Introduction to Food Analysis

Introduction to Food Analysis

• Food consists mainly of living tissues.
• The tissue is comprised of protein, lipids, nucleic acids, carbohydrates, and other materials.
• Essential but non-food items are water and oxygen.
• Food provides the materials for living things' growth, energy, repair, and reproduction.

Food Origin

• Terrestrial food sources depend upon plants and microorganisms.
• Plant growth depends on water and nutrients in the soil, as well as atmospheric carbon dioxide and nitrogen.
• The sun's energy, trapped during photosynthesis, can generate carbohydrates and synthesize other essential biomolecules.

Types of Food Analysis

• There are three different types of food analysis - chemical, sensory and microbiological.

Chemical Analysis

• Chemical analysis assesses nutritional components or to check the purity or composition of food ingredients.
• Crude or proximate analysis include moisture and protein
• Specific analyses focus on components like cholesterol, vitamin C, and iron.

Sensory Analysis

• Sensory analysis evaluates a food's acceptability through senses, filling physiological needs and social interactions.
• The main senses used for sensory analysis are taste, sight, smell, and touch.

Microbiological Analysis

• Microbiological analysis involves detecting and identifying microorganisms and food preparation.
• A key question in food preparation: Are the correct microbes present?

Soil Analysis

• Soil analysis is important for understanding plant properties and nutrient levels, because most food is either plants or derived from them.
• The amounts of sand, clay, and silt influence the soil type and the types of plants that will grow there.

Proximate Analysis

• Proximate analysis estimates the major components of food based on mass.
• It includes moisture (not always on labels), ash (total mineral content, not always on labels), fat (total fat), protein (total protein), carbohydrate and fiber.
• Proximate analysis is performed to ensure food meets legal and food labeling requirements.
• Regulatory bodies determine allowable content percentages (ex. % ash, moisture) with CODEX Alimentarius.
• Proximate analysis data are shown under "Nutrition(al) Facts".
• Analysis methods are not specific, e.g., all lipids are measured as one mass, and ash includes all minerals and inorganic matter.
• Data are expressed as g/100g food or as a percentage of daily requirements/values, included in standard tables of composition.
• Ash data is reported on pet food in addition to human food.
• Moisture data is reported on pet food, and sometimes on human food like cheeses.
• Moisture is not reported on items such as butter or margarine because there is a legal maximum
• Ingredients on a label are listed from highest proportion to lowest.
• For protein - Nitrogen content is determined and then multiplied by a conversion factor.
• Fiber is listed under carbohydrates but is a specific determination.
• For proximate analysis, carbohydrates is calculated by adding the percentages of moisture, ash, fat, and protein, subtracting that sum from 100, and then converting back to mass.
• Carbohydrates includes sugars, fiber, organic acids, trace nitrogenous material (nucleic acids), and determination errors of other constituent groups

Moisture Content

• Moisture content affects mass and shipping costs, it affects microbial growth and food staleness, and some ingredients may cause caking.
• Wheat that is too moist will cake and not mill easily
• Consumer expectations dictate the moisture level of products so they are neither too dry nor too slimy.
• Moisture ensures correct concentration of ingredients, accounts for production losses, and maintains proper packaging moisture.
• Cucumbers and apples have the highest moisture content at 96% while chocolate has the lowest at ≤1
• Flour 10-13% moisture
• Fresh eggs are 74% water
• Meats are 50-74% water

Forms of Water in Foods

• There are three forms of water in foods, each with unique behaviors and functions: free, adsorbed, and bound.

Free Water

• Free water is excess or bulk water, like that in squeezable tomatoes.
• It's available to microorganisms and helps retain shape and consistency in foods.
• Free water also acts as a solvent for minerals and suspends colloids, for example carbohydrates and proteins in milk.

Adsorbed Water

• Adsorbed water is a "coating" around food particles and molecules, such as carbohydrates and proteins.
• This type of water is removable with mild heat.

Bound Water

• Bound water refers to hydrated molecules and water of crystallization.
• Bound water is held within the structure of carbohydrates and proteins.
• Removing bound water can denature or degrade molecules.

Water Activity (aw)

• Water activity is the partial vapor pressure of water in a substance divided by the standard state partial vapor pressure of water.
• It measures water migration in or out of food relative to water activity.
• Honey in humid air absorbs water, whereas salami in dry air dries out.
• It predicts the shelf stability of a food and potential microbial growth.
• Lower water activity usually prevents microbial growth; microbial growth of bacteria and mold is inhibited at less than 0.8 aw.
• Distilled water has water activity of 1.00 while Peanut Butter has water activity of ≤ 0.35
• Examples
  • Salami has water activity of 0.87
  • Milk and Juice has water activity of 0.97
  • Shelf-stable cooked bacon has water activity of <0.85

Factors Affecting Water Analytical Method Choice

• Type of water: consider bulk, adsorbed, and bound water.
• Product nature: oxidation, decomposition, and presence of volatile nonaqueous components all affect method choice.
• High-fat foods can undergo oxidation during heating, leading to increased mass and water undervaluation.
• Sugars heated too long can decompose with water loss, causing an overestimation of water measurement.
• High water content foods may require chemical or physical analysis while low water content foods require drying balance method.

Drying Methods – Air Oven

• An air oven dries samples by heating them and calculating water percentage from the change in mass.
• Variables include oven type (conventional or convection), pressure/air flow, temperature (ideally low, to minimize issues), and pan type (covered or uncovered).

Drying Methods – Vacuum Oven

• It is the standard and most accurate method for moisture determination in most food by reducing oxidation and decomposition.
• Reduces pressure but with a continuous flow of dried air, and often produces higher water content (reduced boiling point under pressure).

Drying Methods – Moisture Balances

• Drying methods, moisture balances use various heat sources including infrared, halogen, or microwave.
• Covered oven pans help prevent water readsorption whereas uncovered ones are simple to use, are often disposable

Distillation Method – Bidwell-Sterling Moisture Test

• A sample is distilled with a water-insoluble solvent under a reflux condenser.
• It uses a solvent with a boiling point higher than H2O to transfer heat and vaporize water.
• It is used for 3-70% moisture, specifically AOAC grain and stock feeds.
• Advantages: uses inert atmosphere, less decomposition, and constant temperature
• Disadvantages: low precision, meniscus reading difficulties, adherence of droplets to the glass, emulsion formation
• A known quantity of food is added into the reaction vessel and toluene or xylene are added (bps > H2O bp). The system is heated and the H2O-solvent vapour evapourates and moves into the condenser where it is cooled and converted back to liquid H2O and collected in the graduated tube (Stirling-Bidwell receiver). The process is continued until no more H2O distills over.

Chemical Methods – Karl Fischer Titration

• This method is used for low moisture foods like dried fruits, vegetables, candies, chocolate, roasted coffee, oils, fats, honey, and powdered milk.
• KF reagent: iodine, sulfur dioxide, imidazole (organic base) in methanol or methoxyethanol.
• The optimum pH for good reaction rate is 4-7.
• There is 1 mol of I2 for each mole of H2O

Karl Fischer Endpoint Detection - Volumetric

• Used for foods with >5% water content; uses large sample amounts is H2O is < 0.05%
• Iodine is the titrant; free iodine has a yellow/brown colour.

Karl Fischer Endpoint Detection - Coulometric

• Used for ppm-5% water.
• Anode solution contains alcohol, base, sulfur dioxide, and iodide.
• Iodine is generated by oxidation of the iodide at the anode until a trace amount of unreacted iodide is detected.

Karl-Fischer Coulometric - Considerations

• It needs to compensate for drift from the slow release of water from glass walls.
• Lower levels generate a linear response for 1-point calibrations (1% H2O standard).
• Foods like chocolate release water slowly and need some processing.

Chemical Methods – Calcium Carbide Method

• Food is mixed with powdered calcium carbide to produce acetylene.
• Acetylene can be measured by loss in mass, volume of gas collected, or pressure of gas.
• Advantages: less expensive
• Disadvantages: Requires calibration and involves a flammable product

Instrumental Methods - IR (Infrared)

• Used for 1-80% moisture.
• It measures water vibration at 3333 cm-1 and 1640 cm-1, or near IR 6000 to 4000 cm-1.
• Near-infrared spectroscopy (NIRS), 800-2500 nm or 6000 to 4000 cm-1, is used.
• The amount of C-H is abundant in lipids, O-H in carbohydrates, and N-H in proteins.
• No sample prep is required, and typical analysis times range from 15-90 seconds.

Instrumental Methods - GC (Gas Chromatography)

• Use cases are cereals, cereal products, fruits, 8-65% moisture.
• Extract moisture with a miscible organic solvent (MeOH or s-BuOH) and run on GC to measure water.
• It works well with samples with low solid content if water is efficiently extracted and extract contains no other substances that have the same retention time as water.

Instrumental Methods - NMR (Nuclear Magnetic Resonance)

• It can detect all forms of water.
• Method 1 positions the food sample in the magnetic field while Method 2 deflects the water nuclei (protons) by a magnetic pulse.
• It is non-destructive, standards can be sealed and reused, expensive

Physical Methods – Refractometry

• It varies based on water percentage ('linear' with mole fraction) with Brix scale.

Physical Methods – Specific Gravity

• Used for brines, alcohols, sugar solutions
• Specific gravity is tested with a hydrometer, pycnometer, Westphal balance or instrumental densitometer

Ash Determination

• Ash is the inorganic residue remaining after incineration of organic matter, such as metal cations with oxide, phosphate, sulfate, nitrate, and chloride anions.
• Ash determination is done to analyze the food's nutrient quality, detect food adulteration or contamination, or prepare a sample for mineral determination
• Ash content varies by food, from 0.2-0.6% in fresh fruit to Up to 12% in processed, dried and slated meats
• Fluid milk as 0.5-1.0% ash content

Ashing Methods – Total Dry Ash

• Samples is heated at 400-700°C in a muffle furnace until ash is grey-white (all organic matter oxidized to CO2).
• High moisture foods should be pre-dried, and pre-ashing is recommended when muffle furnace is preheated to avoid ignition and ash loss.

Ashing Methods – Water Soluble Ash

• Includes dissolving ash in water run sample through filter paper so it isolates any unwanted materials.
• The equation to calculating Water Soluble Ash percentage = % total ash - % water-insoluble ash

Alkalinity of Soluble Ash Determination

• Used to Measure alkali carbonates, titrate filtrate through filter paper, with 0.1 N H2SO4 and identify adulteration with Na2CO3 (milk)

Acid Insoluble Ash Determination

• Measures the dirt and sand present, it's used in soil analysis by dissolving in 10% HCI (run sample through filter paper)

Wet Ashing Methods

• It uses heat and strong acids (HNO3, H2SO4, HCIO4) to oxidize organic matter (faster than dry ashing).
• Lose less volatile minerals because of ion exchange and lower temp.

Fat and Fat Determination

• Lipids are non-polar biological molecules
• Lipids are called "fats" and refer triacylglycerides (triglycerides old term)

Triacylglycerides Classification

• In simple TAGs all R (acyl) groups are the same length
• In mixed TAGs the R groups are different lengths

Triacylglycerides classification: saturated vs unsaturated

• Saturated Acyl chains contain no double bonds
• Unsaturated At least one of the acyl chains contains a double bond
• Unsaturated fats: oils while Saturated fats: solids at room temperature
• Nearly all naturally occurring unsaturated fats have cis stereochemistry (vaccenic acid and rumenic acid are exceptions)
• Unsaturated fats can be saturated by hydrogenation margarine

Iodine Value

• Back titration to determine g of lodine per g of fat
• IBr (in glacial acetic acid) + unsaturated fat → halogenated fat, measured through Wijs solution
• The equation is Iodine value (IV) = gram of 12 per 100 gram of fat

Other Lipids

• Di- and Monoglycerides (Monoacylglycerols) Esters may undergo hydrolysis, fatty acid may be lost

Free Fatty Acids

• Generated because of the degradation of acylglycerols
• Smoke point = burning point of an oil or fat where it produces bluish smoke continuously

Sterols

• High MW cyclic alcohols (26 – 30 carbons) based on a steroid core, with the primary functions of hormones, membrane fluidity, and bile salts
• Cholesterol is absent in plants

Phospholipids

• Derivatives of triacylglycerol where one fatty acid is replaced by phosphate. Usually a polar group (amine, alcohol, amino acid, carbohydrate)
• Lecithin is waxy, plastic-like solid that can be used as an emulsifier, antioxidant, flavor enhancer, lubricant, while white when fresh but yellows with age

Cephalin

• Cephalin Turns white but goes reddish/brown in light and air

Pigments

• Red/yellow colours and is a precursor to vitamin A while displaying Molecular symmetry

Vitamins, Crude Fat Determination

• The acronym ADEK describes fat-soluble vitamins.
• .Crude fat includes fats, oils, and any fat-soluble materials present in the sample
• Milk and beef contains crude fats varying from under 0.10 to 32.5.

Analysis of Materials for fat

• Emulsion are ingredients for the preparation of processed meats (sausages), raw meat (wieners) and mechanically recovered meat
• It constitutes a fine disperions of minute droplets of one liquid in another, like Oil-and-water, with the desired and final composition

Importance of Fat

• Fat has effects on cost, appearance, mouth feel, flavor, aeration, emulsification, tenderness, and nutrition.

Determination of Crude fats

• Emulsifiers stabilize emulstion and consist of polar and non-polar parts, there are often mono digylcerides and fats
• Shortening - fats shorten the gluten strands and short gluten strands are more tender than long strands of gluten ex. Cakes versus bread

Determination of Crude Fats – Advantage

• Sample is not pre-dried (to save time), is quick to test if the operator uses Uses strong corrosive caustics or acids to generate heat, acids or caustics due to fat that has been surrounded by protein or licithin, and difficult to extract
• The determination for fats is through wetting, drying, and reflux with a solvent

Wet Extraction

• It uses of chemicals to separate material before applying centrifugation or heating
• In acid/caustic methods, Gerber heats and centrifuges to separate fat into a bottle while adding isoamyl to keep clear

Dry Extraction

• Can be used for solid samples and is generally more accurate, although they are more drying times

Protein and Protein Determination

• Protein is the major source of amino acids in the GI tract, used as building blocks for cells that bodies cannot get by themselves
• Amino acids are the industry standard for protein deterrmination in food

Kjeldahi method

• Is the analyze, there is nitrogen in most protein content in most food

Dumas and Hash Methods

• Are used but Kjedahl is more common

Kjedahl Method

• Requires analysis for nitrogen, which is then multiplied by the convergence factor through 6.25 converstion factor to get percent factors
• Different materials like milk and wheat different Nitrogen convergence factors

Kjeldahl Method Overview

• Samples are put though Digestion, Distilation, and Titration steps

Carbohydrates and carbohydrate determination

• Carbohydrate categories include sugars, monoliths, disaccarides, and polysaccirades

Polysaccharides in Food

• Starches like amylose and amylopection are digestible
• Polysaccharides provide soluble help benefits

Dietary Fiber Determination (Enzymatic Methods)

• Enzymatic digests and remocal of starch and protein Isolated fractions of Pectin, Hemicellulose, and cellulose aid

pH and Food

• pH is not actually part of private practice, but is used for determining quality, inhibting growth, food context, and overall touch
• It is measured through paper pH and pH water
• Solids that are suspended in the water mixed g/100 is suspended and degreased

Sample Preparation for pH Measurement

• It is prepared through having all liquids and solids being placed in solution in order to have an accurate amount

Soils and Soils Analyses, Soil macronutrients

• Soil is growth medium, made up of organic/inorganic, water, and other living components
• Soil is made up of micronutrients, such as C-Carbon, N-Nitrogen, P-Phosphorus, Ca-Calcium, Mg-Magnesium, S-Sulfer, along with Soil micronutrients

Organic Components, Water

Humus- Dead remains of Decomposed or Decomposing and resisted material

• Water is needed, not available

Why test soils

• To better understand to how to improve crops and yeild for a larger supply of elements needed for soil

Importance of soil pH

• pH effects nutrient values in the soil
• Affects soluble elements and materials
• Phosphate forms insultable and high level conditions for the plants

Plant

• Plants have a large degree for all pH and mineral • NH4+, NO3, PO43-, K, Na, Fe, Mn, Cu, Zn, Ca, Mg • Chemical testing for non-metals (eg spectrophotometric) • ICP or AA for the metals

Food Safety Regulations (SFCR)

• To meet human consuption as set by the Canadian regulations and safety comitte

Parts of the SFCR

• Parts of the SFCR must meet interpretation with tracebility, including a preventrive control plan (PCP), hazard identification, diagrams

Standard for food product

• Need to be approved and allowed for food production

CPC process flow diagram

• Requires material diagram for breakfest cerals Traffic flow and contamination need diagrams to protect, maintain process in order to meet government standard

PCPs and Hazard Identification and Evaluation

• Require steps with ingredients and control the health standard and chemical and the overall process

Traceability

Each product needs to be traceable after product Product needs and regulations and needs to be maintained by the user

Part 11: Traceability

• Identify the name for regulations and the overall business to to protect food quality
• There needs to be a standards identity

Claims and Statements

• Allergens should be included
• Method of production are required

Food

• Specific labeling and requirements
• Ingredients, and food type require certain labelling, like Honey, and infant food

HACCP and HARPC.

• Hazard Analysis and Critical Control Points (HACCP) and Hazard Analysis and Risk-based Preventive Controls (HARPC) are systematic approaches in food safety.

Hazard Analysis

• Any biological,chemical or physcial property that provides to be a threat to a consumer
• Risk is based on probability, severity, and occurrecne

Sensory Analysis of Food

• Taste: Primary taste including of sweet, spicy, and bitter odors, aromas and aromatics , olfactory perception and nerve
• Add vibrancy
• Chemical feeling and the texture factor, which are all reported through balloo and forms