FND 300 Lecture Notes - Lecture 3: Phosphatidylcholine, Yolk, Supercooling

• School: Ryerson University
• Department: Nutrition and Food
• Course: FND 300
• Professor: Yvonne Yuan

Document Summary

Cannot have crystal growth and freezing without nucleation. Ho(cid:373)oge(cid:374)eous: o(cid:374)l(cid:455) o(cid:272)(cid:272)u(cid:396)s i(cid:374) pu(cid:396)e (cid:449)ate(cid:396) (cid:373)ea(cid:374)i(cid:374)g it does(cid:374)"t ha(cid:448)e (cid:373)u(cid:272)h (cid:396)ele(cid:448)a(cid:374)(cid:272)e i(cid:374) food systems. Heterogeneous or catalytic nucleation: can occur in the wall of a container, surface films (pudding), suspended foreign particle. Once you have freezing, and nucleation, it is then easy to have crystal growth. Around -10, potentially going to have fewer crystals that tend to be larger (characteristic of slow freezing); type of freezing at home. Crystal growth in freezer that is -30 degrees will have multiple nuclei and somewhat limited in their growth. O(cid:374)(cid:272)e a p(cid:396)odu(cid:272)t is f(cid:396)oze(cid:374) that is(cid:374)"t the e(cid:374)d of the sto(cid:396)(cid:455) Ice once its formed is not completely inert, hydrogens can flip between individual water molecules causing some instability to the system. Re(cid:272)(cid:396)(cid:455)stallizatio(cid:374) (cid:449)ill o(cid:272)(cid:272)u(cid:396) du(cid:396)i(cid:374)g (cid:272)old sto(cid:396)age; it does(cid:374)"t a(cid:272)tuall(cid:455) i(cid:374)(cid:448)ol(cid:448)e tha(cid:449)i(cid:374)g o(cid:396) (cid:396)e- freezing, occurs within the food item.