खाद्य सुरक्षा, गुणवत्ता मानक व पैकेजिंग

Mechanism of ATP bioluminescence firefly luciferase reaction:

• The reaction produces oxyluciferin rather than L-luciferin, and bioluminescence is in the visible spectrum.
• Bioluminescent light emission occurs in the yellow-green to red visible spectrum ($560\text{--}600\text{ nm}$), not violet/UV at $400\text{ nm}$.
• The reaction oxidizes luciferin to oxyluciferin and emits visible light.
• In the luciferase-catalyzed bioluminescence reaction, luciferin first binds ATP to form luciferyl-AMP. Luciferyl-AMP then reacts with molecular oxygen ($O_2$) through an oxidative decarboxylation pathway producing electronically excited oxyluciferin, carbon dioxide ($CO_2$), water ($H_2O$), AMP, and visible light peaking around $560\text{--}600\text{ nm}$.

Analytical methods for trace mercury determination in drinking water:

• Flame AAS lacks sufficient sensitivity for trace mercury detection at part-per-billion levels.
• Electrothermal (graphite furnace) AAS can detect heavy metals, but mercury's high volatility creates severe analyte losses during ashing stages.
• Cold Vapour Atomic Absorption Spectrometry (CVAAS) is the standard regulatory method (IS 10500 / USEPA 245.1) for detecting trace mercury. Mercury is chemically reduced with stannous chloride ($SnCl_2$) or sodium borohydride to volatile elemental mercury vapor ($Hg^0$), which is sparged at room temperature ('cold') through an optical absorption cell measuring atomic absorption at $253.7\text{ nm}$.
• HPLC is used for organic speciation rather than total elemental mercury analysis.

Enzyme-Linked Immunosorbent Assay (ELISA) is the most widely adopted routine, rapid, and high-throughput commercial screening method for detecting and quantifying mycotoxins (such as aflatoxins, ochratoxin A, deoxynivalenol, and zearalenone) in cereal grains. While HPLC and MS are confirmatory reference chromatographic techniques, commercial grain elevators and quality testing laboratories routinely utilize competitive ELISA kits for rapid field monitoring.

Option analysis:

• Polymerase Chain Reaction (PCR): Detects fungal DNA, not chemical toxin molecules.
• High-Performance Liquid Chromatography (HPLC): Confirmatory chromatographic method, less commonly used for rapid routine grain reception.
• Mass Spectrometry (MS): Sophisticated instrumental method, not a routine quick test.
• Enzyme-Linked Immunosorbent Assay (ELISA): Correct, common antibody-based screening tool universally used in grain industries.

The Reversed Passive Latex Agglutination (RPLA) test is an established, highly specific immunological assay standardly used in food microbiology to detect and titrate bacterial enterotoxins (such as staphylococcal enterotoxins A, B, C, D from Staphylococcus aureus, enterotoxins from Bacillus cereus, and Clostridium perfringens enterotoxin) directly from food extracts or cultures without requiring live animal bioassays.

Option analysis:

• Rapid Photo Latex Arrangement Test: Fabricated term.
• Reversed Passive Latex Agglutination Test: Correct (abbreviated RPLA), standard serological enterotoxin assay.
• Random Photo Light Agglutination Test: Fabricated term.
• Real Passive Light Agglutination Test: Fabricated term.