Nutrition 3330 Exam Notes.docx - Nutrition 3330 \u2013 Exam Notes Lecture 1(After Midterm \u2013 Phytochemicals Phytochemicals \u2013 What are they Plant

Nutrition 3330 Exam Notes.docx - Nutrition 3330 – Exam...

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Nutrition 3330 – Exam Notes Lecture 1 (After Midterm) – Phytochemicals Phytochemicals – What are they? Plant chemicals Generally non-nutritive substances Physiologically active components Aid in plant survival Ex: Allicin in garlic -flavonoids in general -phytoestrogens, etc. Flavonoids – The Stars of the Phytochemicals First understand Polyphenols Flavonoids are a sub-class of polyphenols Polyphenols are the most numerous groups of plant metabolites -ubiquitous in all plant organs; thus, integral part of human diet -range from simple phenolic molecules to highly polymerized compounds -traditionally considered anti-nutrients (due to effects of specific polyphenols to bind macromolecules and reduce food digestibility -renewed interest due: antioxidant capacities and numerous potential beneficial health effects Plant Polyphenols Secondary metabolites of plants Common structural feature: -Aromatic ring with at least one hydroxyl group Synthesized from 2 major pathways: 1. SHIKIMATE pathway 2. ACETATE pathway Contribute to plant morphology (Pigmentation) Involved in growth and reproduction of the plant, providing plants with resistance to pathogens and predators ***Plant stress = increase in phytochemicals What influences the amount in plants?? (can vary greatly within plant species) -light -genetic factors -environmental conditions -germination -degree of ripeness -variety -processing -storage Polyphenols in Food Contribute toward sensory qualities of plant food -presence can increase astringency and bitterness
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-oxidation during processing or storage can affect food characteristics Desirable (ex-browning of cocoa) and undesirable (ex-enzymatic browning = bad flavours) organoleptic qualities as well as colour Influence of Polyphenols in Food on…. Digestibility of Macronutrients: -bind and precipitate protein -reduced absorption…increased feces nitrogen -However, polyphenol must be highly polymerized -How can they affect the other macronutrients?? Mineral Bioavailability: -form complexes with metal cations -interfere with adsorption -how would binding iron be a good thing?? Polyphenols in Food Composition in foods can vary widely -most are phenolic acids and flavonoids (note the large variability) Flavonoids – What are they? Labeled Vitamin P for pigment Discovered that flavonoids enhanced the function of Vitamin C, improving absorption and protecting it from oxidation Evidence is found supporting potent antioxidant effects Sub-group of low molecular weight polyphenolic substances Ubiquitous; present in most plants -concentrated in seeds, fruit skin or peel, bark, flowers Common structure of diphenylpropanes (C6-C3-C6) -2 aromatic rings linked through 3 carbons Basic Flavonoid Structure A ring usually arises from the acetate pathway B ring usually arises from the shikimate pathway (both A&B rings have OH groups attached) C ring determines the major class of flavonoid Flavonoid Classification
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