Summary NUTR 405 Complete A+ Study guide_ Fall 2022
Proximate Analysis Lecture
1. List the five proximate components, their importance to food analysts, and the various methods/apparatus that each can
be determined. **just the methods/apparatus that we covered in lab-not the numerous other methods of analysis that are
covered in the text book
Proximate Analysis: quantitative analysis of any food to determine the percentage of its components
o Determine moisture, ash, fat, protein and carbohydrate content of a food
o Conducted with official methods – Association of Official Analytical (AOAC), American Association for Clinical
Chemistry (AACC), American Oil Chemists Society (AOCS)
Moisture: food item – moisture = total solids – natural food (~70%), fruits and veggies (~95%)
o Role of water in food: texture – either the presence or absence of water
o States of water in food: free water, bound water, adsorbed
o Relevance of measuring water: determine food quality, food stability and preservation, microbial stability, legal
requirements/labeling (QC and QA, flour 12-15%), economic
o Method to determine: oven drying (vacuum or convection ovens), freeze drying (sublimation)
o How to calculate: (amount lost/original wet weight) * 100 = % moisture
Fat: relevance of measuring lipids – nutritional information/labeling, lipid oxidation, physical characteristics of foods, food
quality
o Methods to determine fat content:
1. Goldfisch – continuous, gold standard, food analysis
2. Soxhlet – semi continuous
3. Mojonnier – discontinuous
o How to calculate: (weight of lipid extracted/sample weight) * 100 = % fat
Protein: relevance of measuring protein – determine total protein/individual AAs, investigate functional properties,
nutrition labeling
o Methods to determine protein content:
1. Kjeldahl – gold standard
2. Dumas – combustion reduction purification detection, much faster than kjeldahl (4min v. 1-2hrs)
Actually measuring nitrogen – nitrogen conversion factor (5.3)
3. Bradford – not very conclusive, can be time consuming
Ash: ash content v. mineral content, relevance of measuring ash – nutrition labeling, quality of raw products, microbial
stability, nutrition, processing
o Method to determine ash content:
1. Wet ashing – strong acids + heat
2. Dry ashing – muffle furnace (500-600 C for > 24 hours (AOAC)
o How to calculate: (dry weight/original wet weight) * 100 = % ash
Carbohydrate: classification of CHOs, sweetness appearance, texture
o Relevance of measuring CHOs – nutritional labeling, standards of identity, food quality, economic
o Methods to determine carbohydrate content:
1. Indirect measurement – total % carbohydrate by difference (100 – (%fat + %protein + %ash + % h20 in
100 g food))
2. Direct measurement – sum of weight of individual CHO + fiber via
Chromatographic + electrophoretic methods
Chemical methods
Titration methods
Enzymatic methods
Equipment Overview
This study source was downloaded by 100000844708667 from CourseHero.com on 10-27-2022 01:15:43 GMT -05:00
https://www.coursehero.com/file/37139931/N405-Exam-Study-Guide-docx/
, 1. Recognize the best applications of each apparatus/instrument
1. Instrument & Manufacturer:
1.A Precision Vacuum Oven – quantitative analysis of any food to determine the percent of 5 constituents
1.B Precision Scientific Thelco Convection Oven
1.C LabConco Freezone 4.5 Freeze Dryer
Applications (uses):
Theory of Method:
Oven Drying
Freeze Drying
Pros:
Vacuum Drying
Forced Air Draft Drying
Freeze Drying
Cons (limitations):
Vacuum Drying
Forced Air Draft Drying
Freeze Drying
2. Instrument & Manufacturer: Fisher Scientific Isotemp Programmable Muffle Furnace 650-750 Series
Applications (uses): uses high heat to incinerate all organic material inside
Theory of Method:
Pros: safe, can use multiple samples at once
Cons (Limitations): cross contamination from other samples, unintended loss of ash
3. Instrument & Manufacturer: Elementar Rapid N III
Applications (uses): get the nitrogen content by DUMAS (C, R, P, D)
Theory of method:
Pros: quick, automated, reliable, not utilizing strong chemicals
Cons (Limitations): extremely expensive, high maintenance, technical difficulties
4. Instrument & Manufacturer: LabConco Goldfisch Fat Extractor
Applications (uses): uses organic (fat soluble) solvent to remove fat
Theory of Method:
Pros: gold standard, fast
Cons (Limitations): channeling, ethyl ether drips through, wastes water
5. Instrument & Manufacturer: Rotronic Hygrolab 3 by Rotronic
Applications (uses): measures water vapor coming off product
This study source was downloaded by 100000844708667 from CourseHero.com on 10-27-2022 01:15:43 GMT -05:00
https://www.coursehero.com/file/37139931/N405-Exam-Study-Guide-docx/
Proximate Analysis Lecture
1. List the five proximate components, their importance to food analysts, and the various methods/apparatus that each can
be determined. **just the methods/apparatus that we covered in lab-not the numerous other methods of analysis that are
covered in the text book
Proximate Analysis: quantitative analysis of any food to determine the percentage of its components
o Determine moisture, ash, fat, protein and carbohydrate content of a food
o Conducted with official methods – Association of Official Analytical (AOAC), American Association for Clinical
Chemistry (AACC), American Oil Chemists Society (AOCS)
Moisture: food item – moisture = total solids – natural food (~70%), fruits and veggies (~95%)
o Role of water in food: texture – either the presence or absence of water
o States of water in food: free water, bound water, adsorbed
o Relevance of measuring water: determine food quality, food stability and preservation, microbial stability, legal
requirements/labeling (QC and QA, flour 12-15%), economic
o Method to determine: oven drying (vacuum or convection ovens), freeze drying (sublimation)
o How to calculate: (amount lost/original wet weight) * 100 = % moisture
Fat: relevance of measuring lipids – nutritional information/labeling, lipid oxidation, physical characteristics of foods, food
quality
o Methods to determine fat content:
1. Goldfisch – continuous, gold standard, food analysis
2. Soxhlet – semi continuous
3. Mojonnier – discontinuous
o How to calculate: (weight of lipid extracted/sample weight) * 100 = % fat
Protein: relevance of measuring protein – determine total protein/individual AAs, investigate functional properties,
nutrition labeling
o Methods to determine protein content:
1. Kjeldahl – gold standard
2. Dumas – combustion reduction purification detection, much faster than kjeldahl (4min v. 1-2hrs)
Actually measuring nitrogen – nitrogen conversion factor (5.3)
3. Bradford – not very conclusive, can be time consuming
Ash: ash content v. mineral content, relevance of measuring ash – nutrition labeling, quality of raw products, microbial
stability, nutrition, processing
o Method to determine ash content:
1. Wet ashing – strong acids + heat
2. Dry ashing – muffle furnace (500-600 C for > 24 hours (AOAC)
o How to calculate: (dry weight/original wet weight) * 100 = % ash
Carbohydrate: classification of CHOs, sweetness appearance, texture
o Relevance of measuring CHOs – nutritional labeling, standards of identity, food quality, economic
o Methods to determine carbohydrate content:
1. Indirect measurement – total % carbohydrate by difference (100 – (%fat + %protein + %ash + % h20 in
100 g food))
2. Direct measurement – sum of weight of individual CHO + fiber via
Chromatographic + electrophoretic methods
Chemical methods
Titration methods
Enzymatic methods
Equipment Overview
This study source was downloaded by 100000844708667 from CourseHero.com on 10-27-2022 01:15:43 GMT -05:00
https://www.coursehero.com/file/37139931/N405-Exam-Study-Guide-docx/
, 1. Recognize the best applications of each apparatus/instrument
1. Instrument & Manufacturer:
1.A Precision Vacuum Oven – quantitative analysis of any food to determine the percent of 5 constituents
1.B Precision Scientific Thelco Convection Oven
1.C LabConco Freezone 4.5 Freeze Dryer
Applications (uses):
Theory of Method:
Oven Drying
Freeze Drying
Pros:
Vacuum Drying
Forced Air Draft Drying
Freeze Drying
Cons (limitations):
Vacuum Drying
Forced Air Draft Drying
Freeze Drying
2. Instrument & Manufacturer: Fisher Scientific Isotemp Programmable Muffle Furnace 650-750 Series
Applications (uses): uses high heat to incinerate all organic material inside
Theory of Method:
Pros: safe, can use multiple samples at once
Cons (Limitations): cross contamination from other samples, unintended loss of ash
3. Instrument & Manufacturer: Elementar Rapid N III
Applications (uses): get the nitrogen content by DUMAS (C, R, P, D)
Theory of method:
Pros: quick, automated, reliable, not utilizing strong chemicals
Cons (Limitations): extremely expensive, high maintenance, technical difficulties
4. Instrument & Manufacturer: LabConco Goldfisch Fat Extractor
Applications (uses): uses organic (fat soluble) solvent to remove fat
Theory of Method:
Pros: gold standard, fast
Cons (Limitations): channeling, ethyl ether drips through, wastes water
5. Instrument & Manufacturer: Rotronic Hygrolab 3 by Rotronic
Applications (uses): measures water vapor coming off product
This study source was downloaded by 100000844708667 from CourseHero.com on 10-27-2022 01:15:43 GMT -05:00
https://www.coursehero.com/file/37139931/N405-Exam-Study-Guide-docx/
