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Multi-origin skim milk powder comparative benchmarking.

A. Bienvenue




Multi-origin skim milk powder comparative benchmarking.
D. E. Otter1, C. T. Tay2, R. B. Hashwam2, K. G. Lim2, M. B. Roque2, H. Hardigaluh3, A. Bienvenue*4. 1DEO Dairy Consulting New Zealand, 2Food Innovation & Resource Centre, Singapore Polytechnic Singapore, 3U.S. Dairy Export Council Singapore Ltd Singapore, 4U.S. Dairy Export Council Arlington, VA.

What makes a skim milk powder (SMP) suitable for use in recombined ultra-high-temperature (UHT) milk and/or evaporated milk (EM) applications? Twenty SMP samples manufactured in Canada, Europe, New Zealand and the United States, and intended for UHT or EM use in Southeast Asia, were characterized and used in EM and UHT milk model systems that were tested over 6 mo of storage. The goal was to compare the performance of various origin SMP. Compositionally all the SMP samples met CODEX requirements. Some manufacturers standardized protein levels, while others did not. SMP protein ranged from 32.7 to 37.4% m/m (as is), moisture 3.5 to 4.4% and fat 0.6 to 1.5%. There was minimal variation across the samples in pH, titratable acidity, solubility index, viscosity, bulk density, scorched particles, hygroscopicity, and water activity. Whey protein nitrogen index (WPNI) values were indicative of heat treatment type. Heat coagulation time (HCT) at 140�C varied greatly between the samples (6.5 to 31.6 min). Correlation between HCT and WPNI was 0.57; so WPNI does not appear to be a good predictor of heat stability. The SMPs' color was similar, although there was slightly more yellow (b*) in the powders from NZ. The microbial analysis revealed supplier-specific (not origin) differences between the samples. Aerobic spores (S) were measured using a heat shock of 80�C/12min and heat resistant spores (HRS) 100�C/30min. Mesophilic S and HRS were low. Large variations were seen in thermophilic (T) aerobic plate counts, S and HRS; 11 and 16 SMP samples (EU, NZ, US origin) had low T-S and T-HRS < 300 cfu/g respectively. In the UHT application, all samples withstood the heat treatment without gelling or excessive browning. After storage, minor differences were observed between the samples. In the EM application, one sample gelled after heating, and varying degrees of sedimentation were observed after processing and during storage. Six EM samples (CA, NZ, US origin) performed well throughout the 6 mo shelf life, exhibiting only minor phase separation. Our results show that different origin SMP samples were similar across many parameters with differences in performance being supplier rather than country-specific.

Keywords: skim milk powder, UHT.