ENH 333 Lecture Notes - Lecture 2: Logarithmic Scale, Exponential Growth, Food Industry

• School: Ryerson University
• Department: Environmental Health
• Course: ENH 333
• Professor: Ian Young

Document Summary

Introduction: microbial growth is important to understand, so that it can be controlled, growth of microorganisms in food causes both spoilage and a possible increase in the hazard (if pathogens are present) This is why it is recommended that food not be kept at room temperature for. >2 hours, and that leftovers are eaten within 2-3 days: bacterial growth occurs through four phases: lag, exponential, stationary, and death, growth curves can be plotted as the number of cells on a logarithmic scale (log10. Lag phase is where the bacteria are getting used to their environments. Lag phase = first phase after (cid:272)ells are i(cid:374)trodu(cid:272)ed i(cid:374)to (cid:862)(cid:374)e(cid:449)(cid:863) e(cid:374)(cid:448)iro(cid:374)(cid:373)e(cid:374)t (i. e. food or culture medium) No increase in cell numbers; population remains static. Cells are adapting producing new enzymes. Length of phase is variable depends on conditions. Food industry aims to increase the lag phase indefinitely. Nothing is limiting growth; phase of maximum growth rate.