lecture 3/4

Anylizaing by using qualitative determination, quantitation and structure eludication to target chemical species in sample.

-the traget to be anylzed

-entire sample material including anyalyte

Nutrition labeling Nutrient and health claims Quality control and assurance Toxin identifaction Research Regulatory

-define problem -choose appropriate instrument -sampling -sample pre treatments -accurte analysis and reporting -realiabilty of data

-physiochemical process that provides basis for analytical measuremnts like mass or molecular size, emission/absorption of electromagnetic radiation, electrical/thermal properties

-random selcetion -cone and quarter -riffle box splitting -repeated sampling

Error: differnce between true answer and observation Accuracy: closeness of values to true or accepted value Precision: closeness of values from replicated experiments, variability, dispersion

calories-equation total carb-equation protien-dumas total fat-gas chromatography cholesterol-capillary gas chromatography moisture-draft oven sodium, calcium, iron, potasium-inductively coupled plasma, optical emision spectroscopy

Calories =( g of carb x 4cal/g)+(g of protien x4 cal/g)+ (G of fat x 9 cal/g)

Kjedahl: digestion, neutralzation, distilation and titration (N x6.25), inexpesnive, but only measures total N not just protien N and is very time consuming, lower precision Duma: combustion done at high temp to release N and then uses gas chromatography and then (N x6.25), rapid, no hazardous chemicals, automated, expensive equipment, doesn’t just measure protien N

Biuret and lowry methods: based one peptide bond, complexed with cupric ions to be treated with spectroscopy, less expensive, faster and more simple but cannot detect insoluble protien

Mass loss of product after heating =(wet weight-dry weight)/wet weight x100 -doesn’t for sure reflect true water content as tightly bound water escapes detection and volatile substances may interfere

Dry ashing -some minerals lost, 500-600 degrees, gravimetric analysis Wet ashing -boiling in mixture of acids/oxidizing agents, no lose Atomic absorption/ emission spectroscopy -solubized in acid and can absorb or emit light of specific wavelengths ICP-MS -recomoneded by CFIA for labelling

Soxhlet method -content measured by weight loss of sample or weight of fat removed, using a distilation flask and allow to evaporate then measure -time consuming but complete extraction, manual process, lipids may escape, no worry about temp GC (gas chromatography) -seperation done by difference in volatility of compounds and their affinitys to phase column -convert to TAg equivalents -can be used to determine cholesterol content using saponifcation and toluene, then using cholestane as a refernce -measures only true fats, and can separate fats, time consuming and expensive

Total carbohydrates -determined by difference =100%-(%ash+ moisture +%protein + % fat) -used by CFIA/US regulations for food labeling -not actual measurement of carbs, depends on accuracy of other components Total sugars -sum of all free mono and di -done by removing lipids with ethanol and then removing ethanol with rotary evaporator Dietary fiber -use enzymic-gravimeter/HPLC method -total soluble and insoluble fiber -dry/defat, remove starch by enzyme, precipitate with ethanol, determine protein and ash remains, gravimetric method (insoluble), soluble HPLC

Va -sensitive to environmental factors, use organic solvent, saponification, re-extraction to get -use HPLC and uv detection to measure Vc -can be oxidized -homoginized, acidic environment, reducing agent to extract and measured using same teqnique as A