“I Am What I Eat” I am What I Eat
Why do we need Food? • Energy • Muscle movement • Body temp • Measured in kJ (kilojoules) Eg an apple has 224 kJ of energy (224,000 Joules) • Growth • Material for cell growth • Replacing old cells • Keeping healthy • To keep cells & organs functioning properly
Carbohydrates • Sugars: • Provide fast energy • Eg fruit, honey, lollies • Starch: provide • Provide slow release energy • Eg rice, potatoes • Cellulose • Aka “fibre” • Eg fruit, veges, cereals Note: Excess energy is stored as fat on the body. Food Groups All food contains water • lettuce 93%, peanuts 5% • Protein • Can’t be stored, eat regularly • Material for cell growth / repair • Used in muscle tissue • Fats / Oils (Lipids) • 2.5 times energy of carbs. • Egmarg, butter, fried food • Vitamins & Minerals • Important in cell reactions • In: fruit, beans, nuts, meats
Vitamin C (what’s the big deal?) • An antioxidant • Important in collagen synthesis • Scurvy...onset 1-6months after switching to Vit C free diet • Important in numerous other processes • Generally: enough vits and minerals in most western diets (excess excreted – berocca!, excess toxic?)
Nutritional Panels • List ingredients (largest to smallest) • List allergens (food that cause allergic reactions, eg nuts) • List food additives (chemicals/substances added to food to enhance flavour, taste appearance) • Give serving size so: • You can compare to other foods • You know how big a reasonable portion is • You know how much nutrients a portion gives • Show %RDI or how much of each food type the food contributes to your recommended daily intake Food additive list: http://en.wikipedia.org/wiki/E_number
Double Down Nutritional Panel Questions • How big is one serve / portion? • How much energy from one serve? • How many double downs could you eat before you reach your daily energy of 9000kJ? 4. What percentage of fat? (look at total fat per 100g) 5. How many grams of sodium (salt)? 6. Which food types (fat, carbohydrates, proteins) are high? 7. Are double downs healthy to eat? Why, why not?
Fast Food Diet Task: Build up a poster of a one day diet of fast food that is “healthy” or “balanced” Challenges: • Total energy MUST NOT EXCEED 9270kJ (average daily energy need for a 14 year old male) • MUST contain lipids (fats or oils), vitamins and minerals, protein, carbohydrates (sugar, starch, fibre). • Include a source of CALCIUM & IRON • * less than 70g of fat • ** les than 6g of salt
Food tests http://science.nhmccd.edu/biol/macromol/controls.html http://www.biotopics.co.uk/nutrition/footes.html
Benedict’s Test Simple Sugars • Add a few drops of Benedict’s solution (blue) to solution to be tested (5mL) • Heat carefully • Yellow / green / brick red colour change indicates simple sugars • CLEAN UP!
Iodine Test Starch • Add a few drops of iodine (yellow) to solution to be tested (5mL) • Blue-black colour change indicates starch • CLEAN UP!
Biuret Test Protein • Put solution to be tested in a test tube (5mL) • Add an equal volume of sodium hydroxide (NaOH) • Add 1-2 drops of copper sulfate solution (CuSO4) • Purple colour indicates protein
Filter Paper Test Fat • Rub sample onto filter paper. Label, do the same with water. • Allow to dry • Translucent (semi-see through) marks indicate fat
Put 1mL of ethanol into a test tube. Add a few drops of oil or small piece of crushed up food. Shake, add 1mL of water. Cloudy colour indicates fat or oil Emulsion = Suspension of two liquid ingredients that do not dissolve into each other (eg oil & water) Ethanol Test Lipids
What does Bile do? Do This: • Mix a little oil + vinegar in a test tube. Observe. • Add a small pinch of mustard, mix. Observe. Results Copy title then copy & complete below: • Oil and vinegar d_______ mix 2. The mustard emulsified the oil (this means it spread the o____ through the v_____) 3. Bile e_____ oil and fat in the s____ i_________. This helps d_________ by breaking lipids like f__ and o____ into smaller pieces.
What is a Balanced Diet? • Contains all the food groups: • carbohydrates, lipids (fats & oils), protein, vitamins & minerals • in the right amounts • Has the right amount of energy: • 9,270 kJ or 9.3 MJ (for 14yr old male)