Introduction
Food safety affects everyone's health. From farm to table, every stage of the food supply chain requires rigorous quality control and testing. UV-Vis spectrophotometry is widely used in food testing due to its simple operation, low cost, and excellent reproducibility. UV-Vis spectrophotometers are essential basic instruments in government food safety laboratories, third-party testing agencies, and food industry QC departments.
Food Additive Testing
Synthetic Color Detection:
Abuse of synthetic colors in food is a significant food safety concern. Different synthetic colors have characteristic absorption peaks in the visible region:
- Tartrazine: Maximum absorption at 426nm (yellow)
- Sunset Yellow: Maximum absorption at 480nm (orange-yellow)
- Ponceau 4R: Maximum absorption at 508nm (red)
- Brilliant Blue: Maximum absorption at 630nm (blue)
Preservative Detection:
- Sodium Benzoate: Characteristic absorption at 225nm for beverage and condiment analysis
- Potassium Sorbate: Strong absorption at 252nm (acidic conditions) for dairy and sauce products
Nutritional Analysis
Protein Determination: Bradford method (Coomassie Brilliant Blue) at 595nm offers high sensitivity for food protein analysis. Direct UV method at 280nm is suitable for pure protein solutions.
Sugar Determination: DNS (3,5-dinitrosalicylic acid) colorimetric method at 540nm is widely used for reducing sugar quantification.
Vitamin Determination:
- Vitamin A: Characteristic absorption at 325nm
- Vitamin C (Ascorbic Acid): Characteristic absorption at 245nm in acidic medium
- Vitamin B2 (Riboflavin): Characteristic absorption at 444nm (yellow)
Oil Quality: Peroxide value and acid value can be evaluated via spectrophotometry at specific wavelengths to assess oil oxidation and freshness.
Pesticide Residue Testing
Certain pesticides with characteristic UV absorption can be determined directly or indirectly:
- Organophosphorus Pesticides: Indirect enzyme inhibition-colorimetric method at 410nm
- Pyrethroid Pesticides: Characteristic absorption at specific wavelengths for rapid screening
- Carbamate Pesticides: Derivatization reaction to form colored products for spectrophotometric determination
Food Authentication
Different food sources produce distinct spectral characteristics. Full-wavelength scanning (190-1100nm) combined with chemometrics enables:
- Edible oil classification (olive, peanut, soybean oils)
- Honey adulteration detection (HFCS addition screening)
- Alcoholic beverage authentication
The NanoQuant1920 double-beam spectrophotometer scans at up to 4100nm/min, completing a 190-1100nm full scan in just 30 seconds.
STON Spectrophotometer Solutions
STON NanoQuant series offers multi-level solutions for food testing laboratories:
- NanoQuant756 (190-1100nm, 2nm bandwidth): Deep UV extended to 190nm for vitamin and preservative detection
- NanoQuant1810 (8-inch touch screen, auto curve fitting): Built-in calibration curve function for direct concentration readout
- NanoQuant1920 (double beam, variable slit): Baseline flatness ±0.0005A for trace analysis in complex food matrices
Conclusion
UV-Vis spectrophotometry has extensive applications in food testing. The STON NanoQuant series spectrophotometers provide reliable technical support for food quality and safety testing through their excellent optical performance and comprehensive product range.
