NUTR 405 Proximate Analysis Lecture Complete A+ Exam (elaborations)

NUTR 405 Proximate Analysis Lecture Complete A+ Exam (elaborations) 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 • Determine moisture, ash, fat, protein and carbohydrate content of a food • 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%) • Role of water in food: texture – either the presence or absence of water • States of water in food: free water, bound water, adsorbed • Relevance of measuring water: determine food quality, food stability and preservation, microbial stability, legal requirements/labeling (QC and QA, flour 12-15%), economic • Method to determine: oven drying (vacuum or convection ovens), freeze drying (sublimation) • 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 • Methods to determine fat content: 1. Goldfisch – continuous, gold standard, food analysis 2. Soxhlet – semi continuous 3. Mojonnier – discontinuous • 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 • 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 • Method to determine ash content: 1. Wet ashing – strong acids + heat 2. Dry ashing – muffle furnace (500-600 C for > 24 hours (AOAC) • How to calculate: (dry weight/original wet weight) * 100 = % ash Carbohydrate: classification of CHOs, sweetness appearance, texture • Relevance of measuring CHOs – nutritional labeling, standards of identity, food quality, economic • 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 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 ..............................Continue