Effect of low frequency oscillations on casein micelle size in raw milk

Abstract

The application of vibration therapy of blood flow improvement in the medical field has been explored intensively during recent decades. However, compelling evidence about the health effects of vibration (especially treatment effectiveness) is still unclear. The treatment capabilities of the low power acoustic pulse therapy (APT) have been widely reported. It is known to produce various responses in biological tissues [1, 2]. APT pressure (10 ± 15 megapascal) has been shown to produce new blood vessels and improve tissue function with long term exposure [1]. In our previous investigation [3], an unbalanced vibratory motor was applied to the DeLaval Harmony model milking unit. During in vivo experiments, while milking, the vibrator induced mechanical milking-similar vibrations in the udder. The vibrations were spreading to the entire udder and caused physiotherapeutic effects such as activated physiological processes and increased udder base temperature by 0.57 , thus increasing the blood flow in the udder. The application of low-frequency vibrations did not alter observable changes in milk yield and quality parameters oranimal welfare indicators. Moreover, casein micelle size and milk fat globules can vary depending on farming factors (seasonal variation, stage of lactation), and cow genetics [4]. Here, we aimed to estimate the effect of vibration on casein micelle size in raw milk under in vitro conditions. Casein micelle size analysis was performed using Beckman Coulter - Delsa™Nano Series analyzer. Raw milk samples were exposed to the 25-Hz vertical and 41-Hz horizontal vibrations for 15 s (A sample), 1 min (B sample), 2 min (C sample) and 7 min (D sample). K sample (no vibration) served as control. Milk measurement temperature was 24.5–25.00°C, refractive index was 1.3328, viscosity was 0.8980 (cP), scattering intensity was 30617 (cps), and attenuator was 0.3 (%). The average size of casein micelle size in raw milk distributed as follows: 646.1 nm, 642.3 nm, 640.5 nm, 621.5 and 617.6 nm in K, A, B, C, and D samples, respectively. To sum up, we can state that vibration had no significant influence on casein micelle size in raw milk.