Measurement of Available Lysine in Heated and Unheated Foodstuffs by Chemical and Biological Methods

Boctor, Amal M.; Harper, Alfred E.

doi:10.1093/jn/94.3.289

Cited by 45 publications

(18 citation statements)

References 16 publications

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“…This is in agreement with the results obtained by CALHOUN et al [4], BOCTOR et al [2] and SARWAR et al [13]. A good correlation between lysine intake from corn bread and weight gain or moisture gain was also obtained; 0.76 and 0.82 respectively.…”

Section: Lysine Availability Valuessupporting

confidence: 92%

Availability of essential amino acids in corn flour and corn bread

El‐Shafei¹,

Abbassi

Bassily³

et al. 1983

Nahrung

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The availability of nitrogen, lysine and 9 essential amino acids was determined in corn before and after baking. Lysine avdibdbility was determined by the growth response method on weaning rats using regression analysis of body weight gain or moisture gain against lysine consumed from corn flour and corn bread. The results show a high correlation between lysine consumed and weight gain or moisture gain (r = 0.95) for rats fed the standard diets for 3 weeks. A good correlation was also obtained for corn bread. The results of lysine availability show that baking greatly improves availability by both ways of calculation.The availability of nitrogen and essential amino acids were also investigated by the balance trials with rats. Results show that availability values for nitrogen and all amino acids except threonine increased by baking. Data for food intake, weight gain, food efficiency, PER, NPR and true digestibility revealed that baking had little or no effect on nutritive value of corn tested in this investigation.

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Section: Lysine Availability Valuessupporting

confidence: 92%

Availability of essential amino acids in corn flour and corn bread

El‐Shafei¹,

Abbassi

Bassily³

et al. 1983

Nahrung

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“…Given that background microbial growth contributed by the test material could influence assay results, it is necessary to sterilize the protein source prior to conducting the assay. Autoclaving or heating protein sources and free amino acids to achieve sterility can alter the properties of the protein, including the nutrient and amino acid availability ( Evans & Butts 1949; Boctor & Harper 1968; Bjarnason & Carpenter 1970; Carpenter & Booth 1973; Anderson‐Hafermann et al . 1993 ; Johnson et al .…”

Section: Introductionmentioning

confidence: 99%

Antibiotic amendment for suppression of indigenous microflora in feed sources for an Escherichia coli auxotroph lysine assay

1999

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Growth responses of lysine auxotrophic mutants of Escherichia coli have been used as a measurement of bioavailable lysine in protein sources and animal feeds. Sterilizing feed samples by autoclaving to eliminate non‐specific background growth of indigenous feed micro‐organisms prior to conducting the bacterial assay may introduce chemical and physical alterations to the feeds, influencing the estimation of available feed lysine. In this study, an antibiotic‐ and antifungal‐supplemented medium was constructed to support growth of an E. coli lysine auxotroph assay organism, and was tested for its ability to repress indigenous bacterial and fungal growth in feed samples. To determine which antibiotics to include, an ampicillin‐sensitive E. coli lysine mutant strain (ATCC no. 23812) was screened for antibiotic resistance and transformed with a plasmid carrying an ampicillin resistance gene. Maximum optical density quantitative response of the E. coli auxotroph to lysine was not altered by the antibiotic medium amendments (ampicillin, novobiocin and cycloheximide). Indigenous microfloral growth in a variety of typical animal feeds was suppressed in the presence of the antistatic agents. The estimated lysine recovery was 91·6% and 98·1% when the medium was used in an assay of available lysine in a lysine‐supplemented feed. This indicates that the antibiotic‐amended basal medium can be used for the E. coli‐determined lysine availability of a variety of animal feeds without prior sterilization of the feed sources.

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“…The FDNB-method for the determination of available lysine has been criticized for its overestimation of lysine availability (Boctor and Harper, 1968;Shorrock, Waibel et al, 1977). In this study the problem of overestimation occurs at lower bioavailabilities, especially for the vat and fast conventional samples where the FDNB-Iysine values averaged 31 % greater.…”

Section: Discussionmentioning

confidence: 84%

Available Lysine Content of Blood Meals Determined by Turkey Bioassay and Fluorodinitrobenzene Assay

Noll

Waibel

1984

Poultry Science

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Lysine availability in blood meal as affected by processing method was studied using 53 samples representing 10 manufacturing processes. Each sample was analyzed for total lysine and chemically available lysine using the fluorodinitrobenzene technique (FDNB-Iysine). Bioavailable lysine was determined by turkey poult growth assay. The bioavailability was calculated using the slope ratio method where gain was regressed on dietary lysine content (Method A) or on lysine consumption (Method B). Vat-dried blood meal, representing harsh processing conditions, contained significantly less total lysine, FDNB-Iysine, and bioavailable lysine when compared to spray, DeLaval-Anderson, ring, and flash-dried blood meal. Content of FDNB-Iysine was more correlated with bioavailable lysine than was total lysine. Available lysine as measured by the FDNB-Iysine technique overestimated bioavailable lysine in vat-dried samples. Bioavailable lysine contents as estimated by Method B were greater and more variable than those determined by Method A. (

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Measurement of Available Lysine in Heated and Unheated Foodstuffs by Chemical and Biological Methods

Cited by 45 publications

References 16 publications

Availability of essential amino acids in corn flour and corn bread

Availability of essential amino acids in corn flour and corn bread

Antibiotic amendment for suppression of indigenous microflora in feed sources for an Escherichia coli auxotroph lysine assay

Available Lysine Content of Blood Meals Determined by Turkey Bioassay and Fluorodinitrobenzene Assay

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