why buffalo milk does not contain carotene while cow does
Answers
Milk and other dairy products remains always a source of interest for all nutritionists because of its significant role in human life. It is generally obtained from cows, buffaloes, goats, camels, ewes etc. The most important nutritious components of milk are proteins, carbohydrate, vitamins and fats [1]. Among all proteins, Beta-lactoglobulin (β-lg) is a major protein that exists at the normal pH of bovine milk which account for approximately 10–15% of total milk proteins and about 60% of whey protein [2, 3]. Apart from other essential elements, milk is a rich source of carotenoids. Carotenoids are synthesized in plants but not in animals. Beta-carotene (β-carotene) is one of the members of naturally occurring carotenoids and is abundantly available in plants (fruits and vegetables). It is established that β-carotene is present in cow milk but absent in buffalo, goat and ewe milk [4, 5]. In fact, these animals metabolized the carotenoids into vitamin-A and then passed on to milk. β-carotene is also known as pro vitamin-A, as human body easily converts them into retinol (vitamin-A).
In animal foods, dairy products and liver are the rich sources of vitamin-A along with vitamin-A-active carotenoids (β-carotenes in plants) that are partially converted to retinol by animals during or after absorption. Vitamin-A belongs to a group of fat-soluble compounds (retinyl esters) [6]. Vitamins play key role in metabolism as part of enzymes/co-enzymes and as antioxidants, preventing undesired oxidative processes in the body. Vitamin-A is generally available as retinol, retinal and retinoic acid. It is an essential element and is involved in critical biological processes such as cell growth and development, reproduction, vision (sight) and immune system function etc. [7–9]. Reliable information about the composition of milk and dairy products are of great importance and needs to be labeled properly, in order to fulfill consumer’s demands as well as satisfaction.
Different techniques are available which determines milk ingredients/composition as well as detect milk adulterants. Generally, these techniques are time consuming, required sample pre-treatment as well as skilled professionals. These techniques include high-performance liquid chromatography (HPLC), gas chromatography (GC), colorimetric method, polymerase chain reaction (PCR), mass spectrometry etc. [10–13]. In contrast, optical spectroscopic techniques have the potential to be used for reliable analysis of biological samples [14–18]. Among these spectroscopic techniques, the inherent sensitivity of fluorescence spectroscopy provides alternative tool in resolving the biological samples on molecular level. In recent years, fluorescence spectroscopic technique is becoming a valuable tool for the assessment different fruits and vegetables based on their contents like carotenes [19–21]. The main advantage of this technique lies in the fact that it requires no or little sample preparation. Furthermore, it is nondestructive and suits for in-line industrial processing once it’s established.
The main objective of this study is to identify cow and buffalo milk based on β-carotene and vitamin-A fluorescence spectra in combination with multivariate technique. To the knowledge of authors, no research has been reported previously. Although, the fluorescence spectra of cow and buffalo milk samples are clearly separable in both classical geometry (fixed excitation) as well as front face geometry (synchronous fluorescence), the differences between the two data sets have been further highlighted by applying Principal Component Analysis (PCA) to the fluorescence spectral data of both gender’s milk.