Determination of protein in goat milk by different analytical methods
DOI:
https://doi.org/10.5965/223811711922020245Keywords:
Biuret, Bradford, Kjeldahl, Lowry, goatsAbstract
The objective of this study was to correlate the Biuret, Lowry, Bradford, and Mlikoscan methods used to determine the level of protein in goat's milk and compare them with the Kjeldahl method. Milk samples collected from 18 goats of breeds Saanen (n=5), Anglo-Nubian (n=4), Pardo-alpina (n=5), and Creole (n=4) were analyzed. Correlation analyses between the different methods were performed using the Pearson test and the protein content between different breeds was compared using ANOVA. Total protein (TP) and casein (CN) concentrations obtained by all methods studied were positively correlated with the Kjeldahl method (p<0.01). The Bradford method presented the lowest correlation coefficient. All methods apart from Bradford showed significant differences in TP and CN between the Anglo-Nubian and Pardo-alpina breeds (p<0.05). The Bradford method showed significant differences in TP between the Saanen and Pardo-alpina breeds (p<0.05), and no differences were found between breeds reegarding CN. In conclusion, the Bradford method had the lowest correlation value (TP and CN) with the Kjeldahl, and the Bradford method did not show the same pattern of differences between breeds in TP and CN, as was evidenced in all other methods. Therefore, the use of the Bradford method is not recommended to determine proteins in goat’s milk.
Downloads
References
Al-ABDULKARIM BO et al. 2013. Determination of chemical composition, and storage on dried fermented goat milk product. Journal of the Saudi Society of Agricultural Sciences 12: 161-166.
BARLOWSKA J et al. 2011. Nutritional value and Technological suitability of milk from various animal species used for Dairy Production. Comprehensive Reviews in Food Science and Food Safety 10: 291-302.
BRADFORD M 1976. A rapid and sensitive method for the quantitation of microgram quantities of protein utilizing the principle of protein-dye binding. Analytical Biochemist 72: 248-254.
BRADLEY RL et al. 1992. Chemical and physical methods. In: MARSHALL RT. (Ed.) Standard Methods for the Examination of Dairy Products. Washington DC: American Public Health Association. p.433-531.
DAMIÁN JP et al. 2008. Cheese yield, casein fractions and major components of milk of Saanen and Anglo-Nubian dairy goats. Arquivo Brasileiro de Medicina Veterinária e Zootecnia 60: 1564-1569.
DOS SANTOS ASO et al. 2017. Major goat milk protein: separation and characterization by “Lab-On-A-Chip” microfluidic electrophoresis. Boletim Centro de Pesquisa de Processamento de Alimentos 35: 1-13.
EL-TARABANY MS et al. 2018. Characterization of progesterone profile, physiological responses, milk composition and blood biochemical and hematological indices at the early stage of lactation in goats. Biological Rhythm Research 50: 647-657.
FRAU F et al. 2012. Composición físico-química y calidad microbiológica de leche de cabra en rebaño bajo sistema extensivo en Santiago del Estero (Argentina). Revista de la Facultad de Agronomía, La Plata 111: 1-7.
GORNALL AG et al. 1949. Determination of serum proteins by means of the biuret reaction. Journal of Biological Chemistry 177: 751-766.
KELLER RP & NEVILLE MC 1986. Determination of Total Protein in Human Milk: Comparison of Methods. Clinical Chemistry 32: 120-123.
LONNERDAL BO et al. 1987. Compartmentalization and Quantitation of protein in human milk. The Journal of Nutrition 117: 1385-1395.
LOWRY OH et al. 1951. Protein measurement with the folin phenol reagent. Biology Chemistry 193: 265-275.
AOAC. 1991. Association of Official Analytical Chemists. Official methods of analysis, 15.ed. Washington, DC: AOAC.
OLALLA M et al. 2009. Nitrogen fractions of Andalusian goat milk compared to similar types of commercial milk. Food Chemistry 113: 835-838.
PELÁEZ PUERTO P et al. 2003. Caracterización físico-química de quesos frescos elaborados con leche de cabra en la isla de Tenerife, CYTA. Journal of Food 4: 103-108.
POTOCNIK K et al. 2011. Mare´s milk: composition and protein fraction in comparison with different milk species. Portal Znanstvenih Casopisa Republike Hrvatske 61: 107-113.
RAIMONDO RFS et al. 2013. Dynamic in the concentration of whey proteins in the mammary secretion of goats during the dry period. Small Ruminant Research 113: 239-246.
VEGA S et al. 2007. Características físicas y químicas de leche de cabra de razas Alpino Francesa y Saanen en épocas de lluvia y seca. Revista Salud Animal 29: 160-166.
ZENG SS 1996. Comparison of goat milk standards with cow milk standards for analyses of somatic cell count, fat and protein in goat milk. Small Ruminant Research 21: 221-225.
Downloads
Published
How to Cite
Issue
Section
License
Copyright (c) 2020 Revista de Ciências Agroveterinárias (Journal of Agroveterinary Sciences)
This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.
Authors publishing in this journal are in agreement with the following terms:
a) Authors maintain the copyrights and concede to the journal the copyright for the first publication, according to Creative Commons Attribution Licence.
b) Authors have the authority to assume additional contracts with the content of the manuscript.
c) Authors may supply and distribute the manuscript published by this journal.
