TY - JOUR
T1 - Monitoring Shelf Life of Pasteurized Whole Milk Under Refrigerated Storage Conditions
T2 - Predictive Models for Quality Loss
AU - Ziyaina, Mohamed
AU - Govindan, Byju N.
AU - Rasco, Barbara
AU - Coffey, Todd
AU - Sablani, Shyam S.
N1 - Publisher Copyright:
© 2018 Institute of Food Technologists®
PY - 2018/2/1
Y1 - 2018/2/1
N2 - Abstract: The shelf life of pasteurized milk is generally determined through microbiological analysis. The objective of this study was to correlate microbial quality parameters then to design predictive models for shelf life of pasteurized milk. We analyzed pasteurized milk (3.9% fat) for aerobic plate counts (APCs), psychrotrophic bacteria counts (PBCs), and Bacillus spp. counts at 5, 7, 10, 13, 15, and 19 (±1 °C) to the end of storage time. We also monitored titratable acidity, pH, and, lipase, and protease activity and correlated this with APC, which is the principal index defining shelf life. Results indicate that the shelf life of pasteurized milk was 24, 36, and 72 h at 19, 15, and 13 °C respectively, as determined by APC and acidity indicators. However, milk stored at lower temperatures of 5, 7, and 10 °C had longer shelf life of 30, 24, and 12 d, respectively. A sharp increase in titratable acidity, while decrease pH were observed when APCs reached 5.0 log10 CFU/mL at all storage temperatures. Lipase and protease activities increased with storage temperature. At 5 and 7 °C, however, protease activity was very low. Therefore, we eliminated this parameter from our quality parameters as a potential spoilage indicator. Practical Application: Findings of this research are useful for monitoring the quality of commercial pasteurized milk, particularly in locations where environmental conditions make longer storage difficult. The study also provides valuable information for development of colorimetric shelf life indicators.
AB - Abstract: The shelf life of pasteurized milk is generally determined through microbiological analysis. The objective of this study was to correlate microbial quality parameters then to design predictive models for shelf life of pasteurized milk. We analyzed pasteurized milk (3.9% fat) for aerobic plate counts (APCs), psychrotrophic bacteria counts (PBCs), and Bacillus spp. counts at 5, 7, 10, 13, 15, and 19 (±1 °C) to the end of storage time. We also monitored titratable acidity, pH, and, lipase, and protease activity and correlated this with APC, which is the principal index defining shelf life. Results indicate that the shelf life of pasteurized milk was 24, 36, and 72 h at 19, 15, and 13 °C respectively, as determined by APC and acidity indicators. However, milk stored at lower temperatures of 5, 7, and 10 °C had longer shelf life of 30, 24, and 12 d, respectively. A sharp increase in titratable acidity, while decrease pH were observed when APCs reached 5.0 log10 CFU/mL at all storage temperatures. Lipase and protease activities increased with storage temperature. At 5 and 7 °C, however, protease activity was very low. Therefore, we eliminated this parameter from our quality parameters as a potential spoilage indicator. Practical Application: Findings of this research are useful for monitoring the quality of commercial pasteurized milk, particularly in locations where environmental conditions make longer storage difficult. The study also provides valuable information for development of colorimetric shelf life indicators.
KW - Aerobic plate count
KW - kinetic models
KW - lipase
KW - protease
KW - spoilage
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U2 - 10.1111/1750-3841.13981
DO - 10.1111/1750-3841.13981
M3 - Article
C2 - 29369352
AN - SCOPUS:85041017560
SN - 0022-1147
VL - 83
SP - 409
EP - 418
JO - Journal of food science
JF - Journal of food science
IS - 2
ER -