Search

In this study, the effects of the denaturation degree of whey protein (WP) and whey protein/casein (WP/CN, m/m) ratio in milk powder on the emulsion stability and whipping properties of recombined cream were investigated. The results showed that the cream prepared from milk power with 60% of WP denaturation had good emulsion stability, and the stability of the system decreased with increase in denaturation degree. An increase in the degree of WP denaturation shortened the whipping time and reduced the leakage rate of whey. The emulsion stability at a WP/CN ratio of 1:4 first increased and then decreased to a level higher than the initial one with increasing proportion of WP. In addition, the whipping time of the cream was shortened, and whey leakage was reduced, while foaming rate declined and bubble collapse rate increased. In summary, the cream prepared from milk power with 60% of WP denaturation showed good emulsion stability and whipping properties; it had the best stability at a WP/CN ratio of 2:4 and better foaming capacity and foam stability at a WP/CN ratio of 1:4. Therefore, WP/CN ratio can be adjusted according to the practical needs to improve the functional characteristics of cream products.

In this study, solid phase microextraction (SPME) coupled with gas chromatography-mass spectrometry (GC-MS) was used to investigate the volatile compound profiles of eight dairy fat products (including four butters, two creams and two cultured butters) that are popular on the Chinese market. Their key flavor compounds were identified by calculating relative odor activity value (ROAV) as well as using gas chromatography-olfactometry (GC-O). In total 40 volatiles were found in the eight milk fat products, including 7 aldehydes, 6 methyl ketones, 7 fatty acids, and 7 lactones. A total of 17 volatile compounds were identified as key flavor compounds according to their ROAV, and GC-O identified seven of these compounds. Acetic acid, butanoic acid, hexanoic acid, δ-octanolactone, δ-decanolactone and γ-dodecalactone, all of which had ROAV greater than 1 and could be recognized by GC-O, were considered the most significant flavor compounds in dairy fat products.

Polyglycerol esters (PGEs) are used as emulsifiers in recombined dairy cream (RDC) to improve product quality. In this study, the effects of four PGEs with different polymerization degrees and esterification on the particle size, viscosity, zeta potential, and microrheology of RDC emulsions were investigated, and the whipping time, overrun, serum loss, and firmness of the RDC emulsions were recorded. The results show that the addition of the PGEs reduced the particle size (from 2.75 μm to 1.48–1.73 μm) and increased the viscosity (from 41.92 cP to 73.50–100 cP) and stability (from 0.354 to 0.105–0.128), which were related to the change in interfacial properties and the weakening of Brownian motion, but there were differences in the effect on the whipping behavior of the RDCs. Although the addition of 0.9% triglyceride monolaurate gave the emulsion the best stability, the RDC had a longer whipping time (318 s) and a lower overrun (116.6%). Comparatively, the 0.7–0.9% concentrations of PGE55 and tripolycerol monostearate (TMS) provided RDC with good stability and aeration characteristics, allowing inflation within 100 s and expansion rates of up to 218.24% and 186.88%, respectively. In addition, the higher degree of polymerization of polyglyceryl-10 monstearate (PMS) did not work well at any concentration. These results contribute to understanding the mechanism of action of PGEs and improving the quality of RDC. [ABSTRACT FROM AUTHOR]