NFS386H1 Lecture Notes - Lecture 3: Water Activity
8 Jan 2012
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[ demineralization ] as you move down, the ore size decreases to filter smaller and smaller things. [ are there bacteria in bottled water? ] yes unsafe to reuse bottles because bacterial contamination can occur if not properly cleaned. [ how do you properly freeze apples at home ] Cut into thin slices (for freezing issues) blanch before freezing (avoid browning) Slide 16 browning reaction for thawed apple is because osmosis from slide 14 damages cells] Slide 17 centre of apple has the most browning, least freezing, ice outside but freeze concentrated in the core. Slide 18: thawed apple: drip loss: water out of icf. [ freezing promotes two opposing forces ] frozen food sill has a shelf life because of the unfrozen zones. [ bulk water ] beef jerky: beef, corn syrup solids (sugar), dextrose (sugar) ---> lower water activity capillary water in tubule structures is less available for microbial growth.
