1 Theory.- 1 Introduction.- 2 Assessment of analytical methods and data.- 2.1 Requirements and choice of analytical methods.- 2.2 Presentation of data.- 2.3 Quality of data.- 2.3.1 Procedures to improve quality of data.- 2.4 Statistical assessment of quality of data.- 2.4.1 Precision.- 2.4.2 Reproducibility.- 2.4.3 Accuracy.- 3 Principles of techniques used in food analysis.- 3.1 Classical methods.- 3.1.1 Titrimetric analysis.- 3.1.2 Gravimetric procedures.- 3.1.3 Solvent extraction methods.- 3.1.4 Refractometry.- 3.1.5 Polarimetry.- 3.2 Instrumental and modern methods.- 3.2.1 Spectroscopic methods.- 3.2.2 Chromatography.- 3.2.3 Electrophoresis.- 3.2.4 Immunochemical methods.- 4 Theory of analytical methods for specific food constituents.- 4.1 Sampling.- 4.2 Moisture and water activity.- 4.2.1 Methods of measuring moisture.- 4.3 Protein.- 4.3.1 Kjeldahl method.- 4.3.2 Direct distillation methods.- 4.3.3 Thermal combustion methods.- 4.3.4 Dye binding methods.- 4.3.5 Formol titration.- 4.3.6 Spectroscopic methods.- 4.4 Fats.- 4.4.1 Gravimetric solvent extraction procedures.- 4.4.2 Volumetric methods.- 4.4.3 Instrumental methods.- 4.4.4 Study of the nature of fats and oils.- 4.5 Carbohydrates.- 4.5.1 Determination of available carbohydrates.- 4.5.2 Estimation of dietary fibre in foods.- 4.6 Micronutrients.- 4.6.1 Mineral elements and ash.- 4.6.2 Vitamins.- 4.7 Food energy.- 4.8 Additives.- 2 Experimental.- 5 Experimental procedures - estimation of major food constituents.- 5.1 Laboratory safety.- 5.2 Sampling.- 5.3 Determination of moisture and total solids.- 5.4 Determination of ash content.- 5.5 Determination of mineral elements in foods by atomic absorption spectrophotometry (ashing process).- 5.6 Determination of mineral elements in canned food products by atomic absorption spectrophotometry (non-ashing process).- 5.7 Determination of calcium in foods by permanganate titration.- 5.8 Determination of phosphorus by the vanadate colorimetric method.- 5.9 Determination of phosphorus by the molybdenum blue colorimetric method.- 5.10 Determination of iron by the bipyridyl colorimetric method.- 5.11 Determination of nitrogen and protein by the Kjeldahl method using the Kjeltec instrument.- 5.12 Determination of protein content by the formol titration.- 5.13 Determination of fat by the Soxhlet and Soxtec methods.- 5.14 Determination of the fat content of dairy products by the Gerber method.- 5.15 Determination of fat by the Mojonnier method.- 5.16 Determination of fat by the Rose-Gottlieb method.- 5.17 Determination of fat by the Werner-Schmid method.- 5.18 Determination of the fat content of cheese by the modified SBR (Schmid-Bondzynski-Ratzlaff) method.- 5.19 Determination of fat by the Weibull-Berntrop/Weibull-Stoldt method.- 5.20 Determination of dietary fibre in foods by the neutral detergent fibre method.- 5.21 Determination of dietary fibre by the Englyst enzymatic instrumental method.- 5.22 Determination of dietary fibre in foods by the AOAC enzymatic gravimetric method.- 5.23 Volumetric determination of sugars by copper reduction (Lane and Eynon method).- 5.24 Volumetric determination of sugars by copper reduction (Lane and Eynon method - constant volume modification).- 5.25 DNS colorimetric determination of available carbohydrates in foods.- 5.26 Determination of lactose in milk by the Chloramine-T method.- 5.27 Determination of the lactose content of milk by polarimetry.- 5.28 Determination of lactose in cheese by the phenol colorimetric method.- 5.29 Identification and determination of sugars in milk products by HPLC.- 5.30 Calculation of the calorific value of foods 13.- 6 General food studies.- 6.1 Determination of ascorbic acid by titration.- 6.2 Gas chromatographic study of the fatty acid composition of fats.- 6.3 Determination of the iodine value of fats and oils.- 6.4 Determination of the saponification value of fats.- 6.5 Determination of sulphur dioxide by iodine titration.- 6.6 Determination of total sulphur dioxide (free and combined) using distillation methods.- 6.7 Determination of the salt content of dairy products (Volhard method).- 6.8 Determination of the salt content of brine (Mohr titration).- 6.9 Titrimetric determination of the chloride content of meat products.- 6.10 Colorimetric determination of nitrates and nitrites in meat products and brine.- 6.11 Spectrophotometric determination of antioxidants.- 6.12 Extraction and colorimetric estimation of gallates.- 6.13 Determination of alcohol in beverages by gas chromatography.- 6.14 Determination of alcohol by the distillation method.- 6.15 Titratable acidity of fruit juices.- 6.16 Determination of the acetic acid content of vinegar.- 6.17 Acidity measurements in dairy products.- 6.18 Determination of L-lactic acid in cheese by an enzymatic method.- 7 Additional reading material.
Food laws were fIrst introduced in 1860 when an Act for Preventing the Adulteration of Articles of Food or Drink was passed in the UK. This was followed by the Sale of Food Act in 1875, also in the UK, and later, in the USA, by the Food and Drugs Act of 1906. These early laws were basically designed to protect consumers against unscrupulous adulteration of foods and to safeguard consumers against the use of chemical preservatives potentially harmful to health. Subsequent laws, introduced over the course of the ensuing century by various countries and organisations, have encompassed the features of the early laws but have been far wider reaching to include legislation relating to, for example, specifIc food products, specifIc ingredients and specifIc uses. Conforming to the requirements set out in many of these laws and guidelines requires the chemical and physical analysis of foods. This may involve qualitative analysis in the detection of illegal food components such as certain colourings or, more commonly, the quantitative estimation of both major and minor food constituents. This quantitative analysis of foods plays an important role not only in obtaining the required information for the purposes of nutritional labelling but also in ensuring that foods conform to desired flavour and texture quality attributes. This book outlines the range oftechniques available to the food analyst and the theories underlying the more commonly used analytical methods in food studies.
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