Nova Explore Publications Nova Journal of Medical and Biological Sciences DOI: 10.20286/nova-jmbs-060201 Vol.6 (2) 2017:1-3 www.novaexplore.com
Short Communication Physicochemical Characteristics of Various Milk Samples Hadohum M. Musallam1, Hend M. Almozogai1, Somia S. Amkabis1, Marowa A. Aoag1, Tark M. Hassan1, Esam A. Elhefian 1, Fathi M. Asseid2 1 P
Department of Chemistry, Faculty of Science, Sabratha University, Sabratha, Libya P
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Department of Chemistry, Faculty of Science, University of Zawia, Az Zawiyah, Libya P
Corresponding Author: Esam Abdulkader Elhefian, Department of Chemistry, Faculty of Science, Sabratha University, Sabratha, Libya. Email Address:
[email protected] Received: 2017.05.10 Accepted: 2017.06.12
Abstract Background: Milk is a complex colloidal dispersion composed of fats, proteins, lactose, minerals and other minor compounds. The quality of milk can be monitored by evaluating its physicochemical properties and characteristics. Materials and methods: This work was carried out to evaluate some physicochemical properties, including acidity, density and viscosity of milk samples collected from goat, cow, camel and human (human breast milk based on a baby's sex). Results: Results showed that the highest value of density was recorded for goat milk and cow milk (1.02 and 1.03 g/cm3 respectively) while the highest value of viscosity was recorded for human breast milk for a boy (1.770 cP). It was also found that the acidity of the milk samples increased with increasing time as expected. Studying the composition of the milk samples in terms of carbohydrates (lactose) and proteins showed that the highest percentage of lactose was found in the human breast milk for a boy (6.51%) and the highest percentage of protein was exhibited by goat milk (4.93%). Interestingly, it was observed that the physicochemical properties of human milk depend on the infant's gender. Conclusion: Variations in physicochemical properties are observed in animal milk samples analyzed in this work, which could be helpful for monitoring the quality of the milk for consumption. It is observed also, that variations in human milk depend on the infant' sex, which encourages more studies to be conducted on this topic. P
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Keywords: milk, physicochemical properties, animals, human Introduction Milk is a complex combination of proteins, carbohydrates, fats, minerals, vitamins and other constituents [1,2]. This makes milk essential for human consumption as a complete food supplement in various parts of the world. Milk can be obtained from different animal species, such as goats, cows and camels. However, cow's milk remains the most preferred type of milk. Generally, all types of milk are composed of the same kind of constituents, but in different concentrations. The chemical state of some elements and mineral usually found in milk is very important due to their absorption in the intestine and biological utilization i.e., transport, assimilation in cells and their conversion into biologically system forms. Usually, for cow milk the total calcium content found in the skimmed partition, as skimmed milk is fat-free milk. The major part of calcium usually observed as calcium phosphate in the colloidal phase present mainly in skimmed milk. For example casein micelles or as calcium ions bonded to phosphoserine i.e., about 17% of the total calcium, the remaining part of dissolved calcium as calcium citrate. Cow milk, nearly 100 % of magnesium is found in the skim milk fraction, two-third of which in the soluble phase, in other words approximately 40 % as magnesium citrate, 7 % as magnesium-phosphate and 16 % as free ions. Nova Journal of Medical and Biological Sciences
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The immediate balance of salts of some mineral elements between the soluble and the colloidal phase in cow, goat and sheep milk is important for definition of their nutritional value properties. All essential mineral elements found in milk because by definition it contains the nutritional requirements for growth of the young [3]. Phosphorus is a major element with many important biological compositions in the human body. It is usually present as organic or inorganic phosphate in most body tissues and fluids, and is the main component of many biological compounds, including lipids, proteins, carbohydrates and nucleic acids [4]. The overall concentration of major elements in goat and sheep milk is relatively higher in relation to cow milk (except for sodium), and several times higher in relation to human milk. The concentration of major elements most likely to depend on the species, the individual animal, the method of feeding, lactation stage, and health condition of the udders [5,6]. The content of some elements in milk differs quite reasonably from that in blood. Compared to blood, milk contains more potassium, calcium and phosphorus, and less sodium and chloride. In general, the bioavailability of calcium and magnesium has not yet been sufficiently researched. Among individual animals, such as, sheep, goat and cow milk the bioavailability of iron and zinc from cow milk is quite high, however; significantly lower than in human milk. Physiochemical properties and characteristics are important variables for monitoring the milk quality. The best quality of milk for consumption is usually due to its distinct physical, chemical and biological characteristics, which clearly indicate the importance of this work. The objective of this paper is to evaluate the physicochemical properties and characteristics of various milk samples collected from different species of animals as well as from human. . Materials and methods For the purpose of this study, animal milk samples were collected from healthy goats, cows, and camels of farms located in Sabrathah suburb, northwestern Libya. Human milk was collected from healthy breastfeeding volunteer mothers. The human milk was collected to study its physiochemical properties based on whether the mother’s baby is a boy or girl, and to compare it with the animal milk. All samples were collected between June and October, 2016 and were kept in refrigerator for analysis. The percentage of protein in milk samples was determined by formaldehyde titration method. Lactose content was determined by titration with Fehling's solutions (A and B) method. Density was measured using a Pycnometer while viscosity was recorded using Ostwald viscometer. Acidity was determined by titration method and expressed as percentage lactic acid. All analyses were performed at room temperature. Results and discussion Table 1 shows various physicochemical parameters of the milk samples. Protein contents of the milk samples were in the range of 1.19 % to 4.93 %. The lowest value was found for human breast milk (1.19%) while the highest value was shown by goat milk. The lactose content varied between 4.39% and 6.51 %. The lowest value was recorded for goat milk and the highest value was shown by human breast milk. For the density, values of the milk samples ranged from 1.010 to 1.033 g/cm3. The Minimum density was recorded for human breast milk while the maximum value was shown by cow milk. Viscosity values ranged between 1.141 and 1.770 cP. The lowest value was measured for camel milk and the highest value was registered for human breast milk. Titratable acidity was found to decrease with increasing time (data not shown). Our results show agreement with earlier study reported by El-Hatmil et al (2015) [7] with respect to density and protein content of human, cow, camel and goat milk samples. However, the values of lactose content of camel, cow and goat milk samples reported in this study are higher than the ones reported by Gakkhar et al (2015) [8]. Also, it has been demonstrated that the highest lactose content was found to be in human milk while the lowest was in goat milk [9], which are in a compliance with our findings. Furthermore, this study showed that there are differences in the physical properties and content of human milk. It seems that a human mother makes different milk depending on whether the mother’s baby is a boy or a girl. These results relate directly to contents of minerals and elements in various types of milk as shown especially for goat, cow, and humans [4]. The physicochemical properties studied for the various types of milk clearly indicate the bioavailability of some types of milk over the other. However, each type is valid for its own purposes and the requirements of feeding. A comparative study on complex combination of proteins, carbohydrates, fats, minerals, and elements can be conducted to show the immediate relationship between types of milk in order to enhance the formulation of milk being an essential food for newly born.
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Table 1. Physicochemical properties of cow, camel, goat and human milks. Milk sample
Protein %
Lactose %
Density (g/cm3)
Cow Camel Goat Human breast milk for a boy Human breast milk for a girl
4.25 2.89 4.93 1.36
4.60 4.53 4.39 6.51
1.033 1.024 1.032 1.022
Viscosity (cP) 1.550 1.141 1.580 1.770
1.19
5.46
1.010
1.674
Conclusion This study has shown that the physicochemical properties of milk vary depending on the species. It was found that goat and cow milks exhibited the highest value of density (1.02 and 1.03 g/cm3 respectively) while the highest value of viscosity was recorded for human breast milk for a boy (1.770 cP). It was also found that the human breast milk for a boy exhibited the highest percentage of lactose (6.51%) while goat milk had the highest percentage of protein (4.93%). In addition, the titratable acidity of the milk samples was found to increase with increasing time. Further intensive studies should be carried out to investigate the nutritional value, rheology, and other properties of these types of milk, which are not covered in the present study. Also, it would be of great interest if further studies are conducted on human milk and its variation with a baby's sex. P
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