Development of a novel bioassay for determining the available lysine contents of foods and feedstuffs

Lysine is an important indispensable amino acid, and describing the lysine content of a food or feedstuff provides useful information about nutritional value. However, when a food or feedstuff is subjected to heating the lysine present can be altered to nutritionally unavailable derivatives. These derivatives can revert back to lysine during the acid hydrolysis step used in amino acid analysis causing an overestimate of the lysine content. There have been many chemical methods developed to determine the reactive (unmodified) lysine content of foods and feedstuffs, but these do not take into account the incomplete absorption of lysine from the small intestine. There are also a number of animal-based assays for determining available lysine (the lysine that can be absorbed in a form that can be used for protein synthesis). The true ileal amino acid digestibility assay is commonly used to determine amino acid availability and is accurate for application to unprocessed foods and feedstuffs but is not accurate for lysine and possibly other amino acids when applied to heat-processed foods or feedstuffs. For such protein sources, assays such as the slope-ratio assay, indicator amino acid oxidation assay and the BIOLYSINE™ assay (true ileal digestible reactive lysine assay) have been developed to determine available lysine. The present paper discusses the efficacy of the BIOLYSINE™ assay as well as other assays for determining available lysine in processed foods and feedstuffs.

Download Full-text

Available Lysine in Foods: A Brief Historical Overview

Journal of AOAC International ◽

10.1093/jaoac/91.4.901 ◽

2008 ◽

Vol 91 (4) ◽

pp. 901-906 ◽

Cited By ~ 27

Author(s):

Paul J Moughan ◽

Shane M Rutherfurd

Keyword(s):

Amino Acid ◽

Dietary Protein ◽

Food Processing ◽

Strong Acid ◽

Significant Degree ◽

Processed Foods ◽

Historical Overview ◽

Slope Ratio ◽

Available Lysine ◽

Dietary Protein Utilization

Abstract A brief historical overview is presented on the development of the science addressing lysine bioavailability in foods. Early observations that dietary protein utilization did not always correlate with gross amino acid composition led to an understanding that the amino acid lysine, in particular, can be easily damaged during food processing. Conventional amino acid analysis, involving a strong acid hydrolysis step, can lead to a significant degree of overestimation of lysine in processed foods. More recently, it has been found that not only food lysine content values but also estimates of lysine digestibility and digestible lysine contents may be erroneous. Estimates of absorbed (true ileal digestible) reactive lysine are accurate measures of available lysine. Technically, bioassays such as the slope-ratio assay determine utilized rather than available lysine.

Download Full-text

Comparative Analysis of Some Essential Amino Acids and Available Lysine in Acacia colei and A. tumida Seeds Using Chemical Methods and an Amino Acid Analyzer

Journal of AOAC International ◽

10.5740/jaoacint.11-551 ◽

2013 ◽

Vol 96 (1) ◽

pp. 102-109 ◽

Cited By ~ 3

Author(s):

Olumuyiwa S Falade ◽

Steve R A Adewusi

Keyword(s):

Amino Acids ◽

Comparative Analysis ◽

Amino Acid ◽

Essential Amino Acids ◽

Acid Base ◽

Chemical Methods ◽

Amino Acid Analyzer ◽

Available Lysine

Abstract Methionine, cysteine, tryptophan, and available lysine were determined in Acacia colei and A. tumida seeds and some cereals using chemical methods, and the results were compared to those obtained using an amino acid analyzer. Ba(OH)2 hydrolysis gave the best result of the three methods of hydrolysis (acid, base, and enzyme) tried. Oxidized methionine, cysteine, and tryptophan were not detected, but S-carboxyethylcysteine was estimated as cysteine by the chemical methods, thus overestimating cysteine's content in Acacia seeds. Tryptophan and methionine were higher in cereals than in Acacia seeds, while the level of cysteine and available lysine was higher in Acacia seeds than in cereals. These results agreed with values obtained using the amino acid analyzer and could therefore be used in low budget laboratories.

Download Full-text

Tryptophan requirements in small, medium, and large breed adult dogs using the indicator amino acid oxidation technique1

Journal of Animal Science ◽

10.1093/jas/skz142 ◽

2019 ◽

Vol 97 (8) ◽

pp. 3274-3285 ◽

Cited By ~ 4

Author(s):

James R Templeman ◽

Wilfredo D Mansilla ◽

Lisa Fortener ◽

Anna K Shoveller

Keyword(s):

Amino Acid ◽

Dry Matter ◽

Basal Diet ◽

Acid Oxidation ◽

Total Production ◽

Deficient Diet ◽

Study Objective ◽

Amino Acid Oxidation ◽

Indispensable Amino Acid ◽

Labrador Retrievers

Abstract Tryptophan (Trp) is an indispensable amino acid (AA) for dogs of all life stages; however, although Trp requirements for growing dogs are derived from 3 dose–response studies, there are no empirical data on Trp requirements for adult dogs at maintenance. The study objective was to determine Trp requirements of adult dogs of 3 different breeds using the indicator amino acid oxidation (IAAO) technique. Four spayed or neutered Miniature Dachshunds (5.28 ± 0.29 kg BW), 4 spayed Beagles (9.32 ± 0.41 kg BW), and 5 neutered Labrador Retrievers (30.51 ± 2.09 kg BW) were used. After a 14-d adaptation to a Trp-adequate basal diet (Trp = 0.482% dry matter), all dogs were fed a mildly Trp-deficient diet for 2 d (Trp = 0.092% dry matter) before being randomly allocated to receiving 1 of 7 concentrations of Trp supplementation (final Trp content in experimental diets was 0.092, 0.126, 0.148, 0.182, 0.216, 0.249, and 0.283% dry matter) and all dogs received all Trp treatments. After 2-d adaptation to the experimental diets, dogs underwent individual IAAO studies. Total feed was divided in 13 equal meals; at the sixth meal, dogs were fed a bolus of L-[1-13C]-Phenylalanine (Phe) (9.40 mg/kg BW), and thereafter, L-[1-13C]-Phe was supplied (2.4 mg/kg BW) with every meal. Total production of 13CO2 during isotopic steady state was determined by enrichment of 13CO2 in breath samples and total production of CO2 measured using indirect calorimetry. The maintenance requirement for Trp and the 95% confidence interval (CI) were determined using a 2-phase linear regression model. Mean Trp requirements were estimated at 0.154, 0.218, and 0.157% (dry-matter) for Dachshunds, Beagles, and Labradors, respectively. The upper 95% CI were 0.187, 0.269, and 0.204% (dry-matter) for Dachshunds, Beagles, and Labradors. In conclusion, estimated Trp requirements are higher for Beagles compared with Labradors or Dachshunds, and all estimated requirements are higher than those currently recommended by the NRC and AAFCO.

Download Full-text

Dietary Phenylalanine and Tyrosine Requirements in Healthy Human Pregnancy

Current Developments in Nutrition ◽

10.1093/cdn/nzaa054_050 ◽

2020 ◽

Vol 4 (Supplement_2) ◽

pp. 978-978

Author(s):

Madeleine Ennis ◽

Kenneth Lim ◽

Ronald Ball ◽

Paul Pencharz ◽

Glenda Courtney-Martin ◽

...

Keyword(s):

Amino Acid ◽

Life Stage ◽

Experimental Studies ◽

Late Pregnancy ◽

Acid Oxidation ◽

Current Recommendation ◽

Two Phase ◽

Healthy Human ◽

Dietary Requirement ◽

Indispensable Amino Acid

Abstract Objectives Phenylalanine (PHE), an indispensable amino acid, is required for protein synthesis and is fundamental for proper fetal development. PHE is the precursor for tyrosine (TYR), a conditionally indispensable amino acid that is crucial for synthesis of dopamine, norepinephrine and epinephrine. The current recommendation for PHE + TYR during pregnancy is 36 mg/kg/d, which is factorially determined and not based on experimental studies. Our objective was to experimentally determine PHE + TYR requirements during early (13–19 wks) and late (33–39 wks) gestation, accounting for potential changes in requirement since metabolism and rate of growth are not static throughout pregnancy. Methods 20 women (22–39 y) were studied using the non-invasive stable isotope based indicator amino acid oxidation technique (with L-[1–,13C]Leucine as indicator) for a total of 51 study days. A range of PHE intakes (5 to 100 mg/kg/d) were provided in early and late pregnancy as isonitrogenous and isocaloric meals on separate study days, in the absence of dietary tyrosine. Breath samples were collected at baseline and isotopic steady state. Samples were analyzed for ,13C enrichment on an Isotope Ratio Mass Spectrometer, and the PHE + TYR requirement was determined using two-phase linear regression crossover analysis to identify a breakpoint in ,13CO2 production (represents the minimum dietary requirement) in response to changes in PHE intake. Results Results suggest the PHE + TYR requirement is 43 and 55 mg/kg/d in early and late pregnancy respectively. Conclusions Our preliminary results suggest that PHE + TYR requirements in pregnancy are higher compared to current recommendations, and are different between gestational stages. These results are similar to our previous findings of increased requirements for dietary protein, lysine and PHE (in the presence of excess TYR) in late compared to early pregnancy. They also highlight the need to investigate the dietary requirement of the remaining indispensable amino acids during this life stage. Funding Sources Canadian Institute of Health Research.

Download Full-text

THE EFFECTS OF HYDROUS AND ANHYDROUS AMMONIA TREATMENTS ON THE NUTRITIVE VALUE OF LOW GLUCOSINOLATE-TYPE RAPESEED MEAL (CANOLA MEAL) FOR CHICKS

Canadian Journal of Animal Science ◽

10.4141/cjas82-110 ◽

1982 ◽

Vol 62 (3) ◽

pp. 915-918

Author(s):

Y. K. GOH ◽

A. SHIRES ◽

A. R. ROBBLEE ◽

D. R. CLANDININ

Keyword(s):

Amino Acid ◽

Amino Acid Composition ◽

Key Words ◽

Nutritive Value ◽

Rapeseed Meal ◽

Canola Meal ◽

Lysine Content ◽

Feeding Value ◽

Available Lysine ◽

Amino Acid Contents

The effects of sparging low glucosinolate-type rapeseed meal (Canola meal) with ammonia, in the absence or presence of steam, on its amino acid composition and feeding value for chicks were studied. Sparging treatments had no effects on the amino acid contents of the meals nor were thyroid size or the growth of chicks affected adversely when the variously treated meals were included in diets for chicks at the 20% level. Sparging with steam appeared to increase the available lysine content of the meal and improve its feeding value for chicks. Key words: Canola meal, ammoniation, sinapine, nutritive value, chicks

Download Full-text

Mechanisms of heat damage in proteins

British Journal Of Nutrition ◽

10.1017/s0007114575000360 ◽

1975 ◽

Vol 34 (2) ◽

pp. 325-337 ◽

Cited By ~ 23

Author(s):

Shirley A. Varnish ◽

K. J. Carpenter

Keyword(s):

Heat Treatment ◽

Amino Acid ◽

Amino Acid Composition ◽

Close Agreement ◽

Total Amino Acid ◽

Lysine Content ◽

Chemical Analyses ◽

Chick Growth ◽

Amino Acid Availability ◽

Amino Acid Contents

1. The preparation of a propionylated protein is described, and the effects of this treatment on amino acid composition and availability are compared with the effects of severe heat treatment (autoclaving) of a protein.2. Using chemical analyses, changes exceeding 5% for total tyrosine, histidine, methionine and cystine contents were found after propionylation of the protein. Autoclaving of the protein resulted in changes in total serine, lysine, methionine, cystine and tryptophan contents.3. Microbiological estimates of total amino acid contents were not in close agreement with the chemical estimates for the autoclaved protein.4. Fluorodinitrobenzene-reactive lysine content was reduced to almost zero by propionylation, and by almost 40% by autoclaving.5. Both propionylating and autoclaving protein reduced the amount of lysine available to the chick by about half. In contrast, the availabilities of methionine and tryptophan to the chick were unchanged by propionylation, but were reduced to 0.66 and 0.44 respectively, relative to the untreated protein, by autoclaving.6. Because of the difficulties of obtaining reliable absolute estimates of amino acid availability using chick growth assays, our interpretation of results is mainly based on relative values. The merits of microbiological microbiological estimates of amino acid availability are assessed.

Download Full-text

Available versus digestible dietary amino acids

British Journal Of Nutrition ◽

10.1017/s0007114512002528 ◽

2012 ◽

Vol 108 (S2) ◽

pp. S298-S305 ◽

Cited By ~ 28

Author(s):

Shane M. Rutherfurd ◽

Paul J. Moughan

Keyword(s):

Amino Acids ◽

Amino Acid ◽

Acid Hydrolysis ◽

Acid Content ◽

Amino Acid Analysis ◽

Amino Acid Content ◽

Cysteic Acid ◽

Processed Foods ◽

Dietary Amino Acids ◽

Available Lysine

Available amino acids are those absorbed from the gastrointestinal tract in a form suitable for body protein synthesis. True ileal digestible amino acids are determined based on the difference between dietary amino acid intake and unabsorbed dietary amino acids at the terminal ileum. The accuracy of ileal digestible amino acid estimates for predicting available amino acid content depends on several factors, including the accuracy of the amino acid analysis procedure. In heat processed foods, lysine can react with compounds to form nutritionally unavailable derivatives that are unstable during the hydrochloric acid hydrolysis step of amino acid analysis and can revert back to lysine causing an overestimate of available lysine. Recently, the true ileal digestible reactive (available) lysine assay based on guanidination has provided a means of accurately determining available lysine in processed foods. Methionine can be oxidised during processing to form methionine sulphoxide and methionine sulphone and cysteine oxidised to cysteic acid. Methionine sulphoxide, but not methionine sulphone or cysteic acid, is partially nutritionally available in some species of animal. Currently, methionine and cysteine are determined as methionine sulphone and cysteic acid respectively after quantitative oxidation prior to acid hydrolysis. Consequently, methionine and cysteine are overestimated if methionine sulphone or cysteic acid are present in the original material. Overall, given the problems associated with the analysis of some amino acids in processed foodstuffs, the available amino acid content may not always be accurately predicted by true ileal amino acid digestibility estimates. For such amino acids specific analytical strategies may be required.

Download Full-text