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Chapter 6. Ash and minerals

Chapter 6. Ash and minerals Section 1. Ash 1.1 Ash concept Ash is the inorganic residue from the incineration of organic matter. Ash in food is determined by weighing the dry mineral residue of organic materials heated at elevated temperature (around 550℃). 1.2. Significance of ash

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Chapter 6. Ash and minerals

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  1. Chapter 6. Ash and minerals

  2. Section 1. Ash

  3. 1.1 Ash concept • Ash is the inorganic residue from the incineration of organic matter. • Ash in food is determined by weighing the dry mineral residue of organic materials heated at elevated temperature (around 550℃).

  4. 1.2. Significance of ash • Total ash is a widely accepted index of refinement of food, such as wheat flour or sugar. • Total ash content is a useful parameter of the nutritional value of some foods and feeds.

  5. In fruit jellies and marmalades, ash content is used to estimate the fruit content of the product. • Determine adulteration of some food: juice, beverage, vinegar.

  6. 1.3. Selection of ashing condition • 1) Crucible materials • Porcelain • Quartz • Platinum • 2) Sample amount: the ash amount should be 10-100 mg after ashing.

  7. 3) Temperature: 500-600℃ 4) Time: about 2-5 hours. The ash should be white or grey colour, and no carbon granules in it.

  8. 1.4. Determination procedure • 1) Preparation of porcelain crucible • 2) Pretreatment of sample • 3) Charring: Why should sample be charred before ashing? • 4) Ashing

  9. 1.5. Water-soluble ash and water insoluble ash • Water-soluble ash • Water insoluble ash

  10. Section 2. Mineral elements

  11. 1. Preface • What is mineral elements? • Elements except C、H、O、N. • Constant elements • Trace elements

  12. 2. Determination of calcium • KMnO4 titration • EDTA titration

  13. 3. Determination of ferrous • Colormetric methods • AAS method

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