Food Science Exam 1
dextrinization
-occurs during dry-heating of starch -temp rises rapidly and causes chemical degradation of starch -amylose/amylopectin split into shorter molecules called dextrins. -As starch is heated with dry heat, nonenzymatic browning occurs, and a toasted flavor develops .
importance of a control group
. A control group is an essential part of an experiment because it allows you to eliminate and isolate these variables. essential part of many research designs, allowing researchers to minimize the effect of all variables except the independent variable. receiving no intervention, is used as a baseline to compare groups and assess the effect of that intervention.
where is RS found
RS is found in starchy plant foods such as: beans/legumes starchy fruits and vegetables (such as bananas) whole grains some types of cooked then cooled foods (such as potatoes and rice)
free water
Water that can be extracted easily from foods by squeezing or cutting or pressing is known as free water..
beta prime crystals in fats
beta prime: next larger gives fat smoothness, fresh, high quality margarines stable even during storage most desirable crystals promote fine textured baked products
limitations of sugar substitutes
bitter aftertaste cost amount needed to substitute difference in color/flavor browning may be altered may need other ingredients to perform the functions sugar would handle-cannot provide bulk can it be used in both hot and cold(heat stable or not) most not digestible
Lipid Properties determined by
determined by mix of specific fatty acid on the triglycerides(vs sugars starches) short chain fatty acids:softer fat lower MP(solid to liquid) longer chain: more solid, higher MP unsaturate a bond: softens fat, lowers MP
percent sag
determines comparative tenderness of a gel (depth in container-depth on plate/ depth in container) *100=%
colloidal: foam
dispersed phase-gas continuous phase- liquid eg: egg white foam,Whipped cream, whisked egg white heavy cream, egg white, yolk) and gelatin foams
colloidal systems-suspensoid (solid foam
dispersed phase-gas continuous phase- solid eg: congrealed whipped gelatin, Meringue, bread, cake, ice cream
colloidal: sol
dispersed phase-solid continuous phase-liquid ex. Gravy, white sauce, stirred custard, jam jelly before solidify
colloidal: gels
ex. baked custard, jelly , jam (its been set, cooked) dispersed phase-liquid continuous phase-solid
difference b/w food scientist and dietitian
food scientists analyze food and potential food sources using their knowledge of various sciences, while nutritionists work with clients to develop an eating plan that will be most beneficial to their health. Nutrition studies the relationship between foods and its effect on an individual's health. Nutrition considers topics such as obesity, malnutrition, food insecurity and nutritional deficiencies. In comparison Food Science considers chemical, biological, and physical properties of food in relation to manufacturing, processing, and storage of food products.
starch properties
gelatinization (swelling when heat w/water,takes up water) pasting(thickening increases) gelation (cooling) retrogradation (increase order overtime in storage) synerisis (water loss)
Order of starch processes
gelatinization --> gelation --> retrogradation --> syneresis
properties in common of sugar and starch
gelation(gels and sols) agitation syneresis retrogradation pasting gelitinization
margarine-not a useful addition to our food industry
highly processed pseudo-food that has been engineered to look and taste like butter. loaded with artificial ingredients, and is usually made with industrial vegetable oils that have been hydrogenated to make them more solid. This increases their trans fat content significantly. manufacturers are allowed to label their products with "no trans fat" as long as it contains less than 0.5 grams per serving, which is still a significant amount.
chemical properties of sugars
hydrolysis( of sucrose to glucose and fructose) carmellization (melting of sucrose) maillard reaction (nonenzymatic browning=reducing sugars and amino acids) food turns brown sometimes want and sometimes don't want the above
sources of error in fondant lab
if the crystals are too big, the fondant will not be pliable and will lose its shine and smoothness beating it when still hot not beating it continuously not allowing it to boil at a consistent rate/fully touching/disturbing/moving it while it is heating
pasting
increase in thickness/viscosity exudate leaves granule amylose, moves out of granule into water as amylose moves out granule implodes continued heating will thin
difference or discrimination testing
is there a detectable difference b/w products paired comparison: which is more... triangle test: 3 samples 1 is different, 2 are the same pick the different one duo-trio 3 samples 1 sample=reference 1 is identical to reference 1 is different pick the different 1
why is agitation necessary?
it maintains separation and prevents lumps
coarse suspension
largest molecules >1 micron starch in cold water suspended, if stop stirring, starch falls ex Dressings as mustard seeds, Mexican sauces with seeds, cream soups, pasta products, meat in sauces, meat balls, and yogurts with fruits UNCOOKED CORNSTARCH MIXTURE
treatment of cystallization
leave solution undisturbed or get premature crystallization =grainy product beating initiates crystal formation if beat when hot=crystals form=grainy if beat cooled to room temperature=hard to beat but prevents crystal formation=smoother product once beat crystallization is spontaneous must continue beating to keep crystals small 40-50 degrees
affective testing
like, prefer , accept preference;which prefer hedonic: how much do u like it acceptance: would u buy it each asks a different question
objective methods examples
line spread percent sag
line spread test
measurement of flow of a viscous liquid or semi solid food by determining the spread of a measured amount of sample in a specified time at 90 degree intervals on the template of concentric rings
effect of sugars in starch sols and gels
thickness of cooked product:sol stiffness of cooled product: gel softer gel: more translucent sugar competes w starch granule for water-> decreases swelling sugar increases temperature at which starch thickens sugars make granules more resistant to rupture after gelitinization delays pasting
uses of modified starch
to improve resistance to heat, acid, freezing, shear stress improve storage abilities physical or chemical treatments
length of heating in crystallization
too much inversion-too smooth, too soft- no crystals not enough-too gritty
supersaturated solution
true solution containing more solute than theoretically can be dissolved at that temperature, a situation created by cooling a heated saturated solution carefully ex. sugar solution boiled over 100 degrees(fondant)
3 categories of dispersions in food
true solutions colloidal dispersions coarse suspensions
principles of emulsions
viscosity of the continuous phase presence and concentration of emulsifying agent size of droplets ratio of dispersed phase to continuous phase
treatment vs ingredient in starches
weakened gel by: excessive heating and/or agitation-can break up amylose and weaken future gel
bound water
whereas water that cannot be extracted easily is termed as bound water
sugar substitutes
saccharin aspartame/equal sucralose stevia truvia nectresse tagatose monk fruit in the raw erythritol alliatame
advantages of sensory eval
sensory evaluation is used as an essential design tool in engineering food as it is important to processing, shelf stability and sensory perception, including texture and mouth feel, and it can probe the overall structure as well as the interplay between individual colloidal components
sensory evaluation tests
single sample descriptive affective difference testing
true solutions
smallest in particle size <1 millimicron ex. sugar or salt dissolved in water molecules=solute water=solvent
factors affecting crystallization
solubility of solution (ingredients) temperature of solution concentration of sugar(too low-too few crystals too soft/loose. too many or large crystals-gritty) presence of interfering agents agitation cooling treatment vs ingredients
descriptive testing
specific characteristics(sweet tender) describe an attribute how moist is it how chewy is it
physical properties of sugars
taste sweetness hygroscopicity (capacity to absorb water) solubility in water bulk, mouthfeel energy fermentable by microbes prevents microbial growth in high levels crystallizes when evaporate water
3 major categories of food quality
texture appearance flavour
what about the individual sugars help determine their different properties
'OH' position results in difference i sugars properties: sweetness solubility browning crystallization (vs starch %age of amylose/amylopectin)
What are the effects of sugar on gelation? Acid?
-decreases gelatinization and amylose release (softer) -decreases gelatinization by hydrolysis of granules (softer)
Most starches contain
75% amylopectin and 25% amylose
Two types of starch molecules
Amylose - linear (20-30% in Native) Amylopectin - highly branched (70-80%)
Oilfield emulsions are characterized by several properties including:
Appearance and color BS&W Droplet size Bulk and interfacial viscosities
continuous vs dispersed phase
Continuous phase- Network of solids from the amylose and granules; dispersed phase- water)
crystallization related to margarine
Control of crystallization of lipids is important in many food products, including margarine. the aim is to produce the appropriate number and size distribution of crystals in the correct polymorphic form because the crystalline phase plays a large role in such food properties as appearance, texture, spreadability, and flavor release.
difference b/w fiber and RS
Fermentable insoluble fiber — such as resistant starch —produces the same healthy gasses and acids in the large intestine that soluble fiber does. One important difference between the two types of fibers is that soluble fiber tends to slow digestion while insoluble fiber speeds it up.
gelation
Gelation (gel transition) is the formation of a gel from a system with branched polymers. Branched polymers can form links between the chains, which lead to progressively larger polymers.
health benefits of RS
However, RS still plays an important role in our diets even though we don't necessarily absorb it. When RS is fermented in the large intestine, short chain fatty acids (SCFA) such as acetate, butyrate, and propionate, along with gases are produced. SCFAs can be absorbed into the body from the colon or stay put and be used by colonic bacteria for energy. stimulate blood flow to the colon increase nutrient circulation inhibit the growth of pathogenic bacteria help us absorb minerals help prevent us from absorbing toxic/carcinogenic compounds
functions of margarine in baking
In baking, butter, margarine, shortening and oils are commonly used. Their main functions are to shorten or tenderise the product, to trap air during creaming and so aerate the cake during baking to give good volume and texture, to assist with layering in puff pastry, to help prevent curdling by forming an emulsion, and to add flavour. They also provide some nutritive value. It is important to add the correct amount of fat as too much far will make the baked product greasy and unpleasant to eat, while too little fat will leave you with a product that lacks flavour and stales quickly.
Effects of Added Ingredients
Less firm gels, decreased viscosity Acid - Dextrinization Fat - Waterproofs starch granules Sugar - Delays or inhibits starch gelatinization, type of sugar influences the degree of gelatinization, concentration influences gelatinization temperature.
the need for multiple control groups
Multiple controls also allow finer comparisons of the results (calibration, or standardization) if the expected results from the positive controls have different sizes. For example, in the enzyme assay discussed above, a standard curve may be produced by making many different samples with different quantities of the ...The value of another control group depends on the supplementary information that is available about unobserved biases that are suspected to exist. A second control group provides a test of the assumption that conventional adjustments for observed covariates suffice in estimating treatment effects. test combinations of several treatments or to compare differing doses. These arms can be control groups for some comparisons and experimental groups for other comparisons.
resistant starch
Resistant starch is a type of starch that isn't fully broken down and absorbed, but rather turned into short-chain fatty acids by intestinal bacteria. Some starch — known as resistant starch (RS) — isn't fully absorbed in the small intestine. Instead, RS makes its way to the large intestine (colon), where intestinal bacteria ferment it. RS is similar to fiber (see All About Fiber), although nutrition labels rarely take RS into account.
retrogradation
Retrogradation is a reaction that takes place when the amylose and amylopectin chains in cooked, gelatinized starch realign themselves as the cooked starch cools. Cooked, unmodified starch, when cooled for a long enough period, will thicken (or gel) and rearrange itself again to a more crystalline structure; this process is called retrogradation. During cooling, starch molecules gradually aggregate to form a gel. Molecular associations occur: Amylose-Amylose ; Amylose-Amylopectin; ...
gelitinization
Starch gelatinization is a process of breaking down the intermolecular bonds of starch molecules in the presence of water and heat, allowing the hydrogen bonding sites (the hydroxyl hydrogen and oxygen) to engage more water. This irreversibly dissolves the starch granule in water.
synerisis
Syneresis (also spelled 'synæresis' or 'synaeresis'), in chemistry, is the extraction or expulsion of a liquid from a gel, as when serum drains from a contracting clot of blood. Another example of syneresis is the collection of whey on the surface of yogurt.
The emulsion characteristics also change when the liquid is subjected to changes in the following:
Temperature Pressure Degree of agitation
what about starches affect their individual properties
The amount of amylose/amylopectin present in the granule significantly affects the physicochemical and functional properties of starch: changes bx when boil of strength of a gel % age also affects absorption the % ages are manipulated-affect absorption/digestiob
maillard reaction
The reaction that occurs when sugar or starch and a protein are present in food and dry heat is applied, producing a golden brown colour. The reaction that occurs when a sugar and a protein are in the presence of high dry heat producing a characteristic golden colour and roasted, nutty flavor. Examples are toast, caramel and scrambled eggs that are cooked too long.
goals of food industry
Their main objective is to increase profit from the food you consume. how the food industry became very good in product optimization, taking into account every possible variable that can be altered to increase product sales, except one - consumers' health.
need for multiple control grps cont
To help you conclude that no uncontrolled factors significantly influenced your results. To help you determine that your experimental results are validTo help control for factors that aren't being tested but might affect results. To help control for factors that aren't being tested but might affect results.
what is ripening in fondants
To ripen fondant, form it into a ball, cover it with a damp cloth or paper towel, seal it tightly with plastic wrap, and let cool to room temperature.
useful of food industry
When you process foods, you often make them far easier to store and preserve. Some food processing techniques, such as freezing, preserve the nutritional content preserved food is available for much longer time periods than non-preserved foods, making them easier to keep and store without the consumer having to make more frequent purchases. the ability for producers to ensure food safety and remove or prevent dangerous toxins. Processing enables manufacturers to provide a mostly uniform product. As consumers grow increasingly removed from food production, the role of product creation, advertising, and publicity become the primary vehicles for information about food.
effects of acids on starch sols and gels
decreases viscosity of pastes(hot) decreases gel strength (cooled product) acids break starch molecule into smaller units, move more easily, thin pastes more so than sugar rapid heating at end thins product acid means added liquid, may adjust water used (use less)
Agitation
_______ during gelling disrupts hydrogen bonds already formed—and weakens the ensuing gel.
properties lipids contribute to food
aeration crystallization emulsification (many foods) tenderization flavor mouthfeel plasticity(can manipulate) (spreadability) heat transfers (frying)
sugars and starches
body's main energy source and the preferred type of fuel for your brain cells. all carbohydrates have 4 calories per gram. monosaccharide sugars, disaccharide sugars and polysaccharide starches -- have same general molecular formula of a carbon atom, two hydrogen atoms and an oxygen atom. sucrose and starches are carbohydrates formed by two or more sugars bonded together. The sugars in sucrose and starch must be broken down into glucose molecules in the gastrointestinal tract before your intestines can absorb them. they all eventually turn into glucose for energy.
characteristics about triglycerides that determine melting point of a fat
chain length degree of saturation/unsaturation cis or trans bond previous history of fat(if used lower MP) shorter chains :lower MP unsaturated: lower MP trans bond: more like saturated: high MP
what changes occur in a starch that has been dextrinized?
color turns more brown, flavor gets sweeter, and they lose their thickening power
disadvantages of sensory eval
competition, short timelines, changes in strategy, unavailable materials, and changes in the targets and regulations are some of the barriers that the developer may face. consumer vocabulary might make it hard to interpret representative samples of product users is critical limited information, time consuming expensive subjective opinions, consumer bias
modified starches include
corn starch: 2x thickening ability vs flour browned flour: less thickening due to dextrinization of starch due to the heating (shorter chains of starch-shorter-more soluble) corn and tapioca: thicken equally but tapioca wont settle like corn potato and tapioca: clear but stringy pearl tapioca: not stringy
interfering agents in crystallization
corn syrup honey lipid proteins either physically interfere or promote smoother texture acid(cream of tartar) forms invert sugar (mix of sugars(glu,fruc,suc) different shapes more soluble sweeter interferes w sucrose alignment
objective evaluation
measures one particular attribute of a food rather than overall quality of the product. In the case of new product development it is necessary to change the existing product, for that it is necessary to see acceptance of consumer and only objective testing is not sufficient, even it may be reliable. must be appropriate for the food product being tested. it must measure an attribute of the food that has a major effect on quality. results should be correlated with sensory testing of similar product to make sure that the test is a reliable index of quality of the food. used to assess food quality empirical that is they do not measure an absolute property of the food. results are still meaningful, as long as instruments are calibrated with materials that have similar properties to the foods under test. include all types of instrumental analysis including laboratory test to determine chemical decomposition, nutrient composition and bacterial composition. repeatable and are not subject to human variation. If the equipment is properly maintained and is used correctly, it should give reliable results. necessary to identify contaminants in food and to reveal faulty processing methods as well as testing of deterioration and rancidity. routine quality control of foods and food products. involves instrumentation and use of physical and chemical techniques instead of variable human sensory organs to evaluate food quality.
ripening(crystals)
melting and reforming of crystals within mother liquid occurs slowly over time first: softens then: crystals aggregate unless add interfering substances (similar to retrogradation) invertase may be added to prevent crystals (starch retrogradation) food is dynamic
emulsions in food systems
milk is an oil in water emulsion; margarine is a water in oil emulsion; and ice cream is an oil and air in water emulsion with solid ice particles as well. mayonnaise, salad dressings, and sauces Egg yolk contains 2 emulsifiers—lecithin, which promotes oil in water emulsions, and cholesterol, which promotes water in oil emulsions. Egg yolk is the traditional emulsifier for mayonnaise and other culinary sauces ( proteins, gums, and various esters of fatty acids and poly hydroxyl substrates, like lactic acid, sucrose, and polysorbates)
colloidal dispersions
molecule size b/w true solution and coarse suspension sols: solids w/in liquid gels: liquid in solid foams:air in liquid emulsions':mayonnaise: oil in water butter:water in oil(continuous) cream: oil in water (continuous) emulsifier is the third phase
single sample
presenting one sample early in an experiment to determine acceptability and to aid in decision on future development of the product
