Lesson 2 Flashcards
Dispersed phase
The substance dispersed within another
Continuous phase
The continuous substance around the dispersed phase
Solid in liquid
Sol (starches)
Liquid in solid
Gel (Jams, jellies)
Gas in liquid
Foams (whipped egg whites)
Gas in solid
Solid foam (ice cream)
Liquid in liquid (2 immiscible liquids)
Emulsion (mayonnaise)
Liquid in solid
Solid emulsion (butter)
How many calories in carbohydrates
4 cal/g
What are the monosaccharides?
Glucose, fructose, galactose
What are the disaccharides?
Sucrose (glucose and fructose), lactose (glucose and galactose), maltose (glucose and glucose)
How is honey made?
Nectar contains sucrose which is broken into its components (fructose and glucose 60:40) by invertase in the bees saliva. Some glucose is made into gluconic acid and hydrogen peroxide by glucose oxidase, which act as preservative to the nectar.
What enzyme do lactose intolerant people not have?
Lactase - breaks lactose down
How is lactic acid made?
Lactose is fermented by lactic acid producing bacteria, which is a preservative agent in yogurt and some cheeses
How do you get maltose?
Starch is hydrolyzed by amylase
How do you make High fructose Corn syrup?
Hydrolyze maltose by maltase into glucose, which is then isomerased by glucose isomerase
What is the difference between invert sugar and HFCS?
Invert sugar has a 1:1 ration of fructose and glucose and is made by hydrolyzing sucrose with invertase or an acid
Which sugar is not reducing?
Sucrose (no free OH)
Name the non enzymatic browning reactions
caramelization and Maillard browning
What is caramelization?
Sugars are heated at high temperatures
What is Maillard browning?
Reducing sugar react with nitrogenous compounds. Responsible for the browning on toast
What is gelatinization?
Heating up starch granules in water, thee starch granules absorb water, swell and burst
What is retrogradation?
The reverse of gelatinization - yet cannot reform granules. This can be partially reversed by heating
Calories in fats?
9 cal/g
What is an unsaturated fat?
Contain double bonds
What is a saturated fat?
Contains only single bonds
What are the characteristics of animal fats?
Solid at room temperature, saturated, high melting point, fatty acids packed more tightly
What are the characteristics of vegetable oils?
Liquid at room temperature, unsaturated, packed less tightly, lower melting point than animal fats, less stable
What is the difference in trans and cis unsaturated fatty acids?
Trans fatty acids have a higher melting point since its packed more tightly
What are the types of rancidity?
Oxidative and hydrolytic
What is oxidative rancidity?
Cause off flavours and carcinogenic compounds
What happens when monounsaturated FA and polyunsaturated FAs are exposed to heat, light and O2?
hydroperoxides can form
What is hydrolytic rancidity?
Bonds between glycerol and the FAs are cleaved by lipase, forming free FAs, which is odorous
How do you decrease the rate of oxidative rancidity?
Store away from light, O2 and warmth, avoid repeated exposure to high temperatures, add antioxidants, hydrogenation
What is hydrogenation?
Hardening liquid oils by forcing h atoms into double bonds in the trans configuration
What is the problem with trans fats?
although they behave like saturated fats, LDL cholesterol is increased which increases heart disease. Amount of TF must be labelled
What does lecithin do?
Decrease interfacial tension by forming an emulsion
What do stabilizers do?
Increase viscosity of the continuous phase
What are the calories of proteins?
4 cal/g
What causes allergies?
Intolerance to certain proteins, indigestibility
What is free water?
Water in tissue food systems an in dispersion, available to microorganisms, can be bound by salt and sugar
What is bound water?
Not readily available
What does an Aw of 1 mean?
All water is free
What do organic acids do?
Impart flavour and acidity
What is a low acid food?
pH above 4.6
What is an acid food?
pH below 4.6, does not support disease causing microorganism growth
What makes flavour?
Aroma (volatile) and taste (non volatile)
