WJEC Level 3 Diploma In Food Science And Nutrition

58 ⦁ Phospholipids are molecules that form the main part of cell membranes in plants and animals. ⦁ 7KH\ DUH IRUPHG IURP WZR IDWW\ DFLGV JO\FHURO DQG D SKRVSKDWH JURXS ⦁ ,Q FHOO PHPEUDQHV WKH\ OLQH XS WRJHWKHU LQ D GRXEOH OD\HU D phospholipid bilayer ). ⦁ The phosphate head of the phospholipid is hydrophilic and the fatty acid tails are hydrophobic. ⦁ 7KH WZR OD\HUV DUH OLQNHG E\ JO\FHURO ⦁ ,Q IRRG SUHSDUDWLRQ LW LV SRVVLEOH WR EUHDN XS WKH FHOO PHPEUDQHV H J LQ D SHVWOH DQG PRUWDU DQG RSHQ XS WKH WZR OD\HUV RI SKRVSKROLSLGV VR WKDW WKH K\GURSKLOLF SKRVSKDWH KHDGV JR LQWR ZDWHU DQG WKH K\GURSKRELF WDLOV JR LQWR RLO WKXV SUHYHQWLQJ RLO GURSOHWV IURP MRLQLQJ XS WRJHWKHU Ŝ L H WKH\ HPXOVLI\ WKH PL[WXUH 7KLV LV KRZ DQG ZK\ LQJUHGLHQWV VXFK DV JDUOLF DQG PXVWDUG VHHG ZKLFK FRQWDLQ SKRVSKROLSLG JXPV DUH XVHG WR VWDELOLVH WKH HPXOVLRQV LQ PD\RQQDLVH DQG RWKHU VDXFHV DQG VDODG GUHVVLQJV There are three types of emulsions: 1. Temporary emulsions H J DQ RLO DQG YLQHJDU )UHQFK VDODG GUHVVLQJ 7KHVH ZLOO VHSDUDWH RXW ZLWKLQ DQ KRXU EXW ZLOO WHPSRUDULO\ FRPH WRJHWKHU DJDLQ LI VKDNHQ WKRURXJKO\ 2. Semi-permanent emulsions H J +ROODQGDLVH VDXFH ZKLFK LV PDGH IURP HJJ \RONV DQG EXWWHU 7KHVH ZLOO VHSDUDWH DIWHU D IHZ KRXUV KRZHYHU WKH XVH RI clarified butter WR PDNH WKH VDXFH ZLOO PDNH LW PRUH VWDEOH &ODULʐHG EXWWHU LV XQVDOWHG EXWWHU WKDW KDV EHHQ PHOWHG RQ D ORZ KHDW ZKLFK VHSDUDWHV LW LQWR SXUH EXWWHU IDW PLON VROLGV DQG ZDWHU 7KH ZDWHU ZLOO HYDSRUDWH DQG WKH PLON VROLGV DUH VNLPPHG IURP WKH VXUIDFH DQG UHPRYHG ,I XQFODULʐHG EXWWHU LV XVHG WR PDNH +ROODQGDLVH VDXFH WKH ZDWHU LW FRQWDLQV will weaken the emulsion. 3. Permanent emulsions: H J PD\RQQDLVH 0D\RQQDLVH LV HPXOVLʐHG E\ OHFLWKLQ IURP HJJ \RONV DQG RWKHU SKRVSKROLSLGV IURP JURXQG PXVWDUG 7KHVH ZLOO UHPDLQ DQ HPXOVLRQ IRU D ORQJ WLPH (PXOVLRQV DUH DOVR HLWKHU oil-in-water RU water-in-oil GHSHQGLQJ RQ KRZ PXFK RLO DQG how much water is present. ⦁ 0LON VLQJOH DQG GRXEOH FUHDP DQG PD\RQQDLVH DUH DOO H[DPSOHV RI oil-in-water HPXOVLRQV ZKHUH WKH IDW GURSOHWV DUH VXVSHQGHG LQ WKH ZDWHU DQG GR QRW VHSDUDWH from it ⦁ %XWWHU YHJHWDEOH IDW VSUHDGV DQG YLQDLJUHWWH VDODG GUHVVLQJ DUH DOO H[DPSOHV RI water- in-oil HPXOVLRQV ZKHUH WKH ZDWHU GURSOHWV DUH VXVSHQGHG LQ WKH IDW RLO Extracellular space Phospholipid bilayer Hydrophilic head Hydrophobic tail Lipid (fatty acid) Cytoplasm Chapter 5: The scientific properties of food Unit 3: Experimenting to solve food production problems (LO1)

RkJQdWJsaXNoZXIy Nzc1OTg=