Study on crystallization behavior of Tibet butter

Abstract

Tibetan butter (TB), generally called butter, is a solid oil product extracted from yak milk in the Qinghai-Tibet plateau area. However, due to the limitations of raw material sources and production technology, there is a shortage of TB, so it is important to find substitutes of TB. This paper studied the crystallization behavior of six kinds of commercial TB products in Tibet to provide the theoretical basis for the development of TB substitutes for the production of TB lamps and flowers. This study assessed the crystallization behaviors of the TB samples, including isothermal crystallization process and non-isothermal crystallization process. The microstructure, isothermal crystallization of TB were evaluated by polarized light microscopy and low-pulse NMR spectrometry, respectively. The non-isothermal crystallization process of TB under temperature scanning were investigated using Rheometer, and the crystallization behavior under different cooling rates were determined by differential scanning calorimetry (DSC) procedures. The results showed that the TB was crystallized at a higher supercooling (−10, 0 and 10 °C). Dimensional growth is dominant; at 20 °C, spiral growth dominates. The TB has complex crystallization nucleation behavior. The crystal types of TB are mainly β'-crystal form and β'-like crystal form. The lower the cooling rate, the shorter the crystallization induction time, and the more the number of crystal nuclei. Therefore, during producing TB substitutes in the factory, the cooling rate can be controlled at 10 °C/min to reduce energy consumption and production costs.