Application of a dye-binding method for the determination of available lysine in skim milk powders

2016 ◽  
Vol 196 ◽  
pp. 815-820 ◽  
Author(s):  
Kataneh Aalaei ◽  
Marilyn Rayner ◽  
Eden Tareke ◽  
Ingegerd Sjöholm
1979 ◽  
Vol 42 (3) ◽  
pp. 445-454 ◽  
Author(s):  
Ann F. Walker

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.


2003 ◽  
Vol 66 (8) ◽  
pp. 1439-1443 ◽  
Author(s):  
JEONG-HUN KANG ◽  
FUSAO KONDO

This study was conducted to develop a selective and sensitive method for the determination of bisphenol A (BPA) levels in milk and dairy products. A method based on solvent extraction with acetonitrile and solid-phase extraction (SPE) was developed for the analysis of BPA in milk, yogurt, cream, butter, pudding, condensed milk, and flavored milk, and a method using two SPE cartridges (OASIS HLB and Florisil cartridge) for skim milk was also developed. The developed methods showed good recovery levels (77 to 102%) together with low detection limits (1 μg/liter for milk, yogurt, pudding, condensed milk, flavored milk, and skim milk and 3 μg/liter for cream and butter). These methods are simple, sensitive, and suitable for the analysis of BPA in milk and dairy products. When 40 milk and dairy products were analyzed by the proposed methods, BPA was not identified in noncanned products, but its levels ranged from 21 to 43 μg/kg in canned products, levels that were 60- to 140-fold lower than the migration limits in the European Union and Japan.


LWT ◽  
2016 ◽  
Vol 73 ◽  
pp. 675-682 ◽  
Author(s):  
Kataneh Aalaei ◽  
Marilyn Rayner ◽  
Ingegerd Sjöholm

1955 ◽  
Vol 22 (1) ◽  
pp. 43-47 ◽  
Author(s):  
Kathleen O. Donovan ◽  
J. M. Vincent

A medium has been developed that permits the viable count of milk bacteria to be combined with the determination of biochemical properties likely to be important in milk itself. This has involved the modification of standard glucose-tryptone skim-milk agar by incorporation of two indicators to detect alkali as well as acid production, substitution of lactose for glucose, and increasing the quantity of skim milk for the detection of proteolysis and casein precipitation. The medium has proved particularly valuable in the study of the thermoduric flora of pasteurized milk. The phenomenon of casein precipitation is, however, less reliably determined than are changes in hydrogen-ion concentration and proteolysis.


1965 ◽  
Vol 43 (11) ◽  
pp. 1879-1883 ◽  
Author(s):  
M. A. Krishnaswamy ◽  
S. B. Kadkol ◽  
G. D. Revankar

Ensiled fish was prepared from a local variety of freshwater fish (Barbus carnaticus) by fermentation with a pure culture of Streptococcus lactis, commercial lactose being used as a source of fermentable carbohydrate. The fermented material (pH 4.7) was roller dried. The finished product was cream colored and had a somewhat aromatic odor. It had a protein content of about 72%. Total lysine, available lysine, methionine, cystine, and tryptophan of the ensiled fish (expressed as g/16 g N) were 10.1, 8.1, 3.6, 1.1, and 1.2%, respectively. Hygienically, the product, being free from coliforms, enterococci, Salmonella, coagulase-positive staphylococci, and pathogenic anaerobes, was satisfactory. The biological value of the product as determined by protein efficiency ratio (3.3), net protein utilization (82.3%), and net protein ratio (4.2) was not significantly different from that of skim milk powder, which has a protein efficiency ratio of 3.2, net protein utilization of 82.8%, and net protein ratio of 4.9.


1997 ◽  
Vol 80 (1) ◽  
pp. 25-30 ◽  
Author(s):  
Catharina Y W Ang ◽  
Luo Wenhong

Abstract A rapid and sensitive liquid chromatographic (LC) method was developed for the determination of am- picillin residues in raw bovine milk, processed skim milk, and pasteurized, homogenized whole milk with vitamin D. Milk samples were deprote- inized with trichloroacetic acid (TCA) and acetonitrile. After centrifugation, the clear supernatant was reacted with formaldehyde and TCA under heat. The major fluorescent derivative of ampicillin was then determined by reversed-phase LC with fluorescence detection. Average recoveries of ampicillin fortified at 5,10, and 20 ppb (ng/mL) were all >85% with coefficients of variation <10%. Limits of detection ranged from 0.31 to 0.51 ppb and limits of quantitation, from 0.66 to 1.2 ppb. After appropriate validation, this method should be suitable for rapid analysis of milk for ampicillin residues at the tolerance level of 10 ppb.


1976 ◽  
Vol 59 (5) ◽  
pp. 1146-1149 ◽  
Author(s):  
Kermit C Bachman ◽  
Jan-Hai Lin ◽  
Charles J Wilcox

Abstract Cholesterol can be determined colorimetrically in dairy products at levels of ≥10 μg (coefficient of variation = 5.3%) with an o-phthalaldehyde reagent when non-cholesterol lipids arc eliminated prior to color development. Absorbance for 2 mg tripalmitin was found to be equivalent to about 20 μg cholesterol. Saponification followed by hexane extraction removed interfering lipids. Using the described procedure, 238 individual raw milk samples were found to contain 144.4±37.9 μg cholesterol/ml, while their skim milk portions had 26.5±6.4 μg cholesterol/ml (mean ± standard deviation). The o-phthalaldehyde cholesterol estimates agreed with those obtained by a gas-liquid chromatographic procedure when cheese and ice cream were analyzed by the colorimetric procedure with and without prior fat extraction.


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