Exam 3 Study Guide

Exam 3 Study Guide - Exam3StudyGuide 22/11/200922:35:00...

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Exam 3 Study Guide 22/11/2009 22:35:00 Outcome 1: Describe the basic concepts of flavor, taste, and odor Flavor – encompasses sight, taste, texture, sound (crunch), and smell – all the contributing senses at the time of consumption Taste – the 5 tastes: sweet, sour, bitter, salty, umami Odor – volatile compounds that give food their characteristic aroma; tend to be hydrophobic Outcome 2: Discuss the molecular mechanisms of sweet, sour, salty, bitter and umami taste SWEET o molecular structure: two polar groups (acid and base) and a hydrophobic group; proton donor (acid) and acceptor (base) located at a prescribed distance from complementary groups o intensity: due to gamma hydrophobic binding site BITTER o Molecular structure: a polar and a non-polar group on the same molecule o Receptors: TR2 family; some people are ‘bitter blind’ – protein that has a ‘site’ that can be active or note (like enzymes) SALTY o Molecular structure: cations (salty Na + , Li + ; salty and bitter K + ) and anions (Cl - , citrate, phosphate) o Receptors: ENaC; associated with ion channels SOUR o Molecular structure: associated with [H + ] and associated acid [AH]; not associated with dissociated salt [A - ] o Receptors: associated with ion channels – EnaC, HCN, ASIC o Often involves organic acids (carboxylic) Citric acid Lactic acid
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Acetic acid UMAMI o Molecular structure: compounds like msg and inosine monophosphate o NOT salty, the sodium is part of the molecule but the overall response is different o Receptors: taste mGluR4 o Foods: parm. Cheese, soy sauce, shiitake mushrooms Outcome 3: Discuss how odor, taste, and other sensations (e.g. astringency) are perceived by humans Flavor enhancers – enhance flavors at levels below their individual independent detection limit; increase intensity of overall flavors o Compound – msg, 5’ ribonucleotides o Food – soups, spice mixtures Astringency – dry in the mouth feeling o Compound – alum, polyphenols (tannins) o Food – over brewed tea, young red wine (polyphenols), persimmons o Polyphenols bind with saliva causing a drying of the mouth Pungency – hot, sharp and stinging sensation; activate hot receptor (TRP-VI) and trigeminal nerve o Compound – capsaicin o Food – peppers Cooling – sensation in the mouth; like a decrease in temperature o Compound – two types of effects
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This note was uploaded on 12/10/2009 for the course FS 402 taught by Professor Dr.e.allenfoegeding during the Spring '09 term at N.C. State.

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Exam 3 Study Guide - Exam3StudyGuide 22/11/200922:35:00...

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