solubility increased. The ability of the RSM protein to bind Acid Orange 12 was more severely affected by the autoclave treatment than by oven heating. In this regard, the DBCP of the RSMs was at the lowest after 2 h of heating in the autoclave and after 4 h of heating in the oven. Since the NS values for the RSMs include both protein and non-protein nitrogen while DBCP values measure mainly basic amino acids, the latter values are likely to be more valid for estimating the nutritive value of RSM. The higher correlation coefficient between DBCP and available lysine than between NS and available lysine (0.90 vs. 0.63) would seem to support this conclusion.

Characteristics and Nutritional Value of Various Fish Protein Concentrates

1964 ◽  
Vol 21 (6) ◽  
pp. 1489-1504 ◽  
Author(s):  
H. E. Power
Keyword(s):  
Nutritional Value ◽  
Press Cake ◽  
Raw Materials ◽  
Raw Material ◽  
Water Mixture ◽  
Protein Concentrate ◽  
Fish Protein ◽  
Efficiency Ratio ◽  
Protein Concentrates ◽  
Available Lysine

Excellent quality fish protein concentrate can be prepared from a variety of raw materials. In this study, the use of whole cod, headed, eviscerated cod, cod trimmings, cod press cake and whole herring was studied as a source of raw material for the production of fish protein concentrate. The process previously described by Power for use with cod fillets was satisfactory for use with all material studied with the exception of herring. Final fat contents were between 0.018–0.056%. For use with herring a modification to the process was required to increase the efficiency of the second extraction. The second extraction, which used a 70:30 isopropanol + water mixture was changed to 99% isopropanol. With this modification a final fat content of 0.17% was achieved. The corrected Protein Efficiency Ratio values for all fish protein concentrates, with the exception of those produced from cod trimming press cake, were higher than that for casein. Lysine values, determined microbiologically were between 9.1 and 15.03% of the protein. The available lysine values were between 6.1 and 10.4% of the protein.

APPLICATION OF THE DYE-BINDING TECHNIQUE FOR QUANTITATIVE AND QUALITATIVE ESTIMATION OF RAPESEED MEAL PROTEIN

1979 ◽  
Vol 59 (1) ◽  
pp. 181-188 ◽  
Author(s):  
Y. K. GOH ◽  
D. R. CLANDININ ◽  
A. R. ROBBLEE
Keyword(s):  
Protein Content ◽  
Crude Protein ◽  
Protein Quality ◽  
Binding Capacity ◽  
Rapeseed Meal ◽  
Quantitative Prediction ◽  
Acid Orange ◽  
Dye Binding ◽  
Meal Protein ◽  
Available Lysine

The linear equation Y = 2.2 + 0.27X relating dye-binding capacity with Acid Orange 12 (X) and Kjeldahl crude protein content (Y) of rapeseed meal, derived previously, was applied to 126 commercial samples for estimating the protein contents of the meals. Results indicated that the means of crude protein contents obtained by both dye-binding and Kjeldahl nitrogen analyses were comparable. However, comparisons based on individual samples showed that the dye-binding method underestimated or overestimated the protein content of about 20% of the samples by 1% or more. The deviation was caused mainly by the atypical content of basic amino acids, particularly of lysine, in these meals. Application of the equation for quantitative prediction should, therefore, be limited to rapeseed meals which have been properly processed. On the other hand, the correlations noted between the dye-binding capacity of protein (DBCP, mg Acid Orange 12/g protein) of 21 selected rapeseed meals and the lysine and available lysine contents of the meals (r = 0.84 and 0.79) showed that the ability of the protein to bind Acid Orange 12 may be used as a protein quality index of the samples. This potential was further investigated by studying the effects of autoclaving for varying periods of time at 121 °C on the DBCP of rapeseed meal protein. In this regard, a significant reduction in DBCP of the meals was noted after 45 min of heating. Available lysine values were reduced by autoclaving at a more rapid rate than DBCP values.

Evaluation of Rapid Polarographic Method for Determining Tocopherols in Vegetable Oils and Oil-Based Products

1977 ◽  
Vol 60 (4) ◽  
pp. 890-894
Author(s):  
Arthur E Waltking ◽  
Mary Kiernan ◽  
George W Bleffert
Keyword(s):  
Vegetable Oils ◽  
Nutritional Value ◽  
Gas Liquid Chromatography ◽  
Polarographic Method ◽  
Processing Conditions ◽  
Gas Chromatograph ◽  
Chromatographic Procedure ◽  
Liquid Chromatographic ◽  
Source Of Error

Abstract A polarographic procedure for the determination of the tocopherols in vegetable oils was compared to a conventional gas-liquid chromatographic procedure. The polarographic method is 2–3 times more precise and more rapid, which is an important advantage for monitoring the nutritional value of processing conditions of vegetable oil-based products. Attempts to establish the validity of apparently slightly higher values for α and γ-tocopherols obtained by polarography has implicated the gas chromatograph or derivative formation rather than the extensive prior manipulation of the sample for chromatography as the source of error. Essentially the same results were obtained for α-tocopherol, regardless of the technique used. However, more variable results which were product dependent were obtained for γ- and Δ-tocopherols when gas-liquid chromatography was used.

scholarly journals A comparison of the dye-binding and fluorodinitrobenzene methods for determining reactive lysine in leaf-protein concentrates

1979 ◽  
Vol 42 (3) ◽  
pp. 455-465 ◽  
Author(s):  
Ann F. Walker
Keyword(s):  
Binding Capacity ◽  
Regression Line ◽  
Correlation Coefficients ◽  
Tungstic Acid ◽  
The Other ◽  
Leaf Protein ◽  
Thermal Treatments ◽  
Protein Concentrate ◽  
Leaf Protein Concentrate ◽  
Dye Binding

1. Twenty-eight leaf-protein concentrate (LPC) samples, subjected to different thermal treatments, were produced from five curd batches. For these samples, the fluorodinitrobenzene (FDNB)-reactive lysine values gave closer agreement with dye-binding lysine (DBL) than with the dye-binding capacity (DBC).2. No relationship was established between the dye-bound-after-propionylation (DBAP) and the histidine+arginine value.3. Comparison of dye-bound-protein values with those for tungstic-acid-precipitated nitrogen ×6.25 for the LPC samples showed the heat-damaged samples to lie below the regression line for the other samples.4. Reactive-lysine values by dye-binding and by FDNB methods correlated well with total lysine, but the slopes of the regression line indicated closer agreement for values for samples not damaged by heat.5. The correlation coefficients between DBC and total basic amino acids, DBC and histidine+arginine+DBL, and DBC and histidine+arginine+FDNB-reactive lysine were similar.6. There was no correlation between the lightness of colour of the LPC samples and the availability of lysine.

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