Food analysis

Potassium permanganate is an oxidant and is used in many titrations. Name 3 types of titrations that utilize potassium permanganate as the titrant and indicator.

Iron (Fe2+) or Mohr’s salts, oxalic acid (oxalate), hydrogen peroxide, Copper (II), tannins (other redox reactions)

Explain the purpose of using a standard curve in spectrophotometric analysis.

It establishes a relationship between concentration and absorbance, allowing quantification of unknown samples.

Name 3 methods used for protein determination in food and what type of food are they suitable for?

Kjeldahl (all), Dumas/Dry combustion (all), IR spectroscopy (milk), Bradford (soluble proteins), Biuret (cereals, soy, wheat), BCA (Bicinchoninic acid assay), Lowry

Name 3 methods for determination of protein content in a purified protein solution.

Lowry, BCA, UV at 280 or 220, Bradford, Dumas, Kjeldahl, Biuret

Which four heavy metals are most commonly tested for in food products?

Mercury, cadmium, lead, arsenic

Gas Chromatography (GC) is a staple in food analysis. Name the two primary components of the "mobile phase" and "stationary phase" in a standard GC setup used for flavor analysis.

Mobile phase: An inert carrier gas (e.g., Helium, Nitrogen, or Hydrogen). Stationary phase: A microscopic layer of liquid or polymer on an inert solid support inside the column.

List and describe three classical proximate analysis methods for food composition.

Moisture: Oven drying or Karl Fischer titration Protein: Kjeldahl or Dumas nitrogen analysis Fat: Soxhlet extraction

Define molarity, molality, and normality.

Molarity is moles of substance per liter solution. Molality is moles of substance per kg solvent. Normality is equivalents of substance per liter solution.

Explain the principle of Near-Infrared (NIR) spectroscopy and its application in food analysis.

NIR measures overtones of molecular vibrations (C–H, O–H, N–H) and is used for rapid, non-destructive analysis of moisture, fat, and protein.

Name five antioxidant assays with their full names.

ORAC – Oxygen Radical Absorbance Capacity CUPRAC – Cupric Reducing Antioxidant Capacity β-Carotene bleaching assay TEAC – Trolox Equivalent Antioxidant Capacity FRAP – Ferric Reducing Antioxidant Power DPPH (2,2-diphenyl-1-picrylhydrazyl) assay ABTS (2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)) assay

Give the Osborne protein classification.

Osborne developed a classification of plant proteins based on their solubility in a series of solvents. 1. Albumin (in water). 2. Globulin (in dilute salt). 3. Prolamin (in 70% alcohol) 4. Glutelin (in dilute alkali, 0.1M NaOH solution)

Name 3 tests that can be used to measure the fat content of milk.

Primitive Centrifugal Methods, Gerber, Babcock, Rose- Gottlieb, Schmidt Werner, Mojonnier

Name three methods for protein quality determination.

Protein efficiency ratio, biological value, net protein utilization, PDCAAS (protein digestibility corrected amino acid score), Digestible Indispensable Amino Acid Score (DIAAS)

How can the molecular weight of protein, DNA and RNA be determined?

Proteins: SDS-PAGE, SEC, MS DNA: Agarose gel electrophoresis RNA: Denaturing Gel Electrophoresis

What do the following abbreviations stand for? PV, FSIS, CFR, PER, DP, NMR, ESR, HPLC, AA, ICP- AES, SEM, SDS-PAGE, FTIR, TLC, HETP, GFC, SFC, SEC, CRISPR

PV: Peroxide Value FSIS: Food Safety and Inspection Service CFR: Code of Federal Regulations PER: Protein Efficiency Ratio DP: Degree of Polymerization NMR: Nuclear Magnetic Resonance ESR: Electron Spin Resonance HPLC: High Pressure/Performance Liquid Chromatography AA: Atomic Absorption ICP-AES: Inductively Coupled Plasma Atomic Emission Spectroscopy SEM: Scanning Electron Microscopy SDS-PAGE: Sodium Dodecyl Sulfate Polyacrylamide Gel Electrophoresis FTIR: Fourier Transform Infared Spectroscopy TLC: Thin Layer Chromatography HETP: Height Equivalent to a Theoretical Plate GFC: Gel Filteration Chromatography SFC: Super critical Fluid Chromatography SEC: Size Exclusion Chromatography CRISPR: Clustered Regularly Interspaced Short Palindromic Repeats

Give the resultant color for each of the following L*a*b* scores: 1) L* = 50, a*= 50, b* = 50; 2) L* = 50, a*= 0, b* = 0; 3) L* = 40, a*= 10, b* = 40

red, gray, darker, slightly reddish yellow/mustard yellow

Name three methods to determine the lengths of polysaccharides.

Size-exclusion chromatography (SEC), Gel permeation chromatography (GPC), Viscometry (intrinsic viscosity measurements), Light scattering (static or dynamic), Nuclear Magnetic Resonance (NMR) spectroscopy

What are the major components of HPLC?

Solvent reservoir, pump, column, detector

Name three protocols for measuring reducing sugars.

Somogyi-Nelson, Fehling's, Benedict's methods, DNS (3,5-Dinitrosalicylic acid) method

What do the following abbreviations stand for: SPC, ANOVA, TQM?

SPC: Statistical process control, ANOVA: analysis of variance, TQM: total quality management