Milk & Milk Products: Analytical methods, adulterants and quality parameters MCQs With Answer

Milk & Milk Products: Analytical methods, adulterants and quality parameters MCQs With Answer is a focused quiz compilation designed for M.Pharm students studying MPA 104T Food Analysis. This resource reinforces understanding of laboratory techniques (Gerber, Kjeldahl, FTIR, HPLC, GC-MS), routine quality checks (fat, SNF, total solids, acidity, freezing point), and detection of common adulterants (water, starch, urea, melamine, formalin, hydrogen peroxide). Questions probe principles, sample preparation, interpretation of results, rapid screening tests and regulatory-relevant quality markers such as somatic cell count, pasteurization regimes and residue analysis. Use these MCQs for self-assessment, exam preparation and to deepen applied analytical competence in dairy quality control.

Q1. Which analytical method is classically used to determine total protein content in milk by measuring nitrogen and applying a conversion factor?

• Kjeldahl method measuring total nitrogen followed by conversion to protein
• Babcock method measuring fat after acid digestion
• Gerber method for fat determination using sulfuric acid and centrifugation
• Refractometry to estimate solids-not-fat

Correct Answer: Kjeldahl method measuring total nitrogen followed by conversion to protein

Q2. What is the primary principle of the Gerber method used for milk fat estimation?

• Digestion of protein with sulfuric acid, release and separation of fat by centrifugation aided by amyl alcohol
• Solvent extraction of fat using diethyl ether and petroleum ether
• Infrared absorption spectroscopy to quantify fat peaks
• Gravimetric determination after heat drying of milk

Correct Answer: Digestion of protein with sulfuric acid, release and separation of fat by centrifugation aided by amyl alcohol

Q3. Which rapid laboratory technique provides a multi-component profile (fat, protein, lactose, SNF) of milk using mid-infrared absorption?

• FTIR/Mid-infrared spectroscopy (e.g., MilkoScan)
• Kjeldahl digestion followed by titration
• Standard plate count on agar
• Reichert-Meissl value determination

Correct Answer: FTIR/Mid-infrared spectroscopy (e.g., MilkoScan)

Q4. Which test is most suitable to detect added water in milk by measuring freezing point depression?

• Cryoscopy or freezing point osmometry
• Lactometer density reading at ambient temperature
• Gerber fat estimation
• pH meter measurement only

Correct Answer: Cryoscopy or freezing point osmometry

Q5. Which analytical technique is preferred for confirmatory detection and quantification of melamine adulteration in milk?

• LC-MS/MS or GC-MS after appropriate sample cleanup
• Qualitative iodine test for starch
• Kjeldahl nitrogen estimation alone
• Simple lactometer reading

Correct Answer: LC-MS/MS or GC-MS after appropriate sample cleanup

Q6. The Dumas combustion method for nitrogen analysis differs from Kjeldahl primarily by:

• Combustion of sample with subsequent gas analysis, providing faster total nitrogen measurement without strong acids
• Using sulfuric acid digestion to convert organic nitrogen to ammonium
• Direct chromatographic separation of proteins
• Measuring amino acid profiles by HPLC

Correct Answer: Combustion of sample with subsequent gas analysis, providing faster total nitrogen measurement without strong acids

Q7. Which simple spot test indicates presence of starch in milk?

• Iodine test producing a blue-black color
• Phenolphthalein test for acidity
• Biuret test for proteins
• Peroxide test with potassium iodide-starch paper

Correct Answer: Iodine test producing a blue-black color

Q8. For routine screening of antibiotic residues in milk at the dairy farm, which test principle is commonly used?

• Microbial inhibitor tests (e.g., Delvotest) based on growth inhibition of sensitive bacteria
• HPLC without pre-treatment
• FTIR spectroscopy targeting antibiotic functional groups
• Freezing point determination

Correct Answer: Microbial inhibitor tests (e.g., Delvotest) based on growth inhibition of sensitive bacteria

Q9. Which parameter is a direct indicator of mammary gland health and is used as a quality criterion in raw milk?

• Somatic cell count (SCC)
• Fat percentage determined by Gerber
• Refractive index of milk
• Freezing point depression

Correct Answer: Somatic cell count (SCC)

Q10. Which method is most appropriate to quantify aflatoxin M1 in milk at low ppb levels for regulatory compliance?

• Immunoaffinity column cleanup followed by HPLC with fluorescence detection or LC-MS/MS
• Simple paper strip test for pH
• Gerber method for fat content
• Refractometer reading for solids

Correct Answer: Immunoaffinity column cleanup followed by HPLC with fluorescence detection or LC-MS/MS

Q11. Which adverse effect is the peroxide value test primarily used to assess in milk fat?

• Extent of primary lipid oxidation (peroxides) indicating rancidity
• Protein denaturation due to heat treatment
• Presence of added water
• Somatic cell count changes

Correct Answer: Extent of primary lipid oxidation (peroxides) indicating rancidity

Q12. Which adulterant in milk can be detected by a persistent foaming test and drop in surface tension?

• Detergents or surface-active agents
• Starch
• Hydrogen peroxide
• Urea

Correct Answer: Detergents or surface-active agents

Q13. What is the principle behind using a lactometer to detect adulteration of milk?

• Measurement of relative density to infer added water or high solids content
• Direct chemical reaction with starch to give color
• Quantification of fat by centrifugal separation
• Determination of freezing point depression

Correct Answer: Measurement of relative density to infer added water or high solids content

Q14. Which analytical approach is commonly used for fatty acid profiling of milk lipids to detect adulteration with vegetable oils?

• Gas chromatography (GC) of methylated fatty acid esters
• Kjeldahl nitrogen analysis
• Somatic cell count by microscopy
• Refractometric determination of SNF

Correct Answer: Gas chromatography (GC) of methylated fatty acid esters

Q15. Which parameter is calculated as total solids minus fat and is important for pricing and quality (SNF)?

• Solids-not-fat (SNF)
• Peroxide value
• Somatic cell count
• Acidity expressed as lactic acid%

Correct Answer: Solids-not-fat (SNF)

Q16. Which rapid chemical test indicates presence of hydrogen peroxide in milk?

• Potassium iodide-starch paper turning blue due to liberated iodine
• Iodine test for starch producing blue-black color
• Kjeldahl nitrogen increase
• Acid degree value measurement

Correct Answer: Potassium iodide-starch paper turning blue due to liberated iodine

Q17. Pasteurization using HTST conditions is typically defined as:

• 72°C for at least 15 seconds
• 63°C for 30 minutes
• 135°C for 2–4 seconds (UHT)
• 100°C for 1 minute

Correct Answer: 72°C for at least 15 seconds

Q18. Which method provides sensitive, specific screening for multiple veterinary drug residues simultaneously in milk using high-resolution analysis?

• LC-MS/MS multi-residue methods after solid-phase extraction
• Gerber fat test
• Cryoscopy for water addition
• Simple culture-based microbial count

Correct Answer: LC-MS/MS multi-residue methods after solid-phase extraction

Q19. What does an elevated titratable acidity in raw milk usually indicate?

• Microbial fermentation producing lactic acid or increased bacterial activity
• Higher fat percentage due to creaming
• Added water to dilute solids
• Presence of detergents

Correct Answer: Microbial fermentation producing lactic acid or increased bacterial activity

Q20. Which confirmatory technique is most appropriate to identify pathogenic bacterial species in milk at the genetic level?

• PCR-based assays targeting species-specific genes followed by sequencing if needed
• Gerber method for fat estimation
• FTIR compositional analysis
• Refractometric SNF estimation

Correct Answer: PCR-based assays targeting species-specific genes followed by sequencing if needed

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