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1. Biochemistry of Fruits and vegetables.pptx

  1. Biochemistry of Fruits and vegetables
  2. Biochemistry of Fruits and Vegetables • Plant metabolites • Nutritional and functional properties • Primary metabolites • CHO, Protein, Lipids • Involved in growth and development • Human Nutrition • Secondary metabolites • Nutraceutical and functional properties
  3. Overview of CHO metabolism in fruits During glycolysis, breakdown of sugars occurs to generate the energy required for ripening Invertase Main storage sugars, depends on fruit/veg. variety, etc. Major sugar: Sucrose, glucose and fructose Major polysaccharide: Starch Minor: mannitol and sorbitol (Apple, olive)
  4. Lipids Metabolism • Lipids biosynthesis • Fruits – Avocado and olives • In avocado, lipids are stored as reserve components in the indioblast, a specialized cell type of the mesocarp in form of triglycerides • Veg. – Pulses, oil seed crops • Lipid metabolism is an important part of the ripening process in fruit • The main FA in triglycerides are palmitic (16:0), palmitoleic (16:1), oleic (18:1), and linoleic (18:2) acids. Oil content increases during ripening, and oils are compartimentalized in oleosomes. • Part of cellular membranes • Wax Synthesis and Deposition
  5. PIGMENTS IN FRUITS • In nature, there are three major classes of pigments: • Green Chlorophylls • Chl content increases during green stages and diminishes through maturation, paralleling chloroplast disintegration, process known as degreening • carotenoids providing yellow to red color, and • large group of over 700 structures • hydrophobic nature, these pigments are found in association with lipid–protein complexes • anthocyanins responsible for the red, blue, and violet color • class of flavonoids derived from phenylalanine, are water-soluble, synthesized in the cytosol, and localized in vacuoles, where pH may vary its structure and color • Combination & diversity determine visual aspect of the fruit and their attraction to insects and other animals to ensure seed dispersal
  6. Secondary Metabolites • Not required for normal growth and development, and are not made through metabolic pathways common to all plants. • 40,000 metabolites Terpenoids • repetitive fusion of branched 5‐carbon isoprene units • have diverse functional roles in plants as structural components of membranes (sterols), photosynthetic pigments, ETC, hormones • Food, pharmaceutical, and chemical industries, biofuel products • Examples: carotenoids, tocopherols and tocotrienols, quinones, sterols, sapogenins, and essential oils
  7. Secondary Metabolites Carotenoids • largest group of natural dyes • Some have pro‐vitamin A activity • Antioxidant activity Tocopherols and Tocotrienols • 4 homologues (α, β, γ, and δ), vit. E
  8. Quinones
  9. Phytosterols • Sitosterol, sitostanol, campesterol, brassicasterol, and stigmasterol • calciferol
  10. Phenolic Compounds • Plant phenolic compounds include around 10,000 metabolites • characterized by having at least one aromatic ring bearing one or more hydroxyl groups attached • Examples: Phenols, phenolic acids, phenylacetic acids, hydrohycinnamic acids, naphthoquinones, xanthones, flavonoids, lignans, bioflavonoids, lignins and condensed tannins • also be classified in simple phenols (phenolic acids and coumarins) and polyphenols (flavonoids and nonflavonoids)
  11. Classification of phenolic compounds most widespread group of pigmented flavonoids responsible for most of the red, pink, purple, and blue colors observed in vegetables, fruits, and flowers
  12. Alkaloids • physiological and medicinal properties • caffeine, nicotine, morphine, atropine, quinine Sulfur‐Containing Compounds Antioxidants Organic Acids • Organic acids are among the principal compounds in the fruits producing a sour sensation or acidity • major OA in most fruits are malic and citric acids – Preservation
  13. Effects of processing and storage of food • Water-soluble vitamins (B-group and C) are more unstable than fat- soluble vitamins (K, A, D and E) during food processing and storage. The most unstable vitamins include: • folate • thiamine • vitamin C. • More stable vitamins include: • niacin (vitamin B3) • vitamin K • vitamin D • biotin (vitamin B7) • pantothenic acid (vitamin B5).
  14. Effect of processing on vit. C content in selected vegetables Carotenoids losses in green leafy vegetables during processing Losses in antioxidant activity of some vegetables
  15. The nutritional losses during canning can be minimized by using following guidelines

Hinweis der Redaktion

  1. Mono, di, oligo and polysaccharides B complex source Organic acids and vit. C
  2. Sugar alcohols,mannitol and sorbitol,may be the main transport and storage CHO in some fruits such as apple and olive. The enzymes invertase, sucrose synthase, and sucrose phosphatase synthase are the key enzymes in sucrose metabolism. During glycolysis, breakdown of sugars occurs to generate the energy required for ripening
  3. A pigment is a compound characterized by having a chromophore capable of absorbing visible light
  4. 2-methyl 1,4-naphthoquinone ring. 6 to 13 isoprenoid units (often written as MK-6–13)
  5. interactions of antioxidants with proteins and other food constituents take place, and the activity of some antioxidants may change as a result of hydrolytical processes