A. FUNDAMENTALS OF FOOD ANALYSIS
1. Food Analysis
Food analysis is the systematic determination of the chemical, physical, nutritional, and other relevant characteristics of food. It supports quality control, food safety, product development, regulatory compliance, and research.
2. Chemical Analysis of Foods
Chemical analysis is used throughout food processing, from raw materials and ingredients to processed and finished products, to determine composition and assess product quality.
3. Product Development and Process Evaluation
Analytical measurements are important in food formulation, development of new products, optimization of processing conditions, and evaluation of changes in product quality.
4. Process-Control Analysis
Routine process control commonly uses rapid analytical methods when timely decisions are required. Reference or validated methods may be used for confirmation and regulatory or nutritional measurements.
5. Sampling
Sampling is the process of selecting a representative portion of a food lot for analysis. Proper sampling is essential because analytical results are meaningful only when the sample represents the material being evaluated.
6. Analytical Method Selection
The analytical method should be selected according to the analyte, food matrix, concentration range, required accuracy and precision, detection capability, available equipment, and intended purpose of the measurement.
7. Proximate Analysis
Proximate analysis is a conventional analytical system used to determine major food components, commonly including moisture, ash, protein, fat, and carbohydrate.
8. Food Matrix
The food matrix consists of the physical and chemical components surrounding the analyte. Matrix characteristics can interfere with extraction, reaction, separation, or detection and therefore can affect analytical results.
9. Reference Materials and Quality Control
Reference materials, certified reference materials, blanks, control samples, and check samples are used to evaluate analytical performance and identify problems such as bias, contamination, or poor precision.
10. AOAC INTERNATIONAL
AOAC INTERNATIONAL develops and publishes standardized analytical methods and performance standards for food, agriculture, public health, and related analytical applications. Methods should be selected according to their intended scope and validated performance.
11. Fitness for Purpose
An analytical method is considered suitable when its demonstrated performance is adequate for the intended application, including the required accuracy, precision, selectivity, sensitivity, and applicable concentration range.
12. AACC International
AACC International develops analytical methods and standards widely used for cereals, grains, flours, and cereal-based products.
13. AOCS
The American Oil Chemists’ Society (AOCS) publishes official methods and recommended practices widely used for analysis of fats, oils, oilseeds, and related products.
B. ANALYTICAL PERFORMANCE
14. Accuracy
Accuracy describes the closeness of a measurement result to an accepted reference value or true value.
15. Precision
Precision describes the closeness of agreement among repeated measurements. It is commonly expressed using standard deviation or relative standard deviation.
16. Range
The range is the difference between the highest and lowest observations in a dataset.
17. Standard Deviation
Standard deviation describes the dispersion of observations around their mean and provides an indication of the variability of repeated measurements.
18. Absolute Error
Absolute error is the magnitude of the difference between a measured value and an accepted reference value. The sign of the error can also be retained when reporting signed error.
19. Systematic Error
Systematic error produces a consistent bias in analytical results, causing measurements to deviate from the accepted value in a relatively consistent direction.
20. Sensitivity
Analytical sensitivity describes the change in measurement response produced by a change in analyte concentration. For a linear calibration relationship, it is commonly associated with the slope of the calibration curve.
C. PROXIMATE AND CHEMICAL ANALYSIS
21. Ash
Ash is the inorganic residue remaining after controlled removal or oxidation of the organic matter in a food sample.
22. Ash on Wet and Dry Basis
Ash content may be reported on a wet basis using the original sample mass or on a dry basis after accounting for the moisture content of the sample.
23. Dry Ashing
Dry ashing involves heating a food sample under controlled conditions, commonly in a muffle furnace, until most organic matter is removed and an inorganic residue remains. The required temperature and time depend on the analytical method.
24. Wet Digestion
Wet digestion involves decomposition of organic matter using acids, oxidizing agents, or combinations of reagents. It is frequently used as a sample-preparation step before elemental analysis.
25. Non-Protein Nitrogen
Nitrogen in foods may occur in non-protein compounds such as free amino acids, small peptides, nucleotides, nucleic acids, urea, ammonium compounds, and other nitrogen-containing substances. Therefore, total nitrogen does not always represent true protein alone.
26. Protein Analysis
Common methods for protein estimation include the Kjeldahl method and Dumas combustion method. Spectroscopic methods may also be used when properly calibrated and validated for the particular food matrix.
27. Qualitative Analysis
Qualitative analysis determines the identity or presence of particular substances or components in a food. It can support ingredient verification, authenticity testing, and detection of selected adulterants or contaminants.
28. Quantitative Analysis
Quantitative analysis determines the amount or concentration of a specific analyte in a food. It is used in compositional analysis, quality control, nutritional assessment, and regulatory testing.
29. Titratable Acidity
Titratable acidity measures the amount of standardized alkaline solution required to neutralize acid-reactive substances in a food to a specified endpoint. It is an operational measurement and does not necessarily represent the concentration of a single acid.
30. Molarity
Molarity is the concentration expressed as the number of moles of solute per litre of solution.
31. Normality
Normality expresses concentration as the number of chemical equivalents of solute per litre of solution. Because the equivalent depends on the reaction being considered, normality is reaction-specific.
32. Percentage Concentration
Percentage concentration must specify its basis, such as mass/mass (% m/m), mass/volume (% m/V), or volume/volume (% V/V).
D. PROTEIN ANALYSIS
33. Isoelectric Point
The isoelectric point, or pI, is the pH at which a protein has approximately zero net electrical charge under specified conditions.
34. Isoelectric Focusing
Isoelectric focusing separates proteins according to their isoelectric points. Proteins migrate through a pH gradient until they reach the region where their net electrical charge is approximately zero.
35. SDS Electrophoresis
SDS-polyacrylamide gel electrophoresis separates proteins primarily according to molecular size after treatment with sodium dodecyl sulfate, which largely standardizes their charge-to-mass ratio.
36. Capillary Electrophoresis
Capillary electrophoresis separates charged molecules inside narrow capillaries under an applied electric field. It can provide high separation efficiency using relatively small sample volumes.
37. Antigen
An antigen is a molecule or molecular structure that can be specifically recognized by components of the immune system. Some antigens stimulate an immune response, while others may require additional conditions or immune mechanisms.
38. Antibody
An antibody is an immunoglobulin produced by B cells and plasma cells that specifically recognizes and binds an antigen or antigenic epitope.
39. Capture Antibody
A capture antibody is an antibody immobilized on a solid surface in an immunoassay. It specifically binds the target analyte and is commonly used in sandwich immunoassays.
40. Derivatization
Derivatization is the chemical modification of an analyte to form a derivative with improved properties for analytical separation, detection, stability, or measurement.
E. SPECIALIZED FOOD ANALYSIS
41. Extraneous Matter
Extraneous matter refers to unwanted foreign material present in food or agricultural commodities. Its examination is important for assessing raw-material quality, cleanliness, authenticity, and processing performance.
42. X-Ray Radiography
X-ray inspection can be used in grain and food processing to detect selected internal defects, foreign materials, density differences, and structural abnormalities. Its effectiveness depends on the physical characteristics of the target and product.
43. Near-Infrared Spectroscopy
Near-infrared (NIR) spectroscopy is a rapid, generally non-destructive technique used to estimate properties such as moisture, protein, fat, and other quality parameters when suitable calibration models are developed and validated.
44. Microscopy
Light microscopy, fluorescence microscopy, confocal microscopy, and scanning electron microscopy can be used to study food microstructure, including starch granules, protein networks, cells, microorganisms, crystals, and structural changes caused by processing.
F. WATER AND WASTEWATER ANALYSIS
45. BOD, COD and TOC
Biochemical oxygen demand (BOD), chemical oxygen demand (COD), and total organic carbon (TOC) are different analytical measurements used to characterize organic loading in water and wastewater. They measure different properties and should not be treated as interchangeable.
46. Biochemical Oxygen Demand
Biochemical oxygen demand (BOD) measures the oxygen consumed by microorganisms during biological oxidation of biodegradable substances under specified test conditions.
47. Chemical Oxygen Demand
Chemical oxygen demand (COD) measures the oxygen equivalent associated with chemically oxidizable substances under specified analytical conditions. COD can generally be determined more rapidly than BOD.
G. SPECTROSCOPIC ANALYSIS
48. UV-Visible Spectroscopy
UV-Visible spectroscopy measures the absorption of ultraviolet and visible radiation by substances in a sample. The commonly used UV region is approximately 200–400 nm, while the visible region is approximately 400–700 nm, although the exact boundaries are conventional.
49. Beer-Lambert Law
Under suitable conditions, the Beer-Lambert law relates absorbance to analyte concentration and optical path length:
A = εcl
where A is absorbance, ε is molar absorptivity, c is concentration, and l is optical path length.
50. Spectrophotometer and Monochromator
A basic UV-Visible spectrophotometer consists of a radiation source, wavelength-selection system or monochromator, sample holder, detector, and signal-processing/readout system. The monochromator or wavelength selector isolates the required wavelength region for measurement.